Harvest Indices, Dessert Quality, and Storability of ‘Jonagold’ Apples in Air and Controlled Atmosphere Storage

Starch index (SI) was correlated negatively with starch content and positively with internal ethylene concentration (IEC) and logarithm to the base 10 of IEC (loglEC) in ‘Jonagold’ (Malus domestica Borkh.) apples. The initial rapid increase in SI, loglEC, and yellow ground color coincided with one another and occurred ≈20 days before the increase in IEC and incidence of watercore (WC). In 1984, 1985, and 1986, the first acceptable picking date for British Columbia-grown ‘Jonagold’ was about 10 Oct., when the fruit had attained an acceptable amount of color (50% to 85% area greater than No. 2 red color and 4.0-4.5 yellow color units on a 0-10 scale) and a good level of firmness (73-76 N), soluble solids (13.5% to 14.5%), starch (SI of 6.5-7.0 on a 0-9 scale), and acids (661-782 mg malate/100 ml of juice), but without much WC (2% to 13%) or ethylene (0.3-1.5 μl·liter−1 IEC; 5% to 40% of fruit with IEC > 1 μl·liter−1). Fruit picked on 20 Oct. were softer, lower in acids and storage potential, and more susceptible to WC, coreflush (CF), and breakdown (BD) than those picked 10 Oct. Fruit harvested from mature trees stored well at 0°C in air until February and in controlled atmosphere (CA, 1.5% O2 + 1.5% CO2) until June. Fruit from young trees were large and developed BD in air storage as early as November; fruit afflicted with BD were lower in Ca and higher in K : Ca ratio than those free of the disorder. Dessert and sensory ratings were higher in ‘Jonagold’ than in ‘McIntosh’, ‘Golden Delicious’, ‘Spartan’, and ‘Delicious’ and were also higher in fruit from CA than from air storage.