Effects of sulfate fertilizer on the growth of rice seedlings and accumulation of As,Cd,and Cr in plants
This was conducted to investigate whether sulfate fertilizer application in heavy-metal contaminated soil with sufficient available sulfate could promote the growth of rice(Oryza sativa L.)seedlings and reduce the accumulation of heavy metals in plants,with the intention to provide a scientific basis for the safe production of rice in heavy-metal contaminated paddy fields in Jianghan Plain,Hubei Province,China.The tested soil was collected from the cultivation layer of rice fields with mild arsenic pollution in Honghu City,Hubei Province,China.A pot experiment was employed to study the effects of potassium sulfate fertilizer application(sulfate treatment)instead of potassium chloride fertilizer(CK)on rice seedlings growth,antioxidant system changes,and As,Cd,and Cr uptake and accumulation in rice seedlings.The results showed that sulfate fertilizer treatment increased photosynthesis and promoted the growth of rice seedlings.The net photosynthetic rate and rice shoots fresh weight increased by 67.8%(P＜0.05)and 25.6%(P＜0.05)compared with CK,respectively.Moreover,sulfate application reduced the oxidative stress and enhanced the chelation ability of heavy metals in rice seedlings.Compared with the CK,the activities of superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)and the content of malondialdehyde(MDA)in the leaves of sulfate-treated plants were significantly reduced by 54.8%(P＜0.05),30.5%(P＜0.05),37.3%(P＜0.01),and 36.30%(P＜0.05),respectively.The contents of reduced glutathione(GSH),ascorbic acid(AsA),total non-protein thiol(NPT),and plant chelating peptide(PCs)in rice leaves increased significantly by 7.2%(P＜0.05),38.5%(P＜0.01),7.5%(P＜0.05),and 7.7%(P＜0.01),respectively.In addition,sulfate fertilizer application significantly reduced soil available As and available Cd contents by 71.4%and 46.0%,respectively.Sulfate fertilizer addition promoted the formation of iron film on the root surface and increased the S content in rice seedlings.Moreover,compared with CK,the contents of As,Cd,and Cr in the shoots and roots of plants under sulfate treatment decreased by 13.5%(P＜0.05),10.6%(P＜0.05),and 45.2%(P＜0.01)(shoots),as well as 10%(P＜0.05),15.1%(P＜0.05),and 31.7%(P＜0.01)(roots),respectively.In conclusion,sulfate fertilizer application in paddy soil without sulfate deficiency in Jianghan Plain could promote rice seedlings growth,reduce soil As and Cd availability,and inhibit the uptake and accumulation of As,Cd,and Cr in plants.
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