ISHS Acta Horticulturae 653: IX International Symposium on Plant Bioregulators in Fruit Production
CONTROLLING GROWTH OF SUPER-SPINDLE 'GALA'/M.9 APPLE TREES WITH PROHEXADIONE-CALCIUM, NAA AND ETHEPHON |
| Authors: | S. Guak, M. Beulah, N.E. Looney |
| Keywords: | fruit quality, gibberellin biosynthesis inhibitor, Malus domestica, return flowering |
| Abstract:
Prohexadione-Ca (PHD-Ca; a gibberellin biosynthesis inhibitor), NAA, and ethephon were applied alone and in combination to six-year-old super-spindle ‘Gala’/M.9 apple trees in a commercial high density orchard. NAA was applied either as a paint or whole tree spray. The paint treatment (1:2.5 Stop Drop® NAA/wallpaper paste) was applied to the fresh cut surface of the central leader 2.5 weeks after full bloom. PHD-Ca (250 mg L-1 a.i.) was sprayed 4 weeks after full bloom. Ten days later Stop Drop® NAA at 18 mg L-1 a.i. or ethephon at 300 mg L-1 a.i. were applied as whole tree sprays. PHD-Ca effectively suppressed shoot elongation. Fruit set was significantly increased by PHD-Ca but was decreased by ethephon. PHD-Ca overcame this ethephon effect. Mean fruit weight was reduced by PHD-Ca, and also by both NAA treatments with the spray treatment having the greater effect. Fruit yield was increased by PHD-Ca but was substantially decreased by NAA and ethephon sprays. PHD-Ca had no effects on fruit shape (L/D), firmness, and incidence of fruit stem-end russet. PHD-Ca reduced soluble solids concentration and titratable acidity and delayed fruit maturity and harvest date. Return flowering was reduced by PHD-Ca and NAA treatments (NAA paint was more inhibitive than NAA spray), but was promoted by ethephon. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
