Alleviating Effects Of Exogenous Salicylic Acid On Low Temperature Stress Of Saussurea Arenaria Maxim

Saussurea arenaria Maxim which is one of the typical representatives of alpine meadow plants belongs to the Asteraceae(Compositae)perennial herb.It can be used to cure a cold,headache,sore throat,ulcers carbuncle swollen,food poisoning,heat hyperactivity,hemoptysis,hematemesis and trauma symptoms,etc.Salicylic acid(SA)is distributed in the phloem of the plant and,it is a phenolic white crystalline substance.Scholars have found that salicylic acid has certain regulatory effects on plant growth and development,aging and other physiological processes.When plants suffer from the stress of drought,salt,low temperature,the heavy metals,ultraviolet.salicylic acid will begin to adjust the situation.Salicylic acid(SA)is a typical representative of plant hormones which can increase crop yields and improve fruit quality and resistance to adversity stress,and also has other functions.Exploring the damage of plants caused by the change of environment and the physiological responses of plants can not only help understand the relationship between plants and the environment,but also provide a reference for human to control the growth factors of plants.In this paper,alleviating effects of exogenous salicylic acid on low temperature stress of Saussurea arenaria Maxim.were studied,and hope to offer some reference and theoretical basis for the cultivation and utilization of Saussurea D C.explaining the ecological significance of Saussurea D C grown in the Qinghai-Tibet Plateau environment.In this paper,the seeds of Saussurea arenaria Maxim from Tianjun County of Qinghai province of northeastern of Qinghai-Tibet plateau were used.The experiment was divided into two parts:bud stage test and seedling test.The concentration of SA was set to 0.3 mmol/L,0.5 mmol/L,1.0 mmol/L and distilled water was set as contrast.By plant physiology and biochemistry and other technical means,temperature is set to 0 ? The effects of exogenous salicylic acid on the seed germination rate,osmotic adjustment system,photosynthesis system and antioxidant enzyme system of Salix psammophila under low temperature stress were studied to discuss the the effects of SA cold mechanism on exogenous salicylic acid.The results are as follows:(1)Under different temperature,SA could increase the germination rate of the seeds of Saussurea arenaria Maxim.(2)Under low temperature stress,SA treatment could alleviate the decrease of chlorophyll content and decrease the initial fluorescence Fo value,alleviating the Fv/Fm(PSII potential light energy conversion rate),Fv/Fo,Y(NPQ),and ETR(electron transfer rate)while reducing the values of the maximum fluorescence Fm and Y(NO)(non-regulated energy dissipation),which reduce Light suppression and alleviate the original light energy capture capability of PS ? and the decline rate of the electron transfer capacity.(3)Under low temperature stress,SA reduced the relative conductivity and MDA(malondialdehyde)content,reducing the membrane permeability and maintaining the osmotic pressure balance.(4)Among them,the concentration of 1.0 mmol/L SA treatment group showed the best effect on the cold resistance of the seedlings.