ISHS Acta Horticulturae 275: International Symposium on the Culture of Subtropical and Tropical Fruits and Crops
NUTRITIONAL FACTORS INVOLVED IN PHYSIOLOGICAL POST-HARVEST FRUIT DISORDERS OF AVOCADOS (CV. FUERTE) |
| Authors: | T.J. KOEN, S.F. DU PLESSIS, J.H. TERBLANCHE |
| Abstract:
In a potassium fertiliser experiment and a field survey covering 48 commercial orchards over a period of two seasons, the relationship between soil, leaf and fruit mineral composition and three physiological fruit disorders of avocado, was investigated. The status of K, Ca and Mg in the leaves and soil were found to be closely related to the severity of the grey pulp disorder, with increasing leaf values of K having a positive, and Ca and Mg a negative relationship to grey pulp. Fruit analysis (proximal half) showed a positive relationship between the severity of grey pulp and N- and K-concentration. In the distal half of the fruit, there was a negative relationship between P and grey pulp. In orchards where pulp spot and vascular browning were prominent, a highly significant relationship was obtained between soil Ca, Mg and K and the development of the latter post-harvest disorders. Higher soil Ca and Mg values and a higher Ca+Mg/K ratio were positively related to the occurrence of both pulp spot and vascular browning. Fruit analysis (proximal and distal halves) also showed that an increased K concentration resulted in a decreased occurrence of pulp spot. It was concluded that too low soil K values were probably responsible for the high incidence of these two physiological disorders, rather than too high Ca and Mg values. | |
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