铅污染土壤中水分管理对水稻产量及籽粒铅含量的影响

Effects of Soil Water Management on the Yield and Pb Concentration of Rice Grain in Pb-Polluted Soils

摘要: 选用2个对土壤中铅吸收分配及籽粒铅积累能力存在显著差异的水稻品种为材料，设置不同的土壤铅污染水平及不同时期的土壤干旱处理，研究了土壤水分管理措施对水稻不同品种籽粒产量及籽粒铅含量的影响。结果表明，抽穗后籽粒灌浆期轻度干旱胁迫对水稻产量没有明显影响，但却大幅度提高籽粒铅含量，与淹水灌溉(对照)比较，籽粒铅含量上升38.41%~147.66%。整个盆栽生长期轻度干旱处理的籽粒产量下降幅度最大，减产达到22.47%~31.40%，但对籽粒铅含量的影响因水稻品种不同而有差异；在抽穗前不同时期的干旱处理中，分蘖期轻度干旱处理的籽粒产量下降幅度较小(10%左右)，而籽粒铅含量下降幅度最大，达到28.72%~43.72%；穗分化期轻度干旱处理的籽粒产量也有显著下降，但对籽粒铅含量的影响因土壤铅污染水平及水稻品种的不同而不同。综合分析不同时期的土壤轻度干旱对水稻籽粒产量和籽粒铅含量的影响，在土壤铅污染地区宜选择水稻分蘖期进行土壤轻度干旱处理，可以有效降低籽粒的铅含量，而对水稻产量影响小。

Abstract: In this study, soil water management regimes of slight dryness at different stages of rice growth were designed, and two rice cultivars with different Lead (Pb) accumulation abilities were used. The aim was to investigate the effects of soil water control on the yield and Pb concentration of rice grain. The results show that the grain Pb concentrations were increased significantly (P < 0.05) by slight soil dryness at grain filling stage, compared to the control (well-watered soil), with the increasing rates of 38.41% - 147.66%. But the grain yields were influenced little. Under the slight dryness during whole period of pot planting, the grain yield decreased significantly (P < 0.05) with the decreasing rates of 22.47% - 31.40%, but the effects on grain Pb concentrations differed with rice cultivars. For the water treatments at different stages before panicle heading, the slight dryness at panicle formation stage reduced grain yields significantly (P < 0.05), but the effects on grain Pb concentrations differed with rice cultivars and soil Pb levels. For the slight dryness at tillering stage, the grain yields of two rice cultivars decreased slightly (about 10%), but the grain Pb concentrations were reduced largely, with the decreasing rates of 28.72% - 43.72%. Therefore, with the combined consideration of grain Pb concentration (the principal control factor) and grain yield, the soil water management of slight dryness at tillering stage is the best choice for soil Pb-polluted areas.