Chilling and heat requirement for dormancy breaking and flowering of the plum accessions belonging to the living collection of Morocco

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In this regard, the forcing tests were conducted out on floral buds of all plum cultivars in order to follow the weight of buds in field and under controlled climate conditions. The heat requirements calculation was based on counting the Growing Hours Degree between the endodormancy release date determined by forcing tests and the flowering dates observed in field for each cultivar. Significant differences were revealed in chill and heat requirements between the plum cultivars studied, ranging from 336 to 522 CH, 645 to 1,046 CU, 37.5 to 55.93 CP and 6,618 to 9,673 GDH according to Chilling Hours, Utah, Dynamic and GDH models, respectively. In addition, the results showed great variability between cultivars according to their dormancy levels, ranging from low chill and heat cultivars (INRA-PR38, INRA-PR40 and Santa Rosa) to highest ones (Stanley, Prune d’Ente, Monglobe and Fortune), which generated differences in the dates of endodormancy release and flowering process. Correlations between chill requirements, heat requirements and flowering dates have been established since cultivars with low chill requirements (also low heat requirements) have earlier endodormancy release and flowering dates in comparison to those showed high chill requirements. The results obtained in this investigation constitute a basis to improve knowledge of the plum species cultivated under Moroccan climate conditions and make it possible to determine the most appropriate cultivation areas for these cultivars, given the current and future climate change. Prunus domestica L. Prunus salicina Lindl Chill requirements Heat requirements Endodormancy release flowering Figures Figure 1 Figure 2 Figure 3 Figure 4 Highlights Chill and heat requirements are ranging from 336 to 522 CH, 645 to 1,046 CU, 37.5 to 55.93 CP and 6,618 to 9,673 GDH. The Santa Rosa cultivars, INRA-PR38 and INRA-PR40 could be considered the least sensitive to cold. The Stanley, Prune d'Ente, Monglobe and Fortune cultivars seem to be the most sensitive to cold. Correlations have been revealed between chill requirements, heat requirements and flowering dates. 1. Introduction Stone fruit crops, including plums, particularly European plums ( Prunus domestica L.) and Japanese plums ( Prunus salicina Lindl) are temperate fruits that are grown in different soils (Hamdani et al., 2022 ). This fruit crop is the second most cultivated stone fruit in the world after peaches and nectarines, with total world production reaching 12.2 million tones cultivated on an area of 2.6 million hectares (Fadon et al., 2020). In Morocco, plum is one of the main crops, with a harvested area of more than 16,198 ha and an estimated annual production of about 143,457 tones/year (Hamdani et al., 2021 ). Climate change is a widely accepted reality and its effects on such crop are being felt. Adaptation strategies are being developed and implemented (Hill et al., 1998 ). In Morocco, among the manifestations of these disturbances is the increase in the mean temperature largely highlighted at its effect on the spatial distribution of plant species (Wahid et al., 2007 ; Hamdani et al., 2023 ). Rosaceae are among the arboricultural species that are very affected by these temperature increases, especially in winter. Determining the chill and heat requirements of species/cultivars constitute the first step in any selection or genetic breeding programs for assessing the capacity of adaptation of fruit tree species to climate changes (Ruiz et al., 2007 ). Bud dormancy in fruit trees is a complex trait developed as a tolerance mechanism against low temperatures occurring during winter (Lang et al., 1987 ). It was characterized as much as a normal and reversible physiological state that is characterized by a reduction in metabolic activities and exchanges with the external environment (Hill et al., 1998 ). Dormancy seems to be useful in understanding the changes that can occur in later phenological traits (Dennis, 1994 ). According to Lang et al., ( 1987 ), three distinct phases of dormancy can be distinguished: i) The paradormancy, controlled by agents external to the dormant bud, generally set in at the end of the summer after a very active photosynthetic period, the contribution of the leaves to produce sugars decreases, which is senescence and the fall of the leaves for deciduous species. ii) The endodormancy characterized by the absence of leaves in winter and allows, for deciduous trees, to limit the use of carbon reserves at a time when climatic conditions do not allow the resource to be used for plant growth. During this stage, growth remains impossible even if environmental conditions become favorable again (Barros et al., 2012 ). iii) The ecodormancy characterized by the satisfaction of all chill requirements and the overcome of the endodormancy release and the beginning of the ecodormancy. During this latter, bud growth becomes possible as soon as environmental conditions become favorable after accumulation of heat requirements are met during the spring, resulting in budburst, flowering, foliage, followed by fruit maturation and wood formation. Thus, the cycle starts again (Leida et al., 2012 ). Recently, there has been a lot of interest in investigations related to dormancy and phenological behavior of fruit tree species in the context of current global climate change, in order to assess the impact of temperature variations on the dormancy process and winter chill accumulation in different regions (Rea and Eccel, 2006 ; Maulion et al., 2014 ; Prudencio et al., 2018 ). Therefore, knowledge of chill requirements (CR) occurring the endodormancy release and heat requirements (HR) for tree flowering has been a central theme in horticultural research (Mauliona et al., 2014). The endodormancy release in temperate fruit species is a primary factor determined by these agroclimatic requirements, which are a very important adaptive trait, specific to each cultivar (Campoy et al., 2011 ). Worth mentioning that chill requirements are considered as much as the most discriminating factor to specify the date of bud endodormancy release, affecting directly the flowering process in Prunus species rather than the heat requirements (Sánchez-Pérez et al., 2014). For a proper cycle, the chill and heat requirements of any species must be met. However, this annual process could be negatively affected while also influencing the final production (Luedeling et al., 2012; El Yaacoubi et al., 2019 ). Understanding the chill/heat requirements of a cultivar has several advantages, especially with regard to the control, maintenance and production of trees in order to grow them in areas with a suitable climate (Fennell, 1999 ). Growing species in a climate that does not allow their chill and heat requirements to be met has negative consequences on the vegetative development and fruit yield (Ruiz et al., 2007 ). However, understanding the influence of these agroclimatic requirements on the phenological behavior remains complex, as satisfying the chill and heat requirements and determining the exact date of endodormancy and ecodormancy phases, which requires rigorous approaches. Statistical approaches, namely partial least squares (PLS) regression, have recently made it possible to identify the endodormancy and ecodormancy phases and consequently to quantify the chill and heat requirements of several fruit species, including certain rosaceous species such as apple, almond and cherry trees, as well as olive trees (Luedeling et al., 2013 ; Diez-Palet et al., 2019 ; Pertille et al., 2022 ; El Yaacoubi et al., 2014 , 2019 and 2020 ; Abou-Saaid et al., 2022 ). However, the forcing tests showed many advantages in determining the endodormancy release date in buds. These experiments are the most commonly used with success in rosaceous plants grown in regions characterized by a temperate climate, making it possible to monitor their dormancy kinetics while indicating the depth of dormancy by measuring the average time to reach a budbreak stage, its rate and the speed of budbreak during the test (Dennis, 2003 a). These tests have therefore been used for a comparison between cultivars and regions to study more precisely the transition between dormancy phases in mild winter climates (Malagi et al., 2015 ). On the other hand, the forcing tests can be used to define the date of onset of endodormancy by observing changes in the weight of floral primordia under forced (controlled) and unforced (field) treatments, which has been used successfully on apple and almond (Malagi et al., 2015 ; El Yaacoubi et al., 2016 ) and olive (Abou-Saaid et al., 2022 ). To quantify chill and heat requirements, several models have been developed. Chill requirements are calculated from the initial date of chilling accumulation to the date of endodormancy release using primarily the Chilling Hours (CH) model (Weinberger, 1950 ), followed by further models such as the Utah (CU) (Richardson et al., 1974 ) and the Dynamic (CP) models (Fishman et al., 1987a , b ). Heat requirements are determined from the first day after endodormancy release until the flowering date using GDH model (Richardson et al., 1975 ). In Morocco, studies on chill and heat requirements of plum are scarce. In elsewhere, some have reported a large variability among cultivars, ranging from 118 to 1,323 Chilling Hours (from 118 to 685 CH for Japanese plums which illustrate the lowest chill requirements and from 579 to 1323 CH for European plums with the highest requirements) and from 5,990 to 9,228 GDH (Ruiz et al., 2007 ; Torrecillas et al., 2018). Thus, some Japanese plums were characterized by low chill requirements while European plums were characterized by higher chill requirements (Ruiz et al., 2018 ). Therefore, in the context of climatic changes, it is therefore urgently necessary to select plum cultivars with best agronomic and qualitative performances and which also have potential phenological adaptation traits regarding the current global warming and winter chill decrease highlighted in several regions, traditionally known by this horticultural crop (Campoy et al., 2011 ). The objective of this study was to i) quantify the chill requirements for endodormancy release and the heat requirements for flowering of an ex-situ collection of plum trees grown in Morocco in order to cluster all cultivars (twenty-eight cultivars) according to their chill and heat requirements, ii) highlight the effect of climatic conditions on the modification of plum phenology during the pre- and post-dormancy phases (endodormancy, ecodormancy, flowering) and iii) identify the dormancy phases in response to temperature variation involved in the determination of chill and heat requirements. These logical objectives will allow understanding the plum capacity of adaptation and the favorable climate conditions, in terms of chill and heat availability, to ensure suitable cultivars for future climate conditions. The resulting conclusions will be useful for both researchers in reinforcing new knowledge in their genetic breeding program and for farmers in supporting the varietal distribution in adequation with the different plum growing areas. 2. Materials and methods 2.1 Plant material and site This study was conducted during two cropping seasons, 2020–2021 and 2021–2022. The plant material consisted of twenty-eight plum cultivars (Table 1 ), grafted on the rootstock ‘Myrobolan’, maintained as plant stock on soil in the experimental station of the National Institute of Agricultural Research situated at Ain Taoujdate, Morocco (altitude of 550 m a.s.l. and geographical coordinates 33°55N/5°13'W). These cultivars, including local and foreign genotypes, were assembled in an ex-situ collection following a randomized complete block design (RBC), with ten trees for each cultivar, spaced at 5 x 5 m. Trees were about 25 years old, pruning was done in the same way and fertilization was equivalent for each tree. Pest control was used according to local commercial practices and weeds were fully controlled. Table 1 Local and foreign plum cultivars used in this study. Local cultivars Species Foreign cultivars Species INRA-PR34 Prunus salicina Lindl Friar Prunus salicina Lindl INRA-PR35 Prunus salicina Lindl Fortune Prunus salicina Lindl INRA-PR36 Prunus salicina Lindl Methley Prunus salicina Lindl INRA-PR37 Prunus salicina Lindl Santa Rosa Prunus salicina Lindl INRA-PR38 Prunus salicina Lindl Angelino Prunus salicina Lindl INRA-PR39 Prunus salicina Lindl Black Amber Prunus salicina Lindl INRA-PR40 Prunus salicina Lindl Golden Japan Prunus salicina Lindl INRA-PR41 Prunus salicina Lindl Monglobe Prunus salicina Lindl INRA-PR42 Prunus salicina Lindl Singlobe Prunus salicina Lindl INRA-PR43 Prunus salicina Lindl Stanley Prunus domestica L. INRA-PR44 Prunus salicina Lindl Prune d’Ente Prunus domestica L. INRA-PR45 Prunus salicina Lindl INRA-PR46 Prunus salicina Lindl INRA-PR47 Prunus salicina Lindl INRA-PR48 Prunus salicina Lindl INRA-PR49 Prunus salicina Lindl Timhdit Prunus salicina Lindl The soil texture is sandy-clay by international standards (Jahn et al., 2006 ), slightly calcareous, moderately rich in organic matter, phosphorus and potassium, with a usable water reserve of 1.7 mm cm − 1 . The climate of the region is semi-arid Mediterranean with mild winters and hot and dry summers. The average of the total annual rainfall and temperature during the two years of the experiment were 361 mm and 18°C respectively. 2.2 Climatic and flowering data Daily maximum and minimum temperatures were taken at the official weather station near the experimental site. Average temperatures have been obtained from the high and low temperatures. Daily temperature data were of a high standard controlled to avoid missing data or erroneous readings. Flowering dates were monitored during the two years of the experiment from February 22nd to April 21st in 2021 and from February 23rd to April 19th in 2022, concentrate on the stage of full flowering (when about 50% of the flower heads are opened and the petals are falling). This phenological stage corresponds, to the stage 65 of the BBCH international coding system (Meier, 2001 ). To easier the further statistical analyses, the phenological data were converted into the relevant Julian days, starting on 1st January of every year (Day of the Year: DOY). The flowering observations were assessed on 3 adult trees of each cultivar, the average dates were calculated across the observed trees. 2.3 Determination of the dormancy phases We used the forcing tests described by Tabuenca Abadia (1967) and Fadon et al., (2020) to identify the potential date of the endodormancy release and consequently to determine the endodormancy and the ecodormancy phases. In this regard, the floral bud development was observed directly under the orchard climate conditions as well as under forcing climate conditions in a controlled growing room during 7 days. The date on which dormancy was lifted was determined as being the earliest date on which the weight of the flower buds was measured under artificial forcing conditions was significantly greater than the weight of unforced buds. Based on the dates of breaking dormancy, we determined the two dormancy phases: endodormancy and ecodormancy. We considered the endodormancy phase to extend from the beginning of November up until the release date for endodormancy determined by forcing test; the ecodormancy phase, directly following this period, extended until the observed date of full flowering observed in field (stage 65). Samples of short plum shoots were randomly collected, around trees, from the two experimental fields at weekly intervals and transferred to the laboratory. Two sets of 3 shots were collected from 3 trees on each sampling date: the first, the unforced shoots, was used to take off the flower buds straight away from their base using scalpel, they were then directly weighed before and after dehydration (at ~ 75°C during 48 hours, using oven); the second set (forced buds) was placed in pots containing water in an air-conditioned culture chamber at 23 ± 1°C, using 16/8h of light/dark during 7 consecutive days. Forcing shoots were then used to measure fresh weight and dry weight of buds using precise balance by the same way as for the non-forced samples. Each sampling unit (cultivar × year × sampling date × non-forced/forced buds) comprised weight replicates, three replicates of five buds. In total, we extracted 15 floral buds for each cultivar distributed in three groups from both forced and unforced shoots. Bootstrapping procedure was used to estimate the interval of confidence for each mean weight reading, especially the upper and lower bound for each averaged weight. We considered endodormancy released, when the weight of fresh flowers buds fulfilled two conditions: i) the top of the range for the non-forced bud weight and the lower limit of the range for the forced bud weight remained unchanged overlap and ii) forced buds showed 30–40% greater weights compared to unforced buds. 2.4 Bud water content To assess the water dynamic in floral buds during the endodormancy and the ecodormancy stages, the water content of buds was determined based on the fresh and dry weight measured (FW and DW, respectively) of floral buds, using the previous forcing test. The water content (WC) of floral buds is calculated using the following formula: WC % = [(FW – DW) x 100] x FW − 1 . 2.5 Determination of chill and heat requirements The amounts of chill received by the trees were quantified according to the Chilling Hours (Weinberger, 1950 ), Utah (Richardson et al., 1974 ) and Dynamic (Fishman et al., 1987a , b ) models. In the real world, the initial chill accumulation date begins when the initial minimum positive cold unit value is reached. The chilling requirements of each cultivar were calculated starting in November (initial start of chilling accumulation) up to the endodormancy release date determined using the forcing test. Heat requirements are estimated on the basis of the GDH 4.5 model (Richardson et al., 1975 ), from the first day after the dormancy release to full flowering. 2.6 Statistical analysis SPSS v22 software was used to analyze the data. ANOVA (analysis of variance) was carried out to determine significant distinction for every cultivar among chilling and heat requirements. The Student-Newman and Keuls (SNK) test has been performed to compare the mean values of the traits. Correlation coefficient and significance level have been calculated by correlation of Pearson of average ratios in identifying the relationship among chilling, heat, dormancy and flowering dates. 3. Results and discussion 3.1 Temperature pattern The evolution of daily maximum and minimum temperatures collected from the meteorological station at the experimental site of Ain Taoujdate during the studied years showed different patterns (Fig. 1 a). Focusing on the period from October to April, the period that influences the physiological processes of flower buds of plum, the average daily temperature during the two years of the experiment was 15.36°C and 17.47°C in 2020–2021 and 2021–2022, respectively. Warm temperatures were observed mainly during the last months of the autumn (November) and during spring (Mars) of the year 2020–2021. 2021–2022 was characterized by cold winter (January and February) (about 11.21°C) compared to 2020–2021 (about 12.38°C). 3.2 Chill and heat accumulation Chill and heat accumulations accounted during the two years of experimentation (2020–2021 and 2021–2022) are presented in Fig. 1 (b and c). The chill accumulations between November and March were estimated in Chilling Hours (CH), Chill Units (CU) and Chill Portions (CP) according to Weinberger, Utah and Dynamic models respectively. The chilling accumulation in the experimental field conditions characterized the climate as mild winter. The most effective months for chilling accumulations were December, January and February, with some difference among models. In 2020–2021, the amount of chill accumulated from November to the end of March was 985 CH, 1590 CU and 101 CP and in 2021–2022 the amount of chill accumulated was 935 CH, 1529 CU and 96 CP from November to the end of March. In fact, From November to March and according to Chilling Hours and Utah models, January and February constitute the two months accumulating more chilling units, while January and December highlighted the highest values of chilling using Dynamic model during both studied years (Fig. 1 b, c). However, November was in general, rather weak in terms of chilling accumulation. This weakness is quite normal as the strong accumulations in regions characterized by mild winters do not start until December, which is the case in our studied site. These findings were consistent with previous studies reported by Ruiz et al., ( 2007 ) in Spain, Alburquerque et al., ( 2008 ) in the USA, Campoy et al., ( 2012 ) in South Africa and Guerrero et al., ( 2024 ) in Spain, recording low chilling accumulation during November and high accumulation from December to mid-February. The heat accumulation, estimated in GDH, between February and May during the two years of the experiment 2020–2021 and 2021–2022 were 15,000 and 13,800 GDH, respectively which showed increased heat availability from March. The monthly heat accumulations showed a relatively linear evolution. Previously, the amount of chill and heat accumulated during their experiments showed significant differences depending on the models used and the years 3.3 Determination of the dormancy phases The dynamics of fresh weight in unforced and forced floral buds of the studied plum cultivars showed different patterns (Fig. 2 ). For all cultivar, the dynamics are subdivided into two phases, the first being characterized by slow growth in fresh weight of floral buds, while accelerated in the second phase, showing a clear transition of buds from the endodormancy phase to the ecodormancy one. However, the duration of these dynamics varied considerably from one cultivar to another. In average, early endodormancy release dates (the significant increase of weight in forced buds compared to unforced ones) were recorded for the cultivar group consisting of Santa Rosa, INRA-PR38 and INRA-PR40 (08th February), while late endodormancy dates were observed in the latest cultivar group namely Stanley, Prune d'Ente, Monglobe and Fortune (30th March). These results corroborate with those found by Guerrero et al., ( 2024 ) on plum who reported that the dates of endodormance release occurred between February 18 in early cultivars and March 16 in late ones. El Yaacoubi et al., (2015) and Malagi et al., ( 2015 ) mentioned that the fresh weight of flower buds, both under field and forced conditions, showed differences between cultivars over the years of the experiment. Indeed, all observed dynamics showed a general trend independently of site, cultivar and year. The increase in fresh weight of flower buds after forcing was related to the transition phase from endodormancy to ecodormancy (Sugiura et al., 1995 ). 3.4 Determination of chill and heat requirements Significant differences in chill requirements were observed among the studied cultivars (Table 2 ). The group of cultivars Santa Rosa, INRA-PR38 and INRA-PR40 and could be considered as the lowest chill plum cultivar group (in average 333 CH, 652 CU and 38.05 CP), these cultivars represented the earliest dates of endodormancy release during the two consecutive years. In contrast, the cultivars Stanley, Prune d’Ente, Monglobe and Fortune, seemed to be the highest chill cultivars, with an average of 475.5 CH, 939 CU and 52.78 CP. These high chill cultivars showed the latest dates of endodormancy release. The other cultivars showed intermediate chill requirements. Our results are in agreement with those found by Sherman et al., ( 1992 ) and Chavez et al., (2019), whose showed that plum cultivars grown in the USA accumulated chill requirements 575 (CH) and 275 (CU) on average. Similarly a year before, Ruiz et al., ( 2018 ) and Fadon et al., (2020) reported that some plum cultivars, grown in Spain, accumulated similar amount of chill requirements 383.5 (CH), 660.5 (CU) and 41.45 (CP) on average. The authors reported also that the cultivar Santa Rosa showed the earliest date of endodormancy release (24th January) while Singlobe showed the latest date (12th February). The significant differences between cultivars in chilling accumulation days and the date of endodormancy release could be related to different factors: (i) The clonal plant material grown, its behavior and its chilling accumulation requirements for bud endodormancy release (Yong et al., 2016 ). This variation in chill requirements accumulation could be associated with both the different climatic conditions, including the minimum and maximum temperatures at which cultivars meet their chill requirements, and the annual variations in temperatures present in the study years that result in a remarkable difference between the chill requirements accumulated each year and between the date of dormancy break and the onset of the accumulated chilling hours cannot be accurately determined (Faust et al., 1997 ). ii) The different genotypes showed plasticity in chilling sensitivity. iii) The methodology of the experimental test, in particular the frequency of sample collection, the controlled conditions of the forcing test (Dennis, 2003 b). Furthermore, determining the accumulated chill requirements accurately remains a challenge, as it is difficult to differentiate between paradormancy and endodormancy; this latter is affected by the level of reserves accumulated in the twigs of the tree, which also affect the accumulation of chill requirements (Fan et al., 2010 ). Table 2 Phenological stages and chill/heat requirements of plum cultivars grown in Ain Taoujdate under Moroccan climate conditions during the two years of experimentation according to the Chilling Hours, Utah, Dynamic and GDH models. Cultivar Date of endodormancy release Full Flowering Chill requirements Heat requirements GDH 4.5 Endodormancy duration (days) Ecodormancy duration (days) Chilling Hours (CH) Utah (CU) Dynamic (CP) Santa Rosa Feb. 08th Mar. 03th 331 ab 645 a 37.95 a 6,582 a 99 a 23 abcde INRA-PR38 Feb. 08th Mar. 08th 335 a 648 a 38.16 a 6,618 a 99 a 32 cdef INRA-PR40 Feb. 08th Mar. 17th 335 a 649 a 38.16 a 7,973 cdef 99 a 35 def Timhdit Feb. 12th Mar. 01st 346 ab 680 ab 40.10 ab 6,940 ab 103 a 22 abcde INRA-PR45 Feb. 12th Mar. 13th 346 ab 680 ab 40.10 ab 7,440 bcd 103 a 28 bcdef INRA-PR42 Feb. 12th Mar. 17th 347 ab 682 ab 40.08 ab 6,964 ab 103 a 32 cdef INRA-PR34 Feb. 15th Mar. 13th 357 abc 714 abc 43.80 bcde 7,287 bc 106 ab 25 abcde INRA-PR37 Feb. 15th Mar. 13th 357 abc 714 abc 42.02 abc 7,288 bc 106 ab 25 abcde INRA-PR35 Feb. 19th Mar. 13th 369 abc 749 bcd 44.19 bcdef 7,648 bcd 110 ab 21 abcd INRA-PR43 Feb. 19th Mar. 13th 369 abc 749 bcd 44.19 bcdef 7,648 bcd 108 ab 21 abcd INRA-PR44 Feb. 19th Mar. 13th 369 abc 749 bcd 44.19 bcdef 7,648 bcd 108 ab 25 abcde Methley Feb. 15th Mar. 17th 357 abc 736 bcd 43.19 abcd 7,507 bcd 105 a 28 bcdef INRA-PR47 Feb. 19th Mar. 17th 368 abc 746 bcd 43.82 bcde 7,612 bcd 110 ab 25 abcde INRA-PR36 Feb. 22nd Mar. 17th 379 abc 781 cdef 45.99 cdefg 6,618a 113 abc 21 bcde Angelino Feb. 22nd Mar. 17th 379 abc 781 cdef 45.99 cdefg 7,973 bcde 113 abc 21 abcde INRA-PR41 Mar. 05th Mar. 20th 399 abcd 768 cde 45.21 bcdef 7,833 bcd 120 bc 19 abc INRA-PR39 Mar. 05th Apr. 16th 414 abcd 805 defg 47.30 cdefgh 8,211 efg 124 c 40 f INRA-PR48 Mar. 05th Apr. 12th 414 abcdefg 843 efg 48.14 defgh 8,600 gh 111 ab 36 ef INRA-PR49 Mar. 15th Apr. 01st 445 cdefg 735 bcd 43.20 abcd 7,498 bcd 134 d 15 ab INRA-PR46 Mar. 15th Mar. 29th 446 cde 735 bcd 43.20 abcd 7,498 bcd 149 de 25 abcde Friar Mar. 24th Apr. 05th 473 defg 836 efg 49.23 efgh 8,532 fgh 143 de 11 a Golden Japan Mar. 26th Apr. 16th 484 efg 787 cdef 46.44 cdefg 8,036 def 146 de 19 abc Black Amber Mar. 26th Apr. 16th 484 efg 971 h 52.23 h 9,410 i 145 de 19 abc Singlobe Mar. 30th Apr. 12th 497 fg 1046 i 51.82 h 9,673 i 149 e 11 a Stanley Mar. 30rd Apr. 16th 429 bcdef 844 efg 49.63 fgh 8,613 gh 149 e 15 ab Prune d’Ente Mar. 30rd Apr. 16th 509 fg 858 fg 50.57 gh 8,752 gh 149 e 14 ab Monglobe Mar. 30rd Apr. 16th 509 fg 1034 i 55.93 i 9,547 i 149 e 16 ab Fortune Apr. 03th Apr. 16th 522 g 974 h 51.48 h 8,921 h 153 e 12 a Means indicated by different letters are significantly different (P ≤ 0.05) according to the SNK test. Significant differences in heat requirements were also observed between cultivars (Table 2 ). Thanks to the forcing experiment, the average heat requirement for all cultivars was 8,585 GDH. The cultivar group INRA-PR38, INRA-PR40 and Santa Rosa had the lowest chill and heat requirements (7,277 GDH in average), with the earliest flowering dates during two consecutive years (11th March). Consequently, these cultivars showed the short endodormancy duration (99 days) and the long ecodormancy duration (29 days in average). However, the cultivar group Stanley, Prune d’Ente, Monglobe and Fortune showed the highest values of heat requirement, with an average of 9,080 GDH, with latest flowering dates during the two consecutive years of our study (16 April). These cultivars had the long duration of endodormancy (151 days) and short ecodormancy (14 days). The other groups showed intermediate heat requirements. Our results showed some similarities with previous investigations reported by Ruiz et al., ( 2018 ) and Guerrero et al., ( 2024 ), which have showed that accumulated heat requirements for plum cultivars grown in Spain were 7,609 GDH and 6,934 on average, respectively. Besides, the cultivar Santa Rosa showed the earliest flowering and the cultivar Singlobe showed the latest flowering. The significant differences in heat requirements GDH and flowering dates between plum cultivars could be explained by the significant differences in heat accumulation days between cultivars which are related to the different temperatures and the high coolness of the air fulfilling their chilling requirements. The longer the dormancy is lifted, the higher the number of days needed to fill the GDH for flowering (Ruiz et al., 2018 ). The results were reported a significant variation between cultivars growing under similar climatic conditions in terms of heat requirements for flowering after dormancy lifting. This could be related to differences in the basal temperature required to accumulate these requirements (Campoy et al., 2012 ). According to Ruiz et al., ( 2007 ), the higher heat requirements of cultivars could be due to the fact that these cultivars end their dormancy at a very cold time of the year and, presumably, the accumulation of GDH is less efficient than at later dates with higher temperatures. As well as excessive chill is responsible for 90% of the variation in heat requirements and therefore the cultivars are late flowering and this is a necessary trait to avoid damage generated from late frosts. The date of 15th February is considered the cut-off date for chilling accumulation dedicated to breaking endodormancy dormancy release, and chilling accumulation up to this date appears to be sufficient for the most high chill cultivars to achieve the endodormancy release (Weinberger, 1950 ; Brown, 1957 ; Erez, 1995 ). 3.5 Bud water content The rehydration dynamics and water content levels in unforced and forced plum floral buds during the endodormancy and the ecodormancy phases were investigated in order to assess the water mobility during the two phases in response to temperature variations (Fig. 3 ). The results showed the same pattern of water content evolution in floral bud between years and cultivars, but with different rates. During the two years of the experiment, the endodormancy phase was characterized by a progressive increase of the water content in the floral buds to reach approximatively 50%, especially under forcing conditions. Furthermore, the ecodormancy phase was characterized by a significant increase in water content, to reach 60%. Our results regarding the dynamics of water content in unforced and forced flower buds showed some similarities in the pattern of water with those found by Malagi et al., ( 2015 ) on apple trees grown in France and Brazil. However, these authors showed that the water content of flower buds did not exceed 50–60% during the endodormancy phase, however during the ecodormancy phase the water content was increased up to 77%. These values are somehow higher in comparison to our study conducted on plum. This difference could be explained by the different physiological response between apple and plum in addition to the difference in water and nutrient pathways and the high activity of carbohydrate metabolism leading to flowering, which is expected to be more and more active as the temperature in the field and/or forcing chamber increases as highlighted by Rinne et al., ( 2001 ). This leads to the development of xylem vessels and the recovery of full growth and flowering capacity during the ecodormancy. This could explain the lower rate of xylem development and the low rate of rehydration during cold periods. In this situation, a water content of 77% after forcing could be considered as a threshold that is indicative of the actual establishment of ecodormancy in rosaceous flower buds (Bartolini et al., 2006 ). Indeed, this transition to from the endodormancy to the ecodormancy phase is characterized by the active transport of sorbitol. Moreover, during this phase, a greater volume of water seems to migrate to the buds due to progressive vascular differentiation (Sugiura et al., 1995 ). 3.6 Chill/heat requirements and phenology correlation A bivariate correlation using Pearson's coefficient was used to understand the relationships between all traits measured for all plum cultivars (Table 3 ). Chill requirements were positively correlated with each other as Chill Hours (CH) was correlated with Chill Units (CU) and Chill Portions (CP) with a coefficient of correlation of 0.701 and 0.638, respectively. Similarly, the latter is positively associated with the Chilling Units (CU) with a coefficient of correlation of 0.869. This high correlation between chill requirements has also been reported according to (Campoy et al., 2012 ). Therefore, the Utah and Dynamic models could be used to determine the chilling requirements in the same way (Ruiz et al., 2007 ). The heat requirements are also positively correlated with the chill requirements (CH, CU and CP) with a coefficient of correlation of 0.742, 0.954 and 0.904, respectively. This correlation could be explained by the fact that the higher the chill requirements, the higher the number of days needed to fill heat requirements for flowering and vice versa for early flowering cultivars with low cold and heat levels in mild winter regions and this was the case for our experimental region (North Morocco) (Ruiz et al., 2018 ). However, many previous investigations) carried out on peach and apricot grown in cold winter regions, reported that cultivars with high chill requirements showed lower heat requirements (Okie and Blackburn, 2011 ; Campoy et al., 2012 ). This interplay between chill and heat requirements for bud endodormancy release and flowering is an adaptive survival mechanism that allows high yield cultivars in cold regions to develop in a minimum of time, thereby reducing production costs and increasing the likelihood that the fruiting cycle will be completed in less than one year during the short growing season associated with cold regions (Sparks, 2005 ). Full flowering dates were positively correlated both with chill requirements and endodormancy release dates with a coefficient of correlation of 0.879 and 0.995, respectively. Similarly, based on the full flowering date and chill requirements, the cultivars were grouped into four groups early, medium, late and extra late flowering cultivars (Table 4 and Fig. 4 ), ranging from the group showing low chill requirements and early flowering dates with an average around 16th March to the group of with high chill requirements and very late flowering dates extending to 06th April in average. The other cultivars were classified into two groups, medium and late flowering. This was described by Guerrero et al., ( 2024 ) who mentioned that plum cultivars were classified into three groups according to their chill requirements. The first group being characterized as the lowest in chilling, the second is medium demanding and the last group has the high chilling requirements. The same association was highlighted by Maulion et al., ( 2014 ) on almond, suggesting that under Mediterranean climatic conditions, chill requirements seem to be more important than heat requirements to regulate the flowering date of rosaceous trees due to the late chill satisfaction, mainly in March and April. Nevertheless, the correlation between flowering date and heat requirements of the different cultivars was not significant. Many researchers had reported the same results for almond (Egea et al., 2003 ), apricot (Ruiz et al., 2007 ), and sweet cherry (Alburquerque et al., 2008 ), indicating that flowering date is only slightly influenced by heat requirement and that other factors are more important, notably chill requirements. Our results confirmed this limited relationship between flowering date and heat requirements, implying that other factors are responsible for the variation in flowering date. Similarly, our study did not show a strong correlation between chill requirements and endodormancy release dates, which is in agreement with the data of Campoy et al., ( 2012 ). The duration of endodormancy phase was negatively correlated with ecodormancy phase with a coefficient of correlation of 0.765. This negative correlation is explained by the fact that during the ecodormancy phase i.e. during spring (generally in March), the air temperature starts to increase which allows trees with a very long endodormancy phase to satisfy their heat needs very quickly contrary to trees with low chill requirements which require a rather long ecodormancy phase (Campoy et al., 2012 ). Table 3 Correlations between chill requirements, heat requirements, dates of endodormancy release and flowering dates of the studied plum cultivars. Chilling Hours (CH) Utah (CU) Dynamic (CP) Heat requirements (GDH) Date of endodormancy release Full flowering date Endodormancyduration Ecodormancyduration Chilling Hours (CH) 1 Utah (CU) , 701 ** 1 Dynamic (CP) , 638 ** , 869 ** 1 Heat requirements (GDH) , 742 ** , 954 ** , 904 ** 1 Date of endodormancy release -0,244 0,093 0,312 0,018 1 Full flowering date -0,295 0,063 , 879** -0,014 , 995 ** 1 Endodormancy duration 0,326 0,253 0,324 0,271 0,367 0,115 1 Ecodormancy duration 0,357 0,435 0,546 -0,142 0,437 -0,252 -0,765** 1 **. Correlation is significant at the 0.01 level; *. Correlation is significant at the 0.05 level; significant and potential correlations are shown in bold. Table 4 Classification of DOY ‘day of the year’ full flowering date records for the 28 plum cultivars observed during 2021 and 2022. Cultivars Full flowering date (DOY) Classification INRA-PR38 57 a Early flowering INRA-PR40 57 a Early flowering INRA-PR42 58 a Early flowering INRA-PR45 58.5 a Early flowering Santa Rosa 59 a Early flowering Timhdit 59.5 a Early flowering INRA-PR36 62 ab Medium flowering INRA-PR44 63 ab Medium flowering INRA-PR47 63,5 ab Medium flowering Methley 64 ab Medium flowering Angelino 64 ab Medium flowering INRA-PR41 65.5 ab Medium flowering INRA-PR46 66 ab Medium flowering INRA-PR43 67 ab Medium flowering Golden Japan 69 ab Medium flowering Black Amber 70 ab Medium flowering INRA-PR34 72.5 bc Late flowering INRA-PR35 73.5 bc Late flowering INRA-PR37 74.5 bc Late flowering INRA-PR39 76.5 bc Late flowering INRA-PR49 83 bc Late flowering Friar 86.5 bc Late flowering INRA-PR48 101 c Extra late flowering Singlobe 102 c Extra late flowering Stanley 104 c Extra late flowering Prune d'Ente 106 c Extra late flowering Monglobe 106 c Extra late flowering Fortune 108 c Extra late flowering Means indicated by different letters are significantly different (P ≤ 0.05) according to the SNK test. 4. Conclusion Estimation of the chill and heat requirements of plum cultivars from the INRA ex-situ collection showed a significant difference in agroclimatic requirements between cultivars and years. This work was carried out over a period of two years with a large group of plum cultivars. In the context of the increase of the aridity in our studied area, associated with a decrease in terms of availability of winter chill, the evolution of the varietal profile allowed us to cluster four groups of plum cultivars according to their chill requirements. The most important were those showing chill requirements less than 400 CH, 600 CU and 38 CP (INRA-PR38, INRA-PR40 and Santa Rosa). European (Stanley end Prune d'Ente) and Japanese cultivars types (Fortune and Monglobe) which generally have high chill requirements were recommended for mountain areas. The results showed a strong positive correlation between chill and heat requirements and flowering dates. Therefore, adding to this study detailed data on the phenology and productivity of varieties in contrasting climates will make it possible to deduce the real level of adaptation of varieties to climate change. Thus, the database obtained will be a basis for the selection and genetic breeding programs for the two species. Abbreviations INRA National Institute for Agronomic Research CH Chilling Hours CU Chill units CP Chill portions GDH Degree hours of growth BBCH Biologische Bundesanstalt, Bundessortenamt and Chemical industry Declarations Competing Interests and Funding On behalf of all authors, the corresponding author states that there is no conflict of interest. Author Contribution Conception and design of the study: Jamal Charafi and Adnane El Yaacoubi. The preparation of the material, data collection and analysis has been made by Anas Hamdani and Meryem Erami. The first version of the manuscript has been written by Anas Hamdani and all authors commented on previous versions of the manuscript. The approval of the version of the manuscript for publication has been done by Anas Hamdani, Jamal Charafi, Said Bouda Adnane El Yaacoubi, Meryem Erami, Atman Adiba and Hakim Outghouliast. Data availability The datasets generated and/or analyzed in the course of this study are available from the corresponding author upon reasonable request. Funding The study was carried out with the financial support of the PRIMA program (AdaMedOr project, 2020-2023) funded in Morocco by the Ministry of Higher Education, Scientific Research and Innovation (Ministère de l’Enseignement Supérieur, de la Recherche Scientifique et de l’Innovation), Direction of Scientific Research and Innovation. Acknowledgments The authors thank Younes OGAD and Houssam OUHOUSSA for their help in the field work. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4412987","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":303924502,"identity":"8336c844-9e75-4c13-a9bf-621000868403","order_by":0,"name":"Anas Hamdani","email":"","orcid":"","institution":"National Institute of Agricultural Research, Regional Agricultural Research Center of Meknes","correspondingAuthor":false,"prefix":"","firstName":"Anas","middleName":"","lastName":"Hamdani","suffix":""},{"id":303924503,"identity":"c2b7f1d9-c75f-45b6-9223-38df4971e1b2","order_by":1,"name":"Adnane El 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Charafi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9ElEQVRIiWNgGAWjYBACxgYg8YCBIQHE+ZBQIUGklgSIFsYZCWeI0AIGcC2MbUSoZm4/nfghgcEuj3/24YcND+dZ5Jm3H2Dd8AOfw3pyN0skMCQXS5xLM2xI3CZRLHMmge1mD16/5G4AajmQ2HCGwfwBUEviDIYEths8+LT0v938A6Rl/hn2jw2Jc4Ba+B+w3fyDT8uM3G1gWzac4QE6rAGoRSKB7TZeW2a83WaRYJCcuPEMT2FDwjGQlodtt2XwaDHsz91840OFXeK8M+wbG3/U1AEdlnzs5ht8WhpApAGqzQ14NDAwyOOVHQWjYBSMglEAAgCr5lXMGGvVkwAAAABJRU5ErkJggg==","orcid":"","institution":"National Institute of Agricultural Research, Regional Agricultural Research Center of Meknes","correspondingAuthor":true,"prefix":"","firstName":"Jamal","middleName":"","lastName":"Charafi","suffix":""}],"badges":[],"createdAt":"2024-05-13 11:39:59","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4412987/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4412987/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00704-024-05067-6","type":"published","date":"2024-06-18T15:17:06+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":57082431,"identity":"8909e3a9-fd6a-48fb-ba19-d7fd3202f72f","added_by":"auto","created_at":"2024-05-24 10:53:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":121018,"visible":true,"origin":"","legend":"\u003cp\u003eDaily minimum, maximum and average of monthly mean temperatures (a), chill and heat accumulations recorded using the Chilling Hours, Utah, Dynamic (b) and GDH (c) models from November to April during the two years of experimentation 2020-2021 and 2021-2022 at Ain Taoujdate, Morocco.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4412987/v1/5483a7b56c03b7e34729274a.png"},{"id":57081928,"identity":"1367d50f-b633-4ed1-a6f3-bb4778dd15b4","added_by":"auto","created_at":"2024-05-24 10:45:32","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":122652,"visible":true,"origin":"","legend":"\u003cp\u003eAverage of fresh weights of forced and unforced floral buds of some plum cultivars recorded during two years of experimentation, 2020-2021 and 2021-2022 in Ain Taoujdate, Morocco.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4412987/v1/572a07cde7e4ff52d3eff849.png"},{"id":57081930,"identity":"157e3365-5269-4b65-b6d5-19b184f7a2a3","added_by":"auto","created_at":"2024-05-24 10:45:32","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":112846,"visible":true,"origin":"","legend":"\u003cp\u003eAverage of water content of forced and unforced floral buds of some plum cultivars measured during two years of experimentation, 2020-2021 and 2021-2022 in Ain Taoujdate, Morocco.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4412987/v1/714486837df42a86c3c936c8.png"},{"id":57081927,"identity":"8b435a52-82bd-4de7-8140-90f631a15141","added_by":"auto","created_at":"2024-05-24 10:45:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":36172,"visible":true,"origin":"","legend":"\u003cp\u003eVariation difference in chill requirements (in Chill Portions) between the cultivar groups for each year compared with the average calculated for all cultivars during the two years of experimentation 2020-2021 and 2021-2022 in Ain Taoujdate, Morocco. Plum cultivars have been classified into four significant groups: EF: early, MF: medium, LF: late and ELF: extra late flowering.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4412987/v1/67b2ff5f673357427e22c135.png"},{"id":58823002,"identity":"e86bb4bf-33a6-490e-b54d-5348abcd74b7","added_by":"auto","created_at":"2024-06-21 16:50:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1488352,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4412987/v1/2e52cc67-211b-4d5d-8d2d-8a3e0054200d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Chilling and heat requirement for dormancy breaking and flowering of the plum accessions belonging to the living collection of Morocco","fulltext":[{"header":"Highlights","content":"\u003col\u003e\n \u003cli\u003eChill and heat requirements are ranging from 336 to 522 CH, 645 to 1,046 CU, 37.5 to 55.93 CP and 6,618 to 9,673 GDH.\u003c/li\u003e\n \u003cli\u003eThe Santa Rosa cultivars, INRA-PR38 and INRA-PR40 could be considered the least sensitive to cold.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eThe Stanley, Prune d\u0026apos;Ente, Monglobe and Fortune cultivars seem to be the most sensitive to cold.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCorrelations have been revealed between chill requirements, heat requirements and flowering dates.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"1. Introduction","content":"\u003cp\u003eStone fruit crops, including plums, particularly European plums (\u003cem\u003ePrunus domestica\u003c/em\u003e L.) and Japanese plums (\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl) are temperate fruits that are grown in different soils (Hamdani et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). This fruit crop is the second most cultivated stone fruit in the world after peaches and nectarines, with total world production reaching 12.2\u0026nbsp;million tones cultivated on an area of 2.6\u0026nbsp;million hectares (Fadon et al., 2020). In Morocco, plum is one of the main crops, with a harvested area of more than 16,198 ha and an estimated annual production of about 143,457 tones/year (Hamdani et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Climate change is a widely accepted reality and its effects on such crop are being felt. Adaptation strategies are being developed and implemented (Hill et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). In Morocco, among the manifestations of these disturbances is the increase in the mean temperature largely highlighted at its effect on the spatial distribution of plant species (Wahid et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Hamdani et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Rosaceae are among the arboricultural species that are very affected by these temperature increases, especially in winter. Determining the chill and heat requirements of species/cultivars constitute the first step in any selection or genetic breeding programs for assessing the capacity of adaptation of fruit tree species to climate changes (Ruiz et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBud dormancy in fruit trees is a complex trait developed as a tolerance mechanism against low temperatures occurring during winter (Lang et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1987\u003c/span\u003e). It was characterized as much as a normal and reversible physiological state that is characterized by a reduction in metabolic activities and exchanges with the external environment (Hill et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). Dormancy seems to be useful in understanding the changes that can occur in later phenological traits (Dennis, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1994\u003c/span\u003e). According to Lang et al., (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1987\u003c/span\u003e), three distinct phases of dormancy can be distinguished: i) The paradormancy, controlled by agents external to the dormant bud, generally set in at the end of the summer after a very active photosynthetic period, the contribution of the leaves to produce sugars decreases, which is senescence and the fall of the leaves for deciduous species. ii) The endodormancy characterized by the absence of leaves in winter and allows, for deciduous trees, to limit the use of carbon reserves at a time when climatic conditions do not allow the resource to be used for plant growth. During this stage, growth remains impossible even if environmental conditions become favorable again (Barros et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). iii) The ecodormancy characterized by the satisfaction of all chill requirements and the overcome of the endodormancy release and the beginning of the ecodormancy. During this latter, bud growth becomes possible as soon as environmental conditions become favorable after accumulation of heat requirements are met during the spring, resulting in budburst, flowering, foliage, followed by fruit maturation and wood formation. Thus, the cycle starts again (Leida et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eRecently, there has been a lot of interest in investigations related to dormancy and phenological behavior of fruit tree species in the context of current global climate change, in order to assess the impact of temperature variations on the dormancy process and winter chill accumulation in different regions (Rea and Eccel, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Maulion et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Prudencio et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Therefore, knowledge of chill requirements (CR) occurring the endodormancy release and heat requirements (HR) for tree flowering has been a central theme in horticultural research (Mauliona et al., 2014). The endodormancy release in temperate fruit species is a primary factor determined by these agroclimatic requirements, which are a very important adaptive trait, specific to each cultivar (Campoy et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Worth mentioning that chill requirements are considered as much as the most discriminating factor to specify the date of bud endodormancy release, affecting directly the flowering process in \u003cem\u003ePrunus\u003c/em\u003e species rather than the heat requirements (S\u0026aacute;nchez-P\u0026eacute;rez et al., 2014). For a proper cycle, the chill and heat requirements of any species must be met. However, this annual process could be negatively affected while also influencing the final production (Luedeling et al., 2012; El Yaacoubi et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eUnderstanding the chill/heat requirements of a cultivar has several advantages, especially with regard to the control, maintenance and production of trees in order to grow them in areas with a suitable climate (Fennell, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1999\u003c/span\u003e). Growing species in a climate that does not allow their chill and heat requirements to be met has negative consequences on the vegetative development and fruit yield (Ruiz et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). However, understanding the influence of these agroclimatic requirements on the phenological behavior remains complex, as satisfying the chill and heat requirements and determining the exact date of endodormancy and ecodormancy phases, which requires rigorous approaches. Statistical approaches, namely partial least squares (PLS) regression, have recently made it possible to identify the endodormancy and ecodormancy phases and consequently to quantify the chill and heat requirements of several fruit species, including certain rosaceous species such as apple, almond and cherry trees, as well as olive trees (Luedeling et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Diez-Palet et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Pertille et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; El Yaacoubi et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e and \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Abou-Saaid et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). However, the forcing tests showed many advantages in determining the endodormancy release date in buds. These experiments are the most commonly used with success in rosaceous plants grown in regions characterized by a temperate climate, making it possible to monitor their dormancy kinetics while indicating the depth of dormancy by measuring the average time to reach a budbreak stage, its rate and the speed of budbreak during the test (Dennis, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2003\u003c/span\u003ea). These tests have therefore been used for a comparison between cultivars and regions to study more precisely the transition between dormancy phases in mild winter climates (Malagi et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). On the other hand, the forcing tests can be used to define the date of onset of endodormancy by observing changes in the weight of floral primordia under forced (controlled) and unforced (field) treatments, which has been used successfully on apple and almond (Malagi et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; El Yaacoubi et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) and olive (Abou-Saaid et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). To quantify chill and heat requirements, several models have been developed. Chill requirements are calculated from the initial date of chilling accumulation to the date of endodormancy release using primarily the Chilling Hours (CH) model (Weinberger, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e1950\u003c/span\u003e), followed by further models such as the Utah (CU) (Richardson et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1974\u003c/span\u003e) and the Dynamic (CP) models (Fishman et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1987a\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003eb\u003c/span\u003e). Heat requirements are determined from the first day after endodormancy release until the flowering date using GDH model (Richardson et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e1975\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn Morocco, studies on chill and heat requirements of plum are scarce. In elsewhere, some have reported a large variability among cultivars, ranging from 118 to 1,323 Chilling Hours (from 118 to 685 CH for Japanese plums which illustrate the lowest chill requirements and from 579 to 1323 CH for European plums with the highest requirements) and from 5,990 to 9,228 GDH (Ruiz et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Torrecillas et al., 2018). Thus, some Japanese plums were characterized by low chill requirements while European plums were characterized by higher chill requirements (Ruiz et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Therefore, in the context of climatic changes, it is therefore urgently necessary to select plum cultivars with best agronomic and qualitative performances and which also have potential phenological adaptation traits regarding the current global warming and winter chill decrease highlighted in several regions, traditionally known by this horticultural crop (Campoy et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe objective of this study was to i) quantify the chill requirements for endodormancy release and the heat requirements for flowering of an ex-situ collection of plum trees grown in Morocco in order to cluster all cultivars (twenty-eight cultivars) according to their chill and heat requirements, ii) highlight the effect of climatic conditions on the modification of plum phenology during the pre- and post-dormancy phases (endodormancy, ecodormancy, flowering) and iii) identify the dormancy phases in response to temperature variation involved in the determination of chill and heat requirements. These logical objectives will allow understanding the plum capacity of adaptation and the favorable climate conditions, in terms of chill and heat availability, to ensure suitable cultivars for future climate conditions. The resulting conclusions will be useful for both researchers in reinforcing new knowledge in their genetic breeding program and for farmers in supporting the varietal distribution in adequation with the different plum growing areas.\u003c/p\u003e "},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Plant material and site\u003c/h2\u003e \u003cp\u003eThis study was conducted during two cropping seasons, 2020\u0026ndash;2021 and 2021\u0026ndash;2022. The plant material consisted of twenty-eight plum cultivars (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), grafted on the rootstock \u0026lsquo;Myrobolan\u0026rsquo;, maintained as plant stock on soil in the experimental station of the National Institute of Agricultural Research situated at Ain Taoujdate, Morocco (altitude of 550 m a.s.l. and geographical coordinates 33\u0026deg;55N/5\u0026deg;13'W). These cultivars, including local and foreign genotypes, were assembled in an \u003cem\u003eex-situ\u003c/em\u003e collection following a randomized complete block design (RBC), with ten trees for each cultivar, spaced at 5 x 5 m. Trees were about 25 years old, pruning was done in the same way and fertilization was equivalent for each tree. Pest control was used according to local commercial practices and weeds were fully controlled.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLocal and foreign plum cultivars used in this study.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLocal cultivars\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSpecies\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eForeign cultivars\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSpecies\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFriar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFortune\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMethley\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSanta Rosa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAngelino\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBlack Amber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGolden Japan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMonglobe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSinglobe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStanley\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus domestica\u003c/em\u003e L.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePrune d\u0026rsquo;Ente\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ePrunus domestica\u003c/em\u003e L.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eINRA-PR49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTimhdit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePrunus salicina\u003c/em\u003e Lindl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe soil texture is sandy-clay by international standards (Jahn et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), slightly calcareous, moderately rich in organic matter, phosphorus and potassium, with a usable water reserve of 1.7 mm cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The climate of the region is semi-arid Mediterranean with mild winters and hot and dry summers. The average of the total annual rainfall and temperature during the two years of the experiment were 361 mm and 18\u0026deg;C respectively.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Climatic and flowering data\u003c/h2\u003e \u003cp\u003eDaily maximum and minimum temperatures were taken at the official weather station near the experimental site. Average temperatures have been obtained from the high and low temperatures. Daily temperature data were of a high standard controlled to avoid missing data or erroneous readings. Flowering dates were monitored during the two years of the experiment from February 22nd to April 21st in 2021 and from February 23rd to April 19th in 2022, concentrate on the stage of full flowering (when about 50% of the flower heads are opened and the petals are falling). This phenological stage corresponds, to the stage 65 of the BBCH international coding system (Meier, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). To easier the further statistical analyses, the phenological data were converted into the relevant Julian days, starting on 1st January of every year (Day of the Year: DOY). The flowering observations were assessed on 3 adult trees of each cultivar, the average dates were calculated across the observed trees.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Determination of the dormancy phases\u003c/h2\u003e \u003cp\u003eWe used the forcing tests described by Tabuenca Abadia (1967) and Fadon et al., (2020) to identify the potential date of the endodormancy release and consequently to determine the endodormancy and the ecodormancy phases. In this regard, the floral bud development was observed directly under the orchard climate conditions as well as under forcing climate conditions in a controlled growing room during 7 days. The date on which dormancy was lifted was determined as being the earliest date on which the weight of the flower buds was measured under artificial forcing conditions was significantly greater than the weight of unforced buds. Based on the dates of breaking dormancy, we determined the two dormancy phases: endodormancy and ecodormancy. We considered the endodormancy phase to extend from the beginning of November up until the release date for endodormancy determined by forcing test; the ecodormancy phase, directly following this period, extended until the observed date of full flowering observed in field (stage 65). Samples of short plum shoots were randomly collected, around trees, from the two experimental fields at weekly intervals and transferred to the laboratory. Two sets of 3 shots were collected from 3 trees on each sampling date: the first, the unforced shoots, was used to take off the flower buds straight away from their base using scalpel, they were then directly weighed before and after dehydration (at ~\u0026thinsp;75\u0026deg;C during 48 hours, using oven); the second set (forced buds) was placed in pots containing water in an air-conditioned culture chamber at 23\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u0026deg;C, using 16/8h of light/dark during 7 consecutive days. Forcing shoots were then used to measure fresh weight and dry weight of buds using precise balance by the same way as for the non-forced samples. Each sampling unit (cultivar \u0026times; year \u0026times; sampling date \u0026times; non-forced/forced buds) comprised weight replicates, three replicates of five buds.\u003c/p\u003e \u003cp\u003eIn total, we extracted 15 floral buds for each cultivar distributed in three groups from both forced and unforced shoots. Bootstrapping procedure was used to estimate the interval of confidence for each mean weight reading, especially the upper and lower bound for each averaged weight. We considered endodormancy released, when the weight of fresh flowers buds fulfilled two conditions: i) the top of the range for the non-forced bud weight and the lower limit of the range for the forced bud weight remained unchanged overlap and ii) forced buds showed 30\u0026ndash;40% greater weights compared to unforced buds.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Bud water content\u003c/h2\u003e \u003cp\u003eTo assess the water dynamic in floral buds during the endodormancy and the ecodormancy stages, the water content of buds was determined based on the fresh and dry weight measured (FW and DW, respectively) of floral buds, using the previous forcing test. The water content (WC) of floral buds is calculated using the following formula: WC % = [(FW \u0026ndash; DW) x 100] x FW\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Determination of chill and heat requirements\u003c/h2\u003e \u003cp\u003eThe amounts of chill received by the trees were quantified according to the Chilling Hours (Weinberger, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e1950\u003c/span\u003e), Utah (Richardson et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1974\u003c/span\u003e) and Dynamic (Fishman et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1987a\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003eb\u003c/span\u003e) models. In the real world, the initial chill accumulation date begins when the initial minimum positive cold unit value is reached. The chilling requirements of each cultivar were calculated starting in November (initial start of chilling accumulation) up to the endodormancy release date determined using the forcing test. Heat requirements are estimated on the basis of the GDH\u003csub\u003e4.5\u003c/sub\u003e model (Richardson et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e1975\u003c/span\u003e), from the first day after the dormancy release to full flowering.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Statistical analysis\u003c/h2\u003e \u003cp\u003eSPSS v22 software was used to analyze the data. ANOVA (analysis of variance) was carried out to determine significant distinction for every cultivar among chilling and heat requirements. The Student-Newman and Keuls (SNK) test has been performed to compare the mean values of the traits. Correlation coefficient and significance level have been calculated by correlation of Pearson of average ratios in identifying the relationship among chilling, heat, dormancy and flowering dates.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Temperature pattern\u003c/h2\u003e \u003cp\u003eThe evolution of daily maximum and minimum temperatures collected from the meteorological station at the experimental site of Ain Taoujdate during the studied years showed different patterns (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Focusing on the period from October to April, the period that influences the physiological processes of flower buds of plum, the average daily temperature during the two years of the experiment was 15.36\u0026deg;C and 17.47\u0026deg;C in 2020\u0026ndash;2021 and 2021\u0026ndash;2022, respectively. Warm temperatures were observed mainly during the last months of the autumn (November) and during spring (Mars) of the year 2020\u0026ndash;2021. 2021\u0026ndash;2022 was characterized by cold winter (January and February) (about 11.21\u0026deg;C) compared to 2020\u0026ndash;2021 (about 12.38\u0026deg;C).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Chill and heat accumulation\u003c/h2\u003e \u003cp\u003eChill and heat accumulations accounted during the two years of experimentation (2020\u0026ndash;2021 and 2021\u0026ndash;2022) are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (b and c). The chill accumulations between November and March were estimated in Chilling Hours (CH), Chill Units (CU) and Chill Portions (CP) according to Weinberger, Utah and Dynamic models respectively. The chilling accumulation in the experimental field conditions characterized the climate as mild winter. The most effective months for chilling accumulations were December, January and February, with some difference among models. In 2020\u0026ndash;2021, the amount of chill accumulated from November to the end of March was 985 CH, 1590 CU and 101 CP and in 2021\u0026ndash;2022 the amount of chill accumulated was 935 CH, 1529 CU and 96 CP from November to the end of March. In fact, From November to March and according to Chilling Hours and Utah models, January and February constitute the two months accumulating more chilling units, while January and December highlighted the highest values of chilling using Dynamic model during both studied years (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, c). However, November was in general, rather weak in terms of chilling accumulation. This weakness is quite normal as the strong accumulations in regions characterized by mild winters do not start until December, which is the case in our studied site. These findings were consistent with previous studies reported by Ruiz et al., (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) in Spain, Alburquerque et al., (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) in the USA, Campoy et al., (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) in South Africa and Guerrero et al., (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) in Spain, recording low chilling accumulation during November and high accumulation from December to mid-February. The heat accumulation, estimated in GDH, between February and May during the two years of the experiment 2020\u0026ndash;2021 and 2021\u0026ndash;2022 were 15,000 and 13,800 GDH, respectively which showed increased heat availability from March. The monthly heat accumulations showed a relatively linear evolution. Previously, the amount of chill and heat accumulated during their experiments showed significant differences depending on the models used and the years\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Determination of the dormancy phases\u003c/h2\u003e \u003cp\u003eThe dynamics of fresh weight in unforced and forced floral buds of the studied plum cultivars showed different patterns (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). For all cultivar, the dynamics are subdivided into two phases, the first being characterized by slow growth in fresh weight of floral buds, while accelerated in the second phase, showing a clear transition of buds from the endodormancy phase to the ecodormancy one. However, the duration of these dynamics varied considerably from one cultivar to another. In average, early endodormancy release dates (the significant increase of weight in forced buds compared to unforced ones) were recorded for the cultivar group consisting of Santa Rosa, INRA-PR38 and INRA-PR40 (08th February), while late endodormancy dates were observed in the latest cultivar group namely Stanley, Prune d'Ente, Monglobe and Fortune (30th March). These results corroborate with those found by Guerrero et al., (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) on plum who reported that the dates of endodormance release occurred between February 18 in early cultivars and March 16 in late ones. El Yaacoubi et al., (2015) and Malagi et al., (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) mentioned that the fresh weight of flower buds, both under field and forced conditions, showed differences between cultivars over the years of the experiment. Indeed, all observed dynamics showed a general trend independently of site, cultivar and year. The increase in fresh weight of flower buds after forcing was related to the transition phase from endodormancy to ecodormancy (Sugiura et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1995\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Determination of chill and heat requirements\u003c/h2\u003e \u003cp\u003eSignificant differences in chill requirements were observed among the studied cultivars (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The group of cultivars Santa Rosa, INRA-PR38 and INRA-PR40 and could be considered as the lowest chill plum cultivar group (in average 333 CH, 652 CU and 38.05 CP), these cultivars represented the earliest dates of endodormancy release during the two consecutive years. In contrast, the cultivars Stanley, Prune d\u0026rsquo;Ente, Monglobe and Fortune, seemed to be the highest chill cultivars, with an average of 475.5 CH, 939 CU and 52.78 CP. These high chill cultivars showed the latest dates of endodormancy release. The other cultivars showed intermediate chill requirements. Our results are in agreement with those found by Sherman et al., (\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1992\u003c/span\u003e) and Chavez et al., (2019), whose showed that plum cultivars grown in the USA accumulated chill requirements 575 (CH) and 275 (CU) on average. Similarly a year before, Ruiz et al., (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) and Fadon et al., (2020) reported that some plum cultivars, grown in Spain, accumulated similar amount of chill requirements 383.5 (CH), 660.5 (CU) and 41.45 (CP) on average. The authors reported also that the cultivar Santa Rosa showed the earliest date of endodormancy release (24th January) while Singlobe showed the latest date (12th February). The significant differences between cultivars in chilling accumulation days and the date of endodormancy release could be related to different factors: (i) The clonal plant material grown, its behavior and its chilling accumulation requirements for bud endodormancy release (Yong et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). This variation in chill requirements accumulation could be associated with both the different climatic conditions, including the minimum and maximum temperatures at which cultivars meet their chill requirements, and the annual variations in temperatures present in the study years that result in a remarkable difference between the chill requirements accumulated each year and between the date of dormancy break and the onset of the accumulated chilling hours cannot be accurately determined (Faust et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). ii) The different genotypes showed plasticity in chilling sensitivity. iii) The methodology of the experimental test, in particular the frequency of sample collection, the controlled conditions of the forcing test (Dennis, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2003\u003c/span\u003eb). Furthermore, determining the accumulated chill requirements accurately remains a challenge, as it is difficult to differentiate between paradormancy and endodormancy; this latter is affected by the level of reserves accumulated in the twigs of the tree, which also affect the accumulation of chill requirements (Fan et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePhenological stages and chill/heat requirements of plum cultivars grown in Ain Taoujdate under Moroccan climate conditions during the two years of experimentation according to the Chilling Hours, Utah, Dynamic and GDH models.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCultivar\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eDate of endodormancy\u003c/p\u003e \u003cp\u003erelease\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eFull\u003c/p\u003e \u003cp\u003eFlowering\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e \u003cp\u003eChill requirements\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eHeat\u003c/p\u003e \u003cp\u003erequirements\u003c/p\u003e \u003cp\u003eGDH\u003csub\u003e4.5\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eEndodormancy\u003c/p\u003e \u003cp\u003eduration\u003c/p\u003e \u003cp\u003e(days)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eEcodormancy duration (days)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eChilling Hours (CH)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eUtah (CU)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDynamic\u003c/p\u003e \u003cp\u003e(CP)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSanta Rosa\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 08th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 03th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e331\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e645\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e37.95\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6,582\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e99\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e23\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR38\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 08th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 08th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e335\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e648\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e38.16\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6,618\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e99\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e32\u003csup\u003ecdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR40\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 08th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 17th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e335\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e649\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e38.16\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,973\u003csup\u003ecdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e99\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e35\u003csup\u003edef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTimhdit\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 12th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 01st\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e346\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e680\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e40.10\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6,940\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e103\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e22\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR45\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 12th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 13th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e346\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e680\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e40.10\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,440\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e103\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e28\u003csup\u003ebcdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR42\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 12th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 17th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e347\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e682\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e40.08\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6,964\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e103\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e32\u003csup\u003ecdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR34\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 15th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 13th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e357\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e714\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e43.80\u003csup\u003ebcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,287\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e106\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e25\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR37\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 15th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 13th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e357 \u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e714\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e42.02\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,288\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e106\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e25\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR35\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 19th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 13th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e369\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e749\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e44.19\u003csup\u003ebcdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,648\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e110\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e21\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR43\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 19th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 13th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e369\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e749\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e44.19\u003csup\u003ebcdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,648\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e108\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e21\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR44\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 19th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 13th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e369\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e749\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e44.19\u003csup\u003ebcdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,648\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e108\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e25\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMethley\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 15th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 17th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e357\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e736\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e43.19\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,507\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e105\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e28\u003csup\u003ebcdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR47\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 19th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 17th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e368\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e746\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e43.82\u003csup\u003ebcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,612\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e110\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e25\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR36\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 22nd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 17th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e379\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e781\u003csup\u003ecdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e45.99\u003csup\u003ecdefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6,618a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e113\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e21\u003csup\u003ebcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAngelino\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeb. 22nd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 17th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e379\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e781\u003csup\u003ecdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e45.99\u003csup\u003ecdefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,973\u003csup\u003ebcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e113\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e21\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR41\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 05th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 20th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e399\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e768\u003csup\u003ecde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e45.21\u003csup\u003ebcdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,833\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e120\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e19\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR39\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 05th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 16th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e414\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e805\u003csup\u003edefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e47.30\u003csup\u003ecdefgh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8,211\u003csup\u003eefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e124\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e40\u003csup\u003ef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR48\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 05th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 12th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e414\u003csup\u003eabcdefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e843\u003csup\u003eefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e48.14\u003csup\u003edefgh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8,600\u003csup\u003egh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e111\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e36\u003csup\u003eef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR49\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 15th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 01st\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e445\u003csup\u003ecdefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e735\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e43.20\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,498\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e134\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR46\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 15th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMar. 29th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e446\u003csup\u003ecde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e735\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e43.20\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e7,498\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e149\u003csup\u003ede\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e25\u003csup\u003eabcde\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFriar\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 24th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 05th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e473\u003csup\u003edefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e836\u003csup\u003eefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e49.23\u003csup\u003eefgh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8,532\u003csup\u003efgh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e143\u003csup\u003ede\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e11\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGolden Japan\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 26th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 16th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e484\u003csup\u003eefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e787\u003csup\u003ecdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e46.44\u003csup\u003ecdefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8,036\u003csup\u003edef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e146\u003csup\u003ede\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e19\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBlack Amber\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 26th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 16th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e484\u003csup\u003eefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e971\u003csup\u003eh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e52.23\u003csup\u003eh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9,410\u003csup\u003ei\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e145\u003csup\u003ede\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e19\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSinglobe\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 30th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 12th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e497\u003csup\u003efg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1046\u003csup\u003ei\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e51.82\u003csup\u003eh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9,673\u003csup\u003ei\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e149\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e11\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eStanley\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 30rd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 16th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e429\u003csup\u003ebcdef\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e844\u003csup\u003eefg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e49.63\u003csup\u003efgh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8,613\u003csup\u003egh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e149\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrune d\u0026rsquo;Ente\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 30rd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 16th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e509\u003csup\u003efg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e858\u003csup\u003efg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e50.57\u003csup\u003egh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8,752\u003csup\u003egh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e149\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e14\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMonglobe\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMar. 30rd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 16th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e509\u003csup\u003efg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1034\u003csup\u003ei\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e55.93\u003csup\u003ei\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9,547\u003csup\u003ei\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e149\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e16\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFortune\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eApr. 03th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eApr. 16th\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e522\u003csup\u003eg\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e974\u003csup\u003eh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e51.48\u003csup\u003eh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8,921\u003csup\u003eh\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e153\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e12\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003eMeans indicated by different letters are significantly different (P\u0026thinsp;\u0026le;\u0026thinsp;0.05) according to the SNK test.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSignificant differences in heat requirements were also observed between cultivars (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Thanks to the forcing experiment, the average heat requirement for all cultivars was 8,585 GDH. The cultivar group INRA-PR38, INRA-PR40 and Santa Rosa had the lowest chill and heat requirements (7,277 GDH in average), with the earliest flowering dates during two consecutive years (11th March). Consequently, these cultivars showed the short endodormancy duration (99 days) and the long ecodormancy duration (29 days in average). However, the cultivar group Stanley, Prune d\u0026rsquo;Ente, Monglobe and Fortune showed the highest values of heat requirement, with an average of 9,080 GDH, with latest flowering dates during the two consecutive years of our study (16 April). These cultivars had the long duration of endodormancy (151 days) and short ecodormancy (14 days). The other groups showed intermediate heat requirements. Our results showed some similarities with previous investigations reported by Ruiz et al., (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) and Guerrero et al., (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e), which have showed that accumulated heat requirements for plum cultivars grown in Spain were 7,609 GDH and 6,934 on average, respectively. Besides, the cultivar Santa Rosa showed the earliest flowering and the cultivar Singlobe showed the latest flowering. The significant differences in heat requirements GDH and flowering dates between plum cultivars could be explained by the significant differences in heat accumulation days between cultivars which are related to the different temperatures and the high coolness of the air fulfilling their chilling requirements. The longer the dormancy is lifted, the higher the number of days needed to fill the GDH for flowering (Ruiz et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The results were reported a significant variation between cultivars growing under similar climatic conditions in terms of heat requirements for flowering after dormancy lifting. This could be related to differences in the basal temperature required to accumulate these requirements (Campoy et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). According to Ruiz et al., (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), the higher heat requirements of cultivars could be due to the fact that these cultivars end their dormancy at a very cold time of the year and, presumably, the accumulation of GDH is less efficient than at later dates with higher temperatures. As well as excessive chill is responsible for 90% of the variation in heat requirements and therefore the cultivars are late flowering and this is a necessary trait to avoid damage generated from late frosts.\u003c/p\u003e \u003cp\u003eThe date of 15th February is considered the cut-off date for chilling accumulation dedicated to breaking endodormancy dormancy release, and chilling accumulation up to this date appears to be sufficient for the most high chill cultivars to achieve the endodormancy release (Weinberger, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e1950\u003c/span\u003e; Brown, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e1957\u003c/span\u003e; Erez, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1995\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Bud water content\u003c/h2\u003e \u003cp\u003eThe rehydration dynamics and water content levels in unforced and forced plum floral buds during the endodormancy and the ecodormancy phases were investigated in order to assess the water mobility during the two phases in response to temperature variations (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The results showed the same pattern of water content evolution in floral bud between years and cultivars, but with different rates. During the two years of the experiment, the endodormancy phase was characterized by a progressive increase of the water content in the floral buds to reach approximatively 50%, especially under forcing conditions. Furthermore, the ecodormancy phase was characterized by a significant increase in water content, to reach 60%. Our results regarding the dynamics of water content in unforced and forced flower buds showed some similarities in the pattern of water with those found by Malagi et al., (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) on apple trees grown in France and Brazil. However, these authors showed that the water content of flower buds did not exceed 50\u0026ndash;60% during the endodormancy phase, however during the ecodormancy phase the water content was increased up to 77%. These values are somehow higher in comparison to our study conducted on plum. This difference could be explained by the different physiological response between apple and plum in addition to the difference in water and nutrient pathways and the high activity of carbohydrate metabolism leading to flowering, which is expected to be more and more active as the temperature in the field and/or forcing chamber increases as highlighted by Rinne et al., (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). This leads to the development of xylem vessels and the recovery of full growth and flowering capacity during the ecodormancy. This could explain the lower rate of xylem development and the low rate of rehydration during cold periods. In this situation, a water content of 77% after forcing could be considered as a threshold that is indicative of the actual establishment of ecodormancy in rosaceous flower buds (Bartolini et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Indeed, this transition to from the endodormancy to the ecodormancy phase is characterized by the active transport of sorbitol. Moreover, during this phase, a greater volume of water seems to migrate to the buds due to progressive vascular differentiation (Sugiura et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1995\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Chill/heat requirements and phenology correlation\u003c/h2\u003e \u003cp\u003eA bivariate correlation using Pearson's coefficient was used to understand the relationships between all traits measured for all plum cultivars (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Chill requirements were positively correlated with each other as Chill Hours (CH) was correlated with Chill Units (CU) and Chill Portions (CP) with a coefficient of correlation of 0.701 and 0.638, respectively. Similarly, the latter is positively associated with the Chilling Units (CU) with a coefficient of correlation of 0.869. This high correlation between chill requirements has also been reported according to (Campoy et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Therefore, the Utah and Dynamic models could be used to determine the chilling requirements in the same way (Ruiz et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). The heat requirements are also positively correlated with the chill requirements (CH, CU and CP) with a coefficient of correlation of 0.742, 0.954 and 0.904, respectively. This correlation could be explained by the fact that the higher the chill requirements, the higher the number of days needed to fill heat requirements for flowering and vice versa for early flowering cultivars with low cold and heat levels in mild winter regions and this was the case for our experimental region (North Morocco) (Ruiz et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). However, many previous investigations) carried out on peach and apricot grown in cold winter regions, reported that cultivars with high chill requirements showed lower heat requirements (Okie and Blackburn, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Campoy et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). This interplay between chill and heat requirements for bud endodormancy release and flowering is an adaptive survival mechanism that allows high yield cultivars in cold regions to develop in a minimum of time, thereby reducing production costs and increasing the likelihood that the fruiting cycle will be completed in less than one year during the short growing season associated with cold regions (Sparks, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). Full flowering dates were positively correlated both with chill requirements and endodormancy release dates with a coefficient of correlation of 0.879 and 0.995, respectively. Similarly, based on the full flowering date and chill requirements, the cultivars were grouped into four groups early, medium, late and extra late flowering cultivars (Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), ranging from the group showing low chill requirements and early flowering dates with an average around 16th March to the group of with high chill requirements and very late flowering dates extending to 06th April in average. The other cultivars were classified into two groups, medium and late flowering. This was described by Guerrero et al., (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) who mentioned that plum cultivars were classified into three groups according to their chill requirements. The first group being characterized as the lowest in chilling, the second is medium demanding and the last group has the high chilling requirements. The same association was highlighted by Maulion et al., (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) on almond, suggesting that under Mediterranean climatic conditions, chill requirements seem to be more important than heat requirements to regulate the flowering date of rosaceous trees due to the late chill satisfaction, mainly in March and April. Nevertheless, the correlation between flowering date and heat requirements of the different cultivars was not significant. Many researchers had reported the same results for almond (Egea et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2003\u003c/span\u003e), apricot (Ruiz et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), and sweet cherry (Alburquerque et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), indicating that flowering date is only slightly influenced by heat requirement and that other factors are more important, notably chill requirements. Our results confirmed this limited relationship between flowering date and heat requirements, implying that other factors are responsible for the variation in flowering date. Similarly, our study did not show a strong correlation between chill requirements and endodormancy release dates, which is in agreement with the data of Campoy et al., (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The duration of endodormancy phase was negatively correlated with ecodormancy phase with a coefficient of correlation of 0.765. This negative correlation is explained by the fact that during the ecodormancy phase i.e. during spring (generally in March), the air temperature starts to increase which allows trees with a very long endodormancy phase to satisfy their heat needs very quickly contrary to trees with low chill requirements which require a rather long ecodormancy phase (Campoy et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorrelations between chill requirements, heat requirements, dates of endodormancy release and flowering dates of the studied plum cultivars.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eChilling Hours (CH)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUtah\u003c/p\u003e \u003cp\u003e(CU)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDynamic (CP)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHeat requirements (GDH)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDate of endodormancy release\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFull flowering date\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eEndodormancyduration\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eEcodormancyduration\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eChilling Hours (CH)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eUtah (CU)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e,\u003cb\u003e701\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDynamic (CP)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e,\u003cb\u003e638\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e,\u003cb\u003e869\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHeat requirements (GDH)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e,\u003cb\u003e742\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e,\u003cb\u003e954\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e,\u003cb\u003e904\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDate of endodormancy release\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0,244\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0,093\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,312\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0,018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFull flowering date\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0,295\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0,063\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e,\u003cb\u003e879**\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0,014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e,\u003cb\u003e995\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eEndodormancy\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eduration\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0,326\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0,253\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,324\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0,271\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0,367\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0,115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eEcodormancy\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eduration\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0,357\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0,435\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,546\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0,142\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0,437\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-0,252\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e-0,765**\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e**. Correlation is significant at the 0.01 level; *. Correlation is significant at the 0.05 level; significant and potential correlations are shown in bold.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClassification of DOY \u0026lsquo;day of the year\u0026rsquo; full flowering date records for the 28 plum cultivars observed during 2021 and 2022.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCultivars\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFull flowering date (DOY)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eClassification\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR38\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEarly flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR40\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEarly flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR42\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEarly flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR45\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58.5\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEarly flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSanta Rosa\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEarly flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTimhdit\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.5\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEarly flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR36\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR44\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR47\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63,5\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMethley\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAngelino\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR41\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65.5\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR46\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR43\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGolden Japan\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBlack Amber\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedium flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR34\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e72.5\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLate flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR35\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e73.5\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLate flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR37\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74.5\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLate flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR39\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e76.5\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLate flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR49\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLate flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFriar\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e86.5\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLate flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eINRA-PR48\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e101\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtra late flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSinglobe\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e102\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtra late flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eStanley\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e104\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtra late flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrune d'Ente\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e106\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtra late flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMonglobe\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e106\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtra late flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFortune\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e108\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtra late flowering\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eMeans indicated by different letters are significantly different (P\u0026thinsp;\u0026le;\u0026thinsp;0.05) according to the SNK test.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eEstimation of the chill and heat requirements of plum cultivars from the INRA ex-situ collection showed a significant difference in agroclimatic requirements between cultivars and years. This work was carried out over a period of two years with a large group of plum cultivars. In the context of the increase of the aridity in our studied area, associated with a decrease in terms of availability of winter chill, the evolution of the varietal profile allowed us to cluster four groups of plum cultivars according to their chill requirements. The most important were those showing chill requirements less than 400 CH, 600 CU and 38 CP (INRA-PR38, INRA-PR40 and Santa Rosa). European (Stanley end Prune d'Ente) and Japanese cultivars types (Fortune and Monglobe) which generally have high chill requirements were recommended for mountain areas. The results showed a strong positive correlation between chill and heat requirements and flowering dates. Therefore, adding to this study detailed data on the phenology and productivity of varieties in contrasting climates will make it possible to deduce the real level of adaptation of varieties to climate change. Thus, the database obtained will be a basis for the selection and genetic breeding programs for the two species.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eINRA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNational Institute for Agronomic Research\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eChilling Hours\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCU\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eChill units\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eChill portions\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eGDH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDegree hours of growth\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBBCH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBiologische Bundesanstalt, Bundessortenamt and Chemical industry\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompeting Interests and Funding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOn behalf of all authors, the corresponding author states that there is no conflict of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConception and design of the study: Jamal Charafi and Adnane El Yaacoubi. The preparation of the material, data collection and analysis has been made by Anas Hamdani and\u0026nbsp;Meryem\u003csup\u003e\u0026nbsp;\u003c/sup\u003eErami. The first version of the manuscript has been written by Anas Hamdani and all authors commented on previous versions of the manuscript. The approval of the version of the manuscript for publication has been done by Anas Hamdani, Jamal Charafi, Said Bouda Adnane El Yaacoubi,\u0026nbsp;Meryem\u003csup\u003e\u0026nbsp;\u003c/sup\u003eErami, Atman Adiba and Hakim Outghouliast.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed in the course of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was carried out with the financial support of the PRIMA program (AdaMedOr project, 2020-2023) funded in Morocco by the Ministry of Higher Education, Scientific Research and Innovation (Minist\u0026egrave;re de l\u0026rsquo;Enseignement Sup\u0026eacute;rieur, de la Recherche Scientifique et de l\u0026rsquo;Innovation), Direction of Scientific Research and Innovation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank Younes OGAD and Houssam OUHOUSSA for their help in the field work.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbou-Saaid, O.; El Yaacoubi, A.; Moukhli, A.; El Bakkali, A.; Oulbi, S.; Delalande, M.; Farrera, I.; Kelner, J.-J.; Lochon-Menseau, S.; El Modafar, C.; et al. Statistical Approach to Assess Chill and Heat Requirements of Olive Tree Based on Flowering Date and Temperatures Data: Towards Selection of Adapted Cultivars to GlobalWarming. Agronomy 2022, 12, 2975. https:// doi.org/10.3390/agronomy12122975.\u003c/li\u003e\n\u003cli\u003eAlburquerque, N., Garcia-Montiel, F., Carrillo, A., Burgos, L., 2008. Chilling and heat requirements of sweet cherry cultivars and the relationship between altitude and the probability of satisfying the chill requirements. Environ. Exp. Bot. 64, 162\u0026ndash;170.\u003c/li\u003e\n\u003cli\u003eBarros, P.M., Goncalves, N., Saibo, N.J.M., Oliveira, M.M., 2012. Cold acclimation andfloral development in almond bud break: insights into the regulatory pathways.J. Exp. Bot. 63, 4585\u0026ndash;4596, http://dx.doi.org/10.1093/jxb/err144.\u003c/li\u003e\n\u003cli\u003eBartolini S, Viti R, Laghezali M, Olmez HA (2006) Xylem vessel differentiation and microsporogenesis evolution in \u0026lsquo;Canino\u0026rsquo; cultivar growing in three different climatic areas: Italy, Morocco and Turkey. Acta Hortic 701:135\u0026ndash;140.\u003c/li\u003e\n\u003cli\u003eBrown, D.S., 1957. The rest period of apricot flower buds as described by a regression of time of bloom on temperature. Plant Physiol. 32, 75\u0026ndash;85.\u003c/li\u003e\n\u003cli\u003eChavez, D.; Florkowska, M.; Chen, C.; Cook, J. Home Garden Plums. University of Georgia Extension Bulletin 1518.2019. Available online secure.caes.uga.edu/extension/publications/files/pdf/B%201518_2.PDF (accessed on 12 October 2020).\u003c/li\u003e\n\u003cli\u003eCampoy, J., Ruiz, D., Allderman, L., Cook, N., Egea, J., 2012. 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Japanese plums behavior under water stress: impact on yield and biochemical traits. Heliyon, 8(4).\u003c/li\u003e\n\u003cli\u003eHamdani, A., Bouda, S., Hssaini, L., Adiba, A., Kouighat, M., \u0026amp; Razouk, R. (2023). The effect of heat stress on yield, growth, physiology and fruit quality in Japanese plum \u0026lsquo;Angelino\u0026rsquo;. Vegetos, 1-10.\u003c/li\u003e\n\u003cli\u003eHill, J., Becker, H.C., Tigerstedt, P.M.A., 1998. Quantitative and Ecological Aspects of Plant Breeding. St. Edmundsbury Press, Suffolk, United Kingdom.\u003c/li\u003e\n\u003cli\u003eGuerrero BI, Fado\u0026acute;n E, Guerra ME and Rodrigo J (2024) Perspectives on the adaptation of Japanese plum-type cultivars to reduced winter chilling in two regions of Spain. Front. Plant Sci. 15:1343593. doi: 10.3389/fpls.2024.1343593.\u003c/li\u003e\n\u003cli\u003eLang, B.A., Early, J.D., Martin, G.C., Darnell, R.L., 1987. 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Chilling requirements of peach varieties. Proc. Am. Soc. Hortic. Sci. 56, 122\u0026ndash;128.\u003c/li\u003e\n\u003cli\u003eYong, L. I., FANG, W. C., ZHU, G. R., Ke, C. A. O., CHEN, C. W., WANG, X. W., \u0026amp; WANG, L. R. (2016). Accumulated chilling hours during endodormancy impact blooming and fruit shape development in peach (Prunus persica L.). Journal of Integrative Agriculture, 15(6), 1267-1274.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"theoretical-and-applied-climatology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"taac","sideBox":"Learn more about [Theoretical and Applied Climatology](https://www.springer.com/journal/704)","snPcode":"704","submissionUrl":"https://submission.nature.com/new-submission/704/3","title":"Theoretical and Applied Climatology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Prunus domestica L., Prunus salicina Lindl, Chill requirements, Heat requirements, Endodormancy release, flowering","lastPublishedDoi":"10.21203/rs.3.rs-4412987/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4412987/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe date of endodormancy release and chill requirements of twenty-eight plum cultivars (\u003cem\u003ePrunus domestica\u003c/em\u003e L. and \u003cem\u003ePrunus salicina\u003c/em\u003e Lindl) growing in a collection at the experimental station of the National Institute of Agricultural Research of Meknes (Morocco) were determined according to three models namely the Chilling Hours model (in Chilling Hours, CH), the Utah model (in Chill Units, CU) and the Dynamic model (in Chill Portions, CP). In this regard, the forcing tests were conducted out on floral buds of all plum cultivars in order to follow the weight of buds in field and under controlled climate conditions. The heat requirements calculation was based on counting the Growing Hours Degree between the endodormancy release date determined by forcing tests and the flowering dates observed in field for each cultivar. Significant differences were revealed in chill and heat requirements between the plum cultivars studied, ranging from 336 to 522 CH, 645 to 1,046 CU, 37.5 to 55.93 CP and 6,618 to 9,673 GDH according to Chilling Hours, Utah, Dynamic and GDH models, respectively. In addition, the results showed great variability between cultivars according to their dormancy levels, ranging from low chill and heat cultivars (INRA-PR38, INRA-PR40 and Santa Rosa) to highest ones (Stanley, Prune d’Ente, Monglobe and Fortune), which generated differences in the dates of endodormancy release and flowering process. Correlations between chill requirements, heat requirements and flowering dates have been established since cultivars with low chill requirements (also low heat requirements) have earlier endodormancy release and flowering dates in comparison to those showed high chill requirements. The results obtained in this investigation constitute a basis to improve knowledge of the plum species cultivated under Moroccan climate conditions and make it possible to determine the most appropriate cultivation areas for these cultivars, given the current and future climate change.\u003c/p\u003e","manuscriptTitle":"Chilling and heat requirement for dormancy breaking and flowering of the plum accessions belonging to the living collection of Morocco","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-05-24 10:45:28","doi":"10.21203/rs.3.rs-4412987/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2024-05-18T07:29:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"45976966465342865718785446380942794962","date":"2024-05-17T09:25:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"259951254766333026213292673945547602459","date":"2024-05-16T08:10:32+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-05-16T04:57:24+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-15T22:28:10+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-15T22:28:10+00:00","index":"","fulltext":""},{"type":"submitted","content":"Theoretical and Applied Climatology","date":"2024-05-13T11:38:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"theoretical-and-applied-climatology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"taac","sideBox":"Learn more about [Theoretical and Applied Climatology](https://www.springer.com/journal/704)","snPcode":"704","submissionUrl":"https://submission.nature.com/new-submission/704/3","title":"Theoretical and Applied Climatology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"801b05ce-cbc8-4a9b-988c-fbaab86d8a51","owner":[],"postedDate":"May 24th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-06-21T15:17:06+00:00","versionOfRecord":{"articleIdentity":"rs-4412987","link":"https://doi.org/10.1007/s00704-024-05067-6","journal":{"identity":"theoretical-and-applied-climatology","isVorOnly":false,"title":"Theoretical and Applied Climatology"},"publishedOn":"2024-06-18 15:17:06","publishedOnDateReadable":"June 18th, 2024"},"versionCreatedAt":"2024-05-24 10:45:28","video":"","vorDoi":"10.1007/s00704-024-05067-6","vorDoiUrl":"https://doi.org/10.1007/s00704-024-05067-6","workflowStages":[]},"version":"v1","identity":"rs-4412987","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4412987","identity":"rs-4412987","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}