基施硫肥对水稻吸收和积累镉的影响

Effect of basal application of sulfur fertilizer on cadmium uptake and accumulation in rice

通过田间小区试验,探究基施硫化钠(S1)、硫磺(S2)、亚硫酸钠(S3)、硫酸钠(S4)及半胱氨酸(S5)等5种硫肥对2种具有不同镉积累特性的水稻品种(玉针香、湘晚籼13号)在不同生育期内,各器官对镉吸收和积累的影响及其作用机理。结果表明:添加5种硫肥均能降低2个品种水稻糙米镉含量,与不施硫肥(CK)相比,玉针香的降低了27.03%~83.78%,湘晚籼13号的降低了14.28%~57.14%,且玉针香的S3、S4、S5和湘晚籼13号的S3、S5的糙米镉含量均低于国家食品安全限量标准(GB 2672-2017);添加5种硫肥均降低了2个品种水稻糙米的镉富集系数和转运系数,且均是S3和S5的降幅较大;水稻根、茎、叶非蛋白巯基物质(NPT)和谷胱甘肽(GSH)含量受水稻品种和生育期及硫肥种类影响较大,但各条件下NPT和GSH含量大多呈增大趋势,其中,3个生育期中,拔节期的增幅更大,2个品种中,玉针香的增幅更大,5种硫肥处理中,半胱氨酸处理的增幅更大;基施硫肥能显著降低2个品种水稻成熟期根际土壤可交换态镉含量和S3、S4、S5的根际土壤碳酸盐结合态镉含量,可提高根际土壤残渣态镉含量(湘晚籼13号的S2除外),其他2种形态镉含量受硫肥种类影响较大,但2个品种不同形态镉含量随硫肥种类的变化趋势基本一致;基施硫肥均能显著降低水稻根际土壤pH(湘晚籼13号的S1除外),其中S2的pH降低幅度最大,显著低于其他处理的。综合考虑,基施半胱氨酸硫肥抑制水稻吸收和积累镉的效果较好,且对玉针香的作用效果强于湘晚籼13号的。

Through field plot experiments,the effects of basal application of NaS(S1),sulfur(S2),Na2SO3(S3),Na2SO4(S4),and cysteine(S5),on cadmium(Cd)uptake and accumulation in various organs oftwo rice cultivars(Yuzhenxiang and Xiangwanxian13)with different cadmium accumulation characteristics at different growth stageswere investigated,and the underlying mechanisms were explored.The results showed that adding 5 types of sulfur fertilizers all reduced the cadmium content of paddy riceof the two rice varieties.Compared with the control treatment(CK)without sulfur fertilizer application,Yuzhenxiang’s cadmium content was reduced by ranging from27.03%to 83.78%,and Xiangwanxian13’s was reduced by ranging from14.28%to 57.14%.And,the paddy rice cadmium contentsof Yuzhenxiang’s S3,S4,and S5 treatments and Xiangwanxian13’s S3 and S5 treatments werelower than the national food safety limit standard(GB 2672-2017).Adding 5 types of sulfur fertilizers all reduced the cadmium accumulation coefficientsand translocation coefficientsof paddy riceof the two rice varieties,and the reduction of S3 and S5 treatments were larger.The contentsof non-protein thiol compounds(NPT)and glutathione(GSH)in rice roots,stems,and leaves were greatly affected by rice variety,growth period,and type of sulfur fertilizer.However,the contentsof NPT and GSH were mostlyincreased under each condition,with the largest increase during the booting periodamong the three growthstages,larger increase in Yuzhenxiangthan that in Xiangwanxian13,and the largest increase incysteine treatmentamong the 5 typesof sulfur fertilizer treatments.Applying sulfur fertilizer as a base fertilizer couldsignificantly reduce the rhizosphere soil exchangeable cadmium contentsof rice at maturity for both varieties and the carbonate-bound cadmium contentsin the rhizospheresoilof S3,S4,and S5.It couldalso increase the residual cadmium contentsin the rhizospheresoil of all treatments except for Xiangwanxian13’sS2.And the contentsof the other two forms of cadmium were affected differently by the typesof sulfur fertilizer,butthe trendsof the contentsof different forms of cadmium in the two varieties were basically consistent with the changesof the typesof sulfur fertilizer.All base fertilizer applications couldsignificantly lower the rhizospheresoil pH of rice except for Xiangwanxian13’sS1,with the greatest decrease in the S2 treatment,which was significantly lower thanthose ofthe other treatments.To conclude,the cysteine sulfur fertilizer hada better effect on inhibiting the absorption and accumulation of cadmium in rice,and its effect on Yuzhenxiang was stronger than that on Xiangwanxian13.