Standardization of heat stress mitigation on seed yield and quality in Soybean

Abstract

Pulses and oilseed legumes like soybean are vital for global food and nutritional security due to their rich protein content, nitrogen-fixing ability, and adaptability. However, increasing temperature extremes associated with climate change significantly impact their productivity and seed quality, especially during reproductive stages. This study was conducted to standardize heat stress mitigation strategies to improve seed yield and quality in soybean (Glycine max (L.) Merr.), which plays a dual role as a food and industrial crop due to its high protein and oil content. A field experiment was carried out during January and February 2024 at the ICAR-Indian Institute of Seed Science (Regional Station), GKVK, Bengaluru, using a strip plot design with two sowing dates, nine treatments (including salicylic acid, gibberellic acid, and growth regulators), and four spray stages. The results revealed that both treatment type and stage of application significantly influenced growth and yield attributes. Salicylic acid (T₃ @ 50 ppm) emerged as the most effective treatment, recording the highest plant height (56.04 cm), seed yield (23.85 g/plant), and seedling length (30.01 cm), along with the lowest seed moisture content, indicating accelerated maturity under stress. The vegetative and flowering stage spray (S₄) led to superior performance in terms of plant height, pod number, and seed yield, demonstrating the critical role of timing in stress mitigation. February sowing showed slightly higher seed moisture due to reduced seed-filling duration under high temperatures. Overall, the study highlighted that exogenous application of salicylic acid and timely intervention at specific growth stages significantly enhance heat stress tolerance in soybean. These findings contribute to the development of climate-resilient production strategies, ensuring stable yield and quality in heat-prone environments.