Studies on Chlorosis in Sweet Orange in Agra Region of Uttar Pradesh

Analysis of leaf and soil samples collected from healthy and chlorotic orchards showed that the chlorosis of sweet orange in the Agra region was mainly due to zinc deficiency caused by antagonistic effect of Fe on Zn availability. The critical level of Zn in citrus leaves for clear distinction between healthy and chlorotic plants appeared to be 20 ppm. Generally, the healthy green leaves had lower concentrations of P and Fe and higher levels of N, Ca, Mg and Mn than chlorotic ones. The concentrations of K, S and Cu were more or less in the same range in both cases. The soil samples supporting chlorotic plants had, in general, alow content of available Zn and a high level of available Fe.