Effects of Drought Stress on the Physiological Characteristics of Different Adzuki Bean Varieties at the Seedling Stage

The aim of this study was to select the index of drought resistance in adzuki bean breeding. The effects of three different drought stresses on the physiomorphological characteristics and root associated physiological characteristics of the adzuki bean (‘Baohong 947’,‘Dongbeidahongpao’, and ‘Jinxiaodou 5’) during the seedling stage were studied in a pot experiment. Results showed that drought stress inhibited plant growth, with all indexes showing a certain regularity with increasing drought stress. Compared with the control, the indexes of the three adzuki bean varieties, especially that under severe drought stress, changed effectively. The potential activity of PSⅡ (variable fluorescence/minimal fluorescence, Fv/Fo), maximal photochemical efficiency (variable fluorescence/maximal fluorescence, Fv/Fm), plant height, leaf area, stem diameter, root fresh weight, root activity, and content of soluble protein all decreased, respectively. However, with the decrease in water, the root-shoot ratio, content of proline (Pro), content of soluble sugar, activity of SOD, activity of POD and content of MDA increased, respectively. In short, ‘Dongbeidahongpao’ maintained a relatively superior physiological state under drought stress, exhibiting higher drought resistance than the other two varieties. By principal component analysis, the plant height, leaf area, stem diameter, main root length, root fresh weight, maximal photochemical efficiency (Fv/Fm), root activity, content of soluble sugar, content of soluble protein, activity of SOD, and content of MDA can be used as indexes for identifying drought resistance of the adzuki bean.