Drought tolerance of alfalfa seedlings of 10 varieties under PEG6000 stress

An experiment was conducted to estimate the drought tolerance of alfalfa (Medicago sativa) seedlings of 10 varieties stressed by PEG6000 with the concentrations of 0 (CK)、-0.3、-0.6、-0.9 and -1.2 MPa by measuring cell membrane permeability, malondialdehyde (MDA), free proline (Pro) and carotenoid (Car) concentration as well as superoxide dismutase (SOD) activity. This study showed that the cell membrane permeability, MDA and Car concentration in alfalfa leaves increased and the Pro concentration and SOD activity firstly decreased and then increased as drought stress increased. The maximum range of drought resistance of alfalfa seedlings was at -0.9 MPa water potential around. The subordination function analysis showed that the drought tolerance of 10 alfalfa varieties was German Derby＞Millionaire＞Algonquin＞West blend＞FGZT 106＞Emperor 1#＞Golden Empress＞Affinity＞XinJiang Daye＞Siriver.