Effects Of ABA On The Physiological Resistance Of Soybean Under Zn/Cr Contaminated Stress

Two varieties of soybean (Keyuanluqiuwang and Huangkedou) were used as material, through zinc and chromium artificial polluted pot controlling experiment, the nutrient absorption, antioxidant enzyme activity, soluble sugar, soluble protein content, plant height, number of podding, yields of soybean plant at pod-filling stage and yields at maturing stage were studied under seed soaking and spraying of ABA at different concentration (0μmol/L,1μmol/L,5μmol/L,10μmol/L,20μmol/L,40μmol/L) in order to provide safe production and reference technology for heavy metal polluted farm land. The main results were as follows:(1) ABA improved SOD, POD activity better than CAT activity of soybean plant, played inhibit or promote roles on different plant organs.5and10μmol/L ABA improved SOD, POD, CAT activity of root, stem, leaf, seed, root rhizobium of soybean best,20and40μmol/L ABA suppressed the SOD, POD, CAT activity of root, stem, leaf and grain of soybean, but20μmol/L ABA played a positive role on the SOD, POD activity of root rhizobium of soybean. In general, ABA spraying had better improvement effects than ABA seed soaking on SOD, POD, CAT activity of soybean plant, and Keyuanluqiuwang performed moer sensitive to ABA than Huangkedou.(2) ABA reduced the content of MDA in root, stem, leaf, seed and root rhizobium of soybean under zinc and chromium stress, but the diverseness of different plant organs were not obvious. In all, ABA spraying reduced MDA content in soybean plant more than ABA seed soaking.(3) Except for soluble protein of soybean leaf, the soluble protein and soluble sugar of root, stem, leaf, seed and root rhizobium of soybean were rised by ABA, and1,5and10μmol/L ABA performed better. In general, ABA spraying showed better effect than ABA seed soaking on improving soluble protein and soluble sugar in soybean plant.(4) The absorption of N, P, K of soybean was better improved by5,10μmol/L ABA in common, and20μmol/L ABA showed better effect on P absorption of stem and N absorption of leaf,1μmol/L and40μmol/L ABA showed worse effects on the absorption of N, P, K of soybean than others treatments.(5) The plant height, biomass, podding number and frond number of soybean were lower by most ABA treatments, while20μmol/L ABA spraying and10μmol/L ABA seed soaking could increase the plant height and biomass, podding number and frond number of Keyuanluqiuwang at the same time, and5μmol/L ABA spraying and seed soaking could increase the plant height and biomass, podding number and frond number of Huangkedou at the same time, alleviating the inhibition of plant height, biomass, podding number caused by zinc and chromium stress.(6)1μmol/L、5μmol/L、10μmol/L ABA spraying and seed soaking increase the yields of Keyuanluqiuwang at maturing stage, and10μmol/L ABA performed the best.All the ABA spraying and seed soaking increased the yields of Huangkedou, and10μmol/L ABA performed the best. ABA performed different effects on yield because of different varieties.During the same period, the experiment of ABA on the accumulation o f zinc and chromium of soybean indicated that the accumulation of zinc and chromium of roots and leaves was increased while the seeds reduced. In general, ABA enhanced the antioxidase activity of soybean plant at podding stage, eliminated the excessive ROS caused by zinc and chromium, then the MDA-membrane lipid peroxidation was declined, kept the normal physiological metabolism of soybean plant, and the absorption of N, P, K were promoted, and the accumulation of zinc and chromium in seeds at maturity stage was reduced while the yields were increased at the same time. It indicated that ABA could enhance the resistance of soybean plant and reduce the accumulation of zinc and chromium in soybean seed, alleviating the reduction of yields under zinc and chromium stress. It can provide theoretical reference and improvement ideas for soybean yield and quality maintaining in zinc and chromium contaminated soil.