Soybean Cultivars Research Articles

The potential of insecticides and genetically modified soybean in the control of Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae)

Brazil is the largest soybean producer in the world, and soybean is the most important crop in the country. The use of genetically modified soybean expressing Bt proteins represents a significant milestone in insect pest management in this crop. However, the isolated use of these biotechnologies is not sufficient to control Spodoptera frugiperda larvae, thus the use of insecticides in seed treatment becomes essential. Therefore, the objective of this study was to assess the efficiency of controlling S. frugiperda larvae through insecticides applied to seeds and different biotechnologies in soybean cultivation. The experiments were conducted in a laboratory, following a completely randomized block design in a factorial scheme with twelve treatments, consisting of combinations of soybean cultivars and insecticides in seed treatment. The mortality and foliar consumption of first and third instar S. frugiperda larvae were evaluated. Based on our studies, it was possible to verify that ciantraniliprole is an excellent molecule for controlling first and third instar S. frugiperda larvae. The biotechnology Intacta 2 Xtend, Cry1A.105/Cry2Ab2/Cry1Ac, and the insecticide ciantraniliprole protected soybean against damage caused by S. frugiperda larvae.

Transcriptome profiling uncovers differentially expressed genes linked to nutritional quality in vegetable soybean.

Vegetative soybean (maodou or edamame) serves as a nutrient-rich food source with significant potential for mitigating global nutritional deficiencies. This study undertook a thorough examination of the nutritional profiles and transcriptomic landscapes of six soybean cultivars, including three common cultivars (Heinong551, Heinong562, and Heinong63) and three fresh maodou cultivars (Heinong527, HeinongXS4, and HeinongXS5). Nutrient analysis of the seeds disclosed notable differences in the levels of protein, fat, soluble sugars, vitamin E, calcium, potassium, magnesium, manganese, iron, and zinc across the cultivars. Through comparative transcriptome profiling and RNA sequencing, distinct variations in differentially expressed genes (DEGs) were identified between fresh and traditional maodou cultivars. Functional enrichment analyses underscored the involvement of DEGs in critical biological processes, such as nutrient biosynthesis, seed development, and stress responses. Additionally, association studies demonstrated robust correlations between specific DEG expression patterns and seed nutrient compositions across the different cultivars. Sankey diagrams illustrated that DEGs are strongly linked with seed quality traits, revealing potential molecular determinants that govern variations in nutritional content. The identified DEGs and their relationships with nutritional profiles offer valuable insights for breeding programs focused on developing cultivars with improved nutritional quality, tailored to specific dietary needs or industrial applications.

Far-Red Light Inhibits Soybean Biomass and Yield by Modulating Plant Photosynthesis

Alterations in the light environment can significantly influence soybean morphology and yield formation; however, the effects and mechanisms of different light qualities on these aspects require further investigation. Consequently, we selected soybean cultivars with marked differences in light sensitivity as test materials, conducted experiments with red, blue, and green light qualities against a blue light background, and analyzed parameters related to leaf photosynthetic capacity, chlorophyll fluorescence, morphological characteristics, biomass, and yield variations following different light quality treatments. The results showed that following far-red light treatment, soybean plants exhibited significant shade avoidance syndrome, internode elongation, increased plant height, and a marked reduction in both root and leaf biomass, as well as total biomass. Furthermore, there was a substantial reduction in photosynthetic capacity. This indicated that far-red light exerts an inhibitory effect on soybean growth and yield formation. Red light has basically no regulatory effect on plant morphology and yield, while green light has a yield-increasing effect, but there was a cultivar effect. This study not only enhances our understanding of the mechanisms through which light quality regulates plant photosynthesis but also lays a scientific foundation for future crop light environment management and for the further exploration of light quality’s regulatory potential on crop growth.

Influence of Application Timing and Cultivar on Soybean Tolerance and Weed Control from Diflufenican or a Diflufenican-Containing Premixture

Abstract Bayer CropScience anticipates launching several premixtures for use in soybean, targeted at control of Palmer amaranth. One of the premixtures will contain diflufenican (WSSA Group 12), metribuzin (Group 5), and flufenacet (Group 15) (DFF-containing premixture), offering an alternative site of action for soybean producers. Field experiments were conducted in Arkansas and Michigan to evaluate application timings of the DFF-containing premixture for soybean tolerance and weed control and possible cultivar tolerance differences to diflufenican and the DFF-containing premixture. Soybean injury from the 1X and 2X rates of the DFF-containing premixture ranged from 0% to 60% 14 d after planting (DAP), with injury increasing the closer the herbicide was applied to soybean emergence. Excluding the 2X rate applied 3 DAP in Arkansas in 2023, soybean injury was <20% regardless of location, site year, application timing, and rate. For weed control experiments, only a 1X rate of the DFF-containing premixture was applied at the various application timings. Control of five weed species, encompassing broadleaves and grasses, ranged from 81% to 98%, regardless of application timing by 28 DAP. By 42 DAP, weed control ranged from 71% to 97%, with the 14-d preplant application timing typically being the least effective. The DFF-containing premixture and diflufenican alone were applied PRE at 1X and 2X rates for the soybean cultivar study. Soybean metribuzin sensitivity did not affect the degree of crop response, even on a high pH soil, and injury to soybean never exceeded 20%. Overall, the DFF-containing premixture will be a tool that soybean producers can integrate into a season-long herbicide program for use across the United States regardless of the soybean cultivar.

Stomatal Density Variation Within and Among Different Soybean Cultivars Across Various Growth Stages

Stomata regulate CO2 and water vapor exchange between leaves and the atmosphere, serving as a vital indicator of climate change resilience. Therefore, understanding the difference in stomatal numbers and patterns among different soybean cultivars across growth stages is essential to comprehending the complex mechanisms underlying soybean adaptation to climate change. The accurate measurements of stomatal density in soybean leaves are essential to understanding the complexity of stomatal density by environmental conditions. We demonstrated that the five epidermal sections and five microscopic images taken from both sides of each epidermal section at each leaf position (tip, middle, and bottom) were sufficient for stomatal measurements. Furthermore, we investigated variations in stomatal density among leaflet locations (left, right, and central) and leaf position across different growth stages. Notably, while there was no significant variation between the two leaves of the vegetative cotyledon (VC) stage and among the three leaflets of the V1 (first trifoliate) to V4 (fourth trifoliate) growth stages, leaves of the VC stage exhibited the lowest stomatal density, whereas those of the V4 stage exhibited the highest stomatal density. These findings could serve as a valuable tool for evaluating stomatal density, analyzing physiological differences under adverse climatic conditions, and phenotyping a large-scale population to identify the genetic factors responsible for stomatal density variations in soybean genotypes.

Comparative Analysis of Two Soybean Cultivars Revealed Tolerance Mechanisms Underlying Soybean Adaptation to Flooding.

Flooding stress poses a significant challenge to soybean cultivation, impacting plant growth, development, and ultimately yield. In this study, we investigated the responses of two distinct soybean cultivars: flooding-tolerant Nanxiadou 38 (ND38) and flooding-sensitive Nanxiadou 45 (ND45). To achieve this, healthy seedlings were cultivated with the water surface consistently maintained at 5 cm above the soil surface. Our objective was to elucidate the physiological and molecular adaptations of the two cultivars. Under flooding stress, seedlings of both cultivars exhibited significant dwarfing and a notable decrease in root length. While there were no significant differences in the dry weight of aboveground shoots, the dry weight of underground shoots in ND38 was strikingly decreased following flooding. Additionally, total chlorophyll content decreased significantly following flooding stress, indicating impaired photosynthetic performance of the cultivars. Moreover, malondialdehyde (MDA) levels increased significantly after flooding, particularly in the ND45 cultivar, suggesting heightened oxidative stress. Expression analysis of methylation and demethylation genes indicated that MET1 and DME play crucial roles in response to flooding stress in soybeans. Meanwhile, analysis of the hemoglobin family (GLBs), aquaporin family (AQPs), glycolytic pathway-related genes, and NAC transcription factor-related genes identified GLB1-1 and GLB1-2, GLB2-2, PIP2-6, PIP2-7, TIP2-2, TIP4-1, TIP5-1, Gm02G222400 (fructose-bisphosphate aldolase), Gm19G017200 (glucose-6-phosphate isomerase), and Gm04G213900 (alcohol dehydrogenase 1) as key contributors to flooding tolerance in both soybean cultivars. These findings provide crucial insights into the physiological and molecular mechanisms underlying flooding tolerance in soybeans, which could guide future molecular breeding strategies for the development of flooding-tolerant soybean cultivars.

Quality traits drive the enrichment of Massilia in the rhizosphere to improve soybean oil content

BackgroundSoybean seeds are rich in protein and oil. The selection of varieties that produce high-quality seeds has been one of the priorities of soybean breeding programs. However, the influence of improved seed quality on the rhizosphere microbiota and whether the microbiota is involved in determining seed quality are still unclear. Here, we analyzed the structures of the rhizospheric bacterial communities of 100 soybean varieties, including 53 landraces and 47 modern cultivars, and evaluated the interactions between seed quality traits and rhizospheric bacteria.ResultsWe found that rhizospheric bacterial structures differed between landraces and cultivars and that this difference was directly related to their oil content. Seven bacterial families (Sphingomonadaceae, Gemmatimonadaceae, Nocardioidaceae, Xanthobacteraceae, Chitinophagaceae, Oxalobacteraceae, and Streptomycetaceae) were obviously enriched in the rhizospheres of the high-oil cultivars. Among them, Oxalobacteraceae (Massilia) was assembled specifically by the root exudates of high-oil cultivars and was associated with the phenolic acids and flavonoids in plant phenylpropanoid biosynthetic pathways. Furthermore, we showed that Massilia affected auxin signaling or interfered with active oxygen-related metabolism. In addition, Massilia activated glycolysis pathway, thereby promoting seed oil accumulation.ConclusionsThese results provide a solid theoretical basis for the breeding of revolutionary soybean cultivars with desired seed quality and optimal microbiomes and the development of new cultivation strategies for increasing the oil content of seeds.7196FtKvsnPuUrhB77D9vLVideo

Advances in Soybean Genetic Improvement.

The soybean (Glycine max) is a globally important crop due to its high protein and oil content, which serves as a key resource for human and animal nutrition, as well as bioenergy production. This review assesses recent advancements in soybean genetic improvement by conducting an extensive literature analysis focusing on enhancing resistance to biotic and abiotic stresses, improving nutritional profiles, and optimizing yield. We also describe the progress in breeding techniques, including traditional approaches, marker-assisted selection, and biotechnological innovations such as genetic engineering and genome editing. The development of transgenic soybean cultivars through Agrobacterium-mediated transformation and biolistic methods aims to introduce traits such as herbicide resistance, pest tolerance, and improved oil composition. However, challenges remain, particularly with respect to genotype recalcitrance to transformation, plant regeneration, and regulatory hurdles. In addition, we examined how wild soybean germplasm and polyploidy contribute to expanding genetic diversity as well as the influence of epigenetic processes and microbiome on stress tolerance. These genetic innovations are crucial for addressing the increasing global demand for soybeans, while mitigating the effects of climate change and environmental stressors. The integration of molecular breeding strategies with sustainable agricultural practices offers a pathway for developing more resilient and productive soybean varieties, thereby contributing to global food security and agricultural sustainability.

Effect of Drought Stress During Seed Development on Charcoal Rot and Yield of Soybean.

The primary controls for charcoal rot in soybean, caused by the fungal pathogen Macrophomina phaseolina, are to avoid drought stress and to plant a moderately resistant cultivar. The effects of irrigation and cultivar were determined in 2011 and 2013 at the Lon Mann Cotton Research Station, Marianna, AR. Four soybean cultivars (Hutcheson, Osage, Ozark, and R01581F) were planted in plots with or without added M. phaseolina inoculum and subjected to three furrow irrigation regimes: full-season irrigation (Full), irrigation terminated at R5 (CutR5), and nonirrigated (NonIrr). Normalized difference vegetation index (NDVI) was measured at R3 and R6. At harvest, plants and yields were collected. Roots and stems were split and the extent of visible colonization by M. phaseolina microsclerotia was assessed in the roots with a 1 to 5 scale (RSS) and the percent plant height stem discoloration measured. Precipitation in September and October was 54 and 65% below the 30-year average in 2011 and 2013, respectively. The CutR5 irrigation treatment resulted in one less irrigation than Full each year, but CutR5 NDVIs at R6 and yields were significantly lower than those with Full and not significantly different from those of NonIrr. The CutR5 RSS ratings were greater than either Full or NonIrr. Plant colonization by M. phaseolina was negatively correlated to yield in 2011 but not in 2013. No premature plant death caused by charcoal rot was observed in either year. These results indicated that late-season drought stress may be more important to charcoal rot development than drought stress throughout the season, but other factors are needed to trigger early plant death and subsequent yield losses observed in grower fields.

Leveraging leaf spectroscopy to identify drought-tolerant soybean cultivars

Understanding cultivars' physiological traits variations under abiotic stresses is critical to improve phenotyping and selections of resistant crop varieties. Traditional methods of accessing physiological traits in plants are costly and time consuming, which prevents their use in breeding programs. Spectroscopy data and statistical approaches such as partial least square regression could be applied to rapidly collect and predict several physiological parameters at leaf-level, allowing phenotyping several genotypes in a high-throughput manner. We collected spectroscopy data of twenty soybean cultivars planted under well-watered and drought conditions during the reproductive phase. At 20 days after drought was imposed, we measured leaf pigments content (chlorophyll a and b, and carotenoids), specific leaf area, electrons transfer rate, and photosynthetic active radiation. At 28 days after drought imposition, we measured leaf pigments content, specific leaf area, relative water content, and leaf temperature. Partial least square regression models accurately predicted leaf pigments content, specific leaf area, and leaf temperature (cross-validation R2 ranging from 0.56 to 0.84). Discriminant analysis using 54 wavelengths was able to select the best-performance cultivars regarding all evaluated physiological traits. We showed the great potential of using spectroscopy as a feasible, non-destructive, and accurate method to estimate physiological traits and screening of superior genotypes.

Assessing Soybean Cultivar Resistance to Target Spot Using a Detached Leaf Assay

Target spot (TS), caused by the fungus Corynespora cassiicola, is a foliar disease of increasing importance to soybean in the United States. Identifying cultivar resistance to TS is challenging. The objective of this research was to determine the reactions of a diverse collection of soybean genotypes to TS using a detached leaf inoculation method. A detached unifoliate leaf of each soybean genotype was placed in a Petri dish on moist filter paper, wounded at three locations, inoculated with 10 μl of a 105-conidial suspension of C. cassiicola, and incubated at room temperature (23°C). The percent leaf area with TS symptoms (TSS) was measured digitally at 7, 10, 14, and 17 days after inoculation (DAI), and the area under the disease progress curve (AUDPC) was calculated. Thirty-seven soybean genotypes and three soybean cultivars were evaluated in three replicated trials. At 17 DAI, TSS ranged from 2 to 84%. Significant differences occurred between soybean genotypes at each rating time in each trial. Across the three trials, the reaction of most soybean genotypes ranged from resistant to susceptible. These soybean genotypes were evaluated in the field with natural inoculum at two locations in 2022. TS developed late but differed significantly between genotypes, averaging from 0.35 to 3.35% TSS. Field results were not significantly correlated to the detached leaf results. The detached leaf assay is another tool for screening soybean genotypes for resistance to TS but needs field validation. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Genetic Adaptations of Soybean to Cold Stress Reveal Key Insights Through Transcriptomic Analysis.

Low temperatures greatly restrict the development, growth, and productivity of soybeans, with their effects differing across various cultivars. The present work investigated the transcriptome and physiological reactions of two soybean cultivars, namely "KD52" exhibiting cold tolerance and "DS17" displaying cold sensitivity, to cold stress across a precisely defined period. The soybean plants were subjected to cold treatment at 6 °C for durations of 0, 2, 4, and 8 h. A comparative physiological marker study revealed distinct reactions to cold stress in the two cultivars. The findings showed that increased malondialdehyde levels provided evidence of DS17's heightened vulnerability to lipid peroxidation and membrane degradation. In contrast, the KD52 cultivar exhibited increased activities of antioxidant enzymes, including peroxidase and superoxide dismutase, in response to cold exposure, suggesting a strong antioxidant defense system against oxidative stress. The transcriptomic analysis revealed dynamic responses, mapping 54,532 genes. Within this group, a total of 234 differentially expressed genes (DEGs) were found to be consistently changed at several time intervals, showing unique expression patterns across the two cultivars. Analysis of the association between these important DEGs and the physiological indicators revealed candidate genes that may be involved in controlling oxidative damage and antioxidant defenses. Some key genes showed a progressive rise in expression over time in both cultivars, with a more significant acceleration in KD52, and are probably involved in promoting adaptation processes during extended periods of cold exposure. The identification of improved defense mechanisms in KD52, together with the identification of crucial genes, offers great prospects for enhancing the cold stress resilience of soybean.

Grain yield predictor model using agronomic aspects and vegetative indices of soybean

The objective of this work was to evaluate, through a predictive model, which factors influence soybean yield, using agronomic aspects and vegetative indices, in addition to identifying the best soybean cultivar for the northwest of Rio Grande do Sul. The experimental design used was strips with randomized blocks, consisting of 10 cultivars and five blocks. Analyzing the quantitative characters, the positive contributions to yield came from the grain weight of vegetables with two grains, and the grain weight of the plant, having a strong influence on the average grain yield. The vegetable grain weight with three grains contributed negatively to the yield, as the average grain weight was lower than expected, lowering the average grain yield. For the vegetation indices that contributed positively, the GRAY, IGB and RGRI index stand out, while the BGI, GLI2, GRAY2, IGR, IRB, NRBDI and NG indices had negative contributions to the average grain yield. The NEO 581 E cultivar showed better yield performance, reaching 5780 kg ha⁻1, followed by the SOYTECH 541 I2X cultivar, which reached a yield of 5356 kg ha⁻1. The predictive model identified the main variables that influenced final yield, with Cercospora sojina and Corynespora casiicola, grain weight in three-grain legumes, plant grain weight, GRAY index, IGB, NGBDI and RGRI, the variables that contributed positively to grain yield.

Analysis of Selected Macro- and Microelement Components in the Indigenous Soybean Cultivars from Regions of the Western Himalaya in India

The need to focus on traditional crops for food security has been realized across the globe. ‘Bhat’ is an indigenous soybean variety from the Indian Himalayan Region that has been neglected in recent times due to changing agricultural choices. The present study was conducted on 52 indigenous soybean accessions collected from different villages of Uttarakhand, a hilly state in Northern India, to determine the concentrations of various macro- and microelements in the crop. The analysis used the HHXRF (handheld X-ray fluorescence) spectroscopic technique and atomic absorption spectroscopy (AAS). The findings reveal that the ‘bhat’ is an extremely nutrient-rich crop with calcium being the most significant macronutrient (highest concentration of 27,300 ppm), followed by phosphorus, potassium, and sulphur found in the bhat seeds. The study suggests that samples from Pauri Garhwal (Gwad Khirsu, Bironkhal, Sripur), Tehri (PratapNagar, Singoli), Chamoli (Paini, and Agastyamuni) villages were rich in all the major macronutrients. Among the micronutrients, silicon was found to be the most dominant with the highest concentration of 1920 ppm. This was followed by the dominance of iron, zinc, and manganese in descending order of abundance. Tipri, Chandola Rai Goonth, Chopdiun, and Paini villages were found to have the highest concentrations of microelements. The statistical data analysis confirms that seed samples from different regions are significantly similar in terms of nutrient concentrations, except for Si and Fe, thereby indicating that ‘bhat’ from any of the villages is equally good for consumption. However, seed samples from certain regions were found to be contaminated with heavy metals, indicating soil pollution, which demands attention towards current agricultural practices. The findings show that the crop is an exceptional source of essential and quasi-essential elements and should be promoted to benefit the hill populations.

Weighted Gene Co-Expression Network Analysis Uncovers Critical Genes and Pathways Involved in Soybean Response to Soybean Mosaic Virus

Background: Soybean mosaic virus (SMV) is a globally prevalent and detrimental virus that belongs to the Potyvirus genus. Pathogenic viruses of this genus are typically linear in shape, with dimensions ranging between 630 and 750 nm, and are composed of single-stranded RNA and proteins. We have developed an SMV-resistant soybean line, Dongnong 93-046, which has no significant changes in disease resistance identification in the adult plants and has neat grains with no obvious brown or black markings. To explore the defense mechanisms of soybean against SMV, we performed comparative transcriptomic sequencing of the leaves between the Dongnong 93-046 inoculated with SMV at 8 h (T) and the non-inoculated control (C) on the HiSeq2000 platform. In addition, we performed non-targeted metabolomic sequencing of leaves from the treatment and control groups. Results: We identified a total of 41,189 differentially expressed genes (DEGs). A total of 9809 differentially expressed genes (DEGs) met the criteria of |Log2FC (Fold Change)| ≥ 1 and adjusted p-value ≤ 0.001. Among the 41,189 DEGs identified, 9196 exhibited FPKM values greater than 10. KEGG pathway enrichment analysis of the 9809 DEGs revealed significant enrichment of genes involved in resistance-related pathways such as plant–pathogen interaction, linoleic acid metabolism, mitogen-activated protein kinase (MAPK) signaling pathway, and plant hormone signaling transduction. Functional analysis using MapMan software identified multiple DEGs that were associated with pathways such as jasmonate synthesis and phenylpropanoid biosynthesis. Weighted gene co-expression network analysis (WGCNA) using the differential metabolites and the 9196 DEGs revealed a strong correlation between gene clusters within the Turquoise module and the content of jasmonate-related metabolites. Further functional enrichment analysis of the 894 genes within the gene clusters showed a significant and repeated enrichment of pathways related to plant–pathogen interaction, linoleic acid metabolism, and plant hormone signaling transduction. Subsequent focused pathway analysis identified key genes involved in plant hormone signaling transduction pathways, such as the jasmonate ZIM domain protein Glyma.16G010000, the gene Glyma.01G235600 encoding the essential diterpene reductase required for jasmonate synthesis in the jasmonate biosynthesis pathway, and the transcription factor Glyma.02G232600 involved in the plant–pathogen interaction pathway, among others. This study provides a theoretical framework for understanding the resistance mechanism of soybean cultivar Dongnong 93-046 against the SMV N1 strain, offers potential gene resources for breeding soybean varieties with resistance to SMV, and paves the way for new strategies to control SMV infection, enhance resistance, and improve crop yield and quality.

The productivity of selected soybean cultivars grown using various cultivation methods

Soybean is an important legume crop globally due to its rich protein, oil content, and functional components. The purpose of this study was to evaluate the yield of selected soybean cultivars depending on cultivation methods. The three-year field experiment, conducted from 2018 to 2020 at the Agricultural Experimental Station in Kępa-Puławy, Osiny farm (Institute of Soil Science and Plant Cultivation – State Research Institute in Puławy), investigated these variations. The first experimental factor was the soil cultivation method: A – conventional tillage, B – reduced tillage, and C – strip tillage. The second variable was soybean cultivar: ‘Aldana’ and ‘Merlin’. The soybean cultivars were selected for their differing maturity rates: ‘Aldana’ (000) is an early cultivar, while ‘Merlin’ (000++) semi-late cultivar. The field experiment utilised a split-plot design on Luvisol soil with sandy loam texture, belonging to a good rye complex, class IIIb–IVa, and was replicated four times. The study showed that the productivity (seed and protein yield) of the ‘Merlin’ cultivar grown in the central-eastern part of Poland was approximately 8% higher than that of the ‘Aldana’ cultivar. The cultivation method had a relatively minor influence on soybean yield, the content of selected nutrients, morphological features, and elements of the yield structure. The soil in strip-tillage method was more compact than the soil cultivated with a plough. After harvesting soybeans at a depth of 30, and 40 cm, the compactness of soil in strip-tillage or with reduced tillage was much lower than in spring, highlighting a positive effect of soybean cultivation on loosening the arable layer.

The contribution of pollinators varies among soybean cultivar traits

Soybean is one of the most widely cultivated species worldwide. Empirical studies have shown that animal pollination can contribute between 0 and 50 % to soybean yields. However, the role of animal pollination in soybean production is often overlooked in management decisions. Understanding the factors driving variability in pollinator contribution can aid in developing effective management strategies. In this study, we experimentally assessed the contribution of both autonomous and animal pollination across nine widely cultivated soybean cultivars in the Chaco region of Argentina. Additionally, we explored whether specific traits of these cultivars could explain the observed variability in pollination contribution. We used field exclosure experiments to study cultivars that differed in flower color, genetic modifications, and maturity groups, and analyzed the variability in pollinators’ contributions across years and locations. We found that the overall reduction in production between open and bagged plants was, on average, 40 % (CI 25–51 %). The contribution of pollinators varied depending on flower color, maturity groups, and locations, but not across different years or genetic modifications. Cultivars with purple flowers showed greater differences between open and bagged plants compared to those with white flowers, indicating that flower color may influence the attractiveness of flowers to pollinators. Additionally, pollinators’ contribution varied across maturity groups, potentially due to the differential timing of the flowering affecting the local abundance of pollinators within the crop. Notably, the variable used to estimate pollinators’ contribution (i.e., seeds, pods, or yield) conditioned the results. Pollinators’ contribution can be highly variable, and traits associated with cultivars can help improve our understanding of such heterogeneity. Our results showed that the contribution of pollinators to soybean cultivars in the Chaco region of Argentina ranges from modest to high. This suggests that conserving pollinators and managing agricultural fields at plot and landscape scales can significantly impact soybean production.

Multivariate approach applied to phenotypic traits as a function of the selection of soybean cultivars

The objective of this work was to identify superior soybean cultivars through a multivariate approach applied to phenotypic traits. This study was developed in the 2023/2024 agricultural harvest, in the experimental area of ​​the Regional Institute for Rural Development, at UNIJUÍ. It is located in the municipality of Augusto Pestana, in the state of Rio Grande do Sul, Brazil. The experimental design used was randomized blocks with internal blocks, with the treatment being ten cultivars and five replications. The trial of ten cultivars in the northwest of the state of Rio Grande do Sul demonstrated that the soybean cultivar with the highest yield was NS5922IPRO, with 5235.3 kg ha-1. The multivariate approaches formed two groups to explain the factors that influenced yield, where the first was discrepant for the variables Euschistus heros, phytotoxicity, Fusarium solanie, Macrophomina phaseolina, Conyza bonariensis, production zone area, number of total nodes in the branch, branch number, root length, number of vegetables with 4 grains, number of vegetables with 0 grains and vegetable grain weight of 2 grains. The second similar group for the variables Diabrotica speciosa, Caliothrips brasiliensis, Euschisthus heros, Phakopsora pachyrhizi and Cercospora sojina, area of ​​production zone, number of vegetables with zero grains. The trial of ten cultivars in the northwest of the state of Rio Grande do Sul demonstrated that the soybean cultivar with the highest yield was NS5922IPRO, with 5235.3 kg ha-1. The multivariate approaches formed two groups to explain the factors that influenced grain yield.

Determining factors for the selection of soybean cultivars and the cause and effect relationships with grain yield

The objective of the present study was to apply the trail analysis model to extract the cause and effect action on soybean grain yield as a function of agronomic attributes. The present study was developed in the agricultural years of 2023 and 2024. The experimental design used was strips with randomized blocks, consisting of 10 cultivars and five replications. Through the means comparison test, the highest grain yields were observed in the cultivars C 2531 E, BMX Vênus CE, B 5595 CE and NEO581 CE. It was observed that in addition to the higher grain yield, the cultivar C 2531 CE also presented a higher grain weight per plant, despite having the lowest final plant height and productive zone height among the cultivars. As for BMX Vênus CE, it was observed that despite its medium height, it presented a shorter internode length on the main stem, which optimized the number of total nodes on the main stem, in addition to presenting a high grain weight per plant. Cultivar B 5595 CE can be highlighted for its greater final plant height, as well as greater height of the productive zone, promoting a greater number of total nodes on the main stem. Another highlight of this cultivar is the high number of plants per final linear meter, indicating its adaptability in the field. The cultivar NEO581 E, despite having one of the smallest heights among the cultivars, presented one of the highest grain yields, which can be attributed to the stability of the cultivar in the field, as it showed intermediate performance for all agronomic traits.

SELECTION OF SOYBEAN GENOTYPES TOLERANT TO HIGH TEMPERATURES AND LOW LATITUDE

The edaphic and climatic conditions of the tropical regions of the world constitute a limiting factor for soybean growing, especially through aspects related to the specific photoperiod of the plants. Thus, the aim of this study was to estimate the genetic diversity among 16 Brazilian soybean cultivars [Glycine max (L.) Merrill and 76 plant introductions-PIs based on variables related to production and yield components. The multivariate analyses of Mean Euclidean Distance, Principal Component Analysis, and the UPGMA method summarized the traits evaluated in a dataset with smaller dimensions to facilitate identification of superior genotypes. The 16 Brazilian cultivars and 76 PIs were structured in six diversity panels that were consistent and without duplicates. The Brazilian soybean cultivars Sambaíba and 203404 and the PIs 165524, 407744, 205912, 381660, 203400, and 281911 show potential for providing genes related to tolerance to stress from temperatures greater than 30ºC and latitudes below 10ºS.