GENOTYPE-SPECIFIC PHYSIOLOGICAL, BIOCHEMICAL, AND AGRONOMIC RESPONSES OF SOYBEAN TO WATER-DEFICIT STRESS

Abstract

Water-deficit stress is one of the significant factors limiting soybean productivity, as it affects plant water relations, photosynthetic efficiency, biochemical metabolism, biomass production and reproductive development. The physiological, biochemical and agronomic response of soybeans to different water-deficit conditions was evaluated under different genotypes. Physiological characteristics, such as relative water content, chlorophyll content, leaf area index, and plant height biochemical characteristics, such as sugars and protein-related characteristics and agronomic characteristics, such as number of pods, biological weight, seed weight, seeds per pod, and seed yield, were evaluated in six soybean genotypes. There were significant genotype × stress interactions for plant height, relative water content, sugar concentration, biological weight and seed yield, showing that there are significant differences in the drought response among the genotypic groups. Stress, genotype and their interaction had significant effects on seed yield. Biological weight had the highest positive correlation with seed yield and was the most positive predictor in a regression model after removing the other traits. After adjusting for the other traits as their regression coefficients, chlorophyll A and sugar concentration were negatively correlated with seed yield, while biological weight had the highest positive coefficient. A combination of physiological, biochemical and agronomic variability was also reflected in drought response as shown by principal component analysis.