Effect Of Boron And Molybdenum On Soybean Under Different Moisture

This work was conducted with pot culture from 2004 to 2005 in the horticultural station of North-East Agricultural University in Haerbin. The medium used in pot was a bleached soil and the soybean varieties were Dongnong 42 with high protein content, Dongnong 46 with high oil content and a half-wild soybean. Treatments were divided into two big groups, the normal irrigation and drought stress, of which six levels were set: the control, lower Boron, higher Boron, lower Molybdenum, higher Molybdenum and higher Boron+higher Molybdenum. The dynamic of protective enzymes and non protective enzymes (Pro) of soybean plant of different treatments, the nitrogen and carbon metabolism of soybean plant, uptake of nutrients and its effects on yield and quantity of soybean were studied, the results showed that:Under the two soil moisture conditions, application of Mo increased the activity of protective enzymes (SOD, APX, CAT) and lowered the MDA and the Pro levels thus increased the drought resistant capability of soybean plant. In comparison with the normal irrigation treatments, the activities of superoxide dismutase (SOD) and catalase (APX) were lower and the activity of CAT was higher under the drought stress. The effects of B and Mo were different, the effect of B was bigger in increasing the activities of SOD and APX; but in increasing CAT's activity and in decreasing MDA and Pro contents, B's effect was bigger than that of Mo's. B and Mo stimulate each other. Genetic differences to the application of B and Mo exist among the three varieties of soybean, which was correlated with the entire activity (enzymatic and non enzymatic) of oxidation resistant system. The drought resistant capacities showed, Glycine Max Merrill>Dongnong 42>Dongnong 46.Both B and Mo increased the activities of Glutamine synthetase (GS) and nitrate reductase (NR) of different genetic varieties of soybean. Changing trend of the activities of these two enzymes was similar, showing an increase at first and then a decrease. The activity of GS at the growth stage R₁ was the highest and the lowest at the growth stage R₅. In comparison with the normal conditions, the activities of the two enzymes were lower under the stress condition. There exist certain difference between the effect of B and that of Mo, the result of the application of Mo was better than that of Mo, and they stimulate each other. Influence of Mo application rate on the activity of enzyme was not significant.Under either normal or drought stress conditions, the foliar content of chlorophyll of the three varieties changed in the same way, it increased from the growth stage V₅ to R₃, and decreased thereafter. Both B and Mo increased the foliar content of chlorophyll. The foliar content of chlorophyll of half-wild soybean was lower. B and Mo's effects on the foliar content of chlorophyll was as follows, Mo2>Mol>B2>B1.Under the two moisture conditions, the foliar content of soluble sugar in the same variety...