Effects Of Foliar Application Of Selenium On Arsenic Accumulation Characteristics In Rice

Arsenic is an excessive heavy metal element second only to cadmium in my country’s polluted farmland soil,especially in rice production areas,which seriously threatens my country’s food security and residents’ health.Selenium is not only an essential nutrient element for the human body,but also has the effect of antagonizing the absorption of heavy metals by rice,but the characteristics of the interaction between the two,especially when selenium is applied to the leaves,the distribution characteristics of different leaf organs are still unclear.Therefore,this study took rice"Daohuaxiang No.2" as the research object,using solution culture method to study the effects of selenium application form and concentration on the accumulation of selenium and arsenic in various organs of rice,and screen the forms of selenium application that can reduce the accumulation of arsenic,and clarify that it enters the rice body.The redistribution characteristics of selenium reveal the relationship between the selenium concentration and the amount of arsenic accumulation in rice,and provide a scientific basis for the safe production of rice in arsenic-contaminated areas with selenium fertilizer formulations and optimization schemes for spraying systems.The main findings are as follows:（1）The distribution of exogenous selenium in different leaf positions of rice showed that the selenium content of leaves was the highest when selenium was applied,and the selenium content was gradually decreased along the upper and lower leaves,and organic selenium was more likely to be transported to young leaves;The accumulation of selenium in rice at seedling stage was significantly higher than that of sodium selenate,zinc selenite and selenomethionine treatments.Compared with the control,the sodium selenite treatment increased the selenium content in the selenium-applied leaves（fourth leaf）of rice by 131.35 times,reaching 129.21 mg·kg-1,and the selenium content in the stem and root was 18.62 times and 2.1 8 times that of the control,respectively.（2）Under arsenic stress,the selenium content of different leaves with exogenous selenium applied to the leaves showed a bottom-up bell-shaped distribution.The selenium content was transported and distributed as the center of the selenium applied leaf,and both upper and lower leaves were transported and accumulated in a large amount.In the lower leaves;whether selenium is applied or not,the distribution of arsenic content in the leaves of different leaf positions of rice is gradually decreasing from the root to the top;when arsenic is present,the selenium content in the rice seedlings can be significantly higher than other leaves by applying sodium selenite.Treatment with selenium salt,the selenium enrichment of selenium leaves was as high as 150.08 mg · kg-1,and the absorption and accumulation of arsenic in rice seedlings were significantly inhibited,and the accumulation of arsenic in the roots and aboveground parts of rice was reduced.（3）Under the conditions of low arsenic（25 μmol·L-1）treatment,the treatment of 200 mg·L-1 sodium selenite on leaves promoted the growth of rice seedlings,and significantly increased the fresh weight of the shoots and roots of rice;high arsenic Under the treatment level（50 μmol·L-1）,selenium application can significantly increase the fresh weight of rice seedlings.（4）When the leaves were treated with 150 mg·L-1 sodium selenite,the high concentration of arsenic（50 μmol·L-1）significantly promoted the absorption and accumulation of selenium in the selenium leaves of rice,and inhibited the absorption of arsenic by rice seedlings,and reduced rice Arsenic has the best effect.In conclusion,under hydroponic condition,leaf application of 150 mg·L-1 sodium selenite can achieve selenium enrichment and alleviate high arsenic toxicity of rice seedlings.