Effects And Mechanism Of Organic Water-soluble Fertilizer On Rice Growth And The Uptake Of Cd In Rice

Heavy metal contaminated farmland has become a main restrictive factor to food security.Environmental workers and agricultural producers pay attention to repair and use the contaminated farmland reasonably.To study effects of organic water-soluble fertilizer on rice growth and physiological characteristic in flag leaves and the mechanism of reducing Cd concentration in rice grain,pot experiment combined with indoor thermostatic culture was conducted.The main results are as following:1.The results of pot experiment showed that the growth of rice was promoted,N、P、K absorption and chlorophyll content in rice,yield of rice grain and 1000-grain weight were increased and the activity of CAT、SOD、POD in flag leaves were decreased at early booting stage and early milk stage after application of organic water-soluble fertilizer.Foliar application 750 times diluted organic water-soluble fertilizer is optimum.2.The results regarding foliar application of organic water-soluble zinc fertilizer and inorganic zinc fertilizer showed that foliar application of zinc fertilizer increased the yield while decreased the Cd concentration in rice grain.Yield-increasing effect of foliar application of organic water-soluble zinc fertilizer was lower than that of inorganic zinc fertilizer,while which was conversed of reducing Cd concentration in rice.Foliar application of 0.1%~0.3% organic water-soluble zinc fertilizer and inorganic zinc fertilizer decreased the Cd concentration in rice grain by 26.3%~45.5% and 23.2%~41.4% as compared with the contral treatment.Rice grain yield reached highest by foliar application of 0.2% inorganic zinc fertilizer,while Cd concentration in rice grain was lowest by foliar application of 0.1% organic water-soluble zinc fertilizer.3.The mechanism of organic water-soluble fertilizer decreased the Cd concentration in rice grain were that: 1)The trace element of zinc contained in organic water-soluble fertilizer can be uptaked by rice more quickly,and zinc occupied the binding sites of Cd in rice preferentially,which reduced Cd absorption in rice.2)Application of organic water-soluble fertilizer can meet the demand of essential nutrients to rice,and promoted the transfer of nutrients from rice leaves to underground part,which can reduce Cd absorption from soil to rice.3)The distribution of Cd in rice root、stem and leaf were increased and the Zn concentration in rice grain kept stable after applying organic water-soluble fertilizer which can reduce Cd transfer to rice grain.