Effect of Soil and Foliar Applications of Zn and Foliar Applications of Cu, Mn, Fe Alone and in Combination with Zn on the Incidence of Chlorosis, Fruit Fall, Granulation and Fruit Quality in Sweet Orange [Citrus Sinensis (L.) Osbeck] Variety Blood Red

Two field experiments, one pertaining to studies on the effect of different micro-nutrient sprays and the other relating to soil versus foliar applications of Zn were initiated on 7 year old ‘Blood Red’ variety of sweet orange [Citrus sinesis (L.) Osbeck] on ‘jatti khatti’ (Citrus jambhiri Lush) root stock. Foliar applications of Zn, Zn+Mn, Zn+Fe and Zn+Cu and soil application of Zn at 15 ppm level increased the percentage of healthy trees and decreased those showing minor, medium and acute chlorosis. The percentage of healthy trees was decreased and decline symptoms were intensified in plots receiving no micro-nutrients or those treated with Cu, Fe or Mn. The extent of chlorosis was decreased with the increase in the Zn content of leaves. Soil or foliar applications of Zn and foliar applications of Fe and Mn alone or in combination with Zn did not affect significantly the yield, fruit fall, granulation and the fruit quality. Zn+Cu followed by Cu sprays were significantly better than the other micro-nutrient treatments in reducing granulation and improving fruit quality. Available Cu was deficient in the orchard and there also seemed to be a latent Cu deficiency in sweet orange leaves. The satisfactory limit of 5 to 15 ppm Cu in the leaves might perhaps need further revision.