玉米在花期对高温胁迫十分敏感，通过挖掘耐热资源，培育耐热玉米品种是应对高温热害最有效的方法。本研究在大田自然环境下，调查了花期常温对照与高温逆境下64份不同玉米种质资源的籽粒产量、百粒重、结实率、结实粒数等产量性状。结果表明高温胁迫导致玉米结实粒数减少，结实率降低，，最终导致籽粒产量下降，而且种质间的耐热性存在显著差异，且年份对耐热性也有显著影响。本文利用主成分分析和模糊隶属函数法对所有种质的耐热性进行综合评价。结果表明，籽粒产量、结实粒数、结实率及百粒重可作为评价玉米自交系花期耐热性的主要指标。通过聚类分析筛选出5份耐热型自交系（NL001、PHPR5、CR14、CLWN240和PF5411-1），为培育耐热玉米新品种提供新的种质资源。
英文摘要:
Maize is extremely sensitive to high temperature, especially during flowering. Identifying new germplasm and breeding heat-resistant maize varieties are therefore essential. In this study, we planted 64 different maize germplasm under the natural environment in Chongqing. The grain yield, 100-grain weight, seed setting rate, grain number of these germplasms were investigated under normal temperature and high temperature. The results showed that tolerances of varieties to high temperature existed significant difference, and the year also had a significant effect on heat resistance. High heat stress resulted that the grain number，seed setting rate decreased, and grain yield reduced significantly. Principal Component Analysis (PCA) and Fuzzy Clustering (FC) were used to evaluate tolerances of varieties to high temperature. The results showed that four traits could be used as the major index of high temperature resistance of maize inbred lines. Five maize varieties(NL001，PHPR5，CR14，CLWN240 and PF5411-1) expressed significant tolerance to high temperature. This discovery will provide germplasm for breeding new maize varieties with high temperature tolerance.
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