Botany Department, Lucknow University, Lucknow
Optimum growth and dry matter yield of barley (Hordeum vulgare L. Cv. K. 19) was obtained at 0.065 ppm zinc supply. Plants raised at. 0.0013 ppm or lower levels of zinc developed visible effects of zinc deficiency-minute irregular chlorotic patches in the middle of lamina leading to white-green mottling; the chlorotic areas eventually turning flaccid and necrotic. No visible effects of zinc toxicity were produced upto 26 ppm zinc supply. The critical zinc concentration for maximal yield and threshold of deficiency were 26.0 and 5.8 ppm. respectively.
Zinc deficient plants showed a marked decrease in catalase and increase in peroxidase, acid phosphatase and ribonuclease activities. The effect of zinc deficiency on the enzyme activities was independent of that on cellular protein.
