The Effect Of Excessive Fe～(2+) On Physiological Characteristics Of Soybean And Ultrastructure In Leaf Cells Of Soybean

In these experiments, two varieties of soybean ("Zhechun No.3" and "1601") were employed as the research materials, to study the effect of Fe2+ on some agronomic characteristics, uhrastructure in leaf cells, physiological characteristics and endogenous protective systems in soybean. The main results are summarized as follows:1. Excessive Fe2^ treatment significantly affected some agronomic properties of soybean. Fe2" stress decreased leaf area and leaf specific weight of soybean. Low Fe2^ toxicity inhibited growth of root, and the tip, the length and the surface area of soybean roots all decreased, but high Fe2+ toxicity promoted growth of root.2. Excessive Fe2+ might injure the membranous structures of cells. The ultrastructure of chloroplasts in soybean leaf cells in control (14.24 mg/kg Fe2+) was normal. The chloroplasts became deformed at 100 mg/kg Fe2+ concentration, and the ultrastructural damage of leaf cells was much more serious under 300mg/kg and 500mg/kg level than under 100 mg/kg Fe2+ level.3. Excessive Fe2+ stress inhibited the photosynthesis of soybean. As a whole, the photosynthetic rate and chlorophyll content of soybean leaves were decreased with the increasing intensity of Fe 2+. There was not relationship between the photosynthetic rate and the transpiration rate.4. There were different in the response of two kinds of varieties of soybean to Fe2^. The content of Pro (proline) of soybean leaves increased obviously in "Zhechun No.3" and not in "1601" with increasing of the Fe2+.5. Excessive Fe + affected the content of soluble carbohydrate of soybean leaves. The content of soluble carbohydrate decreased in 3-trifoliate period with the increasing intensity of Fe2+, and it increased obviously in initiation of flowering period of soybean and the best condition to content of soluble carbohydrate are under 100 mg / kg treatment.6. Two varieties of soybean ("Zhechun No.3" and "1601") under high Fe2+ exhibited an increasing of membrane MP (permeability) and MDA (malondialdhyde) content. The change of MP in leaves significantly positively correlated with the change of MDA in leaves.7. Excessive Fe2T affected the activities of antioxidase. "Zhechun No.3" soybean was more sensitive to Fe2+than "1601". With the increase of Fe2+concentration, the activities of CAT (catalase) increased first and decreased afterward, but the activities of POD (peroridase) first decreased and increased afterward in "Zhechun No.3" soybean and POD activity decreased quickly in "1601" soybean.8. Fe2+ influenced root activity of soybean. The root activity decreasedobviously with the increasing concentrations of Fe2+. While under 500mg/kg treatment, the root activity of'Zhechun No.3" soybean increased.9. The genetic variation was discovered in the response of different kinds of varieties of soybean to Fe2+. In our trails, "Zhechun No.3" soybean was sensitive to Fe2+ than "1601" soybean and its resistance to Fe2+was higher than "1601" soybean.