Abstract:

In order to clarify the effects of high temperature stress during grain filling stage on leaf senescence and yield,a field experiment from 2019 to 2020 was conducted with employing heat-sensitive variety(XY335)and heat-resistant variety(ZD958). Simple plastic greenhouse was constructed for heat treatment(HT)during 12-25 days after silking,the natural temperature was set as control(CK). The two years results showed that from 12 to 25 days after silking,high temperature stress significantly reduced the grain weight and yield of summer maize. For ZD958,the grain yield of HT was reduced by 18.8% and 19.3% than CK and thousand kernels weight(TKW)was decreased by 23.4% and 9.1%,respectively.For XY335,the grain yield and TKW of HT were reduced by 29.4%,26.3% and 20.1%,14.2%,respectively.High temperature during grain-filling stage accelerated leaf senescence. The two years results showed that leaf senescence rate(LSR)of ZD958 and XY335 under HT were increased by 76.4%,140.6% and 135.1%,139.6%,respectively.Leaf area duration(LAD)after silking with HT was reduced by 17.7%-36.5% compared with CK. Ear leaf photosynthesis under HT was lowered by 20.0%-42.9% than CK.Correlation analysis results indicated that accelerated LSR under HT had negative correlation with grain yield but without statistical significance(P=0.064 7).LAD after silking,photosynthesis,and SPAD significantly reduced under HT,which showed significant positive correlation with grain yield(P< 0.05). Taken together,heats tress during grain filling significantly accelerated leaf senescence,thus lowering kernel weight and resulting in yield loss. Under high temperature stress,heat-resistant maize variety had higher regulation ability than high temperature-sensitive maize variety,which could significantly mitigate yield loss caused by high temperature stress.

Key words: Summer maize, High temperature, Leaf senescence, Yield