SURVEY OF FRUIT MINERAL CONCENTRATIONS AND POSTHARVEST QUALITY OF NEW-ZEALAND-GROWN HASS AVOCADO (PERSEA-AMERICANA MILL.)

New Zealand 'Hass' avocado (Persea americana Mill.) orchards were surv eyed to determine if an imbalance in fruit mineral concentrations (Cal cium (Ca), Magnesium (Mg), and Potassium (K)) was associated with poor fruit quality. Ranges for average fruit mineral concentrations on sur veyed orchards were: Ca, 25-47 mg/100 g dry weight (DW); Mg, 91-113 mg /100 g DW; and K, 1126-1608 mg/100 g DW. Fruit with low Ca concentrati ons had more vascular browning and flesh browning than fruit with high Ca concentrations. Also, fruit Ca concentrations were lower and the i ncidence of vascular browning higher in fruit that were more mature at harvest. Fruit harvested below the minimum maturity standard (26% DW) had practically no postharvest rots. If harvested above this standard , 12-38% of ripe fruit had severe rots. A new disorder ''anthocyanin s taining'' was observed in the flesh of several fruit. Results are disc ussed in relation to industry options for predicting and managing frui t quality.