2018 ASHS Annual Conference

Peach trees from different ripening seasons may have distinct nutrient concentrations in the removed organs so they might lose different amounts of nutrients through nutrient removal events. The objective of this research was to determine the nutrient concentrations in organs removed from the tree (either as a consequence of orchard management practices or naturally).We used peach trees from different ripening seasons, and calculated the amount of removed nutrients among different cultivars. We selected 18 peach trees of six cultivars from three different ripening seasons (early-season: ‘Desiree’ and ‘Spring Snow’; middle-season: ‘Sweet N Up’ and ‘Coralstar’; late-season: ‘Snow Gem’ and ‘Snow King’), and measured the nutrient concentrations in all the removed organs, including pruned wood, thinned fruitlets, harvested fruits and leaves fallen during autumn. Nutrient analyses showed that early-season cultivars accumulated i) more nitrogen in thinned fruitlets and mature fruits, ii) more potassium in pruned wood, mature fruits and fallen leaves, and iii) more phosphorus in mature fruits and fallen leaves compared to mid- and late-season cultivars. Early-season cultivars lost more nutrients through pruning and leaf fall but lost less nutrients through harvesting compared to mid and late-season cultivars. These results suggest that ripening season can affect peach tree nutrient requirements and fertilization with different levels of nutrients should be applied to the orchards instead of one uniform fertilization program. These findings are expected to help farmers to optimize fertilization plans that are specific to the ripening season of their peach trees.