Yield compensation among plant regions improves soybean adaptation to short-term high-temperature stress during the...

Extreme heat events prolong the reproductive period and threaten soybean yield, whereas the specific stage at which individual fruits growth is delayed, and yield/yield components at the node, region, and plant levels under short-term heat stress in the reproductive stage are elusive. In this study, heat treatments (40/30 °C) were applied at 0-6 days (HT_F0-6), 6-12 days (HT_F6-12), 12-18 days (HT_F12-18), and 0-12 days (HT_F0-12) after the plant's first flower opened, and a control treatment (32/22 °C) was performed. The influences of heat stress on fruit development and yield/yield components at the node, region, and plant levels were investigated. As a result, the growth of individual fruits at nodes was delayed by HT_F0-6 and HT_F0-12, which was primarily caused by the prolongation of flowering to pods with a length of 2 cm. Interestingly, there were no significant differences in yield between the control treatment and the various high-temperature stress treatments at the plant level. Further analysis of the regional yield of soybean showed that the yield in the bottom and top regions of plants played significant roles in compensating for yield loss in the middle region after HT_F0-12. Moreover, the delayed growth of individual fruits in the middle region was negatively correlated with yield. Our results indicate that the prolongation of fruit development induced by HT_F0-6 and HT_F0-12 may adversely affect soybean yield. However, the spatial compensation of plants could help maintain soybean yield under various short-term high temperature stress treatments during the reproductive period, which should be considered when breeding for and selecting heat-tolerant varieties.