115 Performance of Various Apple Scion Cultivar/Rootstock Combinations and Postharvest Fruit Quality
Several cultivar/rootstock combinations were evaluated for overall performance in Mississippi. This study included postharvest fruit quality during storage as influenced by the various rootstocks. Parameters measured were fruit set, scion and stock trunk cross-sectional area, fire blight tolerance, fruit drop, and maturity indices such as fruit size, firmness, fresh fruit weight, soluble solids content, and juice pH. Cultivar/rootstock combinations were `Earligold'/EMLA 7, `Jonagold'/EMLA 111, `Improved Golden'/EMLA 7, `Improved Golden'/EMLA 111, `Scarlet Gala' /EMLA 7, `Jonafree'/Mark, `Macspur'/M 7A, `Royal Gala'/MM 111, and `Williams Pride'/M 7A. Cultivar and rootstock influenced fruit set. `Royal Gala', `Scarlet Gala', `Improved Golden', and `Earligold' showed maximum fruit set among the various cultivars. MM 111 and EMLA 7 rootstocks increased fruit set. Scion cultivars had the greatest trunk diameter on EMLA 111 and MM 111 and the smallest diameter on Mark. Scion cultivars on Mark and M 7A rootstocks showed less susceptibility to fire blight compared to MM 111 and EMLA 111. Cultivars on EMLA 7 showed moderate susceptibility to fire blight. Cultivars `Jonafree', `Williams Pride', `Macspur', and `Scarlet Gala' were least susceptible to fire blight compared to `Royal Gala'. The remaining cultivars were intermediate in susceptibility to fire blight. Fruit size, firmness, fresh fruit weight, soluble solids content, and juice pH were influenced by cultivar. `Jonagold' and `Williams Pride' produced the largest fruit, while `Jonafree' and `Macspur' yielded the smallest fruit. Total soluble solids were not influenced by cultivar and rootstock combinations. Sugar content of the juice increased as the apples matured and ranged from 12% to 14% among the cultivar/rootstock combinations. Firmness was influenced by cultivar but not rootstock. `Jonafree', `Macspur' had firm fruit, while fruit of `Scarlet Gala', `Williams Pride', and `Earligold' was not as firm. After harvest, the cultivars were stored at 2 °C for ≈4 months under controlled conditions and evaluated for soluble solids content, titratable acidity, pH, and firmness at monthly intervals. Overall, firmness, soluble solids content, and titratable acidity in all cultivars decreased with time in storage. `Improved Golden'/EMLA 7, `Royal Gala'/MM 111, and `Jonagold'/EMLA 111 maintained quality during storage, compared with the remaining cultivars/rootstock combinations, and had a longer storage life.