Dissecting heat tolerance and yield stability in maize from greenhouse and field experiments

Abstract High temperature during flowering increasingly reduces maize yield with warming climate. Heat tolerance of maize is however not fully understood in the aspect of flowering characteristics and yield stability, especially in the female flowering patterns. Temperature‐controlled greenhouse studies were conducted to test heat tolerances of four inbred lines and five hybrids, including 30/20 and 40/30°C treatments during 15 days bracketing the silking stage. Field studies were conducted to determine yield stabilities of five hybrids at three stations including four field environments. In greenhouse study, fertility rate and kernel number per ear (KN/ear) of nine genotypes reduced from 34.41–83.03% and 162.0–653.7 at 30/20°C to 0.68–23.13% and 0.3–332.5 at 40/30°C, respectively, mainly due to reduced pollen shed weight (PSW), pollen viability (PV) and silking rate (SR) at 40/30°C. Hybrids Chang7‐2×Qi319 and Chang7‐2×Xian2 showed significantly higher yields and KN/ear at 30/20°C, but only Chang7‐2×Qi319 performed better at 40/30°C. In field studies, Chang7‐2×Xian2, Xian2×Zheng58, Qi319×Xian2 and Chang7‐2×Qi319 were winning hybrids at specific environments. Chang7‐2×Xian2 showed the highest yield potential due to the larger ear size and KN/ear but a lower yield stability because of the lower PSW and PV. Chang7‐2×Qi319 combined high‐yield potential and high‐yield stability, which can be explained by large PSW, high PV and SR, and stable flowering pattern at different environments. Female flowering pattern (e.g. silking dynamics) is also a key determinant of high temperature tolerance and yield stability in maize. Hence, maize male and female organs should be equally concerned when achieving high and stable yield under different adverse environments in warming climate.