Abstract: In this paper,the development characteristics,young ear differentiation and its growth,and spike characters of three varieties of wheat are sin+died under different photo-temperature conditions.The feasible way of getting larger ear and more grain and improving wheat yield is also approached.The results show that different photo-temperature condition during wheat growing period induced by different seeding time makes the emerged date of various development stages of wheat and the lasted days of these stages much difference.In many cases,there exists a significant or very significant negative correlation between the lasted days of young ear differentiation and the mean air temperature and mead daylength.Different accumulated temperature is the main factor which induces the difference of the growth rate of young ear and that of the total number of spikelets per ear.In suitable wheat-planting area,it is practicable to introduce suitable varieties and appropriately shift their seeding to an earlier time to get larger ear and more grain and to improve wheat yield.

Key words: Wheat, Larger ear formation, Air temperature, Daylength, Festuca arundinace, subcellular structure, antioxidant, biomass