Effect Of Salt Stress On The Physiologocal And Ecological Characteristics Of The Three Shrubs

Salinity stress is one of the most serious factors limiting the growth of the plant. Hedysarum scoparium Fish.et Mey.,Caragana korshinskill kom., H. mongolicum Tur(Z) can survive in some extreme environment such as drought, high and low temperature, high salt or alkali concentrations. They are the important plant resources in the northwest China. But it is known a little about the mechanism of its tolerance to salt stress. In this study, the effect of salinity on the seed germination and the seedling growth of the three species were investigated. The main conclusions were followed:1. The responses of the seeds germination of the three species to the NaCl concentration were very similar. Seed germination decreased with the increase of salinity. In the end, germination was completely inhibited. The NaCl concentrations which started to inhibit seed germination for H. scoparium Fish.et Mey.,C. korshinskill kom. and H. mongolicum Tur(Z) were 9, 6and 3g/L NaCl, respectively. The salinities to completely inhibit seed germination were 15, 12and 12g/L NaCl, respectively. The radicles and hypocotyls growth of the three species were inhibited. But the radicle/hypocotyl increased with the increase of salinity.2. The survival rate of the three species under salt stress was different. The survival rate of H. scoparium Fish.et Mey.could maintained at 100% when the concentration of NaCl≤4g/L. The survival rate of C.korshinskill kom. and H. mongolicum Tur(Z) could maintain at 100% when the concentration of NaCl≤2g/L.The tissue humidity content and the height growth rate increased with the increase of salinity.3. The content of MDA in leaves of the there varieties increased under salt stress, as well as the membrane permeability. This indicated that protoplasm membranes were injured by salt stress. The praline content increased under salt stress. The SOD activity of three species increased under low salt stress, whereas decreased under heavy salt stress. The activity of POD and CAT varied irregularly. The chlorophyll content of H. scoparium Fish.et Mey. and C. korshinskill kom. increased with the increase of salinity, whereas H. mongolicum Tur(Z) decreased.4. The results showed that the seed germination and the seedling growth of this three species has tolerance to the salt stress. They could be used as landscape plant in saline soil (the salinity of the soil were under 0.8%) of TianJin.