Effect of Tungsten on the Growth, Dry-Matter Production, and Biochemical Constituents of Cowpea

The effects of various concentrations (0, 5, 10, 15, 20, and 25 mu g g(-1)) of tungsten (W) as sodium tungstate were observed on growth performance, dry-matter production, and selected biochemical constituents of cowpea. Lower applied doses of W promoted root-shoot length whereas greater doses retarded it. Chlorophyll contents and soluble sugars increased with lower applied doses of W. Greater applied doses of W resulted in an increase in the chlorophyll a/b ratio. A significant gradual decrease in proline contents was observed with lower applied doses of tungsten. Tungsten contents in plant material showed a very highly significant (P < 0.001) correlation with soil-applied tungsten.