氮肥品种和用量对水稻产量和镉吸收的影响研究

采用盆栽试验,研究了Cd污染土壤上,不同氮肥品种和用量对水稻产量和Cd吸收的影响。结果表明,与磷钾配施的4个氮肥处理中,施用尿素处理水稻产量最高,其次为施(NH4)2SO4和NH4Cl处理,施NH4NO3处理水稻产量最低。与施(NH4)2SO4、NH4NO3和尿素处理相比,施NH4Cl处理可显著增加水稻对Cd的吸收,并促进Cd由秸秆向籽粒的转移;而其他3种氮肥对水稻秸秆和籽粒中Cd含量的影响效应相当。适量尿素[0.2g(N)·kg-1]处理能显著降低水稻籽粒Cd含量,而不施尿素和高量尿素处理都显著提高了水稻籽粒中的Cd含量。研究表明,在Cd污染的水稻土上,采用抗Cd污染的水稻品种和优化肥、水管理措施,可使稻米中Cd含量低于国家无公害大米的限量指标。

Effect of nitrogen fertilizer type and application rate on cadmium uptake and grain yield of paddy rice

A pot experiment with Cd-contaminated soil was conducted to study the effects of different nitrogen fertilizers and application rates on Cd uptake and grain yield of rice. Among four nitrogen fertilizers combined with same P and K fertilizers, urea produces the highest rice yield. Next is (NH₄)₂SO₄ and NH₄Cl, followed by NH₄NO₃, which produces the lowest yield. Among the four nitrogen fertilizers, NH₄Cl more significantly increases rice Cd content than urea, (NH₄)₂SO₄ and NH₄NO₃. It also facilitates Cd transfer from rice straw to grain. There is no significant difference in Cd contents in straw and grain among the other three nitrogen fertilizers treatment. While optimal rate of urea [0.2 g(N)·kg^-1] significantly lowers Cd content in rice grain, either zero N or high urea application rate significantly enhances grain Cd content. In Cd-contaminated paddy soils, using Cd-resistant rice cultivars in combination with optimized fertilization and water management practices considerably lowers grain Cd content below the maximum permissible level for pollution-free rice production.