DIRECT UPTAKE OF CALCIUM BY THE FRUIT FROM POSTHARVEST APPLICATION

The prestorage drenching of harvested apples with 4 per cent calcium chloride, recommended on the basis of numerous laboratory and field tests, has been extensively used to decrease the risk of breakdown in Jonathan apples commercially stored for up to ten months.
Calcium applied to the fruit surface in this manner is slowly absorbed during the storage period.
Recent studies showed that the calcium content of Jonathan apples was immediately increased by submerging warm fruit in a cold solution of 4 per cent calcium chloride containing a potent surfactant (L77). An average increase of 3 mg Ca/100 g of fruit fresh weight, a quantity considered adequate to offset early senescence, was achieved in 10 minutes for fruit at 20°C placed in a 5°C solution.
With cooling there is a decrease in the internal gas volume of the fruit which favours entry of the solution into the intercellular spaces of the cortex through open lenticels.
Calcium uptake was readily predicted from weight increase during treatment and regulated by adjustment of treatment time and solution content.
Current investigations are directed towards utilizing lower concentrations of calcium chloride when applied by hydrocooling procedures.

Symposium on Mineral Nutrition and Fruit Quality of Temperate Zone Fruit Trees

D.H. DEWEY, J.J. LEE

https://doi.org/10.17660/ActaHortic.1980.92.56