Double adaptability of cold type wheat to drought and rainy weather
冷型小麦对干旱和阴雨的双重适应性

It has been discovered that there existed cold type wheat, warm type wheat and intermediate type wheat in natural world through observations and measurements of wheat canopy temperature (plant temperature) for over 10 years. Canopy temperature of cold type wheat was comparable to or always lower than that of check wheat from year to year; on the contrary, canopy temperature of warm type wheat was always higher than that of check wheat. Canopy temperature of intermediate type wheat had strikingly polymorphism, i.e., there were canopy temperature fluctuation, consistently lower canopy temperature like cold type wheat and consistently higher canopy temperature like warm type wheat in different years. The excellent adaptability of cold type wheat to a wide range of meteoro-ecological conditions has been found through further studies, i.e., under normal weather conditions, the activity of cold type wheat was stronger, metabolic function was better, senescence was lighter than those of other wheat types; On the other hand, under drought and rainy weather conditions with extremely differing unfavorable meteorological factors, cold type wheat with a low canopy temperature could continuously maintain those superiority to warm and intermediate wheat types in a series of important traits, such as leaf functional duration, chlorophyll content, soluble protein content, CAT activity, net photosynthesis rate and kernel plumpness index. The double adaptability of cold type wheat to drought and rainy weather, a very valuable biological trait, could provide solid ecological and physiologic bases to obtain high and stable yield in the various meteoro-ecological conditions and a novel breeding index to breed good varieties with a low wheat plant temperature.