The Specific Characteristics of Wheat With Polymorphic Canopy Temperature
冠层温度多态性小麦的性状特征

Studies show that there exists a difference of canopy temperature (plant temperature) among different wheat genotypes in locations characterized by the completely identical climatic, soil and cultural conditions of any agro ecological regions. Wheat varieties whose canopy temperatures are close to or consistently lower than that of check variety, being the dominant one in the region for a long time during kernel filling and maturing period are named as cold type wheat; while wheat varieties whose canopy temperature are consistently higher than that of check variety are named as warm type wheat. Some important characteristics of cold type wheat are distinctly different from and superior to those of warm type wheat. The differences of canopy temperature and biological characteristics between cold type wheat and warm type wheat are significant and they all show clear monomorphism. Wheat materials and most cultivars are different from cold type wheat and warm type wheat and they show strikingly polymorphism in canopy temperature, that is to say, there are canopy temperature fluctuation, consistently lower canopy temperature like cold type wheat and consistently higher canopy temperature like warm type wheat in different years. The polymorphism of canopy temperature goes well with the polymorphism of other important characteristics, such as leaf functional duration, transpiration rate, net photosynthetic rate and kernel plumpness index, etc. The state closely relates to the environmental conditions especially weather conditions, and not occurs stochastically. The environmental conditions can be evaluated by environmental index. Environmental index for kernel filling and maturing period in one year can be estimated by the mean 1000 kernel weights of the wheat materials used in the trials every year, and the environmental conditions are measured in 5 levels according to the variability of the environmental index. The frequencies of leaf functional duration, depauperation of transpiration rate, depauperation of net photosynthetic rate, and kernel plumpness index of wheat materials and most cultivars above mentioned close to those of cold type wheat, were 71%, 67%, 67% and 46% respectively, in a production year with good weather conditions and high environmental index; while in a production year with very poor weather conditions and low environmental index, the frequencies declined greatly to only 46%, 37%, 16% and 19%, respectively. On the contrary, the frequencies of above mentioned traits of the same wheat materials close to those of warm type wheat were significantly lower than those of the materials close to those of cold type wheat in a production year with advantageous weather conditions (11%, 33%, 33% and 15%), while in a production year with very poor weather conditions, the frequencies rose greatly to 40%, 63%, 84% and 48%, respectively. That is to say, characteristics of wheat materials and most cultivars tend to those of cold type wheat with s