Study on physiological characteristics of five gramineous grass seedlings under drought stress

A water controlling experiment was carried out to determine the effect of drought stress on physiological indexes of five kinds of forage grasses which inclueded Agropyron mongolicum, A. cristatum×A. desertorum, A. desertorum, Psathyrostachys juncea and Bromus inermis by adopting pot culture method. Chlorophyll contents, membrane permeability, proline contents, superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT) activity, and malondialdehyde(MDA) contents were measured at different stage of the drought stress. The drought resistances of the five kinds of forage grasses were comprehensively evaluated by using subjection function method. The results showed that as the extension of drought stress period, the relative water content(RWC) decreased, the water saturation deficit(WSD), cell membrane permeability of the seedlings for the five grasses generally increased. The proline contents, chlorophyll contents, SOD, CAT and POD activity showed as increase-decrease trends. The MDA contents showed as increase-decrease-increase trends. The mean value of membership functions of the five grasses ranged from 0.351 0 to 0.688 1, and the drought resistance of the seedling period showed as: Agropyron desertorum>Psathyrostachys juncea>A. cristatum×A. desertorum>A. mongolicum>Bromus inermis.