Effect of Nitrogen and Boron Applications on Carica papaya L. II. Petiole and Fruit Nutrient Content and N and B Index for Leaf Tissue Analysis

Abstract

Four levels of N (0, 57, 170 and 340 kg/ha) and 4 levels of B (0, 2.3, 4.5 and 6.8 kg/ha) were applied to the P.R. 7-65 papaya variety, growing on an Oxisol. Treatments were initiated when the transplanted seedlings were 3 months old, and were repeated every 6 weeks. Increments of N and B levels increased the petiole and fruit contents of these elements. Except at the highest N application, the leaf content of N decreased as the B supplied was increased; the fruit content of all elements, except P, decreased as the fruit matured; the Ca content of leaves and fruits increased directly with the N and B levels supplied to the soil; Mg increased and Mn decreased significantly in recently matured fruits as the N and B supplies to the soil were increased; the N and B levels associated with the highest yield (24 kg/plant) were 1.48% and 64 p/m, respectively; the petioles contained less N, P, Mg and B, and higher Ca and Mn, and about the same K as the fruits; the B, Ca, Mg and Mn contents decreased as the fruits ripened.