Effects Of Exogenous SAM On The Alleviation And Physiological Mechanism Of Cucumber Seedlings Under Salt Stress

Soil salinization has increasingly become a prominent problem in the modernization process of facility agriculture in China,making salt stress one of the important abiotic stresses facing facing facility cucumber production.In order to improve the salt tolerance of cucumber seedlings,it is important to study the ways and means of enhancing the antioxidant capacity and nitrogen metabolism of Cucumber under salt stress.The effects of exogenous S-adenosy1-L-methionine(SAM)on the alleviating effect and physiological mechanism of Cucumber Seedlings under salt stress were studied in this experiment.The main research results show that:1.Biomass comprehensively reflects the ability of plants to respond to salt stress,and is often used as an index to measure tolerance to stress.In this study,Na Cl stress significantly reduced plant biomass.The most intuitive performance is the growth indicators of seedlings,such as plant height,stem diameter,dry and fresh weight,root length and chlorophyll content decreased significantly.Exogenous SAM significantly restored the growth of Cucumber Seedlings under Na Cl stress.The optimum concentration of exogenous SAM was 0.1m M.2.Under Na Cl stress,the absorption of K+,Ca2+,etc.by plants is affected,which breaks the intracellular ion balance and disturbs metabolism,seriously affecting the normal growth and development of cucumber seedlings.Exogenous SAM can reduce Na + and Ca2 + content and increase K +content,which indicates that exogenous SAM plays an important role in maintaining and regulating ion balance.3.Na Cl stress significantly inhibited the photosynthesis of cucumber seedlings.The photosynthetic parameters,net photosynthetic rate,stomatal conductance and intercellular carbon dioxide concentration of cucumber seedlings decreased in varying degrees.After applying exogenous SAM,the photosynthetic indexes of cucumber seedlings were gradually improved,which indicated that exogenous SAM could alleviate the inhibition of photosynthetic capacity of plants under Na Cl stress,improve photosynthetic capacity,promote plant growth and alleviate salt stress injury.4.When plants are under stress,ROS accumulates in a large number of plants,causing lipid oxidation damage of cell membranes.In this study,MDA content and O 2-content in cucumber were increased under salt stress.The production rate of SOD,POD and CAT enzymes increased significantly in a short time,and ROS content was effectively removed to reduce the destruction of cell membrane structure.5.The accumulation of NO3-and NH4+ in roots and leaves of cucumber seedlings was caused by Na Cl stress.Exogenous SAM significantly enhanced GS/GOGAT activity,At the same time,it enhanced the activity of GDH.,alleviated NH4+ accumulation induced by Na Cl stress,and effectively promoted NH4+assimilation to glutamic acid.