Since most soybean [Glycine max (L.) Merr.] seed is processed into meal and oil, there is a growing concern about environmental effects on soybean seed composition. The aim of this work was to investigate how water deficit affects the well‐known relationship of soybean seed oil and protein concentrations with temperature and, alternatively, with solar radiation during seed fill. We analyzed oil and protein data from multienvironment trials in Argentina (latitude 29° to 38° S). Multiple linear regressions were used to test the effect of water deficit on the relationship between oil, protein, and oil + protein and temperature. The functions relating oil and protein concentrations with average daily mean temperature during seed fill (TmR5R7) changed with water deficit. When precipitation minus potential evapotranspiration during the reproductive period (pp‐PETR1R7) was lower than 70 mm, oil increased linearly with increasing TmR5R7 and with rising water deficit. Meanwhile, protein increased linearly with TmR5R7 but decreased linearly with water deficit. Oil + protein concentration held a linear relationship with TmR5R7 even under water deficit. Cumulative solar radiation during seed fill predicts seed quality but shows lower significance than TmR5R7 This research demonstrates that a water‐stress indicator (pp‐PETR1R7) should be considered in rainfed crops because it affects the well‐known relationship of soybean seed oil and protein concentrations with temperature.

The environment has a significant influence on the expression of traits contributing to soybean nutritional and/or industrial value. The aim of this study was to explore and describe the variability of nontransgenic soybean seed chemical components by investigating the environmental correlations among protein (Pr), oil (O), oleic (Ol), linoleic (La), and linolenic (Ln) acids, oleic to linolenic acid ratio (Ol:Ln) alpha‐ (AT), beta‐ (BT), gamma‐ (GT), delta‐ (DT), and total tocopherols (TT) and total isoflavones (TI) by means of principal component analysis. We analyzed seeds from multienvironment trials involving 23 field trials grown in Argentina (24 to 38° S latitude). A wide range of variability was observed for Ol, Ln, Ol:Ln, AT, BT, and TI. The strongest environment‐induced relationships found were the negative correlation between DT and AT and the positive correlation between DT and Ln. Increased Ol:Ln was negatively correlated with Ln. High values of DT, Ln, and Pr were associated with cool environments, TI content was greater in temperate to cool environments, and AT, O, and Ol:Ln were associated with warm environments. Warm environments would be suitable for obtaining products with higher O concentration of low oxidation capacity and greater vitamin E content. In turn, temperate to cool environments would be suitable for the production of soybean with higher TI, La, Ln, and TT content; in addition, these environments would favor seeds of higher Pr concentration.

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-The objective of this work was to perform a quantitative analysis of the amino acid composition of soybean seeds as affected by climatic variables during seed filling. Amino acids were determined from seed samples taken at harvest in 31 multi-environment field trials carried out in Argentina. Total amino acids ranged from 31.69 to 49.14%, and total essential and nonessential amino acids varied from 12.83 to 19.02% and from 18.86 to 31.15%, respectively. Variance components expressed as the percentage of total variation showed that the environment was the most important source of variation for all traits, followed by the genotype x environment interaction. Significant explanatory linear regressions were detected for amino acid content regarding: average daily mean air temperature and cumulative solar radiation, during seed filling; precipitation minus potential evapotranspiration, during the whole reproductive period; and the combinations of these climatic variables. Each amino acid behaves differently according to environmental conditions, indicating compensatory effects among them.Index terms: Glycine max, environmental variation, multiple linear regression, multi-environment trials, protein composition. Conteúdo de aminoácidos em sementes de soja em função de variáveis climáticasResumo -O objetivo deste trabalho foi realizar uma análise quantitativa da composição de aminoácidos de sementes de soja em função de variáveis climáticas, durante o período de formação do grão. Foram analisados os aminoácidos de amostras de sementes colhidas no momento da colheita a partir de 31 ensaios multiambientais realizados a campo na Argentina. Os aminoácidos totais variaram de 31,69 a 49,14%, e o total de aminoácidos essenciais e não essenciais variou de 12,83 a 19,02% e de 18,86 a 31,15%, respectivamente. Os componentes de variância expressos como percentagem da variação total mostraram que o ambiente foi a fonte de variação mais importante, seguido da interação genótipo x ambiente. Regressões lineares significativas foram detectadas para o conteúdo de aminoácidos em relação a: temperatura média diária do ar e radiação solar acumulada, durante a formação dos grãos; precipitação menos evapotranspiração potencial, durante todo o período reprodutivo; e combinações dessas variáveis climáticas. Cada aminoácido comporta-se de forma diferente de acordo com as variações nas condições ambientais, o que indica efeitos compensatórios entre eles.Termos para indexação: Glycine max, variação ambiental, regressão linear múltipla, ensaios multiambientais, composição de proteínas.