Articles
EFFECT OF PACLOBUTRAZOL ON FRUIT QUALITY: APPLE, PEAR AND CHERRY
In 1983 terminal growth of ‘Top-Red Delicious’ was reduced 80–90% by banding applications, and there was a 12% increase in the Extra Fancy fruit on treated trees.
There was no difference in firmness in either year in fruit of the same size, however acidity was reduced in fruit from treated trees throughout the harvest period.
This trend continued for fruit stored in regular and commercial CA storage.
The ‘Granny Smith’ fruit examined in 1983 was no different in firmness, acidity or soluble solids either at harvest or after regular or commercial CA storage.
Pear: In 1980 mature ‘Anjou’ pear trees on seedling rootstock received a soil surface application of PB at the rate of 20.0 g AI per tree over a 3 X 3 m area under the tree canopy.
There was a slight reduction in extension growth by the end of the first year.
In 1982 the full effect of the chemical was apparent.
Vegetative growth was reduced by about 90%, and the percentage of flower buds was about twice that of untreated trees.
The increase in the number of fruit as well as the high rate of chemical treatment produced fruit which at harvest were 10% smaller than untreated fruit.
However, by applying GA3 at 4 weeks after full bloom to limb units of trees treated with PB size was increased by 18% over the controls.
At harvest there was no difference in soluble solids, however firmness of treated fruit was 13% greater than controls.
Acidity was also slightly lower in fruit from treated trees.
Cherry: In March of 1983 7-year-old ‘Rainier’ cherry trees were treated with 1.0, 2.0 or 4.0 g AI per tree at the trunk soil line in 2 liters of water (trunk drench). Reduction in vegetative growth was evident within 60 days of treatment.
In 1984, anthesis in treated trees occurred about 3 days in advance of controls.
As a result, there was a greater spur leaf surface area exposed during the first 2 weeks after full bloom in treated trees.
Total fruit yield increased 33% at the rate of 1.0 g AI per tree and 105% at 4.0 g AI per tree, however, the average fruit size decreased by 20% at the higher rate.
Stem length and titratable acidity generally decreased as the rate increased; and at all rates firmness was slightly reduced.
Percent soluble solids was no different in treated and untreated trees.