ISHS Acta Horticulturae 441: V Temperate Zone Fruit in the Tropics and Subtropics
PROBLEMS ASSOCIATED WITH THE MATURITY OF EARLY RIPENING APPLE VARIETIES: STARK EARLIEST, BEACON, JONATHAN |
| Authors: | S. Özelkök, M. Burak, K. Kaynas |
| Abstract:
Previous studies carried out on late maturing apple varieties to meet OECD's requirements on starch iodine staining test standards, and to bring about the relationship among three practically important maturity tests; 'starch staining', 'firmness', and 'soluble solids' have been extended to cover early ripening apple cultivars: Stark Earliest, Beacon, and Jonathan, likely preferred for production in the subtropics. Three years of studies conducted on these varieties in 1992, 93 and 94 revealed that the maturity is not uniform on the trees whereon green unripe fruits may appear with overripe fruits in the same bud clusters. Although uniform fruit growth and development may be defined by above tests in early picks regarding maturity, later picks, likely to include exact mature fruits, showed great variability by the tests confirmed by statistical analysis due to unripe and overripe specimens in randomly collected samples. Studies conducted in 1994 based on blushed-color percentage on these varieties using OECD's apple standard yielded more reliable data and thus extrapolating maturity more exacty. The minimum acceptable maturity starts with 10% blush color and ideally should be between 30–60 % on the first two and between 30–50% on Jonathan. Fruits having blush colors exceeding this range developed variety-specific physiological disorders either during marketing or storage. Harvest on early varieties can not be confined to single picks and should, therefore, be expanded to cover several picks such as practiced on stone fruits. This may create problems in orchard management by demanding extra labor. Variety selection with uniform maturity for the ecologies in concern, hence should be carefully taken into account. | |
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