Effect On Physiological And Biochemical Characteristics And Anatomical Structure Of Alfalfa Under Low Temperature Stress

In this experiment,the cold resistance of 12 alfalfa varieties was evaluated,and the alfalfa cultivars with different cold tolerance and cold-resistant alfalfa varieties WL298HQ alfalfa and WL168HQ alfalfa and weak WL903 alfalfa and WL656HQ alfalfa were screened out.The physiological and biological basis of different varieties and cold resistance were observed and the anatomical changes were observed.The physiological basis and structure of cold resistance of alfalfa were revealed.The mechanism of cold resistance of alfalfa was explored from two aspects;anatomical structure,physiological and biochemical level.The main results are as follows:(1)Hardiness and alfalfa stem leaf index of plant height,leaf length,leaf width,leaf width,and the ground biomass,leaf length,plant height,more suitable for cold resistance appraisal indicators.Plant height,leaf length,leaf width,and the width is longer than the correlation of the most widely four indicators,at the same time is also important to analysis alfalfa hardiness four indexes.(2)Strong cold resistance of alfalfa varieties WL298HQ and WL168HQ under low temperature treatment,chlorophyll a/b value is higher than the basic hardiness of alfalfa varieties WL656HQ and WL903.The content of carotenoids found when alfalfa varieties WL298HQ-8℃ than other varieties have stronger frost resistance.Under the different temperature treatment,strong cold resistance of alfalfa varieties WL298HQ and WL168HQ under low temperature processing electrical conductivity and malondialdehyde content is lower than the cold hardiness weak WL656HQ of alfalfa varieties and WL903,showed that cold hardiness weak alfalfa varieties of damage degree is the largest.Strong cold resistance varieties WL298HQ and WL168HQ under low temperature processing basic activity of superoxide dismutase(sod)and catalase were higher than the variety of hardiness weak WL656HQ and WL903.Cryogenic treatment after four varieties of soluble protein content and 25℃ alfalfa were significantly less than normal growth.Alfalfa varieties WL298HQ WL168HQ and soluble sugar content and 25℃ compared normal growth of alfalfa were significantly increased,while WL656HQ and WL903 after treatment 1 and 2 compared to soluble sugar content decreased,compared processed 3 soluble sugar content increase.Alfalfa varieties of chlorophyll under low temperature stress,a/b value,carotenoids,conductivity,mda,SOD activity,CAT activity and soluble protein present a different degree of correlation between the indexes.The content of soluble protein of alfalfa winter hardiness is very important.(3)Under low temperature stress in different temperatures of the differences between the various indicators is not the same,but in general the cold resistance of alfalfa varieties with weak leaf thickness,palisade tissue thickness and sponge tissue thickness basically is greater than the cold hardiness of alfalfa varieties.Leaf thickness,palisade tissue thickness,sponge tissue thickness,ratio of grid sea,tightness of vascular bundle diameter,cell structure,and cellular structure looseness index between different degree of correlation.Gate than the sea is the analysis of an important index of alfalfa hardiness anatomical structure.