钙镁磷肥对土壤Cd生物有效性和糙米Cd含量的影响

通过水稻盆栽试验,研究了施用钙镁磷肥对Cd污染稻田中Ca、Mg、Cd生物有效性的影响和种植水稻(湘晚籼12号、威优46号)后水稻各部位Ca、Mg、Cd含量的差异.结果表明,施用钙镁磷肥能显著提升土壤pH值,降低土壤TCLP提取态Cd含量,且降低效果随着水稻生育期的延长逐渐增强.与对照相比,施用0.8 g·kg-1的钙镁磷肥,使湘晚籼12号种植土壤和威优46号种植土壤TCLP提取态Cd含量在熟化期、灌浆期、分蘖期、成熟期分别下降了12.7%、15.6%、21.5%、61.9%和12.7%、72.6%、42.1%、59.7%.施用钙镁磷肥能显著增加水稻种植土壤中TCLP提取态Ca、Mg含量,降低TCLP提取态Cd含量,同时显著增加水稻各生育期各部位Ca、Mg含量并降低其Cd含量,水稻各部位中Ca、Mg含量与Cd含量均呈现负相关关系,表明外源Ca和Mg的加入对水稻累积Cd产生了拮抗作用.施用钙镁磷肥能显著降低水稻糙米中Cd含量并提高水稻产量.与对照相比,施用0.2~0.8 g·kg-1的钙镁磷肥,水稻湘晚籼12号和威优46号糙米中Cd含量分别下降了36.8%~52.6%和53.3%~75.6%.威优46号比湘晚籼12号更易将土壤Cd向水稻籽粒中转运.

Effects of calcium magnesium phosphate fertilizer on Cd bioavailability in soil and Cd contents in rice

A pot experiment was conducted to investigate the effects of calcium magnesium phosphate fertilizer(CMPF) at application rates of 0,0.2,0.4,and 0.8 g·kg^-1 on soil toxicity characteristic leaching procedure(TCLP)-extractable Ca, Mg, and Cd contents, and those of elements accumulation and distribution in rice plant(Oryza sativa L. Xiangwanxian 12,Weiyou 46).The results showed that application of CMPF significantly increased soil pH values, decreased soil TCLP-extractable Cd contents, and trend enhanced gradually with rice growth. Compared with the control, application of 0.4 g·kg^-1 of CMPF decreased soil TCLP-extractable Cd contents by 12.7%,15.6%,21.5% and 61.9% for Xiangwanxian 12 and by 12.7%,72.6%,42.1% and 59.7% for Weiyou 46,respectively,at four sampling periods (0 d, before transplanting rice seedlings,35 d, the rice tillering stage,65 d, the rice filling stage, and 95 d, rice maturity).Application of CMPF significantly increased contents of TCLP-extractable Ca and Mg and reduced TCLP-extractable Cd contents in soil, increased total contents of Ca and Mg and decreased Cd content in rice plant. A negative correlation between total Ca, Mg contents and total Cd contents in rice plant was observed, and we hypothesized that exogenous Ca and Mg had an antagonistic against Cd accumulation in rice. Application of CMPF obviously decreased Cd contents in brown rice and enhanced rice yield. Compared with the control, application 0.2~0.8 g·kg^-1 of CMPF reduced Cd contents in brown rice by 36.8%~52.6% for Xiangwanxian 12 and by 53.3%~75.6% for Weiyou 46,respectively.The ability of Cd translocation to shoot for Weiyou 46 were stronger than Xiangwanxian 12.