Response and Critical Limits of Zinc for Cotton Grown in Medium Black Calcareous Soils of Saurashtra Region of Gujarat

Pot culture experiment was conducted by using bulk soil samples collected from different Agricultural Research Station, Junagadh Agricultural university, Junagadh and were categorized as low, medium and high with respect to native soil fertility status of zinc. Three treatments with three replicated pots in each type of soil were imposed with common recommended levels of N and K and varied levels of Zn for Zn treatment experiment in the respective sets of pots under each of the low, medium and high fertility soils. Fertilization of zinc significantly increased seed cotton and stalk yields and Zn content in plant as well as in soil. The seed cotton yield response was 16.3 and 24.5 per cent at 5.0 and 10.0 mgkg^-1 Zn levels, respectively. Obviously, the yield response of cotton to added Zn was considerably higher in low Zn soils than in those of medium and high Zn status. The critical levels of available Zn 0.89 mgkg^-1 in soil and concentration of Zn in cotton 4^th leaf at 30 DAS and at maturity in leaf were found to be 57.5 and 24.6 mgkg^-1, respectively.