Root And Photosynthetic Trait Study Of Different Soybean Varieties Under Drought Stress

To investigate effects of drought stress on root traits and photosynthetic physiological of different drought resistance soybean cultivars, stronger drought resistance of Jindou 21,Jindou 31 and drought resistance of weak Liaodou 32,Tiefeng 34 were selected and compared in the pot experiment under drought stress. Results from this thesis can provide theoretical guidance for soybean drought resistance breeding. Results are listed as the following:1 Root traits of soybean cultivars different drought resistanceThe root length, root surface area, root volume, root tip number, root dry weight of soybean cultivars all were the biggest at the filling stage.The root length, root surface area, root volume, root dry weight, root activity and root-shoot ratio of drought resistance of Jindou 21 and Jindou 31 were bigger than those of drought resistance of weak Liaodou 32 and Tiefeng 34. The root diameter of drought resistance varieties were greater than those of non-drought resistance varieties at branching stage and flowering stage, The root diameter of drought resistance varieties were less than those of non-drought resistance varieties at the podding stage and filling stage. The root length, root surface area, root diameter, root volume, root number, root dry weight and root activity were reduced under drought stress,The root-shoot ratio of drought resistance varieties were increased at branching stage and filling stage.The trend of changes of root length, root surface area, root diameter, root volume, the number of root tip number, root dry weight and root vigor were same between drought resistance varieties and non-drought resistance varieties under drought stress. The result indicated that the root characteristics of drought resistance soybean varieties were developed root system2 Photosynthetic characteristics of soybean cultivars different drought resistancePhotosynthetic rate, stomatal conductance, intercellular CO2 concentration and transpiration rate of soybean cultivars all were higher at flowering stage than podding stage.There were no significant differences in drought resistance varieties Jindou 21, Jindou 31and non-drought resistance varieties Liaodou 32,Tiefeng 34 of photosynthetic rate, stomatal conductance, intercellular CO2 concentration and transpiration rate under drought stress.The photosynthetic rate, stomatal conductance, intercellular CO2 concentration and transpiration rate were reduced under drought stress.The stomatal conductance, intercellular CO2 concentration and transpiration rate of drought resistance cultivars were significantly decreased under drought stress at flowering stage. The photosynthetic characteristics of drought resistance varieties were realized by regulating stomatal closure and reducing water transpiration under drought stress.3chlorophyll fluorescence parameters of soybean cultivars different drought resistanceMaximum photochemical efficiency, the actual light quantum efficiency, photochemical quenching coefficient and the electron transfer rate of soybean varieties, flowering stage were higher than the podding stage. Actual light quantum efficiency photochemical quenching coefficient and electron transfer rate were decreased at flowering stage and podding stage under drought stress. The decreased degree of actual light quantum efficiency and photochemical quenching coefficient were higher Non-drought resistant varieties Liaodou 32,Tiefeng 34 than drought resistance varieties Jindou 21,Jindou 31 under drought stress.The change range of drought resistant varieties was smaller, having higher electron transfer rate of drought resistant varieties under drought stress...