Impact of resource limitation during seed development on yield and seed composition in soybean

Soybean is one of the most important crops worldwide. Adverse environmental conditions restrict Soybean productivity and seed quality during reproductive stages, particularly those limiting carbon and nitrogen availability. This study aimed at evaluation of the effect of drought, nitrogen deficiency, and defoliation treatments on yield, and seed composition during seed development. Field study was carried out using a randomized block design to examine the effects of drought, nitrogen deficiency, and defoliation treatments on soybean yield related parameters, pod wall and seed soluble sugars, starch, and protein concentration at 10, 20, and 30 days after the beginning pod (R3) stage (DAR3). The results showed that drought and defoliation treatments exerted pronounced negative effects on pod number, total seed weight, and soluble sugar accumulation. Drought stress led to significant increase in starch accumulation during 10 DAR3. However, at 30 DAR3, starch concentrations decreased to similar levels across all stress treatments. Pod wall function as transit sink was disrupted under drought stress, due to reduced sink strength of the developing seeds, leading to carbohydrate accumulation within the pod wall. Based on protein and carbohydrates content, and yield attributes, soybean showed relatively high tolerance to nitrogen deficiency in terms of overall yield; however, seed quality in the term of protein concentration was significantly reduced. While, severe drought and high level of defoliation during grain filling stages negatively affected both plant yield and seed quality. Such observations can guide optimized irrigation and fertilization strategies to mitigate stress effects and enhance crop productivity and quality.