Effects of Rare Earth Elements Lanthanum on Growth and Antioxidation System of the Greengrocery under Salt Stress

The effects of rare earth elements lanthanum on growth and antioxidation system of the greengrocery under salt stress were investigated. The seed of greengrocery were cultureed in Hoagland nutrient solution with 50mg·L^-1 NaCl and 20, 40, 60, 80, 100, 150mg·L^-1 Lanthanum. Then the treatments cultured in Hoagland nutrient solution with 50mg·L^-1 NaCl, 20mg·L^-1 lanthanum as control. After continued for two weeks, seed germination rate and super oxide dismutase(SOD) and peroxidase ( POD) activities, malondialdehyde (MDA) were measured. The results showed that salt stress could inhibite seed germination and seedling growth of greengrocery, fresh weight marked reduced, dwarf seedlings. Low concentration LaCl₃(20~80mg·L^-1)could promote seed germination and seedling growth of greengrocery, fresh weight marked increased, high seedlings. Salt stress significantly reduced the chlorophyll content of and adding suitable concentration LaCl₃ (20~100mg·L^-1 )could improve of chlorophyll content of the greengrocery seedlings under salt stress and enhance its light transformation ability. But under hoagland nutrient solution with 20mg·L^-1 LaCl₃ processing, chlorophyll content of the greengrocery seedlings had marked reduced(P<;0.05 ). Salt stress can induce the generation of protein. The treaments with proper density LaCl₃ (40~80mg·L^-1) were able to alleviate the pressure of salt stress, and improve the soluble protein content of greengrocery seedling. High concentration LaCl₃(100~150mg·L^-1) under salt stress marked inhibited the the soluble. protein produce of greengrocery seedling. Salt stress could stimulate greengrocery seedlings induction their antioxidant enzymes protection system, make antioxidant enzymes of greengrocery seedling increase, MDA content reduced, Suitable concentration LaCl₃(40-80mg·L^-1) under salt stress can promote antioxidant enzymes relieve the damage of salt stress on seedling, then MDA content reduced. but high levels of LaCl₃ (100~150mg·L^-1)is likely to produce poisonous effect on cells leaded to antioxidant enzymes activity abate, MDA content increased. In brief, salt stress(50mg·L^-1) could inhibited seed germination and seedling growth of greengrocery, and induction antioxidant enzymes emerge, MDA content increased. The treatment with optimum concentration of LaCl₃ could significantly increase antioxidant enzyme activities of greengrocery seedlings, enhance its scavenging reactive oxygen species, reduce lipid per oxidation under salt stress, in order to effectively alleviate the salt stress injury and increase their salt tolerance, and promote greengrocery seedling growth, The optium concentration was 40~80mg·L^-1.