双季稻区镉污染稻田水稻改制玉米轮作对镉吸收的影响

为研究低镉(Cd)污染(Cd为0.35 mg·kg~(-1))稻田改制的农产品安全利用技术,通过双季稻区早-晚稻轮作,玉米-玉米轮作、水稻-玉米轮作和玉米-水稻轮作试验,研究不同轮作制度下土壤有效Cd、作物不同器官Cd含量,Cd富集系数、转移系数和土壤养分的变化。结果表明:不同轮作制度下,水稻根、茎叶和稻米中Cd的平均含量分别为3.66、1.30 mg·kg~(-1)和0.36 mg·kg~(-1);玉米根、茎叶和籽粒中Cd的含量分别为0.50、0.12 mg·kg~(-1)和0.03 mg·kg~(-1);水稻根系、茎叶和籽粒的富集系数平均分别为11.96、4.27和1.19,玉米的分别为1.73、0.50和0.13;水稻的根系向茎叶和茎叶向籽粒转运的转运系数分别为0.36和0.28,玉米的为0.24和0.20;晚稻籽粒Cd含量高于早稻,秋玉米Cd含量高于春玉米;土壤中的碱解氮、有效磷和速效钾不影响作物对Cd的吸收;种植玉米比同季水稻略有增产。研究表明,在Cd轻度污染地区,晚稻改种玉米能保障粮食作物安全,是一种值得推荐的种植制度。

Effects of rice and corn rotation on cadmium uptake in double-cropping cadmium-polluted paddy rice fields

In this study, we examined the effects of rice and corn rotation on soil effective cadmium (Cd) levels, Cd levels in various parts of rice and corn, and coefficients of accumulation and transfer in lightly Cd-polluted (Cd 0.35 mg·kg^-1) double-cropping paddy rice fields. The results showed that the average content of Cd in rice roots, stems and leaves, and grains was 3.66, 1.30 mg·kg^-1, and 0.36 mg·kg^-1, respectively; the content of Cd in corn roots, stems and leaves, and grains was 0.50, 0.12 mg·kg^-1, and 0.03 mg·kg^-1, respectively; the average bio-accumulation coefficients corresponding to rice roots, stems and leaves, and grains were 11.96, 4.27, and 1.19, and those in corn were 1.73, 0.50, and 0.13, respectively; the transfer coefficients from rice roots to the stems and leaves and from the stems and leaves to grains were 0.36 and 0.28, whereas those in corn were 0.24 and 0.20, respectively; the content of Cd in late rice grains was higher than that in early rice grains, and the content of Cd in autumn corn grains was higher than that in spring corn grain; the alkali hydrolysable nitrogen, available phosphorus, and rapid-acting potassium in the soil had no effects on Cd uptake by crops; and the planted corn was slightly more productive than rice during the same season. In summary, planting corn instead of later rice replanting may ensure safer crop grains in lightly Cd-polluted double-cropping paddy rice fields. This rotation can be considered a recommendable planting system.