Effect Of Foliar Selenium-Chitosan Fertilizations On Crops Grown And Quality Under Conditions Of Cadmium

With the increasing of industrial "three wastes" emissions,a large number of heavy metal pollutants into the environment lead to the increasing content of toxic heavy metals in farmland soil,then the pollutants enter into agricultural production,further affect food safety.Measures for soil replacement,crop adsorption forcefully remove the heavy metal content in soil.However,those measures have the disadvantages,such as costly,time consuming and hardly removing in a large scale.Thus,without changing soil attributes,developing simple and effective ways to reduce the content of heavy metal in used parts of the crop has become a trend,and fertilizing in particular crop development periods is one of the most effective methods.Relevant repots have showed selenium and chitosan manure helping crops to resist absorbing heavy metals,based on these reporys we developed methods of applying nano-selenium-ch-itosan compound fertilizer in lettuce and rice planting to study the effect of fertilizer reducing cadmium,lead and other heavy metal content in lettuce and rice.This method may provide a potential measure to avoid heavy metal contaminating agricultural products.Specifically studies are as fllowes:1,The hydroponic experiment study the effects of applying nano-selenium at fol iage on lettuce which grown under conditions of cadmium pollution.The stagnated gr owth of lettuce were observed at different levels of cadmium pollution.However,afte r been spraying nano-selenium fertilizer,growth of lettuce get some recovery.Sprayi-ng Se concentration in the 30mg/L,cadmium concentration of 0.3mg/L solution in lettuce fresh weight increased by 10%,increase the selenium content in lettuce 553.85%,lettuce cadmium reduced 19.24%,indicating that selenium can effectively promote lettuce grown,so lettuce Se,and for crop uptake of cadmium obvious antagonistic effects.2,The effects of foliar application of selenium and chitosan compatibility fertili zer on lettuce quality was studied by the pot experiment,results showed that when th e cadmium content in the soil was 6.8mg/kg case,compatibility fertilizer significant ly increased the yield and quality of lettuce.In which the best compatibility concentr ations(Nano-Se 30mg/L and chitosan 100mg/L),the lettuce fresh weight,chloroph yll content,protein content and soluble sugar content were increased by 50.41%,22.37%,112.73%and 407.66%,the cadmium content was reduced by 21.13%,indicati ng that selenium and chitosan compatibility effectively reduced the cadmium content in lettuce 5 significantly improved the nutritional quality of lettuce,provided a new method for the production of high-quality lettuce.3,Foliar application of selenium and chitosan compatibility fertilizer have an effect on heavy metal polluted conditions under rice cultivation.Firstly,the influence on cadmium absorbed by rice by eight kinds of selenium-chitosan compatibility fertilizer had been studied by the pot experiment,which screened out the best formula of cadmium content that reduced to the most.Then the best formula was chosen to conduct the field experiments in cadmium contaminated soil.The results showed that selenium-chitosan compatibility fertilizer could significantly reduce cadmium content in brown rice under cadmium contaminated conditions To be specific.the compatibility of 100mg/L of chitosan and 90mg/L of nano-selenium showed the optimal effect,reducing rate of cadmium reaching to 35.29%;In field trials with this formula,the best result of cadmium reduction reaching to 20.69%under heavily polluted conditions was also obtained.However,the cadmium content in rice is still seriously out of limit,and maximum cadmium reduction rate of 32%can be achieved under mild conditions Cadmium content in rice was lower than the national limits,indicating that mild cadmium exceeding in rice could be resolved by this compatibility,and selenium content in all varieties increased significantly,reaching Se-rich standards.The compatibility is expected to become the special functioning fertilizer not only can reduce the absorption of cadmium by rice,but also can enrich rice with Se,which provide guarantee for the production of high-quality rice.