Effects of different methods of zinc application on growth and yields of rice in a calcareous soil, West Pakistan

A disorder of the rice plant has been known to exist for more than 20 years at the Kala Shah Raku Government Rice Farm and in the neighboring areas in West Pakistan. The disorder is locally described as “Hadda” and is sometimes referred to as bronzing because the affected leaves show characteristic brown streaks and blotches. In recent years, it has become more serious with the introduction of new improved varieties from The International Rice Research Institute. Since these improved varieties are usually grown at high levels of nitrogen, it has been suspected that the incidence of the disorder is aggravated by vigorous vegetative growth.