Research On The Physiological And Biochemical Characteristics Of Spring Soybean Under Drought Stress

The research was performed at Northeast Agricultural University from 2007 to 2009. Used 15 soybean varieties with drought resistance screening, take the strongest (Heinong 57), moderate (Gailiang 168) and the weakest (Suinong 26) varieties as materials. Drought stress was processed in four stages, as seedling stage, flowering stage, pod-setting stage and seed-filling stage respectively. Used normal water management as control (70%~75% of field maximum water capacity), used moderate (50%~55% of field maximum water capacity) and severe (30%~35% of field maximum water capacity) drought stress in treating. Research on the related physiological indexes of lipid peroxidation matter, osmotic adjustment matter and the activity of protective enzyme in blades and roots after 4 days of lasting drought stress at four stages respectively, the conclusions obtained were as follows:1. Form 15 test materials screening out the strongest and the weakest drought-resistance ability of soybean varieties by tests of osmotic stress, they were Heinong 57 and Suinong 26, the moderate drought-resistance ability of soybean variety was Gailiang 168。2. The content of Chlorophyll in different varieties decreased gradually under drought stress; Root activity decreased with the increase degree of stress at seedling stage and pod-setting stage, while root activity increased first and then decreased at seed-filling stage; The root relative water content of different varieties all decreased under drought stress, and it decreased with the increased degree of stress.3. The content of proline in blades of different varieties decreased under drought stress, and large decreasing amount of severe drought stress; Soluble sugar content increased under drought stress at flowering and pod-setting stage, large decreasing amount of severe drought stress, there was no obvious difference in different varieties; In the whole growth period, the relative conductivity in blades of different varieties increased under drought stress, the increased degree at pod-setting stage was not significant; The content of MDA increased with the increased degree of stress, while it increased under moderate stress and decreased under severe stress in roots.4. The activities of SOD and CAT in blades and roots of different varieties increased under drought stress, there was a larger increasing amount of moderate drought stress than severe drought stress; The CAT activity increased with the increased degree of stress; In the whole growth period, the CAT activity increased in blades and roots, there was a larger increasing amount of moderate drought stress than severe drought stress, and for the same variety, CAT activity in blades was higher than that in roots at different stages.5. Under drought resistance, the content of proline and the relative water content in blades, the MAD content and SOD activity in blades and roots of different varieties were changed significantly with the different drought resistance of varieties, that could directly reflected the changed of soybean physiological under drought stress. And the physiological indexes at flowering and pod-setting stages were more sensitive to drought stress.