SUMMARY

To meet OECD’s requirements on starch iodine staining test standards and to bring about the relationship among three important maturity tests, starch staining, firmness and soluble solids, studies conducted in 1992-94 on two very early (Stark earliest and Beacon) one mid season (Jonathan) and three late maturing (Amasya, Mutsu, and Black Stayman Improved 201) varieties of apples as the second part of the project. Although starch test or firmness appeared to be alternative to each other as reliable test in the first three varieties of apples. It was found that the blush-colour (%) as specified in OECD and TSE standards is more important and reliable in determining the harvest maturity. Storage experiments conducted at 0C on Jonathan showed that maximum storage time for four months is obtainable only from fruits having blush colour between 30-50%. A starch standard characteristic for Amasya was developed through the photographs depicting starch disappearance with advanced maturity and the test was proved to be singly applicable in determining the maturity. Surprise was to find that fruits grown on M9 were of superior quality and of highly yielding although Yalova ecology is known not to be suitable for growing Amasya.

Little standard variations in iodine test compared to firmness as observed among the picked fruits of Mutsu at every harvest along the maturity suggested that the starch test is easily and reliably applicable in determining the maturity of Mutsu apples. Harvested at mid-starch scale, these fruits can be stored for six months with infinitesimal weight loss. For Black Stayman Improved flesh firmness appears to be the most important and reliable test in describing maturity. Starch is strongly retained by the fruit and thus the rate of disappearance is relatively slow. Storage experiments proved that unless entirely covered by the red blush colour the fruits are subject to severe storage scald which detracts the fruits should be harvested when the blush colour has fully developed.