Effects Of Seed Soaking With Sodium Selenite Solution And Foliar Spraying On Rice Yield And Selenium Content

Selenium(Se)is an essential trace element to maintain human health.Because the human body cannot synthesize the required organic selenium,it is necessary to maintain the selenium level in the body through dietary intake.Rice is one of the most important food crops in the world.It is a safe and effective way to supplement human daily selenium intake through food chain by converting inorganic selenium into organic selenium that can be safely absorbed by human body by using rice as carrier.However,in the middle and lower reaches of the Yangtze River,irregular rainfall,flood prevention and uneven fields are common,which cause flooding stress on germination and growth of direct-seeded rice.Therefore,it is of great significance to study seed soaking with sodium selenite under flooding conditions on rice seed germination and seedling growth quality.In addition,our experiments also studied the effect of different foliar application of selenium and different concentrations of sodium selenite on delaying rice senescence and the effect of foliar application of different periods on selenium content in rice.The main results are as follows:1.Selenium seed priming promoted seed germination and increased seedling emergence index and final seedling emergence rate.Selenium decreased malondialdehyde content in seeds,increased starch hydrolysis efficiency,superoxide dismutase,peroxidase,catalase and glutathione peroxidase activities,and soluble protein and total chlorophyll content in seedlings.In addition,Selenium seed priming significantly increased the Se content of seedlings and the total dry weight and yield of rice at maturity.2.Selenium application can delay the senescence rate of rice.After Se application,MDA concentration in rice decreased significantly(the effect was more obvious in the first and second leaves),but when Se application exceeded 75 g/hm~2,MDA concentration began to increase,which slowed down the senescence rate of rice.With the increase of selenium application rate,the selenium concentration in different parts of rice also increased significantly,but the transport and absorption efficiency of selenium increased firstly and then decreased with the increase of selenium concentration.In addition,selenium application also increased grain yield,and the maximum grain yield was obtained when selenium application was 75 g/hm~2.3.Selenium content in different parts of rice was significantly affected by different selenium application periods.With the delay of selenium application period,the selenium content of you increased first and then decreased.The distribution of selenium content in grains before heading was brown rice>husk>white rice,and that in grains after heading was husk>brown rice>white rice.The selenium content in brown rice was the highest 5 d before heading,but the selenium content in white rice was the highest 5 d after heading.The yield of rice increased after Se application,but the yield was significantly higher than that of CK only at 15 d after heading.