The influence of shade and within-tree position on apple fruit size, colour and storage quality

SummaryApple fruits from the inner parts of Cox’s Orange Pippin apple trees differed from those from the outer portions in size, colour and storage behaviour, and similar differences were obtained when parts or all of small trees were artificially shaded. The fruits from the outer portions were larger with a higher proportion of skin coloured red and were more susceptible to bitter pit, to rotting due to Gloeosporium spp. and to soft rot fungi. They were, however, less likely to become shrivelled or to develop core flush than fruits from the inner and lower portions of the trees. Artificially imposed shade reduced the incidence of bitter pit but increased that of core flush as well as reducing fruit size and colour. The higher incidence of bitter pit in well exposed fruits was associated with a decrease in the ratio of calcium to potassium in these fruits. These results suggest that it may be advantageous to pick and store fruits from the exposed and shaded parts of large trees separately and emphasize the need to raise the calcium status of fruits produced by systems of growing which are designed to give increased exposure to a larger proportion of the crop.