Developing practical strategies to improve quality and storability of UK apples


Project Summary: 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.

Project code:
TF 225
01 May 2016 - 30 April 2021
AHDB Horticulture
AHDB sector cost:
Project leader:


About this project

Aims and Objectives
Our aim is to develop practical short-, medium- and long-term strategies to help UK growers to optimise quality and storability of UK apples. In particular for long-term storage beyond April. In order to achieve this aim we will use Gala as a model variety to understand the relationship between quality and fruit dry matter content and how to manipulate this.  We will also seek to develop an accurate predictive harvest maturity timing that works in conjunction with high DMC, and modern storage techniques where respiration and ethylene production has been significantly reduced resulting in improved customer eating experience and grower returns.

1. To carry out a meta-analysis to provide an evidenced-based understanding how fruit DMC can be manipulated to optimise fruit quality.
2. To determine the impact of increasing light interception by pruning and/or using reflective mulches at different stages of fruit development on fruit quality, DMC, storability and consumer acceptability 
3. To quantify the impact of thinning treatments on fruit quality, DMC, storability and consumer acceptability and to develop recommendations for thinning strategies to optimise yield of high quality fruit.
4. To identify the correct timing for harvesting orchards with a high DMC  to maximise the eating quality of fruit in the April to June marketing window, and to establish and validate a protocol using chlorophyll fluorescence to predict this timing.. 
5. To maximise knowledge exchange and communications interaction with international research groups to enhance this research programme
6. To carry out effective project management and mitigation of risks.
Added value
We will add value to this AHDB-funded project by utilising existing published and unpublished relevant data sets available to the consortium, by ensuring that the work programme benefits from the expertise and experiences of participating international apple researchers, and by focussing research efforts on the model variety of Gala.. We recognise that further income will be needed to develop and implement the medium- to long-term solutions and we will seek opportunities with our international collaborators to develop further opportunities for linked RTO-industry projects.
Benefits to Industry:
The aim of this project is to develop practical strategies by which UK growers can optimise quality and storage potential of UK apples using Gala as a model variety. 
Improved availability of consistently high quality fruit will enable UK growers to compete with Southern Hemisphere imports at the start of the new season window. Extending the UK Gala season by 3-4 weeks would generate financial returns of £2-3 million p.a across the industry. 
Offering growers an early prediction method of the onset of a climacteric physiological phase within the fruit would increase the efficiency for managing the harvest period as well as improving fruit quality.
Improved verifiable benchmarks at harvest leading to more consistent fruit quality to give maximum market opportunities.  30% of fruit picked for post April storage, 30% Jan to April and 30% October to December each group maximising its own harvest window with eating quality
Eating quality experience will be improved for consumers; this will encourage repeat purchase and improved health as defined by the “5 a day” government campaign. Improved general health of the UK population would deliver direct cost reductions in health spending budgets.
Greater consumption of English dessert fruit would contribute to improved carbon footprint by reducing reliance on imports which are generally regarded as generating higher carbon emissions. In addition, domestic fruit is grown to verifiable higher environmental standards, fundamental to a more balanced environmental situation, increasingly demanded by today’s consumer.
We also anticipate improvements in on-farm resource use efficiency (light, water, fertilisers, pesticides, labour) and less pre- and post-harvest waste if the project outputs are used to improve light interception, canopy structure and dry matter partitioning. 
Overall, these benefits represent a very strong return on investment. Strategies and guidelines developed for this model variety would be transferable to other UK apple varieties and to pear and stone fruit crops and would help to improve production efficiency, fruit quality and grower margins in the UK tree fruit sector. For instance, increasing the Conference pear market by 5% would generate extra income of £800K p.a