Physiological Compensatory Effection Of Two Type Of Wheat Under Water Stress In North China

Water deficiency and inhomogeneity of spatialand temporal distribution became the major limiting factor of the grain production in China. Agricultural water continued unabated along with the development of society. Developing water-saving agriculture and promoting the efficient use of water resources in North China and the whole country became the inevitable choice.Our objective was to investigate the compensatory effects of water stress and re-watering on varieties, yield and water use efficiency (WUE) in winter cultivars'Shijiazhuang8'(drought resistant) and'Yanmai20'(drought sensitive) in North China during jointing stage and filling stage. The result indicated that:(1) Water stress had impact on physiological indexes during wheat jointing stage and filling stage. On the whole, jointing stage is more sensitive to water than the filling stage and the jointing stage was the ideal stage for the identification of drought resistance of winter wheat.(2) From the duration time, the longer of water stress was on jointing and filling stage, the greater the physiological indicators of winter wheat was affected and WUE may also decrease . When the stress time for 5 days and the mild water stress, two varieties had possibility of compensation, and even had the poss-ibility of super-compensation. When the stress time for10 day, the drought tolerance'Shijiazhuang 8'in mild water stress also have the possibility of super-compensation but non-drought species does not appear overcompensation. Overall, whether the drought tolerance'Shijiazhuang 8'or non-drought'Yanmai20'had a better compensation effect under the short-term water stress and re-watering.(3) From the stress level, the more serious of water stress was on jointing and filling stage, the greater the physiological indexes of winter wheat was affected and WUE may also decrease . The super-compensation may occur after the mild water stress. Two types had different levels of compensation but no super-compensation after the severe water stress. Overall, mild water stress and re-watering can make the species had a better compensation.(4) From the species, the Yanmai20's water potential, relative chlorophyll content, net photosynthetic rate, transpiration rate and fluorescence parameters and other physiological indicators decrease sharply compare to Shijiazhuang8. The physiological indexes of the water resistant cultivar Shijiazhuang8 could compensate rapidly after re-watering. Compensatory effects or even extra compensatory effects could happen and WUE was higher than that of CK after mild water stress and re-watering. Different cultivars had different compensatory under the water stress and re-watering. The drought resistant cultivars had better compensatory compare to the drought sensitive cultivars. The result indicated that the compensatory had effects to water use efficiency. The drought resistant cultivars had higher water use efficiency. So, we can use the compensatory to identify drought resistance.In short, compare to drought sensitive, the drought resistant cultivars showed better compensatory after water stress and the water use efficiency also was higher than the drought sensitive cultivars. So, we could use the compensatory to identify drought resistance. The result also showed it could get higher water use efficiency after mild and short water stress.