ISHS Acta Horticulturae 636: XXVI International Horticultural Congress: Key Processes in the Growth and Cropping of Deciduous Fruit and Nut Trees
FRUITLET THINNING OF THE PEAR CULTIVAR 'ABBE FETEL' WITH NAPHTHALENEACETIC ACID |
| Authors: | P.I. Garriz, H.L. Alvarez, G.M. Colavita |
| Keywords: | chemical thinning, fruit size, quality, growth, maturity, Pyrus communis L. |
| Abstract:
Fruitlets of ‘Abbé Fetel’ (Pyrus communis L.) need to be thinned to reach high commercial quality at harvest. Naphthaleneacetic acid (NAA) was evaluated as a fruitlet thinner at two application dates on 8-year-old pear trees trained to palmette leaders. The study was conducted at the Comahue National University (lat. 38 56’ 67 59’W). Treatments were 1) control, 2) NAA (10 mg L-1), applied on 13 Oct. 2000, at 17 days after full bloom (DAFB) and 3) NAA (10 mg L-1), applied on 23 Oct. 2000, at 27 DAFB. Fruit diameter (FD) was recorded twice weekly (n = 20 per date and treatment). At 138 DAFB (initial commercial harvest), crop load and fruit weight (FW) were determined. Fruits were then graded into size categories. From 138 to 166 DAFB, the maturity indices were measured at weekly intervals. Treatments 2 and 3 resulted in 47.1% and 52.6% of the fruit >70 mm, respectively, compared with 22.2% from the untreated controls. Mean FD was not significantly altered by NAA sprays; the following logistic model best fitted the fruit growth vs. time curve on non-thinned trees: FD = 81.83/(1 + e2.34-0.03DAFB), R2 = 0.97, P < 0.001. At 138 DAFB, there were no statistical differences among treatments in fruit firmness (range 55.5-59.4 N), starch index (range 2.20-2.50), or soluble solids concentration (range 12.2-12.9°Brix). Consequently, our data indicate that NAA applied at 27 DAFB was most effective for thinning ‘Abbé Fetel’ pears, and for enhancing fruit size at ripening, with no effect on the maturity indices. More research is needed to determine the optimum NAA rate and timing under alternative environmental and management conditions. | |
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