不同镉积累类型小麦根际土壤低分子量有机酸与镉的生物积累

Low-molecular-weight organic acids in rhizosphere soil and their effect on cadmium accumulation in two cultivars of wheat

采用土壤培养方法研究低镉积累小麦烟 86 10 3和高镉积累小麦莱州 95 3不同生育期土壤低分子量有机酸含量与组成 ,及其与镉生物积累的关系。结果表明 ,不同镉积累类型小麦在高镉土壤中其根系镉含量差异不显著 ,但地上部镉浓度烟 86 10 3显著低于莱州 95 3,而在低镉土壤中根系和地上部镉浓度烟 86 10 3均显著低于莱州 95 3。根际土壤有机酸 (柠檬酸、酒石酸、乙酸和丙酸 )含量及有机酸总量均为低镉品种烟 86 10 3显著低于高镉品种莱州95 3。两个品种不同生育期有机酸含量均表现为柠檬酸 >酒石酸 >丙酸 >乙酸 ,且各有机酸含量占有机酸总量的百分数表现稳定。小麦镉的生物积累与有机酸种类没有特异性关系 ,但与有机酸的总量有关。根际不同有机酸的水平对于土壤镉的复合或螯合溶解 ,在引起两品种地上部镉生物积累的差异方面起重要作用。

Pot experiment was established to probe the relationship between low-molecular-weight organic acids (LMWOAs) and Cd bioaccumulation in wheat. Two wheat cultivars, Triticum aestivum L Laizhou 953, a high Cd accumulating cultivar, and Yan 86103, a low Cd accumulating cultivar, were compared. The Cd concentration of shoot in Yan 86103 was significantly lower than that in Laizhou 953 in the soil with high Cd content, while there was no significant difference in root Cd content between two cultivars. It was found that the Cd concentration in both root and shoot of Yan 86103 were markedly lower than that in Laizhou 953 in the soil with low Cd content. Total amount of LMWOAs in rhizosphere soil of Yan 86103 were significantly lower than that in Laizhou953,and the content of LMWOAs in two cultivars followed a tendency of citric acid>tartaric acid>propionic acid>acetic acid at both seedling and booting stage. The percent distribution of total LMWOAs in rhizosphere soil of Yan 86103 was very similar to Laizhou 953, and this percent distribution for both two cultivars remains stable from seedling stage to booting stage. Cd accumulation in wheat was highly related to the total amount of LMWOAs in rhizosphere soil, suggesting that the differing levels of LMWOAs present in the rhizosphere soil played an important role in the solubilization of particulate-bound Cd into soil solution and its subsequent bioaccumulation by the high and low accumulating cultivars.