Effects of leaf: Fruit ratios on fruit growth, mineral concentration and quality of mango (Mangifera indica L. cv. Kensington Pride)

Abstract

To determine the effects of leaf:fruit ratios on growth, mineral concentration and quality of fruit, 30 uniform ‘Kensington Pride’ mango trees had selected branches thinned to a single fruit and girdled to provide 30, 60 or 120 leaves per fruit. Control branches were not thinned or girdled and had on average 36 leaves per fruit. Decreasing the leaf:fruit ratio to 30 resulted in smaller fruit with lower dry matter (generally an indication of fruit maturity), but extended the number of days to the stage of eating-soft at 22·C (shelf life) by 2 d, increased pulp Ca concentrations, and improved storage performance by reducing external chilling injury. Increasing the leaf:fruit ratio to 60 produced larger fruit and extended shelf life by approximately 2 d, but had no effect on dry matter or pulp Ca concentrations. A further increase in the leaf:fruit ratio to 120 increased fruit size, dry matter and the severity and incidence of disease but had no effect on shelf life or pulp Ca concentrations. Girdling had an independent effect on skin colour, with fruit from girdled branches having approximately 20% less green and 5–12% more red blush on the skin at eating-soft. Girdling also reduced the concentrations of Mg and K in the mango fruit pulp. Percent dry matter and Ca concentration in fruit pulp had significant but weak, negative and positive correlations with fruit shelf life respectively, indicating that while both were involved in mango ripening, they were not the major determinants.