Studies On Impacts Of Water Stress-rehydration Responses Of Winter Wheat On Its Yield WUE

Water shortage is the major limitation of the food production in China. After the greatest effectiveness of the projects of water saving, the only way to achieve new breakthroughs in water-saving agriculture is to develop biological water saving based on the crop's biological and genetic potential. Wheat is the third largest food crop in China, enhancing the research of identification of wheat cultivars with the drought-tolerance and water-saving characteristics will establish the methods and technology system of drought-tolerance and water-saving wheat cultivars identification which will be the research focus of the future sustainable development of agricultural.Six wheat cultivars were selected with different water use efficiency. The wheat cultivars were grown in pot in rain shelters, and the soil moisture content was controlled, the yield and yield WUE were studied under full watering and water deficit condition at jointing-booting and filling-mature stage. And the effects of different growth period, different drought resistance mechanisms and different levels of WUE and recovery capacity after rehydration to yield WUE were analyzed, then the critical factor related to yield WUE were determined, in order to discuss the reliable physiological traits which are fit for identify water-saving varieties with large quantities of species.The results show that:(1) Based on drought resistance (output indicators) and water-saving characters (yield WUE indicators), the six winter wheat varieties can be divided into four types. Drought-tolerance and water-saving type: Jinmai 47, Luohan 2, Zhengmai 9023; neither drought-tolerance nor water-saving type: Yanmai 20; drought-tolerance but not water-saving type: Yumai 18; water-saving but not drought-tolerance type: Shijiazhuang 8.(2)Different drought resistance mechanism have different effects to yield WUE. Under water deficit condition at jointing-booting stage, the membrane ion leakage has good correlation (R2=0.4099) with yield WUE, while the correlation was very low under full watering condition, and the correlation of osmotic adjustment and yield WUE was very low, and the correlation of stomatal conductance and transpiration rate with yield WUE showed significant correlation. Under full watering condition, the correlation of stomatal conductance and yield WUE was significant, and the coefficient R2 was 0.7841. In filling-mature stage, under full watering and water deficit conditions, the correlation of drought indices and yield WUE was not significant.(3)The correlation of different spatial and temporal scales of WUE and yield WUE showed that, at jointing-booting stage under full watering condition, the correlation of intrinsic WUE, leaf WUE and stage biomass WUE and yield WUE was significant, the correlation of intrinsic WUE and yield WUE was the highest(R2=0.7138). Under water deficit condition, the correlation of intrinsic WUE and stage above biomass WUE with yield WUE was significant, R2 were 0.6602 and 0.6445. At filling-mature stage, the correlation of different spatial and temporal scales of WUE with yield WUE were lower than the correlation at jointing-booting stage.(4)After rehydration at jointing-booting stage, Luohan 2, Jinmai 47, Yumai 18 and Shijiazhuang 8 have strong ability of recovery, but the recovery ability of Yanmai 20 and Zhengmai 9023 were weak. The correlation of transpiration rate, membrane ion leakage rate, stomatal conductance and intrinsic WUE with yield were very high, R2 were 0.8471, 0.7782, 0.7586 and 0.5904, respectively, but these traits didn't have a significant correlation with yield WUE.Therefore, the varieties yield WUE identification should be in the jointing-booting stage. Stomatal conductance and intrinsic WUE can be as the primary identification indexs for yield WUE under full watering condition at jointing-booting stage, and stomatal conductance, intrinsic WUE, stage above biomass WUE, transpiration rate and membrane ion leakage rate can be as the primary identification indexs for yield WUE under water deficit condition at jointing-booting stage. The recovery ability after rehydration is an important factor affecting grain yield, and thus could provide a new idea for the evaluation of yield WUE.