Research On The Mechanism Of Inhibition Of Cadmium Uptake And Accumulation In Rice By Foliar Spraying With Anthocyanin

With the rapid development of economic construction and the acceleration of modernization process,the problem of heavy metal Cd pollution of farmland is becoming more and more serious.China is a large country with a population of 1.4 billion,so food security is an important issue in the current economic construction.Many studies have shown that anthocyanins in plant cells play an important role in resistance to exogenous stress,which is a natural mechanism of plant resistance.Therefore,this study attempts to strengthen this mechanism of resistance artificially,and link it with the rice growth under the polluted farmland,using this mechanism to enhance the rice growth and food security under the polluted farmland,in order to provide scientific basis for improving the food security under the farmland polluted by Cd.Anthocyanins are validated by pot experiment,first of all,excessive expression of rice varieties purple-leaf rice,under Cd stress resistance level and influence on production is superior to the ordinary rice leaf color.Then exogenous spraying anthocyanins,explore under Cd stress,rice antioxidant system and related to the accumulation of heavy metals and rice non-protein thiol system.Finally,the field experiment verified the effect of pot experiment and preliminarily determined the suitable concentration for field spraying.The main research results are as follows:Pot experiment was carried out to study the changes of chlorophyll,carotenoid and anthocyanin contents and biomass and yield factors of four kinds of rice under the stress of low concentration of Cd.The results showed that the chlorophyll content of the four varieties of rice decreased under the stress of exogenous Cd,but the content of carotene in the purple leaves decreased the least and the content of carotene increased slightly,but not by much.The yield of rice was also affected by Cd,with the decrease of 21.25%,11.11%,18.32%and 20.98%,respectively.The effects of anthocyanins on rice growth and Cd accumulation were studied by pot experiment.Considering test site and management to purple-leaf rice,Zhendao 18,Chaoyou 30 as the research object,detecting Cd concentration under the background of high concentration of Cd in soil and CK spraying on the leaf anthocyanins thick liquid,cytochrome,exogenous antioxidant activity changes,leaf cell activity of antioxidant enzyme system changes and changes of heavy metal accumulation related material.The results showed that anthocyanin spraying on the leaves increased the content of cytochrome in three kinds of rice,enhanced the antioxidant capacity and antioxidant enzyme activity in vitro.After anthocyanin spraying,the content of non-protein sulfhydryl group and plant chelating peptide in rice increased,which meant that the chelating ability of Cd ions was improved,and more Cd was fixed in leaf cells,so as to improve the transport coefficient between root and stem leaves and reduce the transport coefficient between stem and leaf and grain.The content of Cd in different tissues of rice was determined.After anthocyanin spraying,the content of Cd in leaf cells increased in all three kinds of rice,while the content of Cd in grain increased,but the content of Cd in root of rice did not change significantly.Thus,foliar anthocyanin spraying enhanced photosynthesis,enhanced growth,and reduced Cd accumulation in rice under Cd stress.The effect of anthocyanin on the growth and heavy metal accumulation of rice was tested in a field experiment,and the optimum concentration of anthocyanin was determined.The content of foliar microfertilizer was referred to six concentration gradients of CK,A1 to A5 were set with reference to the spraying content of foliar microfertilizer,and the above six concentration gradients were sprayed at booting stage considering the actual operation and cost control.The heavy metal content and yield factors of rice were measured and converted to yield per mu.Experiments showed that the concentration of anthocyanin from A1 to A5 decreased the content of Cd in grains,but there was no linear correlation with the concentration of anthocyanin.As the concentration of A1 to A3increased,the grain Cd decreased.At the concentration of A3,namely 7.5 g/L(5L/30 m~2),the reduction of Cd content was the most effective,while A4 and A5 had poor effects.Anthocyanin injection had little effect on rice yield factors,and the yield increased by10.89%under the optimal concentration of A3.Therefore,anthocyanin spraying on the leaf surface at booting stage can effectively reduce the content of Cd in rice grains,improve the grain security and slightly increase the yield.