When 45Ca-labelled calcium chloride solution was applied to the skin of young developing Merton apple fruits, activity in the cortex at maturity was highest in the calyx end region where bitter pit lesions most commonly develop. Fruit age at time of application affected the amount of labelled calcium absorbed but not its longitudinal distribution. Following branch injection of labelled calcium chloride solution 8 weeks before harvest, activity in mature fruits was found mostly in the stem end. Leaves and buds accounted for 95% of the recovered activity, and the fruits for 5%, of which about one-quarter was in the calyx half. The same distribution pattern was found following injection of labelled calcium chloride solution into the fruit stem. The concentration of naturally occurring calcium in the cortex of the mature fruit declined steadily from stem end to calyx end. On the other hand, the magnesium concentration was lowest near the stem end and highest at the calyx end. The potassium concentration remained fairly constant along most of the length of the fruit, with a small increase at each end. The findings are discussed with regard to the longitudinal gradient in bitter pit susceptibility within apple fruits, and to the relative effectiveness of tree sprays of calcium, as compared with soil applications, in the control of the disorder. Results suggest that calcium does not have a trace element role in the control of bitter pit.

Fruit cell numbers in a block of Jonathan apple trees with an alternate cropping rhythm were studied over the period 1955–1962. The number of cells per fruit showed a rhythm in phase with the crop level, while the percentage dry matter showed a rhythm counter to this. Seed numbers per fruit showed no rhythm. The rhythm in cell numbers proved very persistent, continuing for some years under severe thinning treatments. Against this background four types of treatment designed to affect cell numbers were imposed over the period 1957–1962: (1) Decreasing competition between fruits, by thinning by hand, by DNOC, and by NAA. (2) Attempts to increase competition, by delaying abscission with 2,4-D. (3) Attempts to stimulate cell division by kinetin plus synergistic compounds. (4) Attempts to supplement nutrition which forms the background to cell division. No significant effects resulted from the 2,4-D, kinetin, or nutritive supplements, but reducing competition by thinning, either by hand or by DNOC, resulted in an increase in cell numbers which was cumulative over several years. Thinning with NAA did not increase cell numbers. The implications of these results are discussed.

Exposure to O�C for 4 weeks caused a threefold increase in cell membrnno permeability of mature-green tomato fruits (susceptible to chilling injury) hut had no effect on that of cabbage leaves (not susceptible). While tomato fruits chilled for 12 days lost two-thirds of their capacity to esterify phosphate at 20�0, a steady rise in this capacity occurred during chilling of cabbage leaves for 5 weeks. In tomato fruits the rate of phosphate esterification at the chilling temperature fell in 12 days to about one-half of the rate at the commencement of chilling .. It is suggested that the characteristic symptoms of chilling injury in mature-green tomato fruits, viz. increased susceptibility to fungal attack and loss of the capacity to ripen normally. may result from an energy deficit caused by a chilling. induced reduction in the phosphorylative capacity of the tissue.

Cell size, total and protein nitrogen, and preclimacteric respiration have been studied for light and heavy crop fruit of certain Tasmanian-grown apple varieties. Differences in size of fruit from light and heavy crops have been shown to be due mainly to differences in cell size rather than in cell number. Respiration per cell, protein nitrogen per cell, and cell volume were closely intercorrelated but respiration per unit protein is greater in light crop fruit than in heavy crop.

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