Study On Drought Resistance Of Four Plantation Tree Species In Karst Mountain Areas

In this paper, the author has investigated physiological and biochemical response mechanisms of four tree species seedlings to the drought stress in methods of simulating drought stress gradient including Elaeocarpus sylvestris,Eurycorymbus cavaleriei,Cacumen Platycladi and Koelrenteria Paniculata. According to the aspects of productivity and adaptability to drought resistance, the eight indexes such as leaf water saturation deficit,MDA content,proline content,soluble sugar content,POD activity,leaf plasma membrane permeability,biomass and the ratio of root to stem were selected to evaluate the ability of drought resistance of the four tree species.The main results were as follows:There existed a similar changing tendency of leaf water saturation deficit, MDA content and leaf plasma membrane permeability of each tree species under different intensities of drought stress. Those three indexes increased with the increase of drought stress intensity, and got the largest value at the fast-growing stage.Both leaf proline content and soluble sugar content of all tree species seedlings got the highest value under severe drought stress, while the POD activity during the fast-growing period. The effects of drought stress on the four tree species could be ordered as: Eurycorymbus cavalerie> Cacumen Platycladi>Elaeocarpus sylvestris> Koelrenteria Paniculata.The MDA content,POD activity and leaf plasma membrane permeability all decreased to some extent after re-watering under different drought stresses. The activities of seedlings restored in a certain way, but the restoration degree depended on tree species, growth period and degrees of drought stresses.The ratio of root to stem of all four tree species in early growth stage increased with the enhancement of drought stress intensity.The drought resistance of four tree species were assessed comprehensively by means of subordination function method of fuzzy mathematics, and its order was as follows: Cacumen Platycladi >Eurycorymbus cavalerie >Koelrenteria Paniculata >Elaeocarpus sylvestris.