Physiological Response Of Tamarix Leptostachys To Salt Stress And Drought Stress

Drought and soil salinization are two main factors that restrict food security and ecological security in Hetao irrigated area.An important measure to improve the ecological environment of irrigated areas is afforestation,and the selection of drought-resistant and salt-tolerant tree species is the key.A large number of studies have shown that the physiological characteristics of plants in adversity can reflect their adaptability to the environment.In this study,2-year old Tamarix leptostachys was taken as the research object,and the soil water holding capacity and salt ion content in Hetao irrigated area were taken as the stress basis of drought and salt stress.In order to lay a foundation for the promotion and application of Tamarix leptostachys and provide scientific basis for afforestation and urban greening in arid,saline and alkaline areas,the physiological indexes such as chlorophyll content and protective enzyme activity were determined under drought and salt stress,and the adaptability of Tamarix leptostachys to drought and salt stress were analyzed.The results show that:1.Under the extremely severe stress of Na2CO3 and NaCl,the content of chlorophyll a in leaves of Tamarix leptostachys was continuously decreasing with the extension of stress time,while the content of chlorophyll a in other treatment groups was decreasing first and then increasing.The content of chlorophyll b decreased first and then increased.The results showed that extremely severe stress of Na2CO3 and NaCl inhibited the photochemical reaction of chlorophyll and inhibited the photosynthesis of Tamarix leptostachys.2.The growth rate of MDA content under NaCl stress was the highest in all gradients,indicating that NaCl salt stress was more serious to the membrane system of Tamarix leptostachys than NaHCO3 and Na2CO3 salt stress.3.With the extension of stress time,MDA content showed a trend of first increasing and then decreasing,POD activity and CAT activity also showed a trend of first increasing and then decreasing,reflecting the positive response of protective enzymes to the destruction of plant membrane system,indicating that Tamarix leptostachys has a strong self-regulation ability.4.There was a significant difference between MDA content and CK under moderate and severe drought stress(P?0.05),indicating that Tamarix leptostachys thin ear membrane system was damaged under moderate and severe drought stress.Under the stress of moderate and severe drought,POD activity was significantly increased compared with CK(P?0.05),and Pro content was significantly increased compared with CK(P?0.05).Under severe drought stress,CAT activity was significantly increased compared with CK(P?0.05),while SOD was insensitive.The results showed that under mild drought stress,Tamarix leptostachys could maintain normal physiological activities,and under moderate to severe drought stress,Tamarix leptostachys showed strong adaptability by increasing the activity of protective enzyme and the content of Pro.