大田条件下不同钝化剂对空心菜吸收镉的影响及机理

Mechanism and effects of different amendments on cadmium uptake by water spinach (Ipomoea aquatica Forsk.) in field conditions

通过大田试验,研究4种钝化剂(赤泥、海泡石、钙镁磷肥和磷矿粉)对两茬空心菜(Ipomoea aquatica Forsk.)生长和镉吸收的影响。钝化剂施用量为:赤泥(0.5%和1.0%)、海泡石(0.3%和0.5%)、磷矿粉(450和900 kg.hm-2)、钙镁磷肥(450和900 kg.hm-2)。结果表明,各钝化剂均能显著降低土壤有效态镉质量分数,钝化能力大小表现为海泡石>赤泥>钙镁磷肥>磷矿粉;钝化剂提高了空心菜地上部生物量,第1茬时(50 d),施用高量赤泥、低量海泡石和高量钙镁磷肥处理生物量增加最为明显,地上部分别增加78.7%、75.2%和76.6%。第2茬(80 d),高量赤泥与高量磷矿粉处理增加最高,地上部分别增加24.6%和34.5%。钝化剂对空心菜镉吸收影响不同,第1茬时对根系和地上部分别起促进和抑制作用,施用高量赤泥和高量海泡石最能抑制地上部镉累积,镉质量分数分别降低27.3%和23.2%。第2茬时,除海泡石外,钝化剂均显著抑制了根系和地上部的镉吸收,高量磷矿粉和赤泥效果最佳。总体来看,赤泥是保障农产品安全的最佳钝化材料,海泡石效果最差。

Field experiments were conducted to investigate the effects of four amendments（red mud,sepiolite,calcium magnesium phosphate and phosphate rock） on the growth of water sinach（Ipomoea aquatica Forsk.） and the corresponding cadmium uptake..High or low dose of amendments,i.e.,red mud（0.5% and 1.0%）,sepiolite（0.3% and 0.5%）,calcium magnesium phosphate（450 kg.hm-2 and 900 kg.hm-2） and phosphate rock（450 kg.hm-2 and 900 kg.hm-2） were used.The results showed that all amendments decreased the content of soil available cadmium significantly.The passivation ability was in order as： sepiolite red mud calcium magnesium phosphate phosphate rock.The passivators increased the above-ground biomass of water spinach.At the first crop（50 days）,the above-ground biomass increased considerably in treatments with high dose of red mud,low dose of sepiolite and high dose of calcium magnesium phosphate with an increasing rate of 78.7%、75.2% and 76.6%,respectively.At the second crop（80 days）,the above-ground biomass increased most significantly in treatment with high dose of red mud or calcium magnesium phosphate with rate of 24.6% and 34.5%,respectively.In contrast,the influence of passivators on cadmium uptake of water spinach differed between the first and second crop.At the first crop,passivators promoted Cd accumulation in root but inhibited it in above-ground biomass.The inhibition effect on the Cd accumulation in above-ground biomass was most great when high dose of red mud or sepiolite was applied,with the cadmium contents decreased 27.3% and 23.2%,respectively.At the second crop,the Passivators（except the sepiolite） inhibited the cadmium uptake significantly either in root or in above-groud biomass.The inhibition effect was most great when high dose of PhosPhate rock or red mud was applied.Overall,red mud is the best material for protecting farm produce safety and the sepiolite is least useful.