EFFECTS OF NITROGEN AND CALCIUM SUPPLY ON THE INCIDENCE OF INTERNAL FRUIT BREAKDOWN IN ¿TOMMY ATKINS¿ MANGOES (MANGIFERA INDICA L.) GROWN IN A SOILLESS SYSTEM

Abstract

Tommy Atkins mangoes grafted on 13-1 were grown in a soilless system, with basaltic lapilli as substrate, to study the effect of nitrogen and calcium supply on internal fruit breakdown (IFB). Treatments consisted in a complete factorial of 2 nitrogen (0.72 and 5.36 mmol/L) and 2 calcium levels (0.62 and 2.5 mmol/L). Water consumption and nutrient uptake were calculated by difference between quantities supplied and drained. Fruits were harvested at full maturity and the degree of IFB and yield were assessed for each treatment, determining mesocarp mineral content. Nutrient uptake increased as fruit developed, in a greater proportion for Ca than for N, decreasing from the onset of physiological maturity. A significant interaction between the effects of N and Ca was observed for all the studied variables. For low Ca treatments total yield and Ca content of fruits were remarkably reduced in the presence of high nitrogen. The degree of IFB and total-N content of fruits were remarkably greater in the high N treatments, although to a lesser extent for the higher Ca level. The incidence of IFB showed a high positive correlation with the fruit N content and a negative relation with the Ca content.