Effect of foliar treatment with boron and zinc on physiological responses of cow pea [vigna sinensis Cv. cream 7]: II Metabolic activities during growth and development

ABSTRACT

In the present study Vigna sinensis plants cv. Cream 7 were sprayed with 10, 50 and 250 mg/L of boron or zinc. The effect of boron and Zn nutrition on different constituents shoots and roots of Vigna sinensis plants were investigated. At all three concentrations of boron or zinc chlorophyll a, chlorophyll b and carotenoid contents of Vigna sinensis leaves were increased. The low concentrations applied of both boron or zinc mostly increased the reducing sugars, sucrose, polysaccharides, total carbohydrates, DNA and RNA contents concomitantly with increases in the number and activities of gibberellin compounds and decreases the total-N contents of shoots and roots of Vigna sinensis plants. The highest concentrations of boron or zinc induced a significant reduction in DNA and RNA contents in most stages of growth and development of Vigna sinensis plants. In general, all concentrations of boron or zinc induced mostly highly significant decreases in a and [3-amylase activities of shoots and roots of Vigna sinensis plants throughout the experimental period. At flowering and fruiting stages, the highest concentrations of boron or zinc mostly decreased the protease activity in shoots and roots of Vigna sinensis plants, while the lower concentrations of both elements increased this activity. Moreover, the high concentration of boron or zinc mostly induced highly significant increases in RNase activity of Vigna sinensis plants throughout the experimental stages