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Precocity is particularly important for the economic production of intensively planted apple trees. Unfortunately some cultivars show a propensity for barewood on young trees, which limits early production on 2 year-old spur sites. The new cultivar, 'Scifresh' (Jazz™) has shown serious problems of barewood under New Zealand conditions on M.9 and M.26 rootstocks. Barewood has been associated with excessive flowering on feathers and 1 year-old wood. Weak flower clusters develop towards the base of the shoots which do not set fruit and drop off, leaving blind buds. Although there are larger, more well-developed flower clusters on the distal parts of the 1 year-old shoots, cropping these can result in spur extinction. Therefore, in both cases, there is a lack of spur development for the following season resulting in barewood. Experimental treatments have focused on: 1) the effect of timing (January-May) and concentration (400 and 133 mg l-1 gibberellic acid GA3) sprays in the nursery to reduce flowering on 1 year-old wood; and 2) the effect of concentration and timing of localised cytokinin applications in the Spring to re-invigorate blind buds. Two applications of 400 mg l-1 GA3 in late January and late February in the first year in the nursery were effective in eliminating flowering on "knip boom" trees in the following Spring after cutting back. Two applications of 400 mg l-1 GA3, in early and late January, to "knip boom" trees in their second year in the nursery reduced flowering by over 40% when the trees were planted in the orchard. Twelve months later these trees showed an increased density of spur flowers on the original feathers. Aqueous solutions of the cytokinins benzyladenine and thidiazuron, at 500 mg or 2500 mg respectively, were applied by brush, prior to, during and post-budbreak, to sections of barewood on 2 year-old or 3 year-old wood on main branches of 'Scifresh'/M.9 trees. Thidiazuron (at 2500 mg l-1) was far more effective than benzyladenine at inducing growth of dormant buds, even resulting in multiple bud-breaks at individual sites. [ABSTRACT FROM AUTHOR]

For any given genotype, the environment in which an apple is grown can influence the properties of the fruit considerably. While there has been extensive research on the mechanism of the genetic control of fruit quality traits, less effort has been made to investigate the way that these genetic mechanisms interact with the environment. To address this issue, we employed a large 'Royal Gala' × 'Braeburn' population of 572 seedlings replicated over sites in three climatically diverse apple-growing regions in New Zealand. Phenotyping for traits including fruit maturation timing, firmness and dry matter content was performed at each of these three sites for a single growing season (2011), and at two sites (Motueka and Hawke's Bay) for two seasons (2009 and 2010). The phenotype data collected over 2 years at two sites enabled the detection of 190 quantitative trait loci (QTL) that controlled these traits regardless of year or growing location, as well as some chromosomal loci that influenced the traits in a single given environment or year. For those loci that were environmentally stable over three sites, there was an interdependency of fruit maturation date, dry matter content and storage potential within this population, with two regions on Linkage Groups (LGs) 10 and 16 strongly contributing. If these loci were used in a marker-assisted selection programme to select for progeny bearing firmer fruit, this would have the unintentional consequence of selecting, high dry matter content, later maturing apples. In addition, a further 113 new QTLs with a smaller effect were identified, some of which were exhibited only in a single growing environment, demonstrating the underlying complexity of control of traits determining fruit quality, in addition to the need for being aware of environmental effects when developing new apple varieties.