High temperature around flowering and early grain filling greatly reduced maize yield. Hybrids responded differently to high temperature stress, but the underlying mechanisms are unclear, particularly from the perspective of growth season that is widely used to adapt different environments. For this, 162 maize inbred lines with different growing degree days (GDD) were planted at six different environments by adjusting sowing date over four years of 2015 – 2018, including two control treatments and four high temperature treatments during flowering and early grain filling. Yield was significantly positively correlated with GDD but negatively correlated with killing degree days (KDD) across six environments. Daily maximum temperature during flowering and early grain filling was a more important determinant of yield (R² = 0.689) than solar radiation (R² = 0.265) and precipitation (R² = 0.288). Grain yield significantly reduced at high temperature mainly as a result of reduced kernel number per ear (KN/ear). KN/ear was reduced by 11 – 100% among inbred lines at heat stress, and the reductions followed the similar pattern for inbred lines that had different GDDs. Based on GDD, 162 inbred lines were divided into short – (SS) and long – season (LS) groups. Kernel number reductions (% / °C) in SS and LS groups were 14.4 and 12.0, respectively, with significant difference between groups. This revealed that long – season maize lines showed a higher heat tolerance than short – season lines in kernel number formation by maintaining a relatively stable anthesis – silking interval. SS maize was more tolerant to heat stress during early grain filling than LS maize in kernel weight development due to a shorter exposure to heat stress. It is feasible to select of or breed for heat tolerant maize in different regions where maize has different growth seasons. A proper sowing date, along with heat tolerant hybrids should be considered to offset the adverse effects of warming climate.

开花前后的高温和早熟的谷物大大降低了玉米的产量。杂种对高温胁迫的反应不同，但是其潜在机制尚不清楚，特别是从广泛用于适应不同环境的生长季节的角度来看。为此，通过调整2015年至2018年的四年播期，在六个不同的环境下种植了162个不同生长日数（GDD）的玉米自交系，包括在开花和早期灌浆期间的两种控制处理和四种高温处理。在六个环境中，产量与GDD显着正相关，但与杀伤天数（KDD）负相关。开花和灌浆初期的每日最高温度是决定产量的重要因素（R ² = 0.689）比太阳辐射（R ²  = 0.265）和降水（R ² = 0.288）。高温下的谷物产量显着降低，这主要是由于每只耳朵的籽粒数减少（KN /耳）。在热胁迫下，自交系的KN /耳降低了11 – 100％，对于具有不同GDD的自交系，其降低遵循相似的模式。根据GDD，将162个自交系分为短（SS）组和长（LS）组。SS和LS组的内核数减少量（％/°C）分别为14.4和12.0，各组之间存在显着差异。这表明，通过维持相对稳定的花期-吐丝间隔，长季玉米品系比短季玉米品系表现出更高的耐热性。SS玉米在籽粒重发育过程中比LS玉米在早期灌浆过程中对热胁迫的耐受性更高，这是因为较短的热胁迫暴露时间。在玉米具有不同生长季节的不同区域中选择或育种耐热玉米是可行的。应考虑适当的播种日期，以及耐热杂种，以抵消气候变暖的不利影响。