Physiological Indices for Rapid Identification of Sweet Potato Drought Resistance and Selection of Methods

The relationships between the changes of relative water content (RWC), malondialdehyde (MDA) contents, superoxide dismutase (SOD) activity and free proline contents in sweet potato leaves, and drought resistant ability under different concentration of polyethylene glycol (PEG) treatment applied at rhizosphere of sweet potato seedlings were studied. A highly positive correlation between RWC and drought resistance (r = 0. 783, P 0. 01), a highly negative correlation between MDA contents and drought resistance (r= 0. 848, P 0. 01), a highly positive correlation between SOD activity and drought resistance (r=0. 777, P0. 01) was observed. Free proline contents in leaves did not relate obviously to the sweet potato drought resistance under 25 % PEG treatment. The stronger the drought resistance of variety, the less decrease of RWC and increase of MDA contents, the more increase of SOD activity. By determining these physiological indices in sweet potato leaves under 25% PEG treatment, rapid identification of drought resistant ability of different varieties can be obtained in the lab.