Cherry nutrition - the balancing act of feeding fruit for high-quality cherries

Cherry tree nutrition and fruit quality is extremely complex, involving regional soil and climatic factors overlaid by cultural factors of cultivar, irrigation and fertiliser application. Over the last decade our team has investigated within-tree to regional variation, fertigation (particularly N) rate and timing (with irrigation overlays), tree uptake and storage and foliar application of the relatively immobile micronutrients, all within the context of fruit quality. Observational studies of within-tree variability revealed that fruit on vertical structures were associated with lower concentrations of micronutrients than fruit on horizontal wood in Kym green bush systems. Observational study of regional variation found negative correlations between colour development with fruit of higher N, Zn and Mn concentration. Follow-up manipulative trials found that foliar applications (but not fertigation-applied) increased fruit concentration of Mn and Zn, but not Ca, but this did not translate to fruit quality improvements postharvest. Manipulative N rates and timing work on multiple sites over consecutive seasons indicated that increased preharvest application (equivalent to 150 or 240 kg ha(-1)) led to increased fruit N concentration and loss of firmness in N-deficient but not N-sufficient orchard scenarios. Future funded work will use N-15 labelled fertilisers to further investigate tree allocation, storage and re-mobilisation of N, and losses of N below the rootzone with a view to developing a full N, and potentially P and K, budget. This, along with critical climate and soil data will allow the development of a grower decision support tool.