Articles
THE EFFECT OF SUMMER PRUNNING AND CALCIUM FOLIAR SPRAYING OF ‘JONAGOLD’ AND ‘ŠAMPION’ APPLE TREES ON FRUIT STORAGE QUALITY
Apples with low calcium contents are susceptible to storage disorders such as bitter pit, which can be controlled by increasing calcium contents of the fruit.
This may be achieved by spraying with calcium compounds and summer pruning.
The aim of our studies was to compare the effectiveness of these two treatments.
Four-year-old ‘Jonagold’ and ‘Šampion’ apple trees grafted on M 26, were subjected to the following treatments: shoot pinching 3 times in June, July and August, shoot pinching 2 times in June and July, shoot pinching 2 times in June and July restricted to tip leaves, spraying 6 times with 0.5% CaCl2 in June, July and August, and spraying 4 times as above.
The control had no treatments.
The first two pinching treatments decreased mean fruit weight and yield per tree in the third year when compared with the control.
Calcium chloride sprayings had no such effect.
Shoot pinching repeated 3 times increased nitrogen content in the fruit.
No pruning treatment affected potassium or magnesium contents.
The effect of summer pinching on calcium and phosphorus contents was statistically insignificant.
Apples from the trees subjected to two pinchings and 4 sprays had less bitter pit after 85 days of storage than apples from the other treatments and the control.