夏玉米对花期高温逆境的响应与耐热性分析

以浚单996(XD996)、郑单958(ZD958)、先玉335(XY335)为试验材料，采用温控试验，设自然温度(CK，29～32℃)、高温(HT，30、35、38、40℃)处理，研究花期不同程度高温对花粉活力和花丝活力的影响。采用高温胁迫试验，研究花期高温对受精结实、果穗发育、产量及构成因素的影响。结果表明，随着温度升高，各品种高活力花粉呈降低趋势，低活力花粉呈先增后降趋势，无活力花粉呈增加趋势，花丝活力呈降低趋势。模型拟合分析结果表明，以50%为阈值，XD996、ZD958、XY335的花粉活力耐高温临界温度分别为37.0、35.4、33.2℃，花丝活力耐高温临界温度分别为37.4、35.6、33.7℃。高温处理条件下，XD996、ZD958、XY335的受精率分别较CK降低8.8%、12.9%、20.1%，结实率分别较CK降低9.9%、18.4%、36.4%，结实受精比分别较CK降低1.3%、6.2%、20.3%。耐热系数聚类分析结果表明，穗长、穗行数、行粒数、产量为主要耐热鉴定指标，穗粗、秃尖长、百粒重为次要耐热鉴定指标。

Analysis of Response and Resistance of Summer Maize to High Temperature Stress during Anthesis

Xundan996(XD996), Zhengdan958(ZD958) and Xianyu335(XY335) were used as the experimental materials. The temperature-control experiment was conducted to study the effects of varying degrees high temperature during anthesis on pollen viability and filament viability. Meanwhile, the high-temperature stress experiment was conducted to study the effects of heat stress during anthesis on fertilization and fructification, ear development, yield and yield components. The results showed that with the increase of temperature, high-viability pollen showed decrease trend, low-viability pollen showed first increase then decrease trend, inactive-viability pollen showed increase trend, filament viability showed decrease trend. The results of model fitting analysis showed that, using 50% as threshold value, heat-resisting critical temperature of pollen viabilities of XD996, ZD958 and XY335 were respectively 37.0, 35.4, 33.2℃, and that of filament viability of XD996, ZD958 and XY335 were respectively 37.4, 35.6, 33.7℃. Under the treatment of HT, compared with CK treatment, for XD996, ZD958 and XY335, fertilization rate decreased respectively by 8.8%, 12.9%, 20.1%, seed setting rate decreased respectively by 9.9%, 18.4%, 36.4%, ratio of seed set and fertilization decreased respectively by 1.3%, 6.2%, 20.3%. The results of hierarchical cluster of heat tolerance coefficient showed that, ear length, ear row, kernels per row, yield could be used as the major identification indexes of heat resistance of maize hybrid, ear diameter, barren tip length, 100-grain weight could be used as the minor identification indexes of heat resistance of maize hybrid.