Influences Of Water Stress On Growth And Development, Physiological Characteristics And Nutrient Distribution Of Winter Wheat

In order to reveal the psysiological foundation of wheat under water stress and it's nutrient transportion mechanism , an experiment has been carried out in meteorological station of Chinese Academy of Agricultural Sciences . Wheat cultivars CA0045 were sown in PVC pot. Plants were assigned in three treatments: 70%-75% of the field capacity in soil water content; 50%-55% of the field capacity in soil water content; 30%-35% of the field capacity in soil water content. We measure plant height, leaf area, WUE, dry matters, water content of every apparatus, relative chlorophyll content, Fv/Fm, net photosynthetic rate, transpiration rate, stomatal conductance and the content of K, N, P, Ca, Mg, Cu, Zn, Fe, soluble sugar of every apparatus in different stages. Then to analyse the yield components, dry matter distribution and nutrient distribution, and dicuss the effects of water stress on crop morphology, psysiological foundation and the nutrient distribution. The conclusion is summarized as follows:1 The plant height and the leaf area can be the intutionistic index of the winter wheat under water stress. Both of the plant height and the leaf area decreased because of the limited water.2 Before maturing stage, water stress brought more dry matters to the sheath ,at the maturing stage, more dry matters distributed to sheath and leaf, restained the dry matter distribution to the spike. It may be the main reason which do a harmful contribution to the number of spike, kernel number of per spike and the 1000 grain weight under the serious water stress. Water stress brought the wheat a big root,and the moderate stress can do a more positive effect to the root systerm..3 Relative chlorophyll content can on one hand represent the antagonistic ability of the plant and on the other hand ,it can reflect the Fv/Fm index, then we can estimate the destroying degree of the PSâ…¡.4 Water stress enhanced the antagonistic ability of the third leaf between elongation stage and anthesis stage,and this kind of ability enhanced with the the degree of water stress.5 Water stress caused the close of stoma and the decrease of stomatal conductiance and transpiration rate. It may be the main reason which restained the net photosynthetic rate ultimately in this experiment.6 From the heading stage, winter wheat appealed a big amount of water. According to the WUE of three treatments, there still was a big potential to save water for the moderate stress. There was no big differences between moderate stress and serious stress, but the yield under the serious stress was too low ,so it's not feasible for the actual application.7 Moderate water stress increased the distribution of N to spike, enhanced the N use efficiency. For P it showed the same trend with N, but water stress has intercepted more P to the stalk+sheath. From filling stage to maturing, moderate stress promoted P in the leaf distributed to spike. K distribution followed the ordinary rule of the nutrients under water stress: water stress restrained K transport from the stalk, sheath, leaf to the spike. Root is the main systerm to absorb Ca and Mg. Mg content in the leaf became to decrease from maturing stage, it may be the main reason for the decline of relative chlorophyll content. In the anthesis stage ,moderate water stress increased the absorbtion of Mg for the root systerm.8 Root is the main systerm to absorb Cu, Zn, Fe. Serious stress caused the Fe content of the root increase first and then decrease, moderate stress made it higher relative to controll. Water stress restained the absorbtion of Cu in root at first time, then acclerated it. Winter wheat had a big appeal of Zn in heading stage, water stress decreased the absorbtion of Zn in root and sheath at the beginning, then increased it under the serious stress.9 Soluble sugar content can be as an index to reflect the antagonistic ability of different apparatuses. According to the results, stalk and leaf of the late stage have a higher antagonistic ability under serious stress. And the spike under moderate stress had a higher antagonistic ability too. This may be serious stress restrained dry matters transported to spike, that leads the scarcity of carbohydrate, then proteinic hydrolyzation has been accelerated, which decreased suble sugar's anabolism.