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

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 acidtartaric acidpropionic acidacetic 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.