Study On The Physiology Response To Water Stress In Maize Seedling And Their Relationship To Varieties Drouhght Resistance

3 maize varieties which are different in drought resistance were used as materials and 26%PEG(4000) was used to induce water-stress in this experiment. The changes of plant morphology, physiological and biochemical characters and their relationship to varieties drought resistance were studied under water-stress. The result showed:1. Under water-stress the growth of plant was restrained. The plant height declined obviously, and leaf area, accumulation of dry matter were restrained in different degree. The growth of root was accelerated under short-term water-stress(24h),and comparison of the contrast the root length, number of root and root weight increased apparently. But the growth of root was restrained along with the process of water-stress and the indexes declined distinctly. The drought-resistant variety suffered from less damages and damages of the drought-susceptible variety were more.2. Under water-stress the internal physiology metabolize of plant changed distinctly. The relative water content, water-holding capacity , chlorophyll content, soluble protein content and NR activity of leaf declined apparently , and soluble carbohydrate content increased, but the changes of physiology indexes of varieties were different. Root physiology response was different from top. Soluble protein content and NR activity of root, root vigour, root total uptake area increased under short-term water-stress(24h), but the indexes declined along with the process of water-stress. And root active uptake area declined under every treatment of water-stress. Varieties varied in kinetic parameters of K+ absorption under water-stress.The Km and Cmin of the drought-resistant variety were lower than the drought-susceptible variety, but the I_max is higher.3. Under water-stress the balance of production and elimination of free radical in cells was destroyed, and cell membrane systems were harmed. Relative eletric conductivity and MDA content increased obviously, and the drought-resistant variety increased less than the drought-susceptible variety. Under short-term water-stress(24h) SOD activity increased, POD activity decreased, and the change of CAT activity had not orderliness. SOD, POD and CAT activity decreased obviously along with the process of water-stress.4. Under short-term water-stress, the yield of drought-resistant variety increased and the yield of drought-susceptible variety declined, the yeild of varieties declined apparently along with the process of water-stress, the drought-resistant variety reduced less and drought cofficient is higher than the drougnt-susceptible variety. The relationship between the physiology indexes and drought cofficient were studies. The results showed that there are significant correlation between varieties drought resistance and the character of NR activity, SOD activity, MDA content, relative eletric conductivity, leaf relative water content, leaf water-holding capacity, root activity, Km, root length, mumber of root, root/top. Meanwhile the correlation between varieties drought resistance and other characters are not significant.