Preharvest factors and postharvest quality decline of apples.
Jager, A. de; Putter, H. de;
Acta Horticulturae Year: 1999 Issue: No. 485 Pages: 103-110 Ref: 7 ref.
1999
บทคัดย่อ
Two types of experiment were conducted to identify preharvest factors that might be correlated with apple fruit quality at harvest and rate of postharvest loss of quality. The research was planned as a first step towards predicting the loss of quality in terms of firmness, green ground colour, and acid and soluble solids concentration. The first, inventory experiment involved a large number of orchards of Cox's Orange Pippin, Elstar, Red Boskoop and Jonagold, all on M.9 rootstock. Samples for chemical fruit analysis were taken 3 weeks before harvest and at harvest. Fruits for quality measurements were collected at harvest and after ULO (ultra low oxygen) storage and shelf life. In the second experiment, N, P, K, Ca and Mg were applied, each at 5 rates, in a new orchard planted with Elstar on M.9 to create fruits with different concentrations of these nutrients. Fruit firmness at harvest was negatively correlated with fruit N level in August and at harvest and (in Elstar) with leaf N level in Jun
e and July. Green ground colour was correlated positively with leaf and fruit N level in June, July and August, but not in September. Acid concentration was highly correlated with fruit K and Mg levels and with fruit weight at harvest. Total soluble solids content was correlated positively with leaf P level and percentage of dry matter. Following storage and shelf life, fruit characteristics were generally best correlated with characteristics at harvest. To a smaller extent significant correlation was observed with nutrients that did not correlate significantly with the level at harvest (e.g. P and Mg with firmness). The correlation between acid concentration and fruit K and Mg concentration, already high at harvest, was even higher after storage. Multiple regression models explaining the loss of firmness during storage and shelf life had a better percentage of variance accounted for than those explaining the absolute level at any moment. These first results are discussed in physiological terms and with resp
ect to their possible significance for cultural practices and for prediction of fruit quality.