Apple farming systems - current initiatives and some prospective views on how to improve sustainability

Summary

Apple cultivation has evolved tremendously in past decades. Both apple productivity and aesthetic quality of the fruit have been strongly improved resulting from genetic improvement, optimization of tree training and pruning, and orchard design and management. However, these improvements were also done at the expense of an increasing dependence on external inputs such as water, fertilizers and synthetic pesticides. This dependence is now questioned because of the generated environmental pollutions and health issues. In the last decades, an increasing amount of initiatives have been developed that open the way towards more sustainable apple production systems. Concepts as well as on-station and on-farm works are developed in various contexts such as 'integrated fruit production', 'organic farming' and 'agroecology' with the objectives to increase biological regulations of pests and diseases and/or to improve soil fertility. All together results point out the importance of diversifying resources and habitats for beneficial arthropods in the orchard and its vicinity to foster ecosystem services related to pest suppression and to adopt cultural practices enhancing soil fertility. They also indicate some practical guidelines consisting in a better management of grass alleys and lining hedgerows within and around the orchard, respectively. From a more prospective view and taking inspiration from tropical fruit-tree based agroforestry, these works suggest that combining apple trees with other herbaceous and woody plants with various uses (soft fruit, aromatic plants, etc.) opens to more resilient agroecosystems, possibly mitigating climate change. These works also enlarge our vision of the current apple orchard towards a multiproduction system including apple among other productions. From the 'plant science' point of view the idea to grow apple in agroecosystems challenges current knowledge of the plasticity of the apple tree physiology and architecture, and agronomic performance, in response to interactions with neighbouring plants. It also stimulates necessary collaborations with other research fields such as socio-economics, for example on how the grower may handle those complex agroecosystems, optimize labour and valorize production.