ISHS Acta Horticulturae 179: V International Symposium on Growth Regulators in Fruit Production
EFFECT OF ETHYLENE INHIBITORS ON FRUIT SET, OVULE LONGEVITY, AND POLYAMINE LEVELS IN 'COMICE' PEAR |
| Authors: | Carlos H. Crisosto, M. D. Vasilakakis, P.B. Lombard, D. Richardson, R. Tetley |
| Abstract:
'Comice' pear trees are known for low fruit set and crop in spite of a high bloom density. Because of the previous success to increase fruit set and yield obtained with ethylene inhibitors on fruit set of apple and of pear, and polyamines on apple fruit set, aminooxyacetic acid (AOA) at 500 ppm, putrescine (PUT) at 10-5 M, spermine (SPM) at 10-5 M, and spermidine (SPD) at 10-4 M, were sprayed at anthesis on 'Comice' flowers hand pollinated with 'Bartlett' pollen 6 days after anthesis. Senescence of ovule and visible flower parts was delayed by AOA and PUT treatments. SPD delayed senescence of visible flower parts, but not ovule longevity period. AOA and PUT treatments increased the endogenous putrescine levels in the ovary 12–16 days after anthesis. The endogenous putrescine peak appeared to be related to the extended ovule longevity period. Eight days were necessary for 'Williams' pollen tubes to reach 'Comice' ovules under an average ambient temperature of 8°C. Effective pollination period (EPP) determined by percent fruit set of at least 10 days was observed for 'Comice'. The hypothetical EPP determined by the aniline blue test of 9 days confirmed the long EPP for 'Comice'. The lack of increase on fruit set for the AOA and PUT treatments although they extended the ovule longevity, could be due to the long EPP of 11 days, instead 1 day previously reported. | |
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