Developing practical strategies to improve quality and storability of UK apples

UK apple growers have recently expanded their production of Gala and Braeburn in particular, from high intensity plantings. To accommodate this additional volume, it is estimated that around 30% of this harvest must be aimed at later market window, beyond April. The aim is to develop practical strategies in the short-, medium- and long-term to help UK growers to improve the quality of apples at harvest and following storage, in particular long-term storage beyond April. Researchers have linked high dry matter content (DMC) of fruit at harvest to improved eating quality and storage potential, but the underlying basis of this relationship needs to be better understood so that it can be manipulated to deliver premium fruit quality. Focusing on ‘Gala’ as a model variety, we will carry out a ‘meta-analysis’ to improve our understanding of the factors that control fruit DMC and quality. Outputs will inform our work on manipulating resource allocation and DMC through the use of different pruning systems and/or reflective mulches to maximise canopy light interception, and by a range of thinning strategies to manipulate crop load. Treatment effects on the variability in DMC, its chemical components and related quality parameters, within orchards and within the tree will also be identified. We will collaborate with key international research groups to help guide the programme of work, to ensure that our models and conclusions are robust and transferable to growing systems in other countries/continents, and to develop further opportunities for linked RTO-industry projects. As well as optimisation of DMC, post-storage fruit quality depends critically on optimisation of harvest maturity. As DMC does not change significantly during the ripening process, optimum harvest date needs to be accurately determined to maximise eating quality when competing with Southern hemisphere produce. The current method of harvesting Gala for long term storage when starch coverage has declined to 80-85 (% black) does not allow growers enough time to optimise picking before starch levels decline further. Chlorophyll Fluorescence (CF) is a non destructive tool of fruit maturity that may offer the benefit of one extra week notice of optimum pick date. Two years of independent study by Landseer has shown a high correlation between CF and starch coverage, and this project will examine the potential for using this as a practical tool for English growers.