Screening And Comprehensive Evaluation Of High Temperature Resistant Varieties Of Corn In Blossom Period

In recent years,extreme high—temperature weather frequently occurred. Selecting of heat tolerant varieties is a proper precaution to reduce the loss caused by the thermal damage of maize. Our experiment use the 30 main maize hybrids planted in Huang Huai Hai region as materials, field experiment add warmth artificially, high temperature treatment were treated from 8d before silking to 8d after silking. Then the changes of different genotype maize of morphology, physiology and yield traits were studied.what’s more, the indexes for evaluation heat tolerance in maize were screened and evaluated. The results as followed:1. Heat stress has great effects on the growth and development as well as the organ formation, and different genotype maize show significant difference. After high temperature treatment, corn leaf become thinner and specific leaf weight dropped significantly compared with the contrast(p<0.05); the plant height of most of the maize hybrids increased significantly,but there is a significant reduction in the plant stem diameter and accumulation of dry matter. Also, the development of maize male and female spike were arrested and the ASI were prolonged.2. Heat stress has significant effect of corn physiological characteristics. After high temperature treatment, for the ear leaf, the conductivity of the soaking solution increased significantly(P<0.05), and the content of chlorophyll were decreased, resulting in a significant reduction in the net photosynthetic rate(p<0.05).3. Heat stress has a great impact on maize grain yield and yield traits. The number of rows per ear were affected less by heat stress. But it makes corn ear shortened and become thinner, grain number per row decreased, bald tip length longer 100 grain weight decreased and seed setting rate lower, contributing to the result that the maize yield reduced by 11.31%~42.70%,which is significantly.4.According to the analysis of the correlation between the size and the amount of the changes of different self properties of maize genotype after high temperature treatment, we can conclude that Chlorophyll content, net photosynthetic rate, ear length, 100 grain weight, grain number per row and grain yield can be used as the major evaluation index of heat stress resistance of maize hybrid during flowing; the plant height, stem diameter, leaf weight ratio, conductivity, ASI, seed setting rate as an auxiliary index. Using the comprehensive membership function value as evaluation parameters by clustering analysis,the result showed that :Dedan121、Zhongzhong8、Liangsuo88 etc ten maize varieties are high temperature tolerant hybrid;Xianyu335、Yudi216、Zhengyu10 etc 5 maize varieties are high temperature sensitive hybrid.