Fruit pigmentation of four green apple cultivars responds to urea sprays but not to nitrogen fertilization

Abstract

Four green apple (Malus domestica Borkh.) cultivars, 'Granny Smith', 'Mutsu', 'Newtown', and 'Shamrock', were subjected to a factorial experiment of two rates of nitrogen fertilization and three concentrations of foliar urea sprays for 4 years. The higher rate of N (160 kg N/ha) had no effect on ground color or fruit quality relative to the lower rate of 80 kg N/ha. Urea sprays enhanced green pigmentation in 'Granny Smith' and 'Newtown' at harvest and retarded yellowing of fruit in all cultivars during air storage at 0C. Response was similar for area at 0.5% and 1%, and urea sprays did not adversely affect quality. Urea sprays increased fruit N by 23% and 47% for the 11.5% and 1% concentrations, respectively.