Studies On Seed Germination And Salt-resistance Mechanism In Seedlings Of N. Tangutorum

N. tangutorum is excellent shrub with wind prevention and salt resistance, but also is the autoecious plant of Cynomorium songaricum. In this study, on the basis of studying its seed pretreatment, the seedlings were treated in different concentrations of salt combined applying CaCl2 in order to reveal the salt-resistance mechanism and the role of exogenous Ca2+ in its salt resistance.The results show as follows:1. To explore the way to improve seed emergence quality and seedling growth of N. tangutorum, the seeds were pretreated with different methods before soaked at 60℃for 24 hours and sowed. Simultaneously, the seeds without pretreatment was taken as the control. The results showed that the emergence rates in all treatments incresed in the'S'curve fitted to Logistic equation with emergence durations ranging from 38 d to 55 d and the utmost germination rates ranging from 30.2% to 57.8%. The seeds rubbed and rolled with sands showed high emergence quality resulted in good seedling growth, whose emergence rates, emergence vigors, emergence indexs and vigor indexs increased by 15.6% and 13.4%, 60.1% and 6.9%,35.2% and 13.2%,41.5% and 23.3%, respectively, as compared with the control. Especially, the seeds rubbed with sands emergenced in convergence, which was 5 days earlier than the control. All above reveals that the rubbed and rolled treatments for the seeds mixed with sands may breakage their solidly compact endocarp structure and break their dormancy inproving the seeds to emergence and grow. However, it should notices that if operated improperly the rolling may destroy their internal structure.2. N. tangutorum seedlings at 150 d's age were highly adapted to salt stresses.The RC in seedlings directed soaked in 0-3% NaCl solution for 1-4 d gradually reduced to the CK level. TTC reduction ability in the roots were enhanced in two days following treatment. The decrease in TTC reduction ability activated synergy of antioxidant enzymatic activities and eliminated ROS produced by salt stress resulted in enhancement of membrane stability and maintainence of root viability, leading to keep root ility setting up good foundation for regrowth under good environmental condition.3. N. tangutorum seedlings have strong resistance to severe salt stresses. The seedlings were cultured for 1-10 d after irrigated by different salt concentrations of 0-15%, they showed strong antioxidant responsive ability and stable ecophysiological ability. It estimated by combined RC and NaCl concentrations with Logistic equation that the LS50 was 13.5%.4. Some extent of exogenous Ca2+ has efficient effect on improving the membrane satbility and root viability of the Nitraria seedlings resulted in resistance to severe salt stress.