ISHS Acta Horticulturae 800: X International Pear Symposium
EFFECTS OF DIFFERENT BIOREGULATOR APPLICATIONS ON FRUIT SET, YIELD AND FRUIT QUALITY OF 'WILLIAMS' PEARS |
| Author: | G. Lafer |
| Keywords: | Pyrus × communis, pear, 'Williams', plant growth regulator, AVG, GA, Prohexadione-Ca, fruit set, fruit quality |
| Abstract:
Austria produces pears only for the regional market. 'Williams' is the main cultivar for both fresh market and the distillery. Improvement of fruit set on young pear trees with applications of bioregulators can be considered as a useful way for increasing the early yield productivity. Young 'Williams' trees are notorious for low fruit set and crops. Trees in the immature stage often lose most of their fruits due to an excessive June drop. In the growing seasons of 2005 and 2006, different bioregulators were tested on three-year-old 'Williams' trees for their efficiency on improving fruit set. Plant growth regulators including gibberellins (GA3 10 mg L-1), aminoethoxyvinylglycine (AVG) 125 mg L-1, a mixture of auxins (NAAm 7.5 mg L-1 + NAA 2.5 mg L-1 + NOA 9 mg L-1) and Prohexadione-Ca (P-Ca) 250 mg L-1were sprayed at full bloom (BBCH 65). The treatment with auxins was repeated at stage BBCH 67 (fading flowering). A surfactant, Tween 20 (0.1%) was used. Evaluations were made for fruit set after June drop, number of fruits/tree and kg per tree. Yield capacity (number of fruits per cm2 trunk cross sectional area), fruit quality (calibration and internal quality), storability, shoot growth and return bloom were also determined. Applications of AVG and P-Ca produced a significant increase in fruit set expressed as number of fruits per tree and kg per tree. Bloom density was evaluated the following year to indicate the effects of the applied plant growth regulators on flower bud formation. Return bloom was not affected by any plant growth regulator treatment. | |
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