Exogenous Application Of Calcium Chloride And Glycine Betaine Improve Drought Tolerance In Wheat

Two different genotypes of wheat, xiaoyan54 (high drought resistance)and jing 411(susceptible to drought) were used to studied the effects of exogenous application of CaCl2 and glycinebetaine (GB) on improving drought tolerance in wheat. The results were as followings:1. Exogenous application of CaCl2 and glycinebetaine by seed soaking can improve the growth and photosynthetic rate of wheat plants under drought stress(1)Drought stress restrain the growth and development of the wheat plants. Exogenous Ca2+ and glycinebetaine application can alleviate the restraining, increase the fresh and dry weight of root and stem and improve the growth in wheat seedlings. Growth increased in low Ca2+ concentration (0-10 mmol.L-1 CaCl2) but decreased at high Ca2+ concentration (20-30mmol.L-1 CaCl2). 10 mmol.L-1 CaCl2 is the appropriate concentration for improving the growth in wheat seedlings in this study..(2).Exogenous Ca2+ and glycinebetaine application increased proline and soluble sugars contents in the leaves of wheat seedlings. Exogenous Ca2+ application was more effective in increasing the souble sugar content than proline, while no singnificant difference between jing 411 and xiaoyan54. Exogenous GB applied plants accumulated more proline in jing 411 than xiaoyan54, but accumulated more souble sugar in jing 411than xiaoyan54 remarkably.(3) Drought stress decreased the chlorophyll content, photosynthetic rate and the photochemical efficiency. Exogenous Ca2+ and glycinebetaine application increased photosynthetic rate (Pn), practical photochemical efficiency (ФPSII). This could be related to the higher stomatal conduction (Gs).2. Exogenous Ca2+ and glycinebetaine application protected the cytoplasm membrane integrate and the function protein of chloroplast membrane under drought stress. (1) Exogenous Ca2+ and glycinebetaine application alleviated the oxidative injury of drought stress, such as decreased the MDA content, relative electrolyte leakage and the LOX activity under drought stress.Exogenous application of Ca2+ and glycinebetaine decreased the MDA content and the LOX activity more remarkable in jing411 than in xiaoyan54.(2) Exogenous Ca2+ and glycinebetaine application relived the oxidative stress by increasing the activity of anti-oxidative enzyme, such as SOD, POD, CAT and APX, and decreasing the O2- production rate and H2O2 content ExogenousCa2+ application decreased the O2- production rate more remarkably in xiaoyan54 than in jing411.But exogenous glycinebetaine application decreased the H2O2 content in jing411 more remarkably than in xiaoyan54.(3) ExogenousCa2+and glycinebetaine application relived the decrease of Ca2+-ATPase,Mg2+-ATPase activity in chloroplast membrane caused by drought stress.3. The interaction in improving the drought resistance between calcium and glycinebetaine(1) Drought stress restrained the absorbing Ca2+ much more than xiaoyan54. Exogenous Ca2+ and glycinebetaine application increased the Ca2+ content in the leaves of wheat seedlings. Exogenous Ca2+ application increased the Ca2+ content much more than in the leaves of xiaoyan54 than in that of jing411. While exogenous application of GB increased the Ca2+ content much more in the leaves of Jing411 than that of xiaoyan54 under drought stress.(2) Exogenous Ca2+ and glycinebetaine application increased the BADH activity under drought stress. Exogenous Ca2+ application increased the BADH activity more remarkably in xiaoyan54 than in jing411.But the BADH activity increased much more in jing411 than in xiaoyan54 with the application of GB.