Combined effect of high temperature and water-deficit stress imposed at vegetative and reproductive stages on seed quality in soybean

Water deficit and high temperature are important environmental factors restricting plant growth, while the two stresses often occur simultaneously in nature, little is known about how their combination affects plants. Therefore, the main objective of the current study was to provide an overview of the influences of these two stresses independently and in combination on seed quality in soybean. Two soybean genotypes JS 97-52 and EC 538828 were grown at day/night temperatures of 30/22, 34/24, 38/26 and 42/28 °C under green-house conditions. At each temperature, pots were divided into three sets, one set was unstressed while second and third set were subjected to water stress at vegetative and reproductive stage, respectively. The highest average seed yield (10.9 g/pl) was observed at 30/22 °C, which was significantly reduced by 19, 42 and 64% at 34/24, 38/24 and 42/28 °C, respectively. Similarly, compared to unstressed plants (11.3 g/pl) there was 28 and 74% reduction in yield in plants stressed at vegetative and reproductive stage, respectively. Seed quality as determined by germination percentage, seedling vigor index, electrical conductivity, tetrazolium vigor test, oil and protein content were significantly affected by high temperature and water-deficit stress. Thus, both high temperature and water-deficit stress affected the yield and quality of seeds but the effect was more severe when water-deficit stress was imposed at higher temperatures. Also, when water stress was imposed at reproductive stage seed deterioration was more severe as compared to when it was imposed at vegetative stage. © 2018, Indian Society for Plant Physiology.