ISHS Acta Horticulturae 903: IX International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems
CHANGES IN FRUITING BEHAVIOUR AND VEGETATIVE DEVELOPMENT OF 'SCIFRESH' APPLE IN RESPONSE TO ARTIFICIAL SPUR EXTINCTION USING CENTRIFUGAL TRAINING |
| Authors: | D.S. Tustin, G.A. Dayatilake, R.E. Henriod, K.C. Breen, M. Oliver |
| Keywords: | Malus × domestica, floral precocity, growth allocation, yield, fruit size |
| DOI: | 10.17660/ActaHortic.2011.903.83 |
| Abstract:
The new apple cultivar ‘Scifresh’ has several genotypic traits that impair commercial productivity and fruit quality. This study is on the consequences of the exceptional floral precocity of ‘Scifresh’ trees, where almost all terminal, spur and axillary buds flower annually, producing many weakly-developed floral spurs. Observed low fruit set, high sensitivity to chemical thinning and high axillary bud and spur extinction are thought to be responses to ‘Scifresh’ floral behaviour and may be related to competition for resources during early fruit development. Changes in tree management to improve resource allocation to floral spurs early in seasonal development may enhance fruit set and fruit development, thereby increasing productivity, fruit size and quality. Centrifugal Training (CT) tree management, which regulates the density of fruiting sites on branches, was investigated to alter the early-season physiological status of ‘Scifresh’/M.9 trees to improve both cropping and fruit quality. At budbreak, spurs on branches of CT trees were thinned to numbers calculated to produce 4, 5, or 6 fruit per cm2 of branch cross-sectional area when cropped using either one (CT1) or two (CT2) fruit per spur. These treatments were compared with standard New Zealand Vertical Axe tree management (VA) thinned to the same crop treatments after final fruitlet drop. Between 50 and 65% of floral spurs on standard VA trees failed to set any fruit and this proportion was reduced to 25-35% in CT1 and to 18-25% in CT2 treatments. The proportion of spurs that set two or more fruit more than doubled in response to CT. Although CT increased fruit set, both crop density and yields at harvest were lower than with standard VA training for equivalent crop treatments. Mean fruit weight declined in response to increasing crop density, although it was further reduced in those treatments cropped as two fruit per spur. Centrifugal Training altered the composition of vegetative annual shoots at the branch unit level, resulting in a ratio of extension shoots to spurs of 1.36 compared with 0.39 for VA-trained trees. Node number, internode length and basal diameter of extension shoots all increased in response to Centrifugal Training. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
