Fruit growth and mineral element accumulation in Pacific Rose (TM) apple in relation to orchard management factors and calyx-end splitting

The effect of irrigation and crop load of apple (Malus domestica Borkh cv. Pacific Rose) on the fruit growth and mineral element accumulation was inve stigated. Fruit growth and changes in the concentration and contents of nit rogen (N), phosphorus (P), calcium (Ca), magnesium(Mg), and potassium (K) i n the flesh of Pacific Rose(TM) apple fruit were recorded over a growing se ason at the Massey University Fruit Crops Units orchard in the 1998-99 crop season. Fresh mass showed a linear growth while fruit diameter followed a curvilinear growth pattern during the growing season. Low crop load signifi cantly increased fruit size, particularly during the final expansion phase, whereas irrigation had little effect on this attribute. Both low crop load and frequent irrigation treatments increased fruit growth rate, but the ef fect of the irrigation treatments fluctuated considerably during the season . The incidence of fruit splitting was detected at about 20 WAFB when the f ruit attained an asymmetrical growth in shape (LID). The concentrations of N, P, Ca, Mg, and K declined throughout the sampling period. There was howe ver, an increase in concentrations of P and K at the last harvest. The quan tity of individual nutrient elements accumulated by the fruit showed an inc reasing trend during the season. Nitrogen accumulation however, reached max imum at 16 WAFB after which it declined until the last harvest. Fruit miner al element analysis of sound and split fruit revealed that split fruit had higher concentrations and contents of Mg and K and lower contents of Ca and P. As a result, the ratios of Ca:Mg and Ca:K were lower in split fruit as compared with sound fruit.