EFFECT OF LANTHANUM ON POD AND MEMBRANE PERMEABILITY OF RICE UNDER ACID RAIN STRESS

To explore if rare earth element lanthanum could protect from the damage of the germination of rice seed under different acid rain stresses,the activity of peroxidase(POD) and the membrane permeability were investigated.Two simulated acid rain(SAR) solutions of pH 2.5 and 4.0,and neutral solution as control group were used in this study.Rice seeds pretreated with lanthanum were placed in culture dishes and kept at the normal temperature,in which each treatment group involved three dishes and each dish received 50 seeds.During germination,seeds were exposed to simulated acid rain that was replaced everyday to keep a certain pH.The results showed that under the stress of constant acid rain(pH=4.0 and pH=2.5) for 7 days,with the increasing stress time,the change trend in the membrane permeability of the rice seeds were followed the order: increase-decrease-increase.And the activity of POD was increased during all the time.The membrane permeability of the rice seeds was decrease and the activity of POD of rice seed treated with lanthanum were increased compared with that of only stress of acid rain.When cultivated with control solution instead of acid rain(pH=2.5 and pH=4.0) after 5 days,the membrane permeability was decreased,and the activity of POD were increased compared with that of stress of acid rain for 7 days.The results in this study showed that lanthanum could alleviate the damage of acid rain to germination of rice seeds by increasing the ability to repair by themselves of the rice seeds.