Drought resistant physiological characteristics of 4 shrub species in arid valley of MinJiang River

Due to the fohn, there are 161 km of arid valley (170 km2) in Mingjiang River. The higer evaporation and transpiration (1400-2000 mm annually), lower precipitation (400-700mm annually), steep slope and infertile soils result in a atrocious condition for vegetation in the arid valley. Vegetation is dominated by xerophil shrubs and grasses. However they are playing a significant role in the soil and water conservation in the watershed, and provide important references for Grain for Green (converting farmland to forest/grass land) campaign in the arid valley as it is very difficult to grow trees. Drought-resistant physiological characteristics of four native species,i.e., Sophora davidiana,Bauhinia faberi var.microphylla,Convolvulus tragacanthoidesand Artemisia gmelini lochmodophilus have been measured. It was found that The content of Chl,free Pro,soluble sugars increased and evaporation ratio,WSD,RWC and cytolemma osmosis decreased under the drought stress; Integrated assessment on the drought resistant index of four species indicated that the integrated drought resistant index was highest in July (0.507),followed by September,August,June. It was lowest in May (0.442).The result provided a basis for the vegetation restoration especially improving survival of planted species in May and June during which species has weakest drought resistant.