The inheritance of high temperature tolerance in soybean (Glycine max (L.) Merrill)

Objective: Heat stress during flowering and seed filling is an important result of global climate change. Therefore, this study was designed to determine the inheritance of agronomic, physiological and quality characteristics of soybean, the suitable parent and promising hybrids under heat stress. Material and Methods: Arısoy, Pınar, Samsoy, Ataem-7 and Blaze soybean cultivars, and their half-diallel F1 populations were used as material in this study. Also, the Lider cultivar was used as a check. Heat stress was created as artificial during the flowering (R1 - R2) and the beginning of seed filling (R5) in 2020. Diallel analyses were performed for all characteristics. Results: Jinks-Hayman type diallel analysis indicated that all characteristics were controlled by non-additive genes. While general combining ability effects of Ataem-7 and Blaze cultivars were favourable for unfilled pod number, Pınar and Samsoy cultivars had significant and positive general combining ability effects for yield. Pınar × Samsoy combination had positive specific combining ability effects in terms of unfilled pod number and yield. Generally, negative heterotic effects for single-plant yield and seed protein content were determined whereas heterotic effects for seed oil content were a positive direction. Conclusion: Single-plant selection in plant breeding programmes under heat stress should be started in the next generations (F5-F6). Arısoy and Pınar can be successfully used as genitors in heat stress-tolerant breeding. Also, Arısoy × Ataem-7 and Pınar × Samsoy hybrid combinations should be transferred to further generations. Key Words: Heat stress, Heritability, Gene actions, Combining ability, Heterotic effects