Impact of sugarcane streak mosaic virus (SCSMV) on cane and sugar yields of some commercial varieties in Zuénoula, Côte d'Ivoire

Impact of sugarcane streak mosaic virus (SCSMV) on cane and sugar yields of some commercial varieties in Zuénoula, Côte d'Ivoire | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impact of sugarcane streak mosaic virus (SCSMV) on cane and sugar yields of some commercial varieties in Zuénoula, Côte d'Ivoire Migninlbin Marcel OUATTARA, Konan Didier KOUAME, Mamadou CHERIF, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6206450/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Sugarcane streak mosaic virus (SCSMV) is an emerging virus in Côte d'Ivoire. First observed less than 10 years ago, it is now present in all sugar production areas, with a high prevalence in some sites and rapid increase in others. The aim of this study was to assess the impact of SCSMV on cane and sugar yields of six commercial sugarcane varieties in the Zuénoula integrated agricultural unit. Cuttings with four different levels of disease severity were planted and monitored. Agronomic parameters and technological parameters were determined. The level of SCSMV severity on cuttings had a significant effect on all agronomic parameters. Overall, germination rate, tillering, plant height, stem diameter, number of internodes and cane yieldat harvest were significantly reduced by 15 to 29% for plants deriving from cuttings at the highest severity level. SCSMV had no significant effect on fiber content in cane, sucrose content in cane, cane juice sucrose purity and extractable sugar content. Depending on varieties, cane yield losses and extractable sugar yield losses ranged from 13 to 34% and 15 to 42% respectively. The relationships between yield losses and severity levels in cuttings were successfully modelled with the three-parameter Gompertz function for all varieties. Considering the deleterous effect of SCSMV on cane and sugar yields, the planting of healthy cuttings is the key prophylactic mesure to mitigate virus impact. Côte d’Ivoire Gompertz model SCSMV sugarcane yield loss Zuénoula Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 INTRODUCTION Sucrose, also named saccharose, is a natural carbohydrate found in numerous fruits, vegetables and nuts. In tropical and subtropical regions, it is mainly produced from sugarcane ( Saccharum officinarum L.), with Brazil, India, China and Thailand accounting for 70% of global production (FAOSTAT 2024). In Côte d'Ivoire, sugarcane has been cultivated since the 1970s, mainly in the north and centre-west and its harvested area and production were respectively 26268 ha and 2114005 t in 2022 (FAOSTAT 2024). The contribution of sugarcane production to the national gross domestic product (GDP) is around 1% and 3.3% of the agricultural sector, generating over 10,000 jobs (FAO 2019). Its cultivation faces multiple abiotic and biotic constraints among which mosaic disease is an increasing concern (Daugrois et al. 2024 ; Ouattara et al. 2024). In Côte d'Ivoire, mosaic-like symptoms were first observed in 2015 by Kouamé (pers. comm.), and two years later, the occurrence of symptoms exceeded 95% in some commercial fields and nurseries (Ouattara et al. 2024). All these symptoms were attributed to sugarcane streak mosaic virus (SCSMV, newly renamed Poacevirus sacchar i by ICTV, 2024), the plants having been tested negative for other mosaic symptom inducing viruses such as sugarcane mosaic virus (SCMV, newly renamed Potyvirus sacchari by ICTV, 2024), sorghum mosaic virus (SrMV, newly renamed Potyvirus sorghitessellati by ICTV, 2024) and the mastreviruses responsible for sugarcane streak diseases (Daugrois et al. 2024 ; Ouattara et al. 2024). This Poacevirus of the Potyviridae family (Li et al. 2011) was first reported in the USA by Hall (1998) from quarantined genetic material showing mosaic symptoms imported from Pakistan and subsequently reported in most Asian countries such as Bangladesh, China, India, Indonesia, Iran, Sri Lanka, Thailand and Vietnam (Hema et al. 2003; Viswanathan et al. 2011 ; Xu et al. 2010 ; Putra et al. 2014 ; Moradi et al. 2015; Moradi et al. 2018; Zhang et al. 2010). Typical symptoms are yellow streaks distributed over the entire leaf surface. Yellowing and stunting of plants may also be observed (Ouattara et al. 2024). These symptoms and the associated disrupted photosynthesis disturb plant growth and yield. In Indonesia, Putra et al. (2014) have shown that this virus can cause losses in cane yield and sugar yield of 16–17% and 19–22% respectively. This emerging virus is therefore a serious threat to the sugar industry in Côte d’Ivoire. Although a decline in yields has been observed in recent years in sugar complexes in Côte d'Ivoire, no studies have been conducted to associate SCSMV symptoms and damages. This knowledge is however essential to judge the real harmfulness of a bioaggressor and to design and implement effective means of control if necessary. In this context, we conducted a study to investigate the impact of SCSMV on sugarcane yield development in the sugar complex of Zuénoula in Centre Côte d’Ivoire. In this sugar complex, SCSMV disease prevalence is high but conversely disease severity varies according to the varieties and their susceptibility profile (Ouattara et al. 2024). It appeared therefore relevant to investigate the impact of SCSMV severity on cane and sugar yields of various sugarcane varieties. So, the objective of the study was to monitor, for six sugarcane varieties, the plant growth and yield development of plants deriving from cuttings at four severity levels. MATERIALS AND METHODS Experimental set-up A trial was set up on December 15, 2021, on Sucrivoire’s Integrated Agricultural Unit (IAU) located at Zuénoula (Centre Côte d'Ivoire, 7°38’45,05’’ ; 6°9’46,923’’) in order to evaluate the impact of four levels of SCSMV severity on six sugarcane varieties. The two-factor completely randomized design comprised 24 experimental units of 84 m 2 (7 rows of 8 m in length and 1.5 m between rows) (Figure 1). The 6 sugarcane varieties were: M2593/92 (V1), R570 (V2), R98/4001 (V3), R98/4158 (V4), SP711406 (V5) and SP711406Rég (V6). SP711406Rég, obtained by in vitro regeneration showed morphological characteristics different from those of its parent variety SP711406 and was therefore considered as a separate variety in this study. The choice of these 6 varieties was justified by the fact that it was possible to obtain not only symptomatic cuttings but also asymptomatic cuttings to serve as references. Thus, 3-eye cuttings of different severity levels were harvested per variety the day before the trial was set up, using a scale based on the visual scoring of the percentage of symptomatic area on the third extended leaf below the apex: 0 (asymptomatic plant), 1 (1-10% of leaf area with symptoms), 2 (11-30% of leaf area with symptoms), 3 (31-50% of leaf area with symptoms), 4 (51-100% of leaf area with symptoms). A preliminary study comparing visual scoring and SCSMV detection by reverse transcriptase polymerase chain reaction (RT-PCR) showed that SCSMV was never detected in asymptomatic samples, confirming that plants with a severity score of 0 could be considered healthy with confidence (Ouattara et al. 2024). In this trial, only cuttings of the first levels were used (S0, S1, S2 and S3) because no S4 cuttings were found on the varieties tested. The cuttings were planted at a rate of 4 cuttings per linear metre. So, over a length of 8 metres, 32 cuttings were planted. Given that each cutting has 3 eyes (buds), 96 primary seedlings were expected over the 8 meters. Agronomic parameters during vegetation Plant growth parameters were assessed as in Kouamé et al. (2012). The germination rate (Gr) was determined 45 days after planting. The number of developed seedlings was counted per row and divided by the total number of cutting eyes of the row (96). $$\:\text{G}\text{r}\left(\text{\%}\right)=\frac{\text{N}\text{u}\text{m}\text{b}\text{e}\text{r}\:\text{o}\text{f}\:\text{s}\text{e}\text{e}\text{d}\text{l}\text{i}\text{n}\text{g}\text{s}\:}{\text{T}\text{o}\text{t}\text{a}\text{l}\:\text{n}\text{u}\text{m}\text{b}\text{e}\text{r}\:\text{o}\text{f}\:\text{c}\text{u}\text{t}\text{t}\text{i}\text{n}\text{g}\:\text{e}\text{y}\text{e}\text{s}}\:\text{x}\:100$$ Tillering, plant height, plant collar diameter and number of internodes were assessed every two weeks from 4.5 months to 8 months after planting, i.e. 6 assessment dates. Tillering was assessed by counting the total number of primary and secondary stems present on each of the 3 central rows of each experimental unit (i.e. a sampling unit of 8m x 1.5m = 12 m 2 . The number of stems per hectare was determined using the following formula: $$\:\text{T}\text{i}\text{l}\text{l}\text{e}\text{r}\text{i}\text{n}\text{g}\:\left(\text{s}\text{t}\text{e}\text{m}\text{s}/\text{h}\text{a}\right)=\frac{\text{N}\text{u}\text{m}\text{b}\text{e}\text{r}\:\text{o}\text{f}\:\text{s}\text{t}\text{e}\text{m}\text{s}\:\text{p}\text{e}\text{r}\:\text{s}\text{a}\text{m}\text{p}\text{l}\text{i}\text{n}\text{g}\:\text{u}\text{n}\text{i}\text{t}}{12}\times\:10000$$ To assess plant height, stem diameter and number of internodes, 10 plants were randomly marked in each experimental unit (3 plants for the 3rd row, 4 plants for the 4th row and 3 plants for the 5th row). Height was measured from the plant collar to the last visible ochrea on the plant. Diameter was measured at the plant collar, and the number of internodes was determined by counting from the collar to the last ochrea in order to determine the effect of SCSMV on growth rate. Agronomic parameters at harvest Harvest was carried out 12 months after planting (December 15, 2022). Tillering was assessed as before. Plant height, plant collar diameter and number of stem internodes were assessed on 10 plants randomly selected from each of the 3 central rows, i.e. 30 plants per plot. Cane yield (CY) was estimated after weighing the canes of each of the 3 central rows separately (sampling unit of 12 m 2 ) $$\:\text{C}\text{Y}\:\left(\text{t}/\text{h}\text{a}\right)=\frac{\text{W}\text{e}\text{i}\text{g}\text{h}\text{t}\:\text{o}\text{f}\:\text{c}\text{a}\text{n}\text{e}\text{s}\:\text{p}\text{e}\text{r}\:\text{s}\text{a}\text{m}\text{p}\text{l}\text{i}\text{n}\text{g}\:\text{u}\text{n}\text{i}\text{t}}{12}\times\:10000$$ Technological parameters at harvest For each experimental unit, 30 canes were randomly selected after weighing for each of the 3 central rows (i.e. 90 canes per experimental unit), thus constituting 3 primary samples. Each cane in the primary sample was cut into 3 thirds. A secondary sample of 10 reconstituted canes was formed to ensure that the primary sample was homogenized (Kouamé et al. 2012). The secondary samples were ground in a Jeffco mill (model CG03CB). For each secondary sample, 500 g of cane crush was pressed for 1 min using a hydraulic press with a force corresponding to a pressure of 100 kg/cm 2 . The extracted cane juice was used to determine various technological parameters (Kouamé et al. 2012). Determination of soluble dry matter in cane juice (Brix) A few drops of cane juice were placed on the refractometer's measuring prism. Brix was obtained by averaging two readings at 20°C. If the reading was taken at a temperature other than 20°C, it was carefully noted on a Brix temperature correction table (Kouamé et al. 2012), so that the Brix could be corrected. Measurement of sucrose content in cane juice (Pol%J) Cane juice was first purified using ICUMSA method GS5/7 − 1 of 1994, cited by Kouamé et al. (2012). For this, a spatula of basic lead acetate (Horne's salt) was added, at a rate of 1 g per 100 ml juice fraction. After stirring, when clarification was complete, filtration was carried out on Whatman grade 91 filter paper. Once filtration was complete, the saccharimetric tube was rinsed and filled completely with filtered juice. The polarisation of the juice (Pol%J) is the amount of sucrose in 100 g of juice. It is measured with a polarimeter, whose principle is to measure the angle of rotation of the plane of polarization of light, and whose scale is graduated in angular degrees or sucrose degrees. Three polarimetric readings were taken, and the average was adopted as the polarimetric reading. The Schmidt table for the saccharimeter was used to determine the Pol % of the juice by cross-referencing the Brix value with the Pol value read. Determination of sucrose purity in cane juice Sample purity is the sucrose content of total soluble matter. It is calculated as follows: Purity (%) = (Pol%J/Brix) x 100 Determination of cane insoluble dry matter content (F%C) Insoluble dry matter content was determined from the weight of the cake obtained after pressing the 500 g of pulp obtained by grinding the sample as described above (bagasse) (Kouamé et al. 2012). Determination of sucrose content in cane (Pol%C) Sucrose content in cane is the amount of sucrose contained in 100g of cane. It was determined by multiplying the sucrose content of the cane juice (Pol%J) by a factor n derived from bagasse weight (Kouamé et al. 2012). Pol%C = Factor n x Pol%J Determination of extractable sugar content (ES%) The extractable sugar rate (ES%) is defined by an empirical formula taking into account sucrose richness, fiber content in the cane and cane juice purity (Kouamé et al. 2012): ES% = [(0,84 x Pol%C) (1,6–60/Purity) - (0,06 x F%C)] Extractable sugar yield (ESY) Estimated extractable sugar yield is the most decisive selection criterion in sorting the varieties tested, since it takes into account all technological parameters as well as cane yield. The extractable sugar yield (ESY) was obtained by multiplying the value of the extractable sugar rate by the cane yield (CY) according to the following formula: ESY (t/ha) = ES% x CY Determination of yield losses induced by infected cuttings Cane yield loss (CYL) and extractable sugar yield loss (ESYL) were determined for each level of severity Sn (n ∈[1;3]) on the basis of the yield of asymptomatic plants (S0), assuming that the yield of asymptomatic plants was the reference. These losses were determined by the following formulas: CYL Sn (%) = [(CY S0 - CY Sn )/ CY S0 ] x 100 ESYL Sn (%) = [(ESY S0 - ESY Sn )/ ESY S0 ] x 100 Statistical analysis Statistical analyses were performed using STATISTICA 7.1 and XLSTAT 2016 in EXCEL. A Shapiro-Wilk normality test was carried out for all agronomic and technological parameters depending on the SCSMV severity level of the different sugarcane varieties. Tests showed that these variables follow the normal distribution. A Bartlett’s test was carried out to check the homogeneity of variances. Analysis of variance was used to highlight statistical differences at the 5% threshold, and results for agronomic and technological parameters were classified using the Student-Newman-Keuls test. The relationship between yield losses and severity levels in cuttings was modelled with the three-parameter Gompertz function ; $$\:y=\gamma\:{e}^{-\beta\:{e}^{-\alpha\:*severity}}$$ where y is the yield loss (CYL and ESYL) expressed as a percentage; α, β and γ are positive parameters; γ is bounded above by 100. Curves were fitted using the procedure NLIN of SAS software (version 9.4 for Windows, SAS Institute Inc., Cary, NC, USA). RESULTS Effect of SCSMV on germination rate The impact of SCSMV on germination rate depends on the level of severity and the variety. Overall, the average germination rate decreased as disease severity increased. A significant decrease (15%) was observed for S3 severity level (Fig. 2). This decrease varied between the sugarcane varieties (Table 1 ). For SP711406, the germination rate was significantly reduced for S2 level (26% reduction) and S3 level (39% reduction). For M2593/92, R570, R98/4158 and SP711406Rég, the germination rate appeared reduced for S3 but the reduction was not significant. R98/4001 displayed 100% germination whatever the severity level in the cuttings. Table 1 Effect of SCSMV severity level of cuttings on the germination rate of six sugarcane varieties cultivated in Zuénoula, Côte d’Ivoire For a given variety, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test. Variety Severity level of cuttings Germination rate (%) M2593/92 S0 95 ±1 a S1 92 ±8 a S2 89 ±2 a S3 83 ±4 a R570 S0 100 ±0 a S1 100 ±0 a S2 100 ±0 a S3 88 ±6 a R98/4001 S0 100 ±0 a S1 100 ±0 a S2 100 ±0 a S3 100 ±0 a R98/4158 S0 100 ±0 a S1 98 ±2 a S2 94 ±2 a S3 89 ±5 a SP711406 S0 100 ±0 a S1 89 ±7 a S2 74 ±1 b S3 61 ±8 c SP711406Rég S0 100 ±0 a S1 100 ±0 a S2 99 ±1 a S3 89 ±6 a For a given variety, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test. Effect of SCSMV on growth parameters at vegetative stage At 18 weeks after planting (W18), tillering was highest for asymptomatic plants with 116070 canes per hectare and lowest for S3 severity plants with 105977 canes per hectare (Fig. 3a). Between W18 and W20, tillering decreased for all severity levels. From W20, tillering fluctuated slightly from date to date but tillering for S0 severity remained mainly higher than for other severity levels throughout the evaluation period. However, there was no significant difference between the tillering of the different severity levels (P > 0.05) for all evaluations. Concerning plant height, there was no significant difference between severity levels S0 and S1 throughout the evaluation period (Fig. 3b). Plant height for S0 was significantly higher than S3 from the third assessment (W22) with an average reduction of 8,5% which increased to a 10% reduction by the last assessment (W28). Concerning stem diameter, analysis of variance showed a significant difference between the different severity levels (P < 0.0001) (Fig. 3c). Thus, the stem diameter for severity 0 was the highest over the entire evaluation period, with an average diameter of 26.6 mm, and that for severity S3 was the lowest (22.9 mm), with a significant reduction of 13.9%. With regard to the average number of internodes, the analysis showed no significant differences between plants deriving from cuttings at different severity levels (Fig. 3d). Effect of SCSMV on agronomic parameters at harvest The level of SCSMV severity in cuttings had a significant effect on all agronomic parameters at harvest (Table 2 ). Average tillering obtained with asymptomatic cuttings (S0) was 105376 stems/ha. It was significantly reduced from level S1 (93014 stems/ha, -12%) and this reduction reached − 24% for level S3. The average height of plant from asymptomatic cuttings was 320 cm. It was significantly reduced for levels S2 (288 cm, -10%) and S3 (268 cm, -16%). The average diameter of stems from asymptomatic cuttings was 25.1 mm. It was significantly reduced at S1 (22.4 mm, -12%), S2 (22.1 mm, -12%) and S3 (21.6 mm, -16%). The average number of internodes on stems from asymptomatic cuttings was 26.6, significantly reduced at S2 (23.8, -11%) and S3 (23.1, -15%). The yield of stems from asymptomatic cuttings was 166 t/ha. It was significantly reduced for S1 (147 t/ha, 11% yield loss), S2 (133 t/ha, 20% yield loss) and S3 (118 t/ha, 29% yield loss). Table 2 Overall effect of SCSMV severity level of cuttings on sugarcane agronomic parameters at harvest Severity Tillering (stems/ha) Plant height (cm) Stem diameter (mm) Number of internodes per plant Cane yield (t/ha) S0 105376 ±2664 a 320 ±7 a 25.1 ±0.3 a 26.6 ±0.3 a 166 ±6 a S1 93014 ±2843 b 305 ±8 ab 22.4 ±0.5 b 25.1 ±0.6 ab 147 ±5 b S2 87389 ±2295 b 288 ±6 b 22.1 ±0.5 b 23.8 ±0.7 bc 133 ±3 c S3 80351 ±1938 c 268 ±6 c 21.6 ±0.4 b 23.1 ±0.5 c 118 ±5 d P < 10 − 6 P = 0.000012 P = 0.000007 P = 0.000093 P < 10 − 6 For a given parameter, means followed by the same letters in the same row are not significantly different at the 5% threshold according to the Student-Newman-Keuls test. Effect of SCSMV on cane yield depending on sugarcane variety SCSMV severity level had a significant impact on the cane yield (t/ha) of all sugarcane varieties (P < 0.005) except R98/4001 for which yield losses were not significantly different whatever the severity level (Table 3). Cane yield losses observed for severity level S1 were less than 10% for M2593/92, R570, R98/4001 and SP711406, but reached 16% and 21% for R98/4158 and SP711406Rég respectively. Losses increased sharply between S1 and S2 for M2593/92, R570 and SP711406. This increase in yield loss was smoother for R98/4158 and SP711406Rég. Overall, except for R98/4001 which cane yield loss was 13% for severity level S3, other varieties had significant yield losses between 26% and 34%. The relationship between cane yield losses and severity levels in cuttings was successfully modelled with the three-parameter Gompertz function for all varieties (Fig. 4 ). Effect of SCSMV on technological parameters at harvest SCSMV severity level had no significant effect on the following technological parameters: fiber content in cane (F%C), sucrose content in cane (Pol%C), cane juice sucrose purity, extractable sugar content (ES%) (Table 4 ). On the contrary, the level of disease severity had a significant effect on extractable sugar yield (ESY). ESY was the highest for severity level S0 (16.9t/ha) and the lowest for severity level S3 (11.5t/ha) (Table 5 ). Losses in extractable sugar yield (ESYL) of plants from cuttings of severity levels S1, S2, and S3 determined in relation to the yield of plants of severity 0 were 17.6%, 29.4% and 35.3% respectively. The relationship between sugar yield losses and severity levels in cuttings was successfully modelled with the three-parameter Gompertz function for all varieties (Fig. 5 , Table 6 ). Table 4 Overall effect of SCSMV severity level on sugarcane technological parameters: cane insoluble dry matter content (F%C), sucrose content in cane (Pol%C), sucrose purity in cane juice, extractable sugar content (ES%), extractable sugar yield (ESY) Severity F%C Pol%C Purity (%) ES% ESY (t/ha) S0 16.1 ± 1.7 a 13.7 ± 1.3 a 91.2 ± 1.9 a 10.2 ± 1.2 a 16.9 ± 3.3 a S1 16.4 ± 1.4 a 13.0 ± 1.0 a 90.8 ± 2.1 a 9.5 ± 0.9 a 13.9 ± 2.2 b S2 15.6 ± 1.2 a 12.9 ± 1.2 a 90.3 ± 2.5 a 9.6 ± 1.1 a 12.8 ± 1.2 c S3 15.8 ± 1.0 a 13.4 ± 1.2 a 91.4 ± 2.1 a 9.5 ± 0.9 a 11.5 ± 1.4 c P < 10 − 6 For a given parameter, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test. Table 5 Impact of SCSMV severity level of cuttings on extractable sugar yield (ESY) and corresponding yield losses compared to asymptomatic cuttings (ESYL) for six varieties evaluated in Zuénoula, Côte d’Ivoire Variety Severity level of cuttings ESY (t/ha) ESYL (%) M2593/92 S0 16.7 ± 2.5 a 0 S1 14.1 ± 0.7 b 12 S2 11.4 ± 0.4 b 31 S3 11.4 ± 0.6 b 31 R570 S0 19.1 ± 0.2 a 0 S1 15.2 ± 0.5 b 21 S2 12.5 ± 0.3 c 37 S3 11.4 ± 0.4 c 42 R98/4001 S0 13.6 ± 0.6 a 0 S1 11.6 ± 0.2 a 9 S2 12.7 ± 0.4 a 9 S3 11.3 ± 0.2 a 15 R98/4158 S0 15.5 ± 1.5 a 0 S1 13.1 ± 0.4 ab 13 S2 11.2 ± 0.3 b 27 S3 11.1 ± 0.9 b 27 SP711406 S0 15.4 ± 0.4 a 0 S1 13.5 ± 0.9 ab 13 S2 12.5 ± 0.3 ab 20 S3 10.5 ± 1.2 b 33 SP711406Rég S0 18.2 ± 0.7 a 0 S1 14.6 ± 0.5 b 22 S2 13.7 ± 0.5 b 28 S3 12.4 ± 0.3 b 33 For a given variety, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test. Table 6 Parameter estimates of cane yield loss (CYL) and extractable sugar yield loss (ESYL) response curves to SCSMV severity level in cuttings for six varieties evaluated in Zuénoula, Côte d’Ivoire. Variable Variety α β γ R 2 CYL M2593/92 2.0165 12.7761 34.6969 0.995 R570 1.2104 4.5062 31.4949 0.975 R98/4001 0.4181 3.7218 38.1211 0.948 R98/4158 1.7853 3.0139 23.9254 0.971 SP711406 0.4576 4.1948 83.5575 0.865 SP711406Rég 2.9361 5.6749 27.9069 0.997 ESYL M2593/92 3.7532 40.5062 31.0162 0.999 R570 1.7231 3.9557 42.4451 0.996 R98/4001 1.3859 2.4729 14.1941 0.957 R98/4158 4.0518 41.2892 27.3393 0.996 SP711406 0.6582 3.0036 48.5417 0.909 SP711406Rég 2.1852 3.6731 31.8653 0.993 Parameters α, β and γ were estimated by fitting the Gompertz model to observed data: $$\:Yield\:loss\:\left(\%\right)=\gamma\:{e}^{-\beta\:{e}^{-\alpha\:*severity}}$$ The R 2 values correspond to the ratio of regression sum of squares to total sum of squares. DISCUSSION Sugarcane streak mosaic caused by SCSMV is a new emerging viral disease that has recently been reported in all production areas of Côte d'Ivoire (Daugrois et al. 2020, Sorho et al. 2020). An intensive disease monitoring carried out in Zuénoula between 2018 and 2021 showed that the overall prevalence is extremely high (close to 100%) in this production area but there were different levels of severity across varieties (Ouattara et al. 2024). The present study investigated the impact of the SCSMV severity level of sugarcane cuttings on agronomic parameters during vegetation and at harvest, as well as on technological parameters at harvest. We had previously shown the absence of detection of SCSMV in asymptomatic plants (Ouattara et al. 2024), confirming that these plants can be used as uninfected controls in the trials. The present study showed that the germination rate was reduced when the severity of the cuttings was S2 or S3, even though the reduction was not significant for most varieties. SCSMV affected tillering. Its impact was not significant during the vegetative period but was marked and significant at harvest with a reduction ranging from 12% (S1) to 24% (S3). SCSMV significantly reduced plant height and stem diameter at both vegetative and harvest stages. SCSMV had a significant effect on the number of internodes in sugarcane stems (-15% with S3 severity) but interestingly their size was similar regardless of severity level (≈12 cm). The yield of stems from asymptomatic cuttings was 166 t/ha (ranging from 135 to 178 t/ha depending on the veriety) and yield losses ranged from 11% (S1) to 29% (S3). SCSMV severity had a significant impact on cane yield of all sugarcane varieties except R98/4001. The losses in cane yield observed on this variety (13%) were relatively low compared with the other varieties (26–34%), but this variety has a lower yield than the other ones even when S0 cuttings were used. Generally speaking, all agronomic parameters at both vegetative and harvest stages were affected by SCSMV. This impact may be explained by SCSMV-induced chlorosis on plant leaves reducing the potential expression of photosynthetic activity in sugarcane leaves. Indeed, previous studies (Irvine and James 1971; Bagyalakshmi et al. 2012) indicated that the chlorophyll of sugarcane plants infected by the various mosaics (SCMV, SCSMV, SrMV) was destroyed, photosynthesis was weakened and growth was considerably inhibited, resulting in lower germination rates, reduced tillering and lower sugarcane yields. Studying the variety PS 864, Putra et al. (2014) showed that cane yield decreases as disease level increases, and estimated cane yield losses of 16 to 17%. In our study, cane yield losses were much higher, estimated at up to 34% for the variety M2593/92. The level of severity of SCSMV has no significant effect on fiber content in cane (F%C), sucrose content in cane (Pol%C), cane juice sucrose purity nor extractable sugar content (SE%). This latter is in agreement with previous results. Indeed, Putra et al. (2014) also showed that the level of disease caused by SCSMV does not affect sucrose content. This could be explained by the fact that the reducing sugars, i.e. glucose and fructose, accumulated in the sugarcane stalk during growth are more than sufficient to be converted into sucrose during the sugarcane ripening phase. In contrast, SCMV reduces juice content, sucrose content and crystallization rate, which can ultimately reduce sugarcane yield by 10–50%, or even 60–80% (Koike et al. 1989; Viswanathan et al. 2005; He et al. 2006). As a result of its impact on cane yield, SCSMV had a significant effect on extractable sugar yield (ESY). Overall, the yield of extractable sugar obtained with the S0 severity level was 17t/ha and extractable sugar yield losses (ESYL) ranged from 11% (S1) to 30% (S3) but they varied according to variety. Thus the extractable sugar yield losses for severity level S3 ranged from 15% (R98/4001) to 42% (R570). Studying the variety PS 864, Putra et al. (2014) showed that SCSMV caused extractable sugar yield losses of 19–21%. So, in our study we showed that extractable sugar yield losses could be even much higher for some varieties. The magnitude of the impact of the virus on yield should not be evaluated solely on the basis of the percentage loss. Indeed, it also depends on the yield potential of the variety which is realized in the absence of disease. Thus the varieties SP711406 and SP711406Rég both have an ESYL of 33% for severity level S3 but the yield potential of the regenerated variety is significantly higher (18.2t/ha vs 15.4t/ha) resulting in a gross loss differential of almost 2t/ha in favour of the regenerated variety. Variety choice is crucial in a high-risk phytosanitary context as it the case with SCSMV which has a very high prevalence regardless of the sugar complex. Our results suggest that priority should be given to high-potential varieties which can more easily produce an acceptable yield in the presence of the virus. With equivalent yield potentials, preference should then be given to varieties that have shown a certain tolerance at low severity (particularly severity level S1). Finally, our results suggest that prophylactic methods should focus on the health status of the cuttings to ensure a healthy planting. Cuttings from asymptomatic plants are essential and pre-nursery and nursery work should guarantee this status. Declarations Acknowledgements This work was possible thanks to the partnership agreement that exists between the WASCAL-CEA-CCBAD center and the SUCRIVOIRE Company through agreement number 3004_2019. This field work was financed by the company SUCRIVOIRE. For this purpose, our thanks go to the SUCRIVOIRE Company, especially to Eric BOBLAI and Nicaise KOFFI respectively director and director of plantations of the integrated agricultural unit of Zuénoula. We also thank the WASCAL-CEA-CCBAD center for its involvement. Competing interests The authors have no competing interests that are relevant to the content of this article to declare. References Bagyalakshmi K, Parameswari B, Chinnaraja C, Karuppaiah R, Kumar VG, Viswanathan R (2012) Genetic variability and potential recombination events in the HC-Pro gene of Sugarcane streak mosaic virus. Arch Virol 157, 1371-1375. https://doi.org/10.1007/s00705-012-1297-8 Daugrois JH, Roumagnac P, Kouakou Y, Oura OJ, Pita JS (2020) First report of sugarcane streak mosaic virus in sugarcane ( Saccharum spp.) in Côte d'Ivoire. New Dis Rep 41:22-22. http://dx.doi.org/10.5197/j.2044-0588.2020.041.022 Daugrois J, Roumagnac P, Julian C, Filloux D, Putra L, Mollov D, Rott P (2024) Historical Review of Sugarcane Streak Mosaic Virus that Has Recently Emerged in Africa. Phytopathol 114 : 668 – 680. https://doi.org/10.1094/PHYTO-08-23-0291-RVW FAO (2019) Principaux pays agricoles et alimentaires et producteurs. Classification des pays dans le monde, par produit. Division de la statistique de la FAO. www.fao.org/es/ess/top/commodity.html. FAOSTAT (2024): https://www.fao.org/faostat/en/#data (last access: 1 April 2024). Hall JS, Adams B, Parsons TJ, French R, Lane LC, Jensen SG (1998) Molecular cloning, sequencing and phylogenetic relationships of a new potyvirus: sugarcane streak mosaic virus, and a reevaluation of the classification of the Potyviridae. Mol Phylogenetics Evol 10:323–332. https://doi.org/10.1006/mpev.1998.0535 He YS, Li RM (2006) Research Status of Sugarcane Mosaic Virus Disease in China. Sugar Crop China 28 : 47–49. Hema M, Kirthi N, Sreenivasulu P, Savithri HS (2003) Development of recombinant coat protein antibody based IC-RT-PRD for detection and discrimination of Sugarcane streak mosaic virus isolates from Southern Inia. Arch Virol 148: 1185-1193. https://doi.org/10.1007/s00705-003-0015-y International Committee on Taxonomy of Viruses (2024) https://ictv.global/taxonomy (accessed July 31, 2024) Irvine, James E (1971)Photosynthesis in Sugarcane Varieties Infected with Strains of Sugarcane Mosaic Virus. Physiol Plantarum 24 : 51–54. https://doi.org/10.1111/j.1399-3054.1971.tb06714.x Koike H, Gillespie A G (1989) In Ricaud, BT Egan, AG Gillespie, CG Hughes eds., “Mosaic Disease of sugarcane-major disease, pp 301-322. Kouamé DK, Péné BC, Zouzou M (2012) Sélection variétale de la canne à sucre en Côte d’Ivoire : Synthèse des résultats et proposition d’un nouveau schéma de sélection. J Anim Plant Sci 84 : 194-209. https://www.researchgate.net/publication/288432613 Li W, He Z, Li S, Huang Y, Zhang Z (2011) Molecular characterization of a new strain of Sugarcane streak mosaic virus (SCSMV). Arch Virol 156: 2101-2104. https://doi.org/10.1007/s00705-011-1090-0 Moradi N, Rajabi-Memari H, Mehrabi-Koushki M, Taherkhani K, Moazzen-Reza-Mahalle H, Sheikhi F, Nasirpour N, Sanjabifard Z (2015) First report of Sugarcane streak mosaic virus in Iran. New Dis Rep 32: 2. https://doi.org/10.5197/j.2044-0588.2015.032.002 Moradi Z, Mehrvar M, Nazifi E (2018) Genetic diversity and biological characterization of sugarcane streak mosaic virus isolates from Iran. Virus Disease29: 316–323. https://doi.org/10.1007/s13337-018-0461-5 Ouattara MM, Kouame KD, Desbiez C, Girardot G, Ble B, Yao K, Sorho F, Cherif M, Kone N, Kone D, Schoeny A (2024) Sugarcane streak mosaic virus: distribution, prevalence and severity in the integrated farming units of Zuénoula and Borotou‑Koro, Côte d’Ivoire. Eur J Plant Pathol, https://doi.org/10.1007/s10658-024-02951-9 Putra LK, Kristini A, Achadian EM, Damayanti TA (2014) Sugarcane streak mosaic virus in Indonesia: Distribution, characterization, yield losses and management approaches. Sugar Tech, 16, 392-399. https://doi.org/10.1007/s12355-013-0279-9 Sorho F, Sérémé D, Kouamé DK., Koné N, Yao KJ, Ouattara MM, Tapsoba WP, Ouattara B, Koné D (2020) First report of sugarcane streak mosaic virusinfecting sugarcane in Côte d’Ivoire. Plant Dis 105: 0191-2917. https://doi.org/10.1094/PDIS-07-19-1398-PDN Viswanathan R, Karuppaiah R, Ganesh KV (2011) Expression of sugarcane streak mosaic virus (scsmv) coat protein in expression vector as a fusion protein with maltose binding protein. J Sugarcane Res 1 : 63 – 68 Viswanathan R, Balamuralikrishnan M (2005) Impact of mosaic infection on growth and yield of sugarcane. Sugar Tech, 7 : 61–65. https://doi.org/10.1007/BF02942419 Xu DL, Zhou GH, Xie YJ, Mock R, Li R (2010) Complete nucleotide sequence and taxonomy of Sugarcane streak mosaic virus, member of a novel genus in the family Potyviridae . Virus Genes 40 , 432-439. https://doi.org/10.1007/s11262-010-0457-8 Zhang RY, Li WF, Huang YK (2018) Genetic diversity and population structure of Sugarcane streak mosaic virus in Yunnan province, China. Trop Plant Pathol 43: 514-519. https://doi.org/10.1007/s40858-018-0244-y Table 3 Table 3 is not available with this version. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-6206450","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":446768641,"identity":"0cb6aba5-6cab-4d3d-ac19-965344d6a702","order_by":0,"name":"Migninlbin Marcel 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SCHOENY","email":"","orcid":"","institution":"INRAE","correspondingAuthor":false,"prefix":"","firstName":"Alexandra","middleName":"","lastName":"SCHOENY","suffix":""}],"badges":[],"createdAt":"2025-03-11 19:53:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6206450/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6206450/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":81796742,"identity":"2372a757-3c69-402c-bdd5-6b8a09128ffb","added_by":"auto","created_at":"2025-05-02 03:58:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":2202062,"visible":true,"origin":"","legend":"\u003cp\u003eRandomized design involving six sugarcane varieties (V) and four SCSMV severity levels (S) in Zuénoula, Côte d’Ivoire (2021-2022)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6206450/v1/abf638142e593652d77e175d.png"},{"id":81797041,"identity":"ff1f1294-e731-42fe-8fe9-c06729e75cda","added_by":"auto","created_at":"2025-05-02 04:06:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":24276,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of SCSMV severity level of cuttings on average germination rate of sugarcane evaluated in Zuénoula, Côte d’Ivoire\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6206450/v1/d9587ebf763df6e2a34fbd99.png"},{"id":81796746,"identity":"7b0ee337-2cc0-41cc-b9d5-578817de42b8","added_by":"auto","created_at":"2025-05-02 03:58:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":109737,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of SCSMV severity level of cuttings on sugarcane agronomic growth parameters during the vegetative period : a: mean tillering (stems/ha), b: mean plant height (cm), c: mean stem diameter at collar (mm), d: mean number of internodes\u003c/p\u003e\n\u003cp\u003e*: P\u0026gt;0.05; **: 0.0003\u0026lt;P\u0026lt;0.05; ***: P\u0026lt;0.0003\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6206450/v1/99eba8292a9ef7ae0da7f7b1.png"},{"id":81796745,"identity":"76278178-bf62-45ba-ad55-d47cbf25d6e3","added_by":"auto","created_at":"2025-05-02 03:58:21","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":98476,"visible":true,"origin":"","legend":"\u003cp\u003eCane yield loss (CYL) as a function of SCSMV severity level in cuttings of 6 cane varieties. Symbols represent observed values. Lines are fitted curves (Gompertz model)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6206450/v1/89f89170d389464e88d1ac77.png"},{"id":81797046,"identity":"e21c0dce-6c21-46d8-9af3-409fd4b87afa","added_by":"auto","created_at":"2025-05-02 04:06:21","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":100618,"visible":true,"origin":"","legend":"\u003cp\u003eExtractablesugar yield loss (ESYL) as a function of SCSMV severity level in cuttings of 6 cane varieties. Symbols represent observed values. Lines are fitted curves (Gompertz model)\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6206450/v1/a6e4d9eb70b47b63cc5af281.png"},{"id":81797814,"identity":"c7569236-c12b-4df5-85de-8492fe055ba6","added_by":"auto","created_at":"2025-05-02 04:30:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3783359,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6206450/v1/2f51deba-419f-41b9-ac81-fd121295a29d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of sugarcane streak mosaic virus (SCSMV) on cane and sugar yields of some commercial varieties in Zuénoula, Côte d'Ivoire","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eSucrose, also named saccharose, is a natural carbohydrate found in numerous fruits, vegetables and nuts. In tropical and subtropical regions, it is mainly produced from sugarcane (\u003cem\u003eSaccharum officinarum\u003c/em\u003e L.), with Brazil, India, China and Thailand accounting for 70% of global production (FAOSTAT 2024).\u003c/p\u003e \u003cp\u003eIn C\u0026ocirc;te d'Ivoire, sugarcane has been cultivated since the 1970s, mainly in the north and centre-west and its harvested area and production were respectively 26268 ha and 2114005 t in 2022 (FAOSTAT 2024). The contribution of sugarcane production to the national gross domestic product (GDP) is around 1% and 3.3% of the agricultural sector, generating over 10,000 jobs (FAO 2019). Its cultivation faces multiple abiotic and biotic constraints among which mosaic disease is an increasing concern (Daugrois et al. 2024 ; Ouattara et al. 2024). In C\u0026ocirc;te d'Ivoire, mosaic-like symptoms were first observed in 2015 by Kouam\u0026eacute; (pers. comm.), and two years later, the occurrence of symptoms exceeded 95% in some commercial fields and nurseries (Ouattara et al. 2024). All these symptoms were attributed to sugarcane streak mosaic virus (SCSMV, newly renamed \u003cem\u003ePoacevirus sacchar\u003c/em\u003ei by ICTV, 2024), the plants having been tested negative for other mosaic symptom inducing viruses such as sugarcane mosaic virus (SCMV, newly renamed \u003cem\u003ePotyvirus sacchari\u003c/em\u003e by ICTV, 2024), sorghum mosaic virus (SrMV, newly renamed \u003cem\u003ePotyvirus sorghitessellati\u003c/em\u003e by ICTV, 2024) and the mastreviruses responsible for sugarcane streak diseases (Daugrois et al. 2024 ; Ouattara et al. 2024). This Poacevirus of the Potyviridae family (Li et al. 2011) was first reported in the USA by Hall (1998) from quarantined genetic material showing mosaic symptoms imported from Pakistan and subsequently reported in most Asian countries such as Bangladesh, China, India, Indonesia, Iran, Sri Lanka, Thailand and Vietnam (Hema et al. 2003; Viswanathan et al. 2011 ; Xu et al. 2010 ; Putra et al. 2014 ; Moradi et al. 2015; Moradi et al. 2018; Zhang et al. 2010). Typical symptoms are yellow streaks distributed over the entire leaf surface. Yellowing and stunting of plants may also be observed (Ouattara et al. 2024). These symptoms and the associated disrupted photosynthesis disturb plant growth and yield. In Indonesia, Putra et al. (2014) have shown that this virus can cause losses in cane yield and sugar yield of 16\u0026ndash;17% and 19\u0026ndash;22% respectively. This emerging virus is therefore a serious threat to the sugar industry in C\u0026ocirc;te d\u0026rsquo;Ivoire. Although a decline in yields has been observed in recent years in sugar complexes in C\u0026ocirc;te d'Ivoire, no studies have been conducted to associate SCSMV symptoms and damages. This knowledge is however essential to judge the real harmfulness of a bioaggressor and to design and implement effective means of control if necessary. In this context, we conducted a study to investigate the impact of SCSMV on sugarcane yield development in the sugar complex of Zu\u0026eacute;noula in Centre C\u0026ocirc;te d\u0026rsquo;Ivoire. In this sugar complex, SCSMV disease prevalence is high but conversely disease severity varies according to the varieties and their susceptibility profile (Ouattara et al. 2024). It appeared therefore relevant to investigate the impact of SCSMV severity on cane and sugar yields of various sugarcane varieties. So, the objective of the study was to monitor, for six sugarcane varieties, the plant growth and yield development of plants deriving from cuttings at four severity levels.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eExperimental set-up\u003c/h2\u003e\n \u003cp\u003eA trial was set up on December 15, 2021, on Sucrivoire\u0026rsquo;s Integrated Agricultural Unit (IAU) located at Zu\u0026eacute;noula (Centre C\u0026ocirc;te d\u0026apos;Ivoire, 7\u0026deg;38\u0026rsquo;45,05\u0026rsquo;\u0026rsquo;\u0026nbsp;; 6\u0026deg;9\u0026rsquo;46,923\u0026rsquo;\u0026rsquo;) in order to evaluate the impact of four levels of SCSMV severity on six sugarcane varieties. The two-factor completely randomized design comprised 24 experimental units of 84 m\u003csup\u003e2\u003c/sup\u003e (7 rows of 8 m in length and 1.5 m between rows) (Figure 1). The 6 sugarcane varieties were: M2593/92 (V1), R570 (V2), R98/4001 (V3), R98/4158 (V4), SP711406 (V5) and SP711406R\u0026eacute;g (V6). SP711406R\u0026eacute;g, obtained by \u003cem\u003ein vitro\u003c/em\u003e regeneration showed morphological characteristics different from those of its parent variety SP711406 and was therefore considered as a separate variety in this study. The choice of these 6 varieties was justified by the fact that it was possible to obtain not only symptomatic cuttings but also asymptomatic cuttings to serve as references. Thus, 3-eye cuttings of different severity levels were harvested per variety the day before the trial was set up, using a scale based on the visual scoring of the percentage of symptomatic area on the third extended leaf below the apex: 0 (asymptomatic plant), 1 (1-10% of leaf area with symptoms), 2 (11-30% of leaf area with symptoms), 3 (31-50% of leaf area with symptoms), 4 (51-100% of leaf area with symptoms). A preliminary study comparing visual scoring and SCSMV detection by reverse transcriptase polymerase chain reaction (RT-PCR) showed that SCSMV was never detected in asymptomatic samples, confirming that plants with a severity score of 0 could be considered healthy with confidence (Ouattara et al. 2024). In this trial, only cuttings of the first levels were used (S0, S1, S2 and S3) because no S4 cuttings were found on the varieties tested. The cuttings were planted at a rate of 4 cuttings per linear metre. So, over a length of 8 metres, 32 cuttings were planted. Given that each cutting has 3 eyes (buds), 96 primary seedlings were expected over the 8 meters.\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eAgronomic parameters during vegetation\u003c/h3\u003e\n\u003cp\u003ePlant growth parameters were assessed as in Kouam\u0026eacute; et al. (2012). The germination rate (Gr) was determined 45 days after planting. The number of developed seedlings was counted per row and divided by the total number of cutting eyes of the row (96).\u003c/p\u003e\n\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e$$\\:\\text{G}\\text{r}\\left(\\text{\\%}\\right)=\\frac{\\text{N}\\text{u}\\text{m}\\text{b}\\text{e}\\text{r}\\:\\text{o}\\text{f}\\:\\text{s}\\text{e}\\text{e}\\text{d}\\text{l}\\text{i}\\text{n}\\text{g}\\text{s}\\:}{\\text{T}\\text{o}\\text{t}\\text{a}\\text{l}\\:\\text{n}\\text{u}\\text{m}\\text{b}\\text{e}\\text{r}\\:\\text{o}\\text{f}\\:\\text{c}\\text{u}\\text{t}\\text{t}\\text{i}\\text{n}\\text{g}\\:\\text{e}\\text{y}\\text{e}\\text{s}}\\:\\text{x}\\:100$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eTillering, plant height, plant collar diameter and number of internodes were assessed every two weeks from 4.5 months to 8 months after planting, i.e. 6 assessment dates. Tillering was assessed by counting the total number of primary and secondary stems present on each of the 3 central rows of each experimental unit (i.e. a sampling unit of 8m x 1.5m\u0026thinsp;=\u0026thinsp;12 m\u003csup\u003e2\u003c/sup\u003e. The number of stems per hectare was determined using the following formula:\u003c/p\u003e\n\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e$$\\:\\text{T}\\text{i}\\text{l}\\text{l}\\text{e}\\text{r}\\text{i}\\text{n}\\text{g}\\:\\left(\\text{s}\\text{t}\\text{e}\\text{m}\\text{s}/\\text{h}\\text{a}\\right)=\\frac{\\text{N}\\text{u}\\text{m}\\text{b}\\text{e}\\text{r}\\:\\text{o}\\text{f}\\:\\text{s}\\text{t}\\text{e}\\text{m}\\text{s}\\:\\text{p}\\text{e}\\text{r}\\:\\text{s}\\text{a}\\text{m}\\text{p}\\text{l}\\text{i}\\text{n}\\text{g}\\:\\text{u}\\text{n}\\text{i}\\text{t}}{12}\\times\\:10000$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eTo assess plant height, stem diameter and number of internodes, 10 plants were randomly marked in each experimental unit (3 plants for the 3rd row, 4 plants for the 4th row and 3 plants for the 5th row). Height was measured from the plant collar to the last visible ochrea on the plant. Diameter was measured at the plant collar, and the number of internodes was determined by counting from the collar to the last ochrea in order to determine the effect of SCSMV on growth rate.\u003c/p\u003e\n\u003ch3\u003eAgronomic parameters at harvest\u003c/h3\u003e\n\u003cp\u003eHarvest was carried out 12 months after planting (December 15, 2022). Tillering was assessed as before. Plant height, plant collar diameter and number of stem internodes were assessed on 10 plants randomly selected from each of the 3 central rows, i.e. 30 plants per plot.\u003c/p\u003e\n\u003cp\u003eCane yield (CY) was estimated after weighing the canes of each of the 3 central rows separately (sampling unit of 12 m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e$$\\:\\text{C}\\text{Y}\\:\\left(\\text{t}/\\text{h}\\text{a}\\right)=\\frac{\\text{W}\\text{e}\\text{i}\\text{g}\\text{h}\\text{t}\\:\\text{o}\\text{f}\\:\\text{c}\\text{a}\\text{n}\\text{e}\\text{s}\\:\\text{p}\\text{e}\\text{r}\\:\\text{s}\\text{a}\\text{m}\\text{p}\\text{l}\\text{i}\\text{n}\\text{g}\\:\\text{u}\\text{n}\\text{i}\\text{t}}{12}\\times\\:10000$$\u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003eTechnological parameters at harvest\u003c/h3\u003e\n\u003cp\u003eFor each experimental unit, 30 canes were randomly selected after weighing for each of the 3 central rows (i.e. 90 canes per experimental unit), thus constituting 3 primary samples. Each cane in the primary sample was cut into 3 thirds. A secondary sample of 10 reconstituted canes was formed to ensure that the primary sample was homogenized (Kouam\u0026eacute; et al. 2012).\u003c/p\u003e\n\u003cp\u003eThe secondary samples were ground in a Jeffco mill (model CG03CB). For each secondary sample, 500 g of cane crush was pressed for 1 min using a hydraulic press with a force corresponding to a pressure of 100 kg/cm\u003csup\u003e2\u003c/sup\u003e. The extracted cane juice was used to determine various technological parameters (Kouam\u0026eacute; et al. 2012).\u003c/p\u003e\n\u003ch3\u003eDetermination of soluble dry matter in cane juice (Brix)\u003c/h3\u003e\n\u003cp\u003eA few drops of cane juice were placed on the refractometer\u0026apos;s measuring prism. Brix was obtained by averaging two readings at 20\u0026deg;C. If the reading was taken at a temperature other than 20\u0026deg;C, it was carefully noted on a Brix temperature correction table (Kouam\u0026eacute; et al. 2012), so that the Brix could be corrected.\u003c/p\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eMeasurement of sucrose content in cane juice (Pol%J)\u003c/h2\u003e\n \u003cp\u003eCane juice was first purified using ICUMSA method GS5/7\u0026thinsp;\u0026minus;\u0026thinsp;1 of 1994, cited by Kouam\u0026eacute; et al. (2012). For this, a spatula of basic lead acetate (Horne\u0026apos;s salt) was added, at a rate of 1 g per 100 ml juice fraction. After stirring, when clarification was complete, filtration was carried out on Whatman grade 91 filter paper. Once filtration was complete, the saccharimetric tube was rinsed and filled completely with filtered juice. The polarisation of the juice (Pol%J) is the amount of sucrose in 100 g of juice. It is measured with a polarimeter, whose principle is to measure the angle of rotation of the plane of polarization of light, and whose scale is graduated in angular degrees or sucrose degrees. Three polarimetric readings were taken, and the average was adopted as the polarimetric reading. The Schmidt table for the saccharimeter was used to determine the Pol % of the juice by cross-referencing the Brix value with the Pol value read.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eDetermination of sucrose purity in cane juice\u003c/h3\u003e\n\u003cp\u003eSample purity is the sucrose content of total soluble matter. It is calculated as follows:\u003c/p\u003e\n\u003cp\u003ePurity (%) = (Pol%J/Brix) x 100\u003c/p\u003e\n\u003ch3\u003eDetermination of cane insoluble dry matter content (F%C)\u003c/h3\u003e\n\u003cp\u003eInsoluble dry matter content was determined from the weight of the cake obtained after pressing the 500 g of pulp obtained by grinding the sample as described above (bagasse) (Kouam\u0026eacute; et al. 2012).\u003c/p\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003eDetermination of sucrose content in cane (Pol%C)\u003c/h2\u003e\n \u003cp\u003eSucrose content in cane is the amount of sucrose contained in 100g of cane. It was determined by multiplying the sucrose content of the cane juice (Pol%J) by a factor n derived from bagasse weight (Kouam\u0026eacute; et al. 2012).\u003c/p\u003e\n \u003cp\u003ePol%C\u0026thinsp;=\u0026thinsp;Factor n x Pol%J\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003eDetermination of extractable sugar content (ES%)\u003c/h2\u003e\n \u003cp\u003eThe extractable sugar rate (ES%) is defined by an empirical formula taking into account sucrose richness, fiber content in the cane and cane juice purity (Kouam\u0026eacute; et al. 2012):\u003c/p\u003e\n \u003cp\u003eES% = [(0,84 x Pol%C) (1,6\u0026ndash;60/Purity) - (0,06 x F%C)]\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003eExtractable sugar yield (ESY)\u003c/h2\u003e\n \u003cp\u003eEstimated extractable sugar yield is the most decisive selection criterion in sorting the varieties tested, since it takes into account all technological parameters as well as cane yield. The extractable sugar yield (ESY) was obtained by multiplying the value of the extractable sugar rate by the cane yield (CY) according to the following formula:\u003c/p\u003e\n \u003cp\u003eESY (t/ha)\u0026thinsp;=\u0026thinsp;ES% x CY\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003eDetermination of yield losses induced by infected cuttings\u003c/h2\u003e\n \u003cp\u003eCane yield loss (CYL) and extractable sugar yield loss (ESYL) were determined for each level of severity Sn (n \u0026isin;[1;3]) on the basis of the yield of asymptomatic plants (S0), assuming that the yield of asymptomatic plants was the reference. These losses were determined by the following formulas:\u003c/p\u003e\n \u003cp\u003eCYL\u003csub\u003eSn\u003c/sub\u003e (%) = [(CY\u003csub\u003eS0\u003c/sub\u003e - CY\u003csub\u003eSn\u003c/sub\u003e)/ CY\u003csub\u003eS0\u003c/sub\u003e] x 100\u003c/p\u003e\n \u003cp\u003eESYL\u003csub\u003eSn\u003c/sub\u003e (%) = [(ESY\u003csub\u003eS0\u003c/sub\u003e - ESY\u003csub\u003eSn\u003c/sub\u003e)/ ESY\u003csub\u003eS0\u003c/sub\u003e] x 100\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n \u003ch2\u003eStatistical analysis\u003c/h2\u003e\n \u003cp\u003eStatistical analyses were performed using STATISTICA 7.1 and XLSTAT 2016 in EXCEL. A Shapiro-Wilk normality test was carried out for all agronomic and technological parameters depending on the SCSMV severity level of the different sugarcane varieties. Tests showed that these variables follow the normal distribution. A Bartlett\u0026rsquo;s test was carried out to check the homogeneity of variances. Analysis of variance was used to highlight statistical differences at the 5% threshold, and results for agronomic and technological parameters were classified using the Student-Newman-Keuls test.\u003c/p\u003e\n \u003cp\u003eThe relationship between yield losses and severity levels in cuttings was modelled with the three-parameter Gompertz function ;\u003c/p\u003e\n \u003cdiv id=\"Equd\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equd\" name=\"EquationSource\"\u003e$$\\:y=\\gamma\\:{e}^{-\\beta\\:{e}^{-\\alpha\\:*severity}}$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere y is the yield loss (CYL and ESYL) expressed as a percentage; \u0026alpha;, \u0026beta; and \u0026gamma; are positive parameters; \u0026gamma; is bounded above by 100. Curves were fitted using the procedure NLIN of SAS software (version 9.4 for Windows, SAS Institute Inc., Cary, NC, USA).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n \u003ch2\u003eEffect of SCSMV on germination rate\u003c/h2\u003e\n \u003cp\u003eThe impact of SCSMV on germination rate depends on the level of severity and the variety. Overall, the average germination rate decreased as disease severity increased. A significant decrease (15%) was observed for S3 severity level (Fig. 2). This decrease varied between the sugarcane varieties (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). For SP711406, the germination rate was significantly reduced for S2 level (26% reduction) and S3 level (39% reduction). For M2593/92, R570, R98/4158 and SP711406R\u0026eacute;g, the germination rate appeared reduced for S3 but the reduction was not significant. R98/4001 displayed 100% germination whatever the severity level in the cuttings.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eEffect of SCSMV severity level of cuttings on the germination rate of six sugarcane varieties cultivated in Zu\u0026eacute;noula, C\u0026ocirc;te d\u0026rsquo;Ivoire \u003cem\u003eFor a given variety, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test.\u003c/em\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSeverity level of cuttings\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGermination rate (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eM2593/92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e95 \u0026plusmn;1 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e92 \u0026plusmn;8 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e89 \u0026plusmn;2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e83 \u0026plusmn;4 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eR570\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e88 \u0026plusmn;6 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eR98/4001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eR98/4158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e98 \u0026plusmn;2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e94 \u0026plusmn;2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e89 \u0026plusmn;5 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eSP711406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e89 \u0026plusmn;7 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e74 \u0026plusmn;1 b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e61 \u0026plusmn;8 c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eSP711406R\u0026eacute;g\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e100 \u0026plusmn;0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e99 \u0026plusmn;1 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e89 \u0026plusmn;6 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\n \u003cp\u003e\u003cem\u003eFor a given variety, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test.\u003c/em\u003e\u003c/p\u003e\n \u003ch2\u003eEffect of SCSMV on growth parameters at vegetative stage\u003c/h2\u003e\n \u003cp\u003eAt 18 weeks after planting (W18), tillering was highest for asymptomatic plants with 116070 canes per hectare and lowest for S3 severity plants with 105977 canes per hectare (Fig. 3a). Between W18 and W20, tillering decreased for all severity levels. From W20, tillering fluctuated slightly from date to date but tillering for S0 severity remained mainly higher than for other severity levels throughout the evaluation period. However, there was no significant difference between the tillering of the different severity levels (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) for all evaluations. Concerning plant height, there was no significant difference between severity levels S0 and S1 throughout the evaluation period (Fig. 3b). Plant height for S0 was significantly higher than S3 from the third assessment (W22) with an average reduction of 8,5% which increased to a 10% reduction by the last assessment (W28). Concerning stem diameter, analysis of variance showed a significant difference between the different severity levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (Fig. 3c). Thus, the stem diameter for severity 0 was the highest over the entire evaluation period, with an average diameter of 26.6 mm, and that for severity S3 was the lowest (22.9 mm), with a significant reduction of 13.9%. With regard to the average number of internodes, the analysis showed no significant differences between plants deriving from cuttings at different severity levels (Fig. 3d).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\n \u003ch2\u003eEffect of SCSMV on agronomic parameters at harvest\u003c/h2\u003e\n \u003cp\u003eThe level of SCSMV severity in cuttings had a significant effect on all agronomic parameters at harvest (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). Average tillering obtained with asymptomatic cuttings (S0) was 105376 stems/ha. It was significantly reduced from level S1 (93014 stems/ha, -12%) and this reduction reached \u0026minus;\u0026thinsp;24% for level S3. The average height of plant from asymptomatic cuttings was 320 cm. It was significantly reduced for levels S2 (288 cm, -10%) and S3 (268 cm, -16%). The average diameter of stems from asymptomatic cuttings was 25.1 mm. It was significantly reduced at S1 (22.4 mm, -12%), S2 (22.1 mm, -12%) and S3 (21.6 mm, -16%). The average number of internodes on stems from asymptomatic cuttings was 26.6, significantly reduced at S2 (23.8, -11%) and S3 (23.1, -15%). The yield of stems from asymptomatic cuttings was 166 t/ha. It was significantly reduced for S1 (147 t/ha, 11% yield loss), S2 (133 t/ha, 20% yield loss) and S3 (118 t/ha, 29% yield loss).\u003c/p\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eOverall effect of SCSMV severity level of cuttings on sugarcane agronomic parameters at harvest\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 7.4028%;\"\u003e\n \u003cp\u003eSeverity\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 17.1895%;\"\u003e\n \u003cp\u003eTillering (stems/ha)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 15.1819%;\"\u003e\n \u003cp\u003ePlant height (cm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 18.0678%;\"\u003e\n \u003cp\u003eStem diameter (mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 27.6035%;\"\u003e\n \u003cp\u003eNumber of internodes per plant\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 14.5546%;\"\u003e\n \u003cp\u003eCane yield (t/ha)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4028%;\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 17.1895%;\"\u003e\n \u003cp\u003e105376 \u0026plusmn;2664 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.1819%;\"\u003e\n \u003cp\u003e320 \u0026plusmn;7 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 18.0678%;\"\u003e\n \u003cp\u003e25.1 \u0026plusmn;0.3 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 27.6035%;\"\u003e\n \u003cp\u003e26.6 \u0026plusmn;0.3 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 14.5546%;\"\u003e\n \u003cp\u003e166 \u0026plusmn;6 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4028%;\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 17.1895%;\"\u003e\n \u003cp\u003e93014 \u0026plusmn;2843 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.1819%;\"\u003e\n \u003cp\u003e305 \u0026plusmn;8 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 18.0678%;\"\u003e\n \u003cp\u003e22.4 \u0026plusmn;0.5 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 27.6035%;\"\u003e\n \u003cp\u003e25.1 \u0026plusmn;0.6 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 14.5546%;\"\u003e\n \u003cp\u003e147 \u0026plusmn;5 b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4028%;\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 17.1895%;\"\u003e\n \u003cp\u003e87389 \u0026plusmn;2295 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.1819%;\"\u003e\n \u003cp\u003e288 \u0026plusmn;6 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 18.0678%;\"\u003e\n \u003cp\u003e22.1 \u0026plusmn;0.5 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 27.6035%;\"\u003e\n \u003cp\u003e23.8 \u0026plusmn;0.7 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 14.5546%;\"\u003e\n \u003cp\u003e133 \u0026plusmn;3 c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4028%;\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 17.1895%;\"\u003e\n \u003cp\u003e80351 \u0026plusmn;1938 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.1819%;\"\u003e\n \u003cp\u003e268 \u0026plusmn;6 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 18.0678%;\"\u003e\n \u003cp\u003e21.6 \u0026plusmn;0.4 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 27.6035%;\"\u003e\n \u003cp\u003e23.1 \u0026plusmn;0.5 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 14.5546%;\"\u003e\n \u003cp\u003e118 \u0026plusmn;5 d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 7.4028%;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 17.1895%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;10\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;6\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 15.1819%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u0026thinsp;=\u0026thinsp;0.000012\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 18.0678%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u0026thinsp;=\u0026thinsp;0.000007\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 27.6035%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u0026thinsp;=\u0026thinsp;0.000093\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 14.5546%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;10\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;6\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eFor a given parameter, means followed by the same letters in the same row are not significantly different at the 5% threshold according to the Student-Newman-Keuls test.\u003c/em\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\n \u003ch2\u003eEffect of SCSMV on cane yield depending on sugarcane variety\u003c/h2\u003e\n \u003cp\u003eSCSMV severity level had a significant impact on the cane yield (t/ha) of all sugarcane varieties (P\u0026thinsp;\u0026lt;\u0026thinsp;0.005) except R98/4001 for which yield losses were not significantly different whatever the severity level (Table 3). Cane yield losses observed for severity level S1 were less than 10% for M2593/92, R570, R98/4001 and SP711406, but reached 16% and 21% for R98/4158 and SP711406R\u0026eacute;g respectively. Losses increased sharply between S1 and S2 for M2593/92, R570 and SP711406. This increase in yield loss was smoother for R98/4158 and SP711406R\u0026eacute;g. Overall, except for R98/4001 which cane yield loss was 13% for severity level S3, other varieties had significant yield losses between 26% and 34%. The relationship between cane yield losses and severity levels in cuttings was successfully modelled with the three-parameter Gompertz function for all varieties (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e\n \u003ch2\u003eEffect of SCSMV on technological parameters at harvest\u003c/h2\u003e\n \u003cp\u003eSCSMV severity level had no significant effect on the following technological parameters: fiber content in cane (F%C), sucrose content in cane (Pol%C), cane juice sucrose purity, extractable sugar content (ES%) (Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). On the contrary, the level of disease severity had a significant effect on extractable sugar yield (ESY). ESY was the highest for severity level S0 (16.9t/ha) and the lowest for severity level S3 (11.5t/ha) (Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e). Losses in extractable sugar yield (ESYL) of plants from cuttings of severity levels S1, S2, and S3 determined in relation to the yield of plants of severity 0 were 17.6%, 29.4% and 35.3% respectively. The relationship between sugar yield losses and severity levels in cuttings was successfully modelled with the three-parameter Gompertz function for all varieties (Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, Table \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eOverall effect of SCSMV severity level on sugarcane technological parameters: cane insoluble dry matter content (F%C), sucrose content in cane (Pol%C), sucrose purity in cane juice, extractable sugar content (ES%), extractable sugar yield (ESY)\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSeverity\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eF%C\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePol%C\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePurity (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eES%\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eESY (t/ha)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e91.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e90.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2 b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e90.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e91.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4 c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;10\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;6\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cem\u003eFor a given parameter, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test.\u003c/em\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eImpact of SCSMV severity level of cuttings on extractable sugar yield (ESY) and corresponding yield losses compared to asymptomatic cuttings (ESYL) for six varieties evaluated in Zu\u0026eacute;noula, C\u0026ocirc;te d\u0026rsquo;Ivoire\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSeverity level of cuttings\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eESY (t/ha)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eESYL (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eM2593/92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eR570\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e42\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eR98/4001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eR98/4158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eSP711406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"4\"\u003e\n \u003cp\u003eSP711406R\u0026eacute;g\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eS3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cem\u003eFor a given variety, means followed by the same letters are not significantly different at the 5% threshold according to the Student-Newman-Keuls test.\u003c/em\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eParameter estimates of cane yield loss (CYL) and extractable sugar yield loss (ESYL) response curves to SCSMV severity level in cuttings for six varieties evaluated in Zu\u0026eacute;noula, C\u0026ocirc;te d\u0026rsquo;Ivoire.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026alpha;\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026beta;\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026gamma;\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCYL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eM2593/92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.0165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e12.7761\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e34.6969\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.995\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eR570\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.2104\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.5062\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e31.4949\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.975\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eR98/4001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.4181\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.7218\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e38.1211\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.948\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eR98/4158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.7853\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.0139\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e23.9254\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.971\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSP711406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.4576\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.1948\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e83.5575\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.865\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSP711406R\u0026eacute;g\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.9361\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.6749\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27.9069\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.997\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eESYL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eM2593/92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.7532\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e40.5062\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e31.0162\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eR570\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.7231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.9557\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e42.4451\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.996\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eR98/4001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.3859\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.4729\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e14.1941\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.957\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eR98/4158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.0518\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e41.2892\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27.3393\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.996\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSP711406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.6582\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.0036\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e48.5417\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.909\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSP711406R\u0026eacute;g\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.1852\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.6731\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e31.8653\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.993\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e\n \u003cp\u003eParameters \u0026alpha;, \u0026beta; and \u0026gamma; were estimated by fitting the Gompertz model to observed data:\u003c/p\u003e\n \u003cdiv id=\"Eque\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Eque\" name=\"EquationSource\"\u003e$$\\:Yield\\:loss\\:\\left(\\%\\right)=\\gamma\\:{e}^{-\\beta\\:{e}^{-\\alpha\\:*severity}}$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cem\u003eThe R\u003c/em\u003e \u003csup\u003e\u0026nbsp;\u003cem\u003e2\u003c/em\u003e\u0026nbsp;\u003c/sup\u003e \u003cem\u003evalues correspond to the ratio of regression sum of squares to total sum of squares.\u003c/em\u003e\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eSugarcane streak mosaic caused by SCSMV is a new emerging viral disease that has recently been reported in all production areas of C\u0026ocirc;te d'Ivoire (Daugrois et al. 2020, Sorho et al. 2020). An intensive disease monitoring carried out in Zu\u0026eacute;noula between 2018 and 2021 showed that the overall prevalence is extremely high (close to 100%) in this production area but there were different levels of severity across varieties (Ouattara et al. 2024).\u003c/p\u003e \u003cp\u003eThe present study investigated the impact of the SCSMV severity level of sugarcane cuttings on agronomic parameters during vegetation and at harvest, as well as on technological parameters at harvest. We had previously shown the absence of detection of SCSMV in asymptomatic plants (Ouattara et al. 2024), confirming that these plants can be used as uninfected controls in the trials. The present study showed that the germination rate was reduced when the severity of the cuttings was S2 or S3, even though the reduction was not significant for most varieties. SCSMV affected tillering. Its impact was not significant during the vegetative period but was marked and significant at harvest with a reduction ranging from 12% (S1) to 24% (S3). SCSMV significantly reduced plant height and stem diameter at both vegetative and harvest stages. SCSMV had a significant effect on the number of internodes in sugarcane stems (-15% with S3 severity) but interestingly their size was similar regardless of severity level (\u0026asymp;12 cm). The yield of stems from asymptomatic cuttings was 166 t/ha (ranging from 135 to 178 t/ha depending on the veriety) and yield losses ranged from 11% (S1) to 29% (S3). SCSMV severity had a significant impact on cane yield of all sugarcane varieties except R98/4001. The losses in cane yield observed on this variety (13%) were relatively low compared with the other varieties (26\u0026ndash;34%), but this variety has a lower yield than the other ones even when S0 cuttings were used. Generally speaking, all agronomic parameters at both vegetative and harvest stages were affected by SCSMV. This impact may be explained by SCSMV-induced chlorosis on plant leaves reducing the potential expression of photosynthetic activity in sugarcane leaves. Indeed, previous studies (Irvine and James 1971; Bagyalakshmi et al. 2012) indicated that the chlorophyll of sugarcane plants infected by the various mosaics (SCMV, SCSMV, SrMV) was destroyed, photosynthesis was weakened and growth was considerably inhibited, resulting in lower germination rates, reduced tillering and lower sugarcane yields. Studying the variety PS 864, Putra et al. (2014) showed that cane yield decreases as disease level increases, and estimated cane yield losses of 16 to 17%. In our study, cane yield losses were much higher, estimated at up to 34% for the variety M2593/92. The level of severity of SCSMV has no significant effect on fiber content in cane (F%C), sucrose content in cane (Pol%C), cane juice sucrose purity nor extractable sugar content (SE%). This latter is in agreement with previous results. Indeed, Putra et al. (2014) also showed that the level of disease caused by SCSMV does not affect sucrose content. This could be explained by the fact that the reducing sugars, i.e. glucose and fructose, accumulated in the sugarcane stalk during growth are more than sufficient to be converted into sucrose during the sugarcane ripening phase. In contrast, SCMV reduces juice content, sucrose content and crystallization rate, which can ultimately reduce sugarcane yield by 10\u0026ndash;50%, or even 60\u0026ndash;80% (Koike et al. 1989; Viswanathan et al. 2005; He et al. 2006). As a result of its impact on cane yield, SCSMV had a significant effect on extractable sugar yield (ESY). Overall, the yield of extractable sugar obtained with the S0 severity level was 17t/ha and extractable sugar yield losses (ESYL) ranged from 11% (S1) to 30% (S3) but they varied according to variety. Thus the extractable sugar yield losses for severity level S3 ranged from 15% (R98/4001) to 42% (R570). Studying the variety PS 864, Putra et al. (2014) showed that SCSMV caused extractable sugar yield losses of 19\u0026ndash;21%. So, in our study we showed that extractable sugar yield losses could be even much higher for some varieties. The magnitude of the impact of the virus on yield should not be evaluated solely on the basis of the percentage loss. Indeed, it also depends on the yield potential of the variety which is realized in the absence of disease. Thus the varieties SP711406 and SP711406R\u0026eacute;g both have an ESYL of 33% for severity level S3 but the yield potential of the regenerated variety is significantly higher (18.2t/ha vs 15.4t/ha) resulting in a gross loss differential of almost 2t/ha in favour of the regenerated variety. Variety choice is crucial in a high-risk phytosanitary context as it the case with SCSMV which has a very high prevalence regardless of the sugar complex. Our results suggest that priority should be given to high-potential varieties which can more easily produce an acceptable yield in the presence of the virus. With equivalent yield potentials, preference should then be given to varieties that have shown a certain tolerance at low severity (particularly severity level S1). Finally, our results suggest that prophylactic methods should focus on the health status of the cuttings to ensure a healthy planting. Cuttings from asymptomatic plants are essential and pre-nursery and nursery work should guarantee this status.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003eThis work was possible thanks to the partnership agreement that exists between the WASCAL-CEA-CCBAD center and the SUCRIVOIRE Company through agreement number 3004_2019. This field work was financed by the company SUCRIVOIRE. For this purpose, our thanks go to the SUCRIVOIRE Company, especially to Eric BOBLAI and Nicaise KOFFI respectively director and director of plantations of the integrated agricultural unit of Zu\u0026eacute;noula. We also thank the WASCAL-CEA-CCBAD center for its involvement.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003eThe authors have no competing interests that are relevant to the content of this article to declare.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBagyalakshmi K, Parameswari B, Chinnaraja C, Karuppaiah R, Kumar VG, Viswanathan R (2012) Genetic variability and potential recombination events in the HC-Pro gene of Sugarcane streak mosaic virus. Arch Virol 157, 1371-1375. https://doi.org/10.1007/s00705-012-1297-8 \u003c/li\u003e\n\u003cli\u003eDaugrois JH, Roumagnac P, Kouakou Y, Oura OJ, Pita JS (2020) First report of sugarcane streak mosaic virus in sugarcane (\u003cem\u003eSaccharum\u003c/em\u003e spp.) in C\u0026ocirc;te d\u0026apos;Ivoire. New Dis Rep 41:22-22. http://dx.doi.org/10.5197/j.2044-0588.2020.041.022 \u003c/li\u003e\n\u003cli\u003eDaugrois J, Roumagnac P, Julian C, Filloux D, Putra L, Mollov D, Rott P (2024) Historical Review of Sugarcane Streak Mosaic Virus that Has Recently Emerged in Africa. Phytopathol 114 : 668 \u0026ndash; 680. https://doi.org/10.1094/PHYTO-08-23-0291-RVW \u003c/li\u003e\n\u003cli\u003eFAO (2019) Principaux pays agricoles et alimentaires et producteurs. Classification des pays dans le monde, par produit. Division de la statistique de la FAO. www.fao.org/es/ess/top/commodity.html.\u003c/li\u003e\n\u003cli\u003eFAOSTAT (2024): https://www.fao.org/faostat/en/#data (last access: 1 April 2024).\u0026ensp;\u003c/li\u003e\n\u003cli\u003eHall JS, Adams B, Parsons TJ, French R, Lane LC, Jensen SG (1998) Molecular cloning, sequencing and phylogenetic relationships of a new potyvirus: sugarcane streak mosaic virus, and a reevaluation of the classification of the Potyviridae. Mol Phylogenetics Evol 10:323\u0026ndash;332. https://doi.org/10.1006/mpev.1998.0535 \u003c/li\u003e\n\u003cli\u003eHe YS, Li RM (2006) Research Status of Sugarcane Mosaic Virus Disease in China. Sugar Crop China 28 : 47\u0026ndash;49.\u003c/li\u003e\n\u003cli\u003eHema M, Kirthi N, Sreenivasulu P, Savithri HS (2003) Development of recombinant coat protein antibody based IC-RT-PRD for detection and discrimination of Sugarcane streak mosaic virus isolates from Southern Inia. Arch Virol 148: 1185-1193. https://doi.org/10.1007/s00705-003-0015-y \u003c/li\u003e\n\u003cli\u003eInternational Committee on Taxonomy of Viruses (2024) https://ictv.global/taxonomy (accessed July 31, 2024)\u003c/li\u003e\n\u003cli\u003eIrvine, James E (1971)Photosynthesis in Sugarcane Varieties Infected with Strains of Sugarcane Mosaic Virus. Physiol Plantarum 24 : 51\u0026ndash;54. \u003cstrong\u003ehttps://doi.org/10.1111/j.1399-3054.1971.tb06714.x\u003c/strong\u003e \u003c/li\u003e\n\u003cli\u003eKoike H, Gillespie A G (1989) In Ricaud, BT Egan, AG Gillespie, CG Hughes eds., \u0026ldquo;Mosaic Disease of sugarcane-major disease, pp 301-322. \u003c/li\u003e\n\u003cli\u003eKouam\u0026eacute; DK, P\u0026eacute;n\u0026eacute; BC, Zouzou M (2012) S\u0026eacute;lection vari\u0026eacute;tale de la canne \u0026agrave; sucre en C\u0026ocirc;te d\u0026rsquo;Ivoire : Synth\u0026egrave;se des r\u0026eacute;sultats et proposition d\u0026rsquo;un nouveau sch\u0026eacute;ma de s\u0026eacute;lection. J Anim Plant Sci 84 : 194-209. https://www.researchgate.net/publication/288432613 \u003c/li\u003e\n\u003cli\u003eLi W, He Z, Li S, Huang Y, Zhang Z (2011) Molecular characterization of a new strain of Sugarcane streak mosaic virus (SCSMV). Arch Virol 156: 2101-2104. https://doi.org/10.1007/s00705-011-1090-0 \u003c/li\u003e\n\u003cli\u003eMoradi N, Rajabi-Memari H, Mehrabi-Koushki M, Taherkhani K, Moazzen-Reza-Mahalle H, Sheikhi F, Nasirpour N, Sanjabifard Z (2015) First report of Sugarcane streak mosaic virus in Iran. New Dis Rep 32: 2. \u003cstrong\u003ehttps://doi.org/10.5197/j.2044-0588.2015.032.002\u003c/strong\u003e \u003c/li\u003e\n\u003cli\u003eMoradi Z, Mehrvar M, Nazifi E (2018) Genetic diversity and biological characterization of sugarcane streak mosaic virus isolates from Iran. Virus Disease29: 316\u0026ndash;323. https://doi.org/10.1007/s13337-018-0461-5 \u003c/li\u003e\n\u003cli\u003eOuattara MM, Kouame KD, Desbiez C, Girardot G, Ble B, Yao K, Sorho F, Cherif M, Kone N, Kone D, Schoeny A (2024) Sugarcane streak mosaic virus: distribution, prevalence and severity in the integrated farming units of Zu\u0026eacute;noula and Borotou‑Koro, C\u0026ocirc;te d\u0026rsquo;Ivoire. Eur J Plant Pathol, https://doi.org/10.1007/s10658-024-02951-9 \u003c/li\u003e\n\u003cli\u003ePutra LK, Kristini A, Achadian EM, Damayanti TA (2014) Sugarcane streak mosaic virus in Indonesia: Distribution, characterization, yield losses and management approaches. Sugar Tech, 16, 392-399. https://doi.org/10.1007/s12355-013-0279-9 \u003c/li\u003e\n\u003cli\u003eSorho F, S\u0026eacute;r\u0026eacute;m\u0026eacute; D, Kouam\u0026eacute; DK., Kon\u0026eacute; N, Yao KJ, Ouattara MM, Tapsoba WP, Ouattara B, Kon\u0026eacute; D (2020) First report of sugarcane streak mosaic virusinfecting sugarcane in C\u0026ocirc;te d\u0026rsquo;Ivoire. Plant Dis 105: 0191-2917. https://doi.org/10.1094/PDIS-07-19-1398-PDN \u003c/li\u003e\n\u003cli\u003eViswanathan R, Karuppaiah R, Ganesh KV (2011) Expression of sugarcane streak mosaic virus (scsmv) coat protein in expression vector as a fusion protein with maltose binding protein. J Sugarcane Res 1 : 63 \u0026ndash; 68 \u003c/li\u003e\n\u003cli\u003eViswanathan R, Balamuralikrishnan M (2005) Impact of mosaic infection on growth and yield of sugarcane. \u003cem\u003eSugar Tech,\u003c/em\u003e \u003cstrong\u003e7 \u003c/strong\u003e: 61\u0026ndash;65. https://doi.org/10.1007/BF02942419 \u003c/li\u003e\n\u003cli\u003eXu DL, Zhou GH, Xie YJ, Mock R, Li R (2010) Complete nucleotide sequence and taxonomy of Sugarcane streak mosaic virus, member of a novel genus in the family \u003cem\u003ePotyviridae\u003c/em\u003e. Virus Genes\u003cem\u003e 40\u003c/em\u003e, 432-439. https://doi.org/10.1007/s11262-010-0457-8 \u003c/li\u003e\n\u003cli\u003eZhang RY, Li WF, Huang YK (2018) Genetic diversity and population structure of Sugarcane streak mosaic virus in Yunnan province, China. Trop Plant Pathol 43: 514-519. https://doi.org/10.1007/s40858-018-0244-y \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table 3","content":"\u003cp\u003eTable 3 is not available with this version.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Côte d’Ivoire, Gompertz model, SCSMV, sugarcane, yield loss, Zuénoula ","lastPublishedDoi":"10.21203/rs.3.rs-6206450/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6206450/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSugarcane streak mosaic virus (SCSMV) is an emerging virus in C\u0026ocirc;te d'Ivoire. First observed less than 10 years ago, it is now present in all sugar production areas, with a high prevalence in some sites and rapid increase in others. The aim of this study was to assess the impact of SCSMV on cane and sugar yields of six commercial sugarcane varieties in the Zu\u0026eacute;noula integrated agricultural unit. Cuttings with four different levels of disease severity were planted and monitored. Agronomic parameters and technological parameters were determined. The level of SCSMV severity on cuttings had a significant effect on all agronomic parameters. Overall, germination rate, tillering, plant height, stem diameter, number of internodes and cane yieldat harvest were significantly reduced by 15 to 29% for plants deriving from cuttings at the highest severity level. SCSMV had no significant effect on fiber content in cane, sucrose content in cane, cane juice sucrose purity and extractable sugar content. Depending on varieties, cane yield losses and extractable sugar yield losses ranged from 13 to 34% and 15 to 42% respectively. The relationships between yield losses and severity levels in cuttings were successfully modelled with the three-parameter Gompertz function for all varieties. Considering the deleterous effect of SCSMV on cane and sugar yields, the planting of healthy cuttings is the key prophylactic mesure to mitigate virus impact.\u003c/p\u003e","manuscriptTitle":"Impact of sugarcane streak mosaic virus (SCSMV) on cane and sugar yields of some commercial varieties in Zuénoula, Côte d'Ivoire","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-02 03:58:16","doi":"10.21203/rs.3.rs-6206450/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"0f9a6cae-b528-43f1-94c5-d35032e6b9d6","owner":[],"postedDate":"May 2nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-06-24T09:53:45+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-02 03:58:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6206450","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6206450","identity":"rs-6206450","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}