Nutrient status of apple orchards in Canterbury, New Zealand. 1. Levels in soil, leaves and fruit and the prevalence of storage disorders

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Abstract The nutrient status (N, P, K, Ca, Mg, K, Fe, Mn, Zn and Cu) of 26 Cox's Orange Pippin and 20 Braeburn apple orchard sites in the Canterbury region of New Zealand was evaluated by soil, leaf and fruit analysis. Concentrations of available nutrients in soils ranged widely but those in leaves and fruit were generally confined to a relatively narrow range. Concentrations of leaf N were high in the study area, as were levels of extractable soil P, and it is suggested that reductions in fertilizer additions of these nutrients would generally be appropriate. Soil, leaf and fruit nutrient contents were generally not well correlated with one another. The only highly significant correlations (P≤0.001) were between leaf and fruit Ca for Cox's and soil and fruit Mg for Braeburn. The poor correlations were attributed to the empirical nature of soil tests, the presence of large nutrient reserves within the tree framework and the effects of cultural and environmental factors on nutrient uptake and translocation by the trees. The storage disorders bitter pit and senescent breakdown in Cox's and lenticel blotch pit in Braeburn were observed in apples harvested from some of the study sites. Such disorders were generally associated with low concentrations of Ca (≤.2.5 mg/100 g) in samples of cortical plugs taken from fruit at harvest.