Rootstock affects fruit nutrient profile and bitter pit incidence of apple

We evaluated fruit bitter pit incidence of 'Honeycrisp' apple as affected by rootstock and then related it to the nutrient levels and ratios of nutrients. Two field experiments were evaluated: one at Geneva NY planted in 2007 with 20 rootstocks and the second plot planted in 2008 at Peru, NY with 41 rootstocks. Fruit yield, fruit size and peel nutrient concentration were measured from 2016 to 2020 at harvest. Bitter pit incidence was evaluated on 50 fruits from each tree after three months in regular atmosphere storage. Significant differences in bitter pit incidence and peel nutrient concentrations were observed among rootstocks. The ratios of K/Ca and N/Ca were evaluated and were well correlated with bitter pit incidence. There were rootstocks that consistently had greater peel nutrient concentrations indicating that differences among rootstocks are stable across years. Among rootstocks, B.9, G.65, G.214 and M.9T337 had the lowest bitter pit incidence, while G.210, M.7, G.814, B.118 and G.41 had high bitter pit incidence. Other rootstocks had intermediate levels of bitter pit and included G.30, G.935, G.4202, M.9Pajam2, G.11, G.16, CG.4210, CG.5046, CG.5202 and M.26.