Microorganisms Improve Physiological Performace to Oil Palm Seedings Growth Promote

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It is the oilseed that has stood out in the production of oil of high economic value. The main global producers are Malaysia and Indonesia. In Brazil, the cultivated area is concentrated in the state of Pará. Seedling production requires a long nursery period and high consumption of chemical fertilizers. Currently, studies reporting the use of microbial technology to minimize the excessive use of chemical fertilizers and promote earlier seedling development. The objective of this study was to evaluate biometrics, biomass accumulation and gas exchange in oil palm seedlings inoculated with microorganisms. The experiment was conducted in a greenhouse, in a completely randomized design with five treatments, consisting of the inoculation of four Trichoderma microorganisms and a control, with five replications. The data were subjected to analysis of variance and treatment means were compared using the SNK test (P < 0.05). The inoculation of microorganisms promoted the growth of oil palm seedlings. The height, stem diameter, number of leaves, leaf area, root length, total chlorophyll, net photosynthesis, stomatal conductance, transpiration, dry mass of leaves, aerial part, root and total, increased on average in inoculated seedlings compared to control seedlings. Total soluble sugars, on the other hand, decreased for inoculated plants compared to the control. Starch decreased compared to control. Therefore, the results show that better photosynthetic performance may be associated with the promotion of growth in oil palm seeds inoculated with microorganisms. It is likely that some physiological mechanisms are being activated by microorganisms for greater growth. Elaeis guineensis microbial technology growth photosynthesis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 INTRODUCTION The oil palm ( Elaeis guineensis Jacq.) belongs to the Arecaceae family, originating from the African continent. Among oilseed crops, it is the most productive in the world, standing out in the production of oil of high economic value, with potential for the production of biodiesel, in addition to being widely used in the production of foodstuffs, pharmaceuticals, among others (Chagas et al., 2019 ) The main world producers are Malaysia and Indonesia, together they represent 80% of world production, and export large quantities of oil to the international market, especially to the European Community, the United States, India and China (IBGE, 2020). In Brazil, the Brazilian Association of Oil Palm Producers (MAPA 2018) estimates a cultivated area of around 236 thousand hectares, with a leading role in the State of Pará (88%), followed by the States of Bahia (11%) and Roraima (1%). The production of oil palm seedlings with standard quality requires a long nursery period, high consumption of chemical fertilizers and high operating costs. According to data from the Brazilian Agriculture and Livestock Confederation (2022), from January 2020 to March 2022, the nominal prices of the main fertilizers increased by 288%. However, there are studies that show that microbial technology is effective in minimizing the use of too much chemical fertilizer, as well as producing an early and robust plant (Bender et al. 2016; Sattar et al. 2019 ). Microorganisms that promote plant growth, such as some genera of fungi and bacteria, considered free-living, constitute a technology capable of generating benefits for agricultural production, reducing production costs for the producer and negative impacts on the environment (Glick 2012 ). Several genera of bacteria that have the ability to colonize the roots of seedlings live in full rhizosphere activity and are therefore called rhizobacteria. These bacteria and some fungi, mainly from the genus Trichoderma, are the most studied microorganisms and used as biofertilizers and biocontrol agents (Dutta and Podil, 2010)Several studies have highlighted the benefit of using growth-promoting microorganisms in palm trees, such as oil palm (Lima et al. 2020), açaí palm (Castro et al. 2019 ) and coconut palm (Cardoso et al. 2021 ). The hypothesis of the present study is that microorganisms alter photosynthetic performance and, from this, enhance the growth of oil palm seedlings. The objective was to evaluate growth through biometrics and biomass accumulation, and measure photosynthetic performance through gas exchange in leaves of oil palm seedlings inoculated with microorganisms. MATERIAL AND METHODS The experiment was conducted at the Plant Protection Laboratory (LPP/UFRA) and in a greenhouse located in Belém-PA, (01°27'29”S, 48°26'06”W), with an area of approximately 70m 2 , composed through door and walls with wooden structure and steel screens, canvas roof, thick cement floor, 3.40m ceiling height, ventilation and natural lighting. The greenhouse was covered with 100 µm polyethylene film containing anti-UV radiation. The experiment was carried out in a completely randomized design with five treatments: 4 growth-promoting microorganisms and the control, with five replications each. Oil palm seeds (Compacta x Ghana genotype) were sown in plastic trays for seedling production containing a substrate composed of crushed coconut fiber (Golden Mix Mix). At 30 days after germination, the seedlings that had two expanded leaves and a height close to 12 cm were transplanted into plastic bags (45 x 45 cm, length x height) with a volume of 25.74 dm 3 containing terrycloth as substrate. The cultivation was carried out in the nursery of the Federal Rural University of the Amazon in Belém, PA, (1° 27' 13.234" S 48° 26' 32.658" W) which presents climatic characteristics of the AFI type according to the Koppen-Geiger classification. During the experimental period (February to September 2021) the environmental conditions were 32 ± 2 ºC air temperature, 75 ± 5% relative humidity, 2 ± 0.2 kPa air DPV and 800 ± 100 µmol m − 2 s − 1 470 of incident radiation. The pH of the substrate and the concentrations of macro and micronutrients were adjusted according to the soil analysis (fertilization manual 2022). The plants were irrigated daily by self-compensation drip to replace water lost through evapotranspiration and maintain soil moisture close to pot capacity, which was measured by weighing the experimental units (Klar et al. 1966 ). The bacteria UFRABA01 (Bacillus amyloliquefaciens) , UFRAB124 (Bacillus sp.) and MIX of five strains of Trichoderma Asperellum (T06, T09, T12 and T52) and FT-12 (Trichoderma sp.) from oil palm cultivation, where they were obtained and stored in the microorganism bank of the Plant Protection Laboratory (LPP) located at the Federal Rural University of the Amazon (UFRA). The rhizobacteria were cultivated in solid medium 523 (Kado et al. 1970) for 48 h at 28 ° C. The bacterial suspensions were prepared with distilled and sterilized water and were adjusted in the spectrophotometer to an absorbance of 0.1 at 550 nm, which corresponds to a bacterial suspension density of 10 − 8 CFU. mL − 1 . The Trichoderma fungus isolates were cultivated in PDA (potato dextrose agar) culture medium and incubated for five days at 28 ° C, where a suspension was prepared from each isolate at a concentration of 10 8 conidia / ml (Rêgo et al. 2014). The seedlings had their roots standardized by cutting them with scissors and before transplanting them into plastic bags with the substrate, they were immersed in the bacterial and fungal suspension for 20 min. Control seedlings were immersed in liquid culture medium 523 (Kado et al. 1970) without inoculation of microorganisms. After that, three inoculations were carried out at 15, 30 and 45 days after transplanting, adding 100 mL of the bacterial and fungal suspension to the base of the plant to evaluate the response in the plant and the promotion of plant growth (Lima et al. 2020). Biometric data and biomass accumulation were evaluated six months after transplanting. Plant height and root length were measured with a graduated metal ruler, while the stem diameter was measured with a digital caliper (accuracy of 0.02 mm). The number of leaves was evaluated through direct counting of the emitted leaves and the total leaf area was estimated by the dry mass of leaf discs measuring 7 mm in diameter (3 discs per leaf). The seedlings were sectioned into roots and shoots, and dried in a forced ventilation oven at 65 ºC, until constant weight, for weighing and determination of dry biomass (Baxter and Stewart 2013 ). Gas exchange parameters were measured in the second physiologically mature and completely expanded leaf, from the apex to the base, from the second month after inoculation with growth-promoting microorganisms in oil palm seedlings. Net CO 2 assimilation ( A ), stomatal water vapor conductance ( gs ), intercellular CO 2 concentration ( Ci ) and transpiration rate ( E ) were measured between 10:00 and 12:00 hours using a system portable open-flow gas exchange system (LI-6400XT, LI-COR, Lincoln, NE) under an external CO 2 concentration of 400 µmol mol − 1 air and artificial photosynthetically active radiation (PAR) of 1000 µmol photons m 2s-1. This measurement interval (10:00–12:00 h) was adjusted according to the diurnal gas exchange curve previously obtained for the species. All measurements were carried out under air temperature of 31 ± 2°C, relative humidity of 63 ± 2%, incident radiation of 600 ± 100 µmol m-2s-1 and air vapor pressure deficit of 1.9 ± 0.2kPa. The amount of blue light was adjusted to 10% of photosynthetically active radiation to optimize stomatal opening. The relative chlorophyll content was initially estimated by the chlorophyllometer 258 (SPAD − 502) in the same leaves used for gas exchange measurements. To quantify total soluble sugars and starch, the methodology of Dubois (1956) was used. The plant samples were subjected to extraction with 80% ethanol by heating in a water bath at 100°C. After submission at high temperature, the samples were centrifuged at 10,000 rpm for 5 minutes, and from this activity, the supernatant destined for sugar analysis and the pellet destined for starch analysis were separated. For total soluble sugars, 100µL of supernatant must be collected and 400 µL of distilled water must be added. Following the analyses, 0.5 mL of 5% phenol and 2.5 mL of concentrated H 2 SO 4 must be added . Finally, the samples must be vortexed and left to react for 20 minutes. The reading can be done on a spectrophotometer at an absorbance range of 490 nm. The pellet must be extracted in HClO 4 for 30 minutes at room temperature. Following extraction, samples must be centrifuged and the supernatant collected. The starch analytical process follows the same criteria as total soluble sugars. The reading must be carried out using a spectrophotometer with an absorbance range of 490 nm. Data were subjected to analysis of variance (ANOVA) and means were compared using the Student-Newman-Keuls test ( P < 0.05) using the R software (R Core Team, 2022). To represent the data obtained, the mean and standard error were calculated, in addition to creating graphs in the EXCEL program, Microsoft 365 version. RESULTS All seedlings inoculated with microorganisms increased biometric variables. For height, the increases were 36% for MIX, 36% for UFRAT12, 42% for UFRABA01 and 32% for UFRA124 in relation to non-inoculated seedlings (control). The duct diameter increased by 45% for MIX, 48% for UFRAT12, 55% for UFRABA01 and 49% for UFRA124 in relation to the control. The number of leaves increased by 13% for Mix, 13% for UFRAT12, 25% for UFRABA01 and 13% for UFRA124 compared to the control. The relative total chlorophyll content (SPAD) increased in inoculated seedlings by 17%, 13% and 14% for Mix, UFRAT12 and UFRABA01, respectively, in relation to control seedlings (Fig. 1). Leaf area increased in inoculated seedlings by 262%, 188%, 217% and 225% for UFRABA01, UFRA124, UFRAT12 and Mix, respectively, in relation to control seedlings (Fig. 1). Root length increased in inoculated seedlings by 54%, 71%, 20% and 18% for Mix, UFRAT12, UFRAB01 and UFRAB124, respectively, compared to control seedlings (Fig. 1). The inoculated seedlings increased biomass accumulation in relation to the control. For leaf dry mass, shoot dry mass and total dry mass there was an increase of 241%, 228% and 213% respectively for UFRABA01 compared to the control. Root dry mass increased by 71% for MIX in relation to the control (Fig. 2). The inoculated seedlings increased the average values of gas exchange parameters in relation to the control, except for the concentration of intercellular carbon ( C i ) (Fig. 2). For net photosynthesis there was an increase of 67% for UFRABA01, 57% for UFRA124, 63% for UFRAT12 and 59% for the mix compared to the control. Stomatal conductance increased by 24% for UFRABA01, 18% for UFRA124 and 29% for UFRAT12 and Mix in relation to the control. Transpiration increased in inoculated seedlings by 21%, 19%, 24% and 24% for UFRABA01, UFRA124, UFRAT12 and Mix, respectively, in relation to control seedlings (Fig. 3). The inoculated seedlings reduced the average values of the total sugar parameters in relation to the control by 7.8% for MIX, UFRABA01, UFRAB124 and 37.07% for UFRAT12. In the starch evaluation, there was an average reduction of 24% for UFRAT12 and UFRAB124 in relation to the control (Figure 4). DISCUSSION The present study sought to report the physiological changes modulated by microorganisms to promote the growth of oil palm seedlings. The advantages of using microorganisms have already been studied in oil palm (Mba et al. 2015 ), (Lima et al. 2020), and other palm trees such as açaí (Castro et al. 2019 ) and coconut trees (George et al. 2013 ), which highlighted the benefits of these microorganisms in promoting growth and increasing vigor. The rhizosphere is a dynamic and complex environment in which roots play a very important role with the exudation of compounds such as carbohydrates, amino acids, organic acids, proteins, vitamins and several other compounds whose function is to attract microorganisms, which can help nutrient availability and biosynthesis of compounds related to plant growth (Gouda et al. 2018 ). All microorganisms induced an increase in root length and biomass. This increase in the root is possibly influenced due to fungi have the ability to produce elements such as acid and alkaline phosphatase enzymes, and organic acids that increase the amount of phosphorus available to plants, as observed in in vitro solubilization tests carried out by Silva et al. ( 2012 ) who tested the ability of the 4 isolates from the treatment with the mixture of four isolates of Trichoderma asperellum (T06; T09; T12; T52) to solubilize calcium phosphate in solid culture medium (Ribas et al. 2016 ). The work developed by Syafiq et al. (2021), showed that fungi of the species Trichoderma asperellum promote the growth of inoculated oil palm seedlings compared to non-inoculated seedlings. This increase occurs because these microorganisms are probably able to induce the production of phytohormones, siderophores and substances that increase the solubilization of insoluble phosphorus. In other words, the larger root system increases the contact area of the roots with the soil and improves water and nutrient absorption; and this may have influenced the accumulation of aerial part biomass. It was observed that all growth-promoting microorganisms induced an increase in biometric and biomass parameters, which can be attributed to several direct or indirect mechanisms, such as direct mechanisms, rhizobacteria act in the direct solubilization of insoluble P sources, N fixation and/or regulation of the concentration of plant growth regulators, such as indole acetic acid (IAA) produced by some rhizobacteria (Nascente et al. 2017 ). Studies by Lima et al . (2020) show that the use of microorganisms causes hormonal changes, as when the rhizobacteria UFRAB01 was inoculated in oil palm seedlings, it resulted in an increase of 66% the content of indole acetic acid (IAA), 44% for abscisic acid (ABA) and a 24% reduction in the concentration of 1-carboxylic acid-1-aminocyclopropane (ACC) and an increase in the ratio of indole acetic acid (IAA)/1-carboxylic acid-1-aminocyclopropane (ACC) by 100% compared to the control, that is, this increase in phytohormone levels in leaf tissues may be associated with the biometric increase in the biomass of the root, aerial part and on the efficiency of nutrient use in oil palm seedlings in the nursery phase. The relative total chlorophyll content increased in seedlings that were inoculated with growth promoters. Chlorophylls are pigments responsible for capturing, absorbing and transmitting light that will be used in photosynthesis. These pigments play a fundamental role in the conversion of light radiation into chemical energy, in the form of ATP and NADPH (Taiz and Zeiger 2009). Chlorophylls are related to the photosynthetic efficiency of plants, as well as their growth and adaptation to different environments (De Jesus and Marenco 2008 ). According to Castro et al. (2014), a plant that has a higher concentration of chlorophyll a may have higher net photosynthesis rates, due to the greater efficiency of the photosynthetic system in the PSI and PSII photosystems. Thus, the greater stomatal opening that occurred in inoculation treatments allowed more CO 2 molecules to enter and be fixed, through the efficiency of energy production caused by the greater presence of chlorophylls in the leaves. Thus, the optimization of the photosynthetic process allowed the production of more photoassimilates, resulting in a greater increase in biomass. The increase in the aerial part, as well as the number of leaves and leaf shoots, can be associated with the ability of rhizobacteria to induce the synthesis of gibberellins and cytokinins that regulate leaf expansion and chlorophyll synthesis (Dodd et al. 2010 ; Kang et al. 2014 ). The greatest number of leaves was obtained only with UFRAB01, however the other rhizobacteria and fungi induced greater leaf area, which resulted in greater growth of the aerial part and accumulation of leaf biomass. These benefits can be attributed to the ability of rhizobacteria to signal the gibberellin and cytokinin biosynthesis pathway (Chauhan et al. 2015 ). Cardoso et al., 2021 , working with microorganisms, observed that there was a promotion of the growth of coconut seedlings with significant increases in the dry matter weight of the aerial part (47%), dry matter weight of the root (122%), dry matter weight total drought (35%), height (26%) and diameter (30%) compared to the control treatment. The larger leaf area directly influences greater light capture and CO 2 assimilation (Zhang et al. 2017). All growth promoters induced an increase in net CO 2 assimilation ( A ), stomatal conductance ( gs ) and transpiration ( E) in relation to control plants. This response suggests that the important steps of photosynthesis were enhanced by promoters, such as a possible modulation of the activity of the Rubisco enzyme, vital for fixing the carbon dioxide molecule. Thus, the results suggest a better integrity of the photosynthetic apparatus that can contribute to the improvement in CO 2 assimilation activity and production of photoassimilates. The greatest assimilation of CO 2 ( A ) can be attributed to the greater degree of stomata opening (gs), which allows greater entry of CO 2 into the leaves and favors an increase in net photosynthesis. In rice plants inoculated with rhizobacteria, an increase in the net photosynthetic rate was observed, which was attributed to the positive influence on the opening and closing of stomata, which directly affected gas exchange and contributed to plant growth (Nascente et al. 2017 ). The greater stomatal opening, in addition to favoring the entry of CO 2 into the leaves, directly influences the greater loss of water through transpiration (Silva et al. 2017 ). In this study, the higher transpiration rate can be attributed to the greater stomatal opening induced by all growth promoters. The higher total transpiration rate induced by the promoters can be attributed, in addition to the stomatal opening, to the greater total leaf area and aerial part. When there is abundant water and solar radiation incident on the leaves, this ends up favoring high photosynthetic activity, there is a high demand for CO 2 within the leaf, and the stomatal pores open widely, reducing stomatal resistance to the diffusion of CO 2 (Flexas et al. 2012 ). In this situation, there are large losses of water through transpiration, however, when there are large amounts of water it becomes viable for the plant to “exchange” for photosynthesis elements to increase its growth (Taiz and Zeiger 2013; Castro et al. 2019 ). There were no changes in the intercellular concentration of CO 2 ( Ci ), however, when we evaluated this combined with other physiological variables, we found that biostimulated seedlings had a better efficiency of the photosynthetic apparatus because induced an increase in net CO2 assimilation ( A ), stomatal conductance ( gs ) and transpiration – ( E ). These benefits can result in greater production of photoassimilates, which can be allocated to plants to support growth or be assimilated into reserve products or used by promoters through root exudates (Silva et al. 2017 ). All biostimulated plants showed a reduction in total soluble sugar content. According to (Smeekens 2003 ), these sugars are used to produce energy through cellular respiration, transforming glucose into carbon dioxide and water, releasing energy that is used to drive growth processes. Furthermore, AST are converted into different types of organic compounds, such as starch, lipids, proteins and nucleic acids, which are essential for cell growth and the formation of plant tissues (Rolland et al. 2006 ; Ruan 2014 ). In this context, it can be inferred that the lower AST content in inoculation treatments is due to its conversion into an increase in biomass, resulting in an increase in the parameters of height, stem diameter, number of leaves and root length. Treatments with FT12 and UFRAB124 showed lower starch concentration compared to the control. This can be explained because, throughout the day, plants store excess products generated by photosynthesis in the form of starch. This starch is an energy reserve that is used when sunlight is not available to carry out photosynthesis. During this process, starch is converted into simpler sugars, such as glucose and fructose, which are transported out of the chloroplasts and transformed into sucrose. This strategy makes it possible to meet the energy needs of plants when the photosynthetic machinery is not functioning (Smirnova et al. 2015 ). The high concentration of starch in oil palm seedlings is probably related to the reserve tissues, in the case of palm trees, the haustorium, which contains a large amount of this carbohydrate at this stage, corroborating the results of starch concentrations in seedlings of the Butia palm species. capitata (Oliveira et al. 2013 ) and Acrocomia aculeata (Bicalho et al. 2016 ). (Shoresh and Harman 2008 ) observed that the increase in starch in corn seedlings inoculated with Trichoderma harzianum was related to the content of glyceraldehyde-3-P-dehydrogenase (GAPDH), which is an essential enzyme in the glycolytic pathway and this pathway is closely related starch synthesis. CONCLUSION The better photosynthetic performance induced by the inoculation of microorganisms in oil palm seedlings induced the promotion of crop growth. Probably, some physiological mechanisms that involve the modulation of CO 2 assimilation and mobilization of photoassimilates may be activated by microorganisms to sustain the large energy demand necessary for greater growth. The greater growth of seedlings inoculated with microorganisms can contribute to better quality in the production of seedlings with less time spent in the nursery. The inoculation of microorganisms can be used as a clean technology that contributes to the sustainable management of the production of Oil Palm seedlings in nurseries. Declarations CREDIT AUTHOR STATEMENT Authors' contribution, using an accurate and detailed description of their various contributions to the published work. - 1 Danielle Pereira Mendonça: Conceptualization, Methodology, Validation, Research, Resources, Data Curation, Writing - Original Draft, Writing - Review and Editing, Visualization. - 1 Maria Luiza Brito Brito: Methodology, Validation, Research, Resources - 1 Juliana Tavares Dias: Methodology, Validation, Research, Resources - 1 Verônica Daniely Pereira Paes da Silva: Methodology, Validation, Research, Resources - 1 Mauro Junior Borges Pacheco: Resources, Data Curation, Writing - Original Draft - 1 Thayná da Cruz Ferreira: Writing - Review and Editing - 1 Maria Carolina Sarto Fernandes Rodrigues: Writing - Review and Editing - 2 Dalton Dias da Silva Júnior: Conceptualization, Methodology, Resources - 1 Gisele barata Silva: Conceptualization, Methodology, Resources - 1* Gledson Luiz Salgado de Castro: Conceptualization, Methodology, Validation, Research, Resources, Data Curation, Writing - Original Draft, Writing - Review and Editing, Visualization. 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Plant Physiol 147:2147–2163. https://doi.org/10.1104/PP.108.123810 Silva JC da, Torres DB, Lustosa DC, et al (2012) Biocontrol of sheath blight on rice and growth promotion by Trichoderma isolates from the Amazon. Revista de Ciências Agrarias - Amazon Journal of Agricultural and Environmental Sciences 55:243–250. https://doi.org/10.4322/RCA.2012.078 Silva PA, Cosme VS, Rodrigues KCB, et al (2017) Drought tolerance in two oil palm hybrids as related to adjustments in carbon metabolism and vegetative growth. Acta Physiol Plant 39:1–12. https://doi.org/10.1007/S11738-017-2354-4/TABLES/1 Smeekens S (2003) SUGAR-INDUCED SIGNAL TRANSDUCTION IN PLANTS. https://doi.org/101146/annurev.arplant51149 51:49–81. https://doi.org/10.1146/ANNUREV.ARPLANT.51.1.49 Smirnova J, Fernie AR, Steup M (2015) Starch degradation. Starch: Metabolism and Structure 239–290. https://doi.org/10.1007/978-4-431-55495-0_7/COVER Valente Lima J, Tinôco RS, Olivares FL, et al (2020) Hormonal imbalance triggered by rhizobacteria enhance nutrient use efficiency and biomass in oil palm. Sci Hortic 264:109161. https://doi.org/10.1016/J.SCIENTA.2019.109161 Ministério da Agricultura, Pecuária e Abastecimento Conselho do Agronegócio Câmara Setorial da Cadeia Produtiva da Palma de Óleo 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 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-3386256","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":242673111,"identity":"b22e98b3-3a9c-4713-9be4-eb0b779bcf83","order_by":0,"name":"Danielle Pereira Mendonça","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-4641-1748","institution":"Universidade Federal Rural da Amazônia: Universidade Federal Rural da Amazonia","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Danielle","middleName":"Pereira","lastName":"Mendonça","suffix":""},{"id":242673112,"identity":"a0a18f40-f8e5-46e0-9f23-50c6264de601","order_by":1,"name":"Maria Luiza Brito Brito","email":"","orcid":"","institution":"Universidade Federal Rural da Amazônia: Universidade Federal Rural da Amazonia","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Maria","middleName":"Luiza Brito","lastName":"Brito","suffix":""},{"id":242673113,"identity":"295f59cb-e626-495e-9f2f-97424f84fd7c","order_by":2,"name":"Juliana Tavares Dias","email":"","orcid":"","institution":"Universidade Federal Rural da Amazônia: Universidade Federal Rural da Amazonia","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Juliana","middleName":"Tavares","lastName":"Dias","suffix":""},{"id":242673114,"identity":"157f3f78-64bd-46e7-8275-77f242546f91","order_by":3,"name":"Verônica Daniely Pereira Paes da Silva","email":"","orcid":"","institution":"Universidade Federal Rural da Amazônia: Universidade Federal Rural da Amazonia","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Verônica","middleName":"Daniely Pereira 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Universidade Federal Rural da Amazonia","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Maria","middleName":"Carolina Sarto Fernandes","lastName":"Rodrigues","suffix":""},{"id":242673118,"identity":"46f70558-a21e-4257-862e-b5670f0db410","order_by":7,"name":"Dalton Dias da Silva Júnior","email":"","orcid":"","institution":"Universidade Federal Rural da Amazônia: Universidade Federal Rural da Amazonia","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Dalton","middleName":"Dias da Silva","lastName":"Júnior","suffix":""},{"id":242673119,"identity":"166046ca-d43f-4180-837f-b78ebb1b8eb9","order_by":8,"name":"Gisele Barata Da Silva","email":"","orcid":"","institution":"Universidade Federal Rural da Amazônia: Universidade Federal Rural da Amazonia","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gisele","middleName":"Barata Da","lastName":"Silva","suffix":""},{"id":242673120,"identity":"fafb215a-24c1-4b9b-958c-5cb2351253c9","order_by":9,"name":"Gledson Luiz Salgado De Castro","email":"","orcid":"","institution":"Universidade Federal Rural da Amazônia: Universidade Federal Rural da Amazonia","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gledson","middleName":"Luiz Salgado","lastName":"De Castro","suffix":""}],"badges":[],"createdAt":"2023-09-25 20:59:51","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3386256/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3386256/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":45379286,"identity":"0aa64b69-1c84-4aa0-8be7-1485d569990e","added_by":"auto","created_at":"2023-10-28 18:16:43","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":24351,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of growth-promoting microorganisms on height (A), stem diameter (B), number of leaves (C), leaf area (D), total chlorophylls (E) and root length (F) in seedlings oil palm\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eColumns represent means ± standard deviation of 5 replicates. Different capital letters indicate significant differences between means according to the SNK test ( \u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3386256/v1/5a14959742c20ee7450a7631.png"},{"id":45379909,"identity":"f5e79f29-1d8b-423a-a2f8-7a84be5f8ce4","added_by":"auto","created_at":"2023-10-28 18:24:43","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":24485,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of growth-promoting microorganisms on leaf dry mass (A), shoot dry mass (B), root dry mass (C) and total dry mass (D) in oil palm seedlings.\u003c/p\u003e\n\u003cp\u003eColumns represent means ± standard deviation of 5 replicates. Different capital letters indicate significant differences between means according to the SNK test ( \u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3386256/v1/fbaae21ebd74b9c0e394e1b0.png"},{"id":45379288,"identity":"83e3dedc-ccae-46be-b6e0-b869768191fe","added_by":"auto","created_at":"2023-10-28 18:16:43","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":24753,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of growth-promoting microorganisms on Height (A) Net photosynthesis - A, (B) stomatal conductance - gs, (C) intercellular carbon Ci and (D) transpiration - E in oil palm seedlings.\u003c/p\u003e\n\u003cp\u003eColumns represent means ± standard deviation of 5 replicates. Different capital letters indicate significant differences between means according to the SNK test ( \u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3386256/v1/2a40a21769823a5e30df2689.png"},{"id":45379908,"identity":"a7040aff-2821-4880-af02-f80b36c1e020","added_by":"auto","created_at":"2023-10-28 18:24:43","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":20987,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of growth-promoting microorganisms on total soluble sugars – AST (A) and starch (B) in oil palm seedling \u003cem\u003eleaves.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eColumns represent means ± standard deviation of 5 replicates. Different capital letters indicate significant differences between treatment means according to the SNK test ( \u003cem\u003eP \u003c/em\u003e\u0026lt;0.05).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3386256/v1/52df057b62b8be1b8b41fc66.png"},{"id":45379290,"identity":"9c61b59e-5e73-4d66-bfc1-b576f015b3ae","added_by":"auto","created_at":"2023-10-28 18:16:43","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":180337,"visible":true,"origin":"","legend":"\u003cp\u003eOil palm seedlings, 6 months old, inoculated with microorganisms. (T1) Trichoderma Mix; (T2) UFRAB01; (T3) Trichoderma sp. ; (T4) UFRAB124 and (T5) control.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3386256/v1/6a27afead66290d0ec252962.png"},{"id":52632145,"identity":"dafe8f2c-09b8-4672-b4d9-55c17969fed0","added_by":"auto","created_at":"2024-03-13 20:22:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":670139,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3386256/v1/2d38a7b5-a6e6-48fc-955e-9e051c76e6ce.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eMicroorganisms Improve Physiological Performace to Oil Palm Seedings Growth Promote\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThe oil palm (\u003cem\u003eElaeis guineensis\u003c/em\u003e Jacq.) belongs to the \u003cem\u003eArecaceae\u003c/em\u003e family, originating from the African continent. Among oilseed crops, it is the most productive in the world, standing out in the production of oil of high economic value, with potential for the production of biodiesel, in addition to being widely used in the production of foodstuffs, pharmaceuticals, among others (Chagas et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eThe main world producers are Malaysia and Indonesia, together they represent 80% of world production, and export large quantities of oil to the international market, especially to the European Community, the United States, India and China (IBGE, 2020). In Brazil, the Brazilian Association of Oil Palm Producers (MAPA 2018) estimates a cultivated area of around 236 thousand hectares, with a leading role in the State of Par\u0026aacute; (88%), followed by the States of Bahia (11%) and Roraima (1%).\u003c/p\u003e \u003cp\u003eThe production of oil palm seedlings with standard quality requires a long nursery period, high consumption of chemical fertilizers and high operating costs. According to data from the Brazilian Agriculture and Livestock Confederation (2022), from January 2020 to March 2022, the nominal prices of the main fertilizers increased by 288%. However, there are studies that show that microbial technology is effective in minimizing the use of too much chemical fertilizer, as well as producing an early and robust plant (Bender et al. 2016; Sattar et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Microorganisms that promote plant growth, such as some genera of fungi and bacteria, considered free-living, constitute a technology capable of generating benefits for agricultural production, reducing production costs for the producer and negative impacts on the environment (Glick \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSeveral genera of bacteria that have the ability to colonize the roots of seedlings live in full rhizosphere activity and are therefore called rhizobacteria. These bacteria and some fungi, mainly from the genus Trichoderma, are the most studied microorganisms and used as biofertilizers and biocontrol agents (Dutta and Podil, 2010)Several studies have highlighted the benefit of using growth-promoting microorganisms in palm trees, such as oil palm (Lima \u003cem\u003eet al.\u003c/em\u003e 2020), a\u0026ccedil;a\u0026iacute; palm (Castro et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) and coconut palm (Cardoso et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe hypothesis of the present study is that microorganisms alter photosynthetic performance and, from this, enhance the growth of oil palm seedlings. The objective was to evaluate growth through biometrics and biomass accumulation, and measure photosynthetic performance through gas exchange in leaves of oil palm seedlings inoculated with microorganisms.\u003c/p\u003e"},{"header":"MATERIAL AND METHODS","content":"\u003cp\u003eThe experiment was conducted at the Plant Protection Laboratory (LPP/UFRA) and in a greenhouse located in Bel\u0026eacute;m-PA, (01\u0026deg;27'29\u0026rdquo;S, 48\u0026deg;26'06\u0026rdquo;W), with an area of approximately 70m 2 \u003csup\u003e,\u003c/sup\u003e composed through door and walls with wooden structure and steel screens, canvas roof, thick cement floor, 3.40m ceiling height, ventilation and natural lighting. The greenhouse was covered with 100 \u0026micro;m polyethylene film containing anti-UV radiation. The experiment was carried out in a completely randomized design with five treatments: 4 growth-promoting microorganisms and the control, with five replications each.\u003c/p\u003e \u003cp\u003eOil palm seeds (Compacta x Ghana genotype) were sown in plastic trays for seedling production containing a substrate composed of crushed coconut fiber (Golden Mix Mix). At 30 days after germination, the seedlings that had two expanded leaves and a height close to 12 cm were transplanted into plastic bags (45 x 45 cm, length x height) with a volume of 25.74 dm 3 containing terrycloth as substrate. The cultivation was carried out in the nursery of the Federal Rural University of the Amazon in Bel\u0026eacute;m, PA, (1\u0026deg; 27' 13.234\" S 48\u0026deg; 26' 32.658\" W) which presents climatic characteristics of the AFI type according to the Koppen-Geiger classification. During the experimental period (February to September 2021) the environmental conditions were 32\u0026thinsp;\u0026plusmn;\u0026thinsp;2 \u0026ordm;C air temperature, 75\u0026thinsp;\u0026plusmn;\u0026thinsp;5% relative humidity, 2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 kPa air DPV and 800\u0026thinsp;\u0026plusmn;\u0026thinsp;100 \u0026micro;mol m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e s \u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e 470 of incident radiation. The pH of the substrate and the concentrations of macro and micronutrients were adjusted according to the soil analysis (fertilization manual 2022). The plants were irrigated daily by self-compensation drip to replace water lost through evapotranspiration and maintain soil moisture close to pot capacity, which was measured by weighing the experimental units (Klar et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1966\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe bacteria UFRABA01 (Bacillus \u003cem\u003eamyloliquefaciens)\u003c/em\u003e, UFRAB124 (Bacillus sp.) and MIX of five strains of \u003cem\u003eTrichoderma Asperellum\u003c/em\u003e (T06, T09, T12 and T52) and FT-12 (Trichoderma sp.) from oil palm cultivation, where they were obtained and stored in the microorganism bank of the Plant Protection Laboratory (LPP) located at the Federal Rural University of the Amazon (UFRA). The rhizobacteria were cultivated in solid medium 523 (Kado et al. 1970) for 48 h at 28 \u0026deg; C. The bacterial suspensions were prepared with distilled and sterilized water and were adjusted in the spectrophotometer to an absorbance of 0.1 at 550 nm, which corresponds to a bacterial suspension density of 10 \u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e CFU. mL \u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The \u003cem\u003eTrichoderma\u003c/em\u003e fungus isolates were cultivated in PDA (potato dextrose agar) culture medium and incubated for five days at 28 \u0026deg; C, where a suspension was prepared from each isolate at a concentration of 10\u003csup\u003e8\u003c/sup\u003e conidia \u003csup\u003e/\u003c/sup\u003e ml (R\u0026ecirc;go et al. 2014).\u003c/p\u003e \u003cp\u003eThe seedlings had their roots standardized by cutting them with scissors and before transplanting them into plastic bags with the substrate, they were immersed in the bacterial and fungal suspension for 20 min. Control seedlings were immersed in liquid culture medium 523 (Kado et al. 1970) without inoculation of microorganisms. After that, three inoculations were carried out at 15, 30 and 45 days after transplanting, adding 100 mL of the bacterial and fungal suspension to the base of the plant to evaluate the response in the plant and the promotion of plant growth (Lima et al. 2020).\u003c/p\u003e \u003cp\u003eBiometric data and biomass accumulation were evaluated six months after transplanting. Plant height and root length were measured with a graduated metal ruler, while the stem diameter was measured with a digital caliper (accuracy of 0.02 mm). The number of leaves was evaluated through direct counting of the emitted leaves and the total leaf area was estimated by the dry mass of leaf discs measuring 7 mm in diameter (3 discs per leaf). The seedlings were sectioned into roots and shoots, and dried in a forced ventilation oven at 65 \u0026ordm;C, until constant weight, for weighing and determination of dry biomass (Baxter and Stewart \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eGas exchange parameters were measured in the second physiologically mature and completely expanded leaf, from the apex to the base, from the second month after inoculation with growth-promoting microorganisms in oil palm seedlings. Net CO \u003csub\u003e2\u003c/sub\u003e assimilation ( \u003cem\u003eA\u003c/em\u003e ), stomatal water vapor conductance ( \u003cem\u003egs\u003c/em\u003e ), intercellular CO \u003csub\u003e2 concentration\u003c/sub\u003e ( \u003cem\u003eCi\u003c/em\u003e ) and transpiration rate ( \u003cem\u003eE\u003c/em\u003e ) were measured between 10:00 and 12:00 hours using a system portable open-flow gas exchange system (LI-6400XT, LI-COR, Lincoln, NE) under an external CO \u003csub\u003e2\u003c/sub\u003e concentration of 400 \u0026micro;mol mol \u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e air and artificial photosynthetically active radiation (PAR) of 1000 \u0026micro;mol photons m 2s-1. This measurement interval (10:00\u0026ndash;12:00 h) was adjusted according to the diurnal gas exchange curve previously obtained for the species. All measurements were carried out under air temperature of 31\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C, relative humidity of 63\u0026thinsp;\u0026plusmn;\u0026thinsp;2%, incident radiation of 600\u0026thinsp;\u0026plusmn;\u0026thinsp;100 \u0026micro;mol m-2s-1 and air vapor pressure deficit of 1.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2kPa. The amount of blue light was adjusted to 10% of photosynthetically active radiation to optimize stomatal opening. The relative chlorophyll content was initially estimated by the chlorophyllometer 258 (SPAD \u0026minus;\u0026thinsp;502) in the same leaves used for gas exchange measurements.\u003c/p\u003e \u003cp\u003eTo quantify total soluble sugars and starch, the methodology of Dubois (1956) was used. The plant samples were subjected to extraction with 80% ethanol by heating in a water bath at 100\u0026deg;C. After submission at high temperature, the samples were centrifuged at 10,000 rpm for 5 minutes, and from this activity, the supernatant destined for sugar analysis and the pellet destined for starch analysis were separated. For total soluble sugars, 100\u0026micro;L of supernatant must be collected and 400 \u0026micro;L of distilled water must be added. Following the analyses, 0.5 mL of 5% phenol and 2.5 mL of concentrated H \u003csub\u003e2\u003c/sub\u003e SO \u003csub\u003e4 must be added\u003c/sub\u003e. Finally, the samples must be vortexed and left to react for 20 minutes. The reading can be done on a spectrophotometer at an absorbance range of 490 nm. The pellet must be extracted in HClO \u003csub\u003e4\u003c/sub\u003e for 30 minutes at room temperature. Following extraction, samples must be centrifuged and the supernatant collected. The starch analytical process follows the same criteria as total soluble sugars. The reading must be carried out using a spectrophotometer with an absorbance range of 490 nm.\u003c/p\u003e \u003cp\u003eData were subjected to analysis of variance (ANOVA) and means were compared using the Student-Newman-Keuls test ( \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) using the R software (R Core Team, 2022). To represent the data obtained, the mean and standard error were calculated, in addition to creating graphs in the EXCEL program, Microsoft 365 version.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eAll seedlings inoculated with microorganisms increased biometric variables. For height, the increases were 36% for MIX, 36% for UFRAT12, 42% for UFRABA01 and 32% for UFRA124 in relation to non-inoculated seedlings (control). The duct diameter increased by 45% for MIX, 48% for UFRAT12, 55% for UFRABA01 and 49% for UFRA124 in relation to the control. The number of leaves increased by 13% for Mix, 13% for UFRAT12, 25% for UFRABA01 and 13% for UFRA124 compared to the control. The relative total chlorophyll content (SPAD) increased in inoculated seedlings by 17%, 13% and 14% for Mix, UFRAT12 and UFRABA01, respectively, in relation to control seedlings (Fig.\u0026nbsp;1). Leaf area increased in inoculated seedlings by 262%, 188%, 217% and 225% for UFRABA01, UFRA124, UFRAT12 and Mix, respectively, in relation to control seedlings (Fig.\u0026nbsp;1). Root length increased in inoculated seedlings by 54%, 71%, 20% and 18% for Mix, UFRAT12, UFRAB01 and UFRAB124, respectively, compared to control seedlings (Fig.\u0026nbsp;1).\u003c/p\u003e \u003cp\u003eThe inoculated seedlings increased biomass accumulation in relation to the control. For leaf dry mass, shoot dry mass and total dry mass there was an increase of 241%, 228% and 213% respectively for UFRABA01 compared to the control. Root dry mass increased by 71% for MIX in relation to the control (Fig.\u0026nbsp;2).\u003c/p\u003e \u003cp\u003eThe inoculated seedlings increased the average values of gas exchange parameters in relation to the control, except for the concentration of intercellular carbon ( \u003cem\u003eC\u003c/em\u003e \u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e ) (Fig.\u0026nbsp;2). For net photosynthesis there was an increase of 67% for UFRABA01, 57% for UFRA124, 63% for UFRAT12 and 59% for the mix compared to the control. Stomatal conductance increased by 24% for UFRABA01, 18% for UFRA124 and 29% for UFRAT12 and Mix in relation to the control. Transpiration increased in inoculated seedlings by 21%, 19%, 24% and 24% for UFRABA01, UFRA124, UFRAT12 and Mix, respectively, in relation to control seedlings (Fig.\u0026nbsp;3).\u003c/p\u003e \u003cp\u003eThe inoculated seedlings reduced the average values of the total sugar parameters in relation to the control by 7.8% for MIX, UFRABA01, UFRAB124 and 37.07% for UFRAT12. In the starch evaluation, there was an average reduction of 24% for UFRAT12 and UFRAB124 in relation to the control (Figure 4).\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe present study sought to report the physiological changes modulated by microorganisms to promote the growth of oil palm seedlings. The advantages of using microorganisms have already been studied in oil palm (Mba et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), (Lima et al. 2020), and other palm trees such as a\u0026ccedil;a\u0026iacute; (Castro et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) and coconut trees (George et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), which highlighted the benefits of these microorganisms in promoting growth and increasing vigor.\u003c/p\u003e \u003cp\u003eThe rhizosphere is a dynamic and complex environment in which roots play a very important role with the exudation of compounds such as carbohydrates, amino acids, organic acids, proteins, vitamins and several other compounds whose function is to attract microorganisms, which can help nutrient availability and biosynthesis of compounds related to plant growth (Gouda et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). All microorganisms induced an increase in root length and biomass. This increase in the root is possibly influenced due to fungi have the ability to produce elements such as acid and alkaline phosphatase enzymes, and organic acids that increase the amount of phosphorus available to plants, as observed in \u003cem\u003ein vitro\u003c/em\u003e solubilization tests carried out by Silva et al. (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) \u003cem\u003ewho\u003c/em\u003e tested the ability of the 4 isolates from the treatment with the mixture of four isolates of \u003cem\u003eTrichoderma asperellum\u003c/em\u003e (T06; T09; T12; T52) to solubilize calcium phosphate in solid culture medium (Ribas et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe work developed by Syafiq et al. (2021), showed that fungi of the species \u003cem\u003eTrichoderma asperellum\u003c/em\u003e promote the growth of inoculated oil palm seedlings compared to non-inoculated seedlings. This increase occurs because these microorganisms are probably able to induce the production of phytohormones, siderophores and substances that increase the solubilization of insoluble phosphorus. In other words, the larger root system increases the contact area of the roots with the soil and improves water and nutrient absorption; and this may have influenced the accumulation of aerial part biomass.\u003c/p\u003e \u003cp\u003eIt was observed that all growth-promoting microorganisms induced an increase in biometric and biomass parameters, which can be attributed to several direct or indirect mechanisms, such as direct mechanisms, rhizobacteria act in the direct solubilization of insoluble P sources, N fixation and/or regulation of the concentration of plant growth regulators, such as indole acetic acid (IAA) produced by some rhizobacteria (Nascente et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Studies by Lima \u003cem\u003eet al\u003c/em\u003e. (2020) show that the use of microorganisms causes hormonal changes, as when the rhizobacteria UFRAB01 was inoculated in oil palm seedlings, it resulted in an increase of 66% the content of indole acetic acid (IAA), 44% for abscisic acid (ABA) and a 24% reduction in the concentration of 1-carboxylic acid-1-aminocyclopropane (ACC) and an increase in the ratio of indole acetic acid (IAA)/1-carboxylic acid-1-aminocyclopropane (ACC) by 100% compared to the control, that is, this increase in phytohormone levels in leaf tissues may be associated with the biometric increase in the biomass of the root, aerial part and on the efficiency of nutrient use in oil palm seedlings in the nursery phase.\u003c/p\u003e \u003cp\u003eThe relative total chlorophyll content increased in seedlings that were inoculated with growth promoters. Chlorophylls are pigments responsible for capturing, absorbing and transmitting light that will be used in photosynthesis. These pigments play a fundamental role in the conversion of light radiation into chemical energy, in the form of ATP and NADPH (Taiz and Zeiger 2009). Chlorophylls are related to the photosynthetic efficiency of plants, as well as their growth and adaptation to different environments (De Jesus and Marenco \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). According to Castro et al. (2014), a plant that has a higher concentration of chlorophyll a may have higher net photosynthesis rates, due to the greater efficiency of the photosynthetic system in the PSI and PSII photosystems. Thus, the greater stomatal opening that occurred in inoculation treatments allowed more CO \u003csub\u003e2 molecules\u003c/sub\u003e to enter and be fixed, through the efficiency of energy production caused by the greater presence of chlorophylls in the leaves. Thus, the optimization of the photosynthetic process allowed the production of more photoassimilates, resulting in a greater increase in biomass.\u003c/p\u003e \u003cp\u003eThe increase in the aerial part, as well as the number of leaves and leaf shoots, can be associated with the ability of rhizobacteria to induce the synthesis of gibberellins and cytokinins that regulate leaf expansion and chlorophyll synthesis (Dodd et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Kang et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The greatest number of leaves was obtained only with UFRAB01, however the other rhizobacteria and fungi induced greater leaf area, which resulted in greater growth of the aerial part and accumulation of leaf biomass. These benefits can be attributed to the ability of rhizobacteria to signal the gibberellin and cytokinin biosynthesis pathway (Chauhan et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Cardoso et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e, working with microorganisms, observed that there was a promotion of the growth of coconut seedlings with significant increases in the dry matter weight of the aerial part (47%), dry matter weight of the root (122%), dry matter weight total drought (35%), height (26%) and diameter (30%) compared to the control treatment.\u003c/p\u003e \u003cp\u003eThe larger leaf area directly influences greater light capture and CO \u003csub\u003e2 assimilation\u003c/sub\u003e (Zhang \u003cem\u003eet al.\u003c/em\u003e 2017). All growth promoters induced an increase in net CO \u003csub\u003e2 assimilation\u003c/sub\u003e ( \u003cem\u003eA\u003c/em\u003e ), stomatal conductance ( \u003cem\u003egs\u003c/em\u003e ) and transpiration ( \u003cem\u003eE)\u003c/em\u003e in relation to control plants. This response suggests that the important steps of photosynthesis were enhanced by promoters, such as a possible modulation of the activity of the Rubisco enzyme, vital for fixing the carbon dioxide molecule. Thus, the results suggest a better integrity of the photosynthetic apparatus that can contribute to the improvement in CO \u003csub\u003e2\u003c/sub\u003e assimilation activity and production of photoassimilates.\u003c/p\u003e \u003cp\u003eThe greatest assimilation of CO \u003csub\u003e2\u003c/sub\u003e ( \u003cem\u003eA\u003c/em\u003e ) can be attributed to the greater degree of stomata opening (gs), which allows greater entry of CO \u003csub\u003e2\u003c/sub\u003e into the leaves and favors an increase in net photosynthesis. In rice plants inoculated with rhizobacteria, an increase in the net photosynthetic rate was observed, which was attributed to the positive influence on the opening and closing of stomata, which directly affected gas exchange and contributed to plant growth (Nascente et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe greater stomatal opening, in addition to favoring the entry of CO \u003csub\u003e2\u003c/sub\u003e into the leaves, directly influences the greater loss of water through transpiration (Silva et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). In this study, the higher transpiration rate can be attributed to the greater stomatal opening induced by all growth promoters. The higher total transpiration rate induced by the promoters can be attributed, in addition to the stomatal opening, to the greater total leaf area and aerial part. When there is abundant water and solar radiation incident on the leaves, this ends up favoring high photosynthetic activity, there is a high demand for CO \u003csub\u003e2\u003c/sub\u003e within the leaf, and the stomatal pores open widely, reducing stomatal resistance to the diffusion of CO \u003csub\u003e2\u003c/sub\u003e (Flexas et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). In this situation, there are large losses of water through transpiration, however, when there are large amounts of water it becomes viable for the plant to \u0026ldquo;exchange\u0026rdquo; for photosynthesis elements to increase its growth (Taiz and Zeiger 2013; Castro et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThere were no changes in the intercellular concentration of CO \u003csub\u003e2\u003c/sub\u003e ( \u003cem\u003eCi\u003c/em\u003e ), however, when we evaluated this combined with other physiological variables, we found that biostimulated seedlings had a better efficiency of the photosynthetic apparatus because induced an increase in net CO2 assimilation ( \u003cem\u003eA\u003c/em\u003e ), stomatal conductance ( \u003cem\u003egs\u003c/em\u003e ) and transpiration \u0026ndash; ( \u003cem\u003eE\u003c/em\u003e ). These benefits can result in greater production of photoassimilates, which can be allocated to plants to support growth or be assimilated into reserve products or used by promoters through root exudates (Silva et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAll biostimulated plants showed a reduction in total soluble sugar content. According to (Smeekens \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2003\u003c/span\u003e), these sugars are used to produce energy through cellular respiration, transforming glucose into carbon dioxide and water, releasing energy that is used to drive growth processes. Furthermore, AST are converted into different types of organic compounds, such as starch, lipids, proteins and nucleic acids, which are essential for cell growth and the formation of plant tissues (Rolland et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Ruan \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). In this context, it can be inferred that the lower AST content in inoculation treatments is due to its conversion into an increase in biomass, resulting in an increase in the parameters of height, stem diameter, number of leaves and root length.\u003c/p\u003e \u003cp\u003eTreatments with FT12 and UFRAB124 showed lower starch concentration compared to the control. This can be explained because, throughout the day, plants store excess products generated by photosynthesis in the form of starch. This starch is an energy reserve that is used when sunlight is not available to carry out photosynthesis. During this process, starch is converted into simpler sugars, such as glucose and fructose, which are transported out of the chloroplasts and transformed into sucrose. This strategy makes it possible to meet the energy needs of plants when the photosynthetic machinery is not functioning (Smirnova et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The high concentration of starch in oil palm seedlings is probably related to the reserve tissues, in the case of palm trees, the haustorium, which contains a large amount of this carbohydrate at this stage, corroborating the results of starch concentrations in seedlings of the Butia palm species. \u003cem\u003ecapitata\u003c/em\u003e (Oliveira et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) and \u003cem\u003eAcrocomia aculeata\u003c/em\u003e (Bicalho et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). (Shoresh and Harman \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) observed that the increase in starch in corn seedlings inoculated with \u003cem\u003eTrichoderma harzianum\u003c/em\u003e was related to the content of glyceraldehyde-3-P-dehydrogenase (GAPDH), which is an essential enzyme in the glycolytic pathway and this pathway is closely related starch synthesis.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe better photosynthetic performance induced by the inoculation of microorganisms in oil palm seedlings induced the promotion of crop growth. Probably, some physiological mechanisms that involve the modulation of CO \u003csub\u003e2 assimilation\u003c/sub\u003e and mobilization of photoassimilates may be activated by microorganisms to sustain the large energy demand necessary for greater growth.\u003c/p\u003e \u003cp\u003eThe greater growth of seedlings inoculated with microorganisms can contribute to better quality in the production of seedlings with less time spent in the nursery. The inoculation of microorganisms can be used as a clean technology that contributes to the sustainable management of the production of Oil Palm seedlings in nurseries.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCREDIT AUTHOR STATEMENT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors\u0026apos; contribution, using an accurate and detailed description of their various contributions to the published work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eDanielle Pereira Mendon\u0026ccedil;a:\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eConceptualization, Methodology, Validation, Research, Resources, Data Curation, Writing - Original Draft, Writing - Review and Editing, Visualization.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eMaria Luiza Brito Brito:\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Methodology, Validation, Research, Resources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eJuliana Tavares Dias:\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Methodology, Validation, Research, Resources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eVer\u0026ocirc;nica Daniely Pereira Paes da Silva:\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Methodology, Validation, Research, Resources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eMauro Junior Borges Pacheco:\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eResources, Data Curation, Writing - Original Draft\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eThayn\u0026aacute; da Cruz Ferreira:\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eWriting - Review and Editing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eMaria Carolina Sarto Fernandes Rodrigues:\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eWriting - Review and Editing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e2\u0026nbsp;\u003c/sup\u003eDalton Dias da Silva J\u0026uacute;nior:\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eConceptualization, Methodology, Resources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1\u0026nbsp;\u003c/sup\u003eGisele barata Silva:\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eConceptualization, Methodology, Resources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u003csup\u003e1*\u0026nbsp;\u003c/sup\u003eGledson Luiz Salgado de Castro:\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Conceptualization, Methodology, Validation, Research, Resources, Data Curation, Writing - Original Draft, Writing - Review and Editing, Visualization.\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBaxter HL, Stewart CN (2013) Effects of altered lignin biosynthesis on phenylpropanoid metabolism and plant stress. 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World J Microbiol Biotechnol 29:109\u0026ndash;117. https://doi.org/10.1007/S11274-012-1163-6\u003c/li\u003e\n\u003cli\u003eGlick BR (2012) Plant growth-promoting bacteria: mechanisms and applications. Scientifica (Cairo) 2012:1\u0026ndash;15. https://doi.org/10.6064/2012/963401\u003c/li\u003e\n\u003cli\u003eGouda S, Kerry R, Das G, Paramitiotis S (2018) Revitaliza\u0026ccedil;\u0026atilde;o do crescimento das plantas promovendo rizobact\u0026eacute;rias para o desenvolvimento sustent\u0026aacute;vel na agricultura. Microbiol\u0026oacute;gico\u003c/li\u003e\n\u003cli\u003eHassan Tuan Muhammad Syafiq T, Ali Nusaibah S, Yusop Rafii M (2021) Effectiveness of Bioinoculants Bacillus cereus and Trichoderma asperellum as Oil Palm Seedlings Growth Promoters. pertanika.upm.edu.myTHT Muhammad Syafiq, SA Nusaibah, MY RafiiPertanika Journal of Tropical Agricultural Science, 2021\u0026bull;pertanika.upm.edu.my 44:157\u0026ndash;170. https://doi.org/10.47836/pjtas.44.1.09\u003c/li\u003e\n\u003cli\u003eIBGE. Produ\u0026ccedil;\u0026atilde;o Agr\u0026iacute;cola Municipal 2020. Rio de Janeiro, 2020. Dispon\u0026iacute;vel em: https://sidra. ibge.gov.br/pesquisa/pam/tabelas. Acesso em: 12 09 2023.\u003c/li\u003e\n\u003cli\u003eJesus SV, Marenco RA (2008) O SPAD-502 como alternativa para a determina\u0026ccedil;\u0026atilde;o dos teores de clorofila em esp\u0026eacute;cies frut\u0026iacute;feras. Acta Amazon 38:815\u0026ndash;818. https://doi.org/10.1590/S0044-59672008000400029\u003c/li\u003e\n\u003cli\u003eKado C, Phytopathology MH-, 1970 undefined Selective media for isolation of agrobacterium, Corynebacterium, Erwinia, Pseudomonas and Xanthomonas. apsnet.orgCI Kado, MG HeskettPhytopathology, 1970\u0026bull;apsnet.org\u003c/li\u003e\n\u003cli\u003eKang S-M, Latif Khan A, You Y-H, et al (2014) Gibberellin production by newly isolated strain Leifsonia soli SE134 and its potential to promote plant growth. researchgate.netSM Kang, AL Khan, YH You, JG Kim, M Kamran, IJ LeeJournal of microbiology and biotechnology, 2014\u0026bull;researchgate.net 24:106\u0026ndash;112. https://doi.org/10.4014/jmb.1304.04015\u003c/li\u003e\n\u003cli\u003eKlar AE, Villa Nova NA, Marcos ZZ, Cerv\u0026eacute;llini A (1966) Determina\u0026ccedil;\u0026atilde;o da umidade do solo pelo m\u0026eacute;todo das pesagens. Anais da Escola Superior de Agricultura Luiz de Queiroz 23:15\u0026ndash;30. https://doi.org/10.1590/S0071-12761966000100003\u003c/li\u003e\n\u003cli\u003eMba OI, Dumont MJ, Ngadi M (2015) Palm oil: Processing, characterization and utilization in the food industry \u0026ndash; A review. Food Biosci 10:26\u0026ndash;41. https://doi.org/10.1016/J.FBIO.2015.01.003\u003c/li\u003e\n\u003cli\u003eNascente AS, de Filippi MCC, Lanna AC, et al (2017) Biomass, gas exchange, and nutrient contents in upland rice plants affected by application forms of microorganism growth promoters. Environmental Science and Pollution Research 24:2956\u0026ndash;2965. https://doi.org/10.1007/S11356-016-8013-2/TABLES/6\u003c/li\u003e\n\u003cli\u003eOliveira NCC, Lopes PSN, Ribeiro LM, et al (2013) Seed structure, germination, and reserve mobilization in Butia capitata (Arecaceae). Trees - Structure and Function 27:1633\u0026ndash;1645. https://doi.org/10.1007/S00468-013-0910-0/FIGURES/6\u003c/li\u003e\n\u003cli\u003eRibas PP, Rech R, Matsumura ATS, Van der Sand ST (2016) Potencial in vitro para solubiliza\u0026ccedil;\u0026atilde;o de fosfato por Trichoderma spp.\u003c/li\u003e\n\u003cli\u003eRolland F, Baena-Gonzalez E, Biol. JS-AnnuRevP, 2006 undefined (2006) Detec\u0026ccedil;\u0026atilde;o e sinaliza\u0026ccedil;\u0026atilde;o de a\u0026ccedil;\u0026uacute;car em plantas: mecanismos conservados e novos. annualreviews.orgF Rolland , E Baena-Gonzalez , J SheenAnu Rev Plant Biol, 2006 \u0026bull; anualreviews.org 57:675\u0026ndash;709. https://doi.org/10.1146/annurev.arplant.57.032905.105441\u003c/li\u003e\n\u003cli\u003eRuan YL (2014) Sucrose metabolism: Gateway to diverse carbon use and sugar signaling. Annu Rev Plant Biol 65:33\u0026ndash;67. https://doi.org/10.1146/ANNUREV-ARPLANT-050213-040251\u003c/li\u003e\n\u003cli\u003eSattar A, Naveed M, Ali M, et al (2019) Perspectives of potassium solubilizing microbes in sustainable food production system: A review. Applied Soil Ecology 133:146\u0026ndash;159. https://doi.org/10.1016/J.APSOIL.2018.09.012\u003c/li\u003e\n\u003cli\u003eShoresh M, Harman GE (2008) The Molecular Basis of Shoot Responses of Maize Seedlings to Trichoderma harzianum T22 Inoculation of the Root: A Proteomic Approach. Plant Physiol 147:2147\u0026ndash;2163. https://doi.org/10.1104/PP.108.123810\u003c/li\u003e\n\u003cli\u003eSilva JC da, Torres DB, Lustosa DC, et al (2012) Biocontrol of sheath blight on rice and growth promotion by Trichoderma isolates from the Amazon. Revista de Ci\u0026ecirc;ncias Agrarias - Amazon Journal of Agricultural and Environmental Sciences 55:243\u0026ndash;250. https://doi.org/10.4322/RCA.2012.078\u003c/li\u003e\n\u003cli\u003eSilva PA, Cosme VS, Rodrigues KCB, et al (2017) Drought tolerance in two oil palm hybrids as related to adjustments in carbon metabolism and vegetative growth. Acta Physiol Plant 39:1\u0026ndash;12. https://doi.org/10.1007/S11738-017-2354-4/TABLES/1\u003c/li\u003e\n\u003cli\u003eSmeekens S (2003) SUGAR-INDUCED SIGNAL TRANSDUCTION IN PLANTS. https://doi.org/101146/annurev.arplant51149 51:49\u0026ndash;81. https://doi.org/10.1146/ANNUREV.ARPLANT.51.1.49\u003c/li\u003e\n\u003cli\u003eSmirnova J, Fernie AR, Steup M (2015) Starch degradation. Starch: Metabolism and Structure 239\u0026ndash;290. https://doi.org/10.1007/978-4-431-55495-0_7/COVER\u003c/li\u003e\n\u003cli\u003eValente Lima J, Tin\u0026ocirc;co RS, Olivares FL, et al (2020) Hormonal imbalance triggered by rhizobacteria enhance nutrient use efficiency and biomass in oil palm. Sci Hortic 264:109161. https://doi.org/10.1016/J.SCIENTA.2019.109161\u003c/li\u003e\n\u003cli\u003eMinist\u0026eacute;rio da Agricultura, Pecu\u0026aacute;ria e Abastecimento Conselho do Agroneg\u0026oacute;cio C\u0026acirc;mara Setorial da Cadeia Produtiva da Palma de \u0026Oacute;leo\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"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":"Elaeis guineensis, microbial technology, growth, photosynthesis","lastPublishedDoi":"10.21203/rs.3.rs-3386256/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3386256/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e \u003cem\u003eElaeis guineensis\u003c/em\u003e Jacq. It is the oilseed that has stood out in the production of oil of high economic value. The main global producers are Malaysia and Indonesia. In Brazil, the cultivated area is concentrated in the state of Par\u0026aacute;. Seedling production requires a long nursery period and high consumption of chemical fertilizers. Currently, studies reporting the use of microbial technology to minimize the excessive use of chemical fertilizers and promote earlier seedling development. The objective of this study was to evaluate biometrics, biomass accumulation and gas exchange in oil palm seedlings inoculated with microorganisms. The experiment was conducted in a greenhouse, in a completely randomized design with five treatments, consisting of the inoculation of four Trichoderma microorganisms and a control, with five replications. The data were subjected to analysis of variance and treatment means were compared using the SNK test (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The inoculation of microorganisms promoted the growth of oil palm seedlings. The height, stem diameter, number of leaves, leaf area, root length, total chlorophyll, net photosynthesis, stomatal conductance, transpiration, dry mass of leaves, aerial part, root and total, increased on average in inoculated seedlings compared to control seedlings. Total soluble sugars, on the other hand, decreased for inoculated plants compared to the control. Starch decreased compared to control. Therefore, the results show that better photosynthetic performance may be associated with the promotion of growth in oil palm seeds inoculated with microorganisms. It is likely that some physiological mechanisms are being activated by microorganisms for greater growth.\u003c/p\u003e","manuscriptTitle":"Microorganisms Improve Physiological Performace to Oil Palm Seedings Growth Promote","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-10-28 18:16:38","doi":"10.21203/rs.3.rs-3386256/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":"26c57b43-e93c-4bb6-b34b-f3963f37d299","owner":[],"postedDate":"October 28th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-13T20:14:41+00:00","versionOfRecord":[],"versionCreatedAt":"2023-10-28 18:16:38","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3386256","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3386256","identity":"rs-3386256","version":["v1"]},"buildId":"wLkW0s4AflPzk-lpfg-fK","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}