Studies On Drought And Salinity Resistant Physiology And Biochemistry Characteristics Of Main Tree Species In Qaidam Basin

Under the background of increasing drought and secondary salinization,we study the characteristics of drought and salinity resistant physiology and biochemistry of Atriplex canescens,Elaeagnus angustifolia L.,Lycium ruthenicum Murr and Lycium barbarum in Qaidam Basin.These research results can provide theoretical and technical reference for the selection of plants in this area.The experiment was taken by potting control method.The effects of water stress,saline-alkali stress on the growth,leaf water,photosynthesis,osmotic adjustment substances and enzyme activity of antioxidant system characteristics of the four plants seedlings were studied.We can have a deep understanding of the response mechanism of the four plants to stress environment.And we can also calculate the plant water tolerance threshold and saline-alkali threshold.The main conclusions of this paper are as follows:(1)A.canescens has certain drought resistance and strong salt tolerance.The soil water content for A.canescens to maintain normal photosynthetic progress is 10.1 5%-18.61%and the optimal soil water content is 14.73%.The growth and photosynthetic capacity will significantly decreased when the soil water content is lower than 12.65%or higher than 19.61%.Mortality will occur when the soil water content is under 6.78%.The salt resistant threshold of A.canescens is 249.31 ± 12.54 mmol/L.When subjected to 50mmol/L solution,the growth and photosynthetic capacity of A.canescens increased compared with control,and then decreased with the increasing stress.Accumulation of osmotic substance and improvement of antioxidant enzymes are the key salt tolerance mechanism.(2)Elaeagnus angustifolia L.is great drought resistance and weak salt tolerance species.The soil water content of maintaining normal photosynthesis is 10.15%-18.61%and the optimal water soil content is 14.73%.The wilting soil water content with a net photosynthetic rate of 0 is 5.24%.Elaeagnus angustifolia L.responds to soil drought stress through increasing root to shoot ratio,increasing water use efficiency,accumulating the content of Pro,SS and SP in the cell and increasing the activities of SOD,POD and ACT.When the concentration of solution exceed 155.85mmol/L,the growth and photosynthetic capacity were inhibited and the photosynthetic apparatus was irreversibly destroyed.Besides,the organic osmotic adjustment ability was decreased and the activity of the antioxidant system enzyme was decreased.(3)Lycium ruthenicum Murr is great drought resistance and salt tolerance species.The soil water content for Lycium ruthenicum Murr to maintain normal photosynthetic progress is 11.24%-18.81%and the optimal soil water content is 15.15%.Mortality will occur when the soil water content is under 6.01%.The salt resistance threshold of Lycium ruthenicum Murr is 0-258.85mmol/L.When subjected to 50mmol/L solution,the growth and photosynthetic capacity increased compared with control.Reducing leaf water potential,accumulating the content of Pro,SS and SP in the cell and increasing the activities of SOD,POD and ACT,regulating photosynthesis are important regulation mechanism against drought stress and saline-alkali stress.But under high concentration of salt-saline stress,these mechanism were destroyed.(4)Lycium barbarum has certain drought resistant and salt tolerant.The soil water content of maintaining normal photosynthesis is 12.98%-20.73%and the optimal water soil content is 17.20%.The wilting soil water content with a net photosynthetic rate of 0 is 7.12%.Lycium barbarum responds to the soil drought stress through increasing root to shoot ratio,regulating photosynthesis,increasing water use efficiency,accumulating the content of Pro,SS and SP and increasing the activities of SOD,POD and ACT.When subjected to 50mmol/L solution,the growth and photosynthetic capacity have no significant different compared with control.But under 216.81mmol/L salt-saline stress treatment,the photosynthetic was irreversibly destroyed and the symptoms of salt damage were obvious.(5)Combined with the 32 physiological indexes,main component and comprehensive analysis of membership functions were comprehensively analyzed.Elaeagnus angustifolia L.has the strongest drought tolerance,followed by the Lycium ruthenicum Murr and the Atriplex canescens,Lycium barbarum has the weakest.Lycium ruthenicum Murr has the strongest drought tolerance,followed by Atriplex canescens,Lycium barbarum;Elaeagnus angustifolia L.has the weakest.(6)There were some interactions between soil water content,soil salt content and net photosynthetic rate of the 4 kinds seedlings.Fitting the soil water content and salinty content to the maximum daily net photosynthetic rate of the seedlings by models.The soil water content of the seedling growth tolerance threshold of Atriplex canescens,Elaeagnus angustifolia L.,Lycium ruthenicum Murr,and Lycium barbarum were 9.2-9.32%,8.65-8.84%,8.2-8.49%,8.2-8.53%,and the soil saline solution concentration were 290.20-295.22mmol/L,184.20-189.34mmol/L,270.60-276.82 mmol/L,and 212.20-218.52 mmol/L.