Effects Of Cadmium Pollution On Phytohormone Contents And Growth Of Glycine Max Plants

A pot experiment was conducted to study the effects of different external Cd concentrations on growth of Glycine max plants, four types of phytohormone contents and change of other physiological indexes, to analyse the distributing state of Cd in root, stem, leaf, shell and grain and the absorption and transfer rule of other nutritient element, to discuss the relationships of soil Cd concentrations and phytohormone content changes in the plant leaves, of soil Cd concentrations and change of other physiological indexes, and the effects of different external Cd stress on the absorption and transfer of N, P, K and Zn, and the quality of Glycine max; to screen out the better sensitive phytohormone or physiological indexes as indicators of Cd pollution, to set up the relationships between Cd pollution levels in soil and phytohormone contents of Glycine max plants, to make clear the biology mechanism of Cd stress on growth of Glycine max plants. The main results showed as the follows:1. Soil Cd inhibited the synthesis of indoleacetic acid (IAA) and zeatin (Z) in Glycine max leaves, and this inhibition increased with increasing in treatment time and Cd concentrations. Cd stimulated the synthesis of gibbrellins (GA3) at lower concentrations, but inhibited the synthesis of GA₃ at higher concentrations. When the Cd concentration was 0.25 mg·kg^-1, GA₃ contents of Glycine max was the highest. Different Cd concentrations stimulated the synthesis of abscisic acid (ABA) in Glycine max leaves, and this stimulation increased with increasing in treatment time and Cd concentrations. IAA*GA₃ values decreased with treatment time and Cd concentrations, and the positive correlative relationship with a correlation coefficient of 0.991 was between the reciprocal of IAA*GA₃ and Cd concentrations. The value of the ABA/IAA increased along with the increment of Cd concentrations, and the positive correlative relationship between the value of ABA/IAA and Cd concentrations was 0.982. The values of IAA*GA₃ or ABA/IAA can express the change of Cd concentrations.2. Cd stress increased the height of Glycine max and the dry weight of the plants at lower concentrations, but inhibited these biomasses at higher concentrations. This pattern was consistent with that of Cd stress on the GA₃. The positive correlative relationship between GA₃ in the leaves and the height was a correlation coefficient of...