Articles
GROWTH REGULATORS AND CALCIUM ACCUMULATION IN APPLE FRUIT
In the experiments reported here, we have tried to manipulate the fruit hormonal content by applying exogenous growth regulators only to fruits, in an attempt to modify their sink power for calcium.
The fruits were treated by dipping apple fruits attached to the trees in solutions either of one single regulator or of a mixture of two or three different regulators.
In both the years 1977 and 1978, the time of applications was either the beginning of July (referred to as ‘early’ applications) or the beginning of August (referred to as ‘late’ applications). The apple varieties were Golden Delicious, Cox’s Orange Pippin and Cherry Cox’s.
At least 20–25 fruits were used in each treatment.
When comparing the fruit mineral composition, a decrease in the ratios N/Ca, K/Ca and K/(Mg + Ca) was taken as an indication of better storage properties, at least as far as physiological disorders are concerned.
Variance analysis showed many significant differences between the treatments for one variety and one time of application but we have looked for some identical results obtained in both years whatever the variety might be.
In the early applications, two treatments, i.e.
IAA (Indolyl-3-acetic acid) and the mixture hyaluronidase + GA3, decreased calcium content and increased the ratios N/Ca, K/Ca and K/(Mg + Ca). In the late applications, hyaluronidase and the mixture hyaluronidase + GA3 increased the different ratios.