ISHS Acta Horticulturae 463: VIII International Symposium on Plant Bioregulation in Fruit Production
THINNING APPLES AND PEARS IN A NORDIC CLIMATE. III. THE EFFECT OF NAA, ETHEPHON AND LIME SULFUR ON FRUIT SET, YIELD AND RETURN BLOOM OF THREE APPLE CULTIVARS |
| Author: | M. Meland |
| Keywords: | Thinning, NAA, Ethephon, Lime sulfur, fruit set, yield, return bloom, Malus domestica Borkh. |
| Abstract:
A field experiment examined the effect of using naphthalene acetic acid (NAA), lime sulfur and ethephon to thin the three apple cultivars ‘Summerred’, ‘Red Gravenstein’ and ‘Aroma’. NAA at three concentrations; 10, 20 and 30 mg/l and 5 % lime sulfur with or without the addition of 150 mg/l ethephon were applied at petal fall and full bloom, respectively. The experiment started in 1990 and was conducted for a period of three years for ‘Red Gravenstein’ and ‘Aroma’ and two years for ‘Summerred’. The effects of NAA were largely additive; fruit set, yield and fruit number decreased with increasing concentration for all the three cultivars. Neither thinning nor return bloom were promoted of a low dosage of ethephon. Increasing NAA-concentrations promoted return bloom only for the ‘Aroma’ cultivar. Lime sulfur thinned ‘Aroma’ slightly. Minor phytotoxic symptoms on the leaves of the highest concentrations of NAA were observed. | |
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