Effect Of La（NO₃）₃ On Physiological Activity In Alfalfa（Medicago Sativa）under Nacl Stress

Salt stress has an important effect on the yield,quality and physiological metabolism of alfalfa,is one of the important abiotic stresses that affect the physiological and biochemical reactions of alfalfa;In recent study,the rare earth element Lanthanum nitrate has a good effect on alleviating plant stress.In this study,alfalfa was used as material to study the effects of lanthanum nitrate on physiological indexes of alfalfa under NaCl stress,the main analysis was carried out on The relative conductivity,chlorophyll content,proline,malondialdehyde,soluble sugar,superoxide dismutase and peroxidase,to explore the effect of lanthanum nitrate on alfalfa NaCl stress.The results included:1.Leaf sprayed with 100 mg/L-200 mg/L lanthanum nitrate had a relieving effect on the relative conductivity of alfalfa under 200 mmol/L NaCl stress;But with the increasing concentration of lanthanum nitrate,the relative conductivity of alfalfa under salt stress would increase.Under the condition of 100 mmol/L NaCl stress,the alleviation effect of lanthanum nitrate increased first and then weakened.2.100 mg/L lanthanum nitrate has a mitigating effect on the decomposition of chlorophyll in alfalfa under 100 mmol/L NaCl stress;For alfalfa without salt stress,50 mg/L lanthanum nitrate promoted its chlorophyll synthesis.3.50 mg/L-100 mg/L lanthanum nitrate has a mitigating effect on the production of malondialdehyde(MDA)in alfalfa under 100 mmol/L NaCl stress.4.50 mg/L-200 mg/L lanthanum nitrate has a alleviating effect on the increase of Proline content in alfalfa under 200 mmol/L NaCl stress;100 mg/L-200 mg/L Lanthanum nitrate treatment promotes the increase of Proline in alfalfa under 100 mmol/L NaCl stress.5.Lanthanum nitrate did not significantly alleviate the increase of soluble sugar in alfalfa under NaCl stress;High concentration of NaCl and high concentration of lanthanum nitrate have an enhanced effect on the increase of soluble sugar.6.100 mg/L and 400 mg/L lanthanum nitrate could increase the activity of superoxide dismutase under 100 mmol/L NaCl stress,which could alleviate the effect of salt stress;under200 mmol/L NaCl stress,different concentrations of lanthanum nitrate can improve the activity of superoxide dismutase,which play a role in alleviating salt stress.7.Under 100 mmol/L NaCl stress,100mg/L lanthanum nitrate treatment group decreased peroxidase activity;under 200 mmol/L NaCl stress,the activity of peroxidase was decreased in 100 mg/L-200 mg/L lanthanum nitrate treated group,While the 50mg/L and 400mg/L lanthanum nitrate treatment groups increased the activity of peroxidase.