Rootstock Affects Ripening, Color, and Shape of ‘Starkspur Supreme Delicious’ Apples in the 1984 NC-140 Cooperative Planting

Abstract

In 1984, ‘Starkspur Supreme Delicious’ apple trees on B.9, MAC.1, MAC.39, P.1, P.22, domestic seedling, M.4, M.7 EMLA, M.26 EMLA, B.490, P.2, P.16, P.18, C6, and A.313 were planted in Belchertown, MA, West Lafayette, IN, Parlier, CA, and Princeton, KY. In Massachusetts, rootstock and year interacted to affect fruit ripening, as measured by internal C ₂H ₄concentration, soluble solids concentration, the development of watercore, and starch disappearance. In general, however, ripening was correlated with tree vigor, with the most dwarfing rootstocks resulting in the earliest ripening. The most consistently early ripening fruit were from trees on B.9 and P.16, and the most consistently late ripening fruit from trees on M.4, P.18, and domestic seedling. Soluble solids concentrations from Indiana and California fruit supported this relationship between ripening and vigor; however, no consistent effect of rootstoclc on soluble solids concentration was measured in Kentucky. Flesh firmness was negatively related to tree vigor in California, positively related to vigor in Indiana, and not related to vicor in Kentucky and Massachusetts. The development of red color was negatively related to vigor in California and not related to vigor in Indiana. The length-to-diameter ratio of fruit was positively related to vigor in Indiana.