Rootstock Affects Maturity of `Starkspur Supreme Delicious' Apples

Additional index words.Malus domestica, ripening, flesh firmness, soluble solidsWe determined the influence of nine rootstocks with 'Starkspur Supreme Delicious' apple (Malus domestica Borkh.)scions on maturity indices; percent fruit drop, soluble solids concentration (SSC), and flesh firmness.Rootstock can influence fruit maturity (Autio et al., 1991; Barden, 1988; Drake et al., 1988; Fallahi et al., 1985); however, the climate and soil in western Kentucky differ substantially from where most of the studies have been conducted.As part of the NC-140 cooperative research, a planting of 'Starkspur Supreme Delicious' apple on the rootstocks M.7 EMLA, M.9 EMLA, M.26 EMLA, M.27 EMLA, M.9, MAC 9 (MARK), MAC 24, OAR 1, and Ottawa 3 was established in 1980 on a Tilsit silt loam at the Univ. of Kentucky Research and Education Center, Princeton, Ky.Experimental details have been reported by Autio et al. (1991).Fruit drop, flesh firmness (penetrometer with a l-cm probe), and SSC (hand refractometer) over the 5 years from 1985-89 varied significantly among rootstocks (Table 1).Fruit drop and SSC were highest for trees on