Rootstock, K, and N fertilizer effects in a high density orchard on seasonal mineral elements, endogenous ethylene, maturation and storage quality of 'Starkspur Golden Delicious' apples

Graduation date: 1983Leaf and fruit seasonal mineral fluctuations, fruit endogenous\ud ethylene, maturity and quality of 'Starkspur Golden Delicious' apple\ud (Malus domestica Borkh.) on six rootstocks: Seedling, Mailing (M)1,\ud M7, M26, Mailing Merton (MM)106, OAR-1, in a high density orchard\ud with two levels of each of the soil applied potassium (K₂SO₄) and\ud nitrogen (urea) fertilizers were studied in 1980-1982.\ud Leaf concentrations of N, P, and K decreased but Mg and Ca increased,\ud while fruit concentrations of all elements generally decreased as the\ud growing season progressed. Lighter fruit crops resulted in higher\ud concentrations of K in the leaf and lower Ca in the fruit.\ud Scion leaves on OAR-1 rootstock had significantly less Ca\ud than those on M7, MM106 and Ml and less Mg than those on M26.\ud Fruit concentrations of N, K, P, Mg, Fe, and Cu on OAR-1 were\ud lower as a result of a higher percentage of carbohydrates contributing\ud to fruit dry weight. However, B concentrations of both\ud leaf and fruit on OAR-1 were higher than all rootstocks. Rootstock\ud M26 induced significantly more leaf Mg than those on Ml,\ud MM106 and OAR-1 and had lower fruit B concentrations than most\ud of the tested rootstocks. Trees on M7 occasionally showed\ud higher fruit N, K, P, Fe and Cu concentrations than most other\ud rootstocks. Scion fruits on OAR-1 had the lowest content of\ud all minerals (except B) partially due to their smaller size\ud compared to other rootstocks. Higher potassium fertilizer significantly\ud decreased leaf Ca and Mg concentrations while higher\ud nitrogen increased leaf N and Mg and fruit N, but decreased\ud P and K levels in both leaves and fruits.\ud Fruits from trees on OAR-1 produced endogenous and evolved\ud ethylene later but had lighter color and higher soluble solids\ud both at harvest and after storage and were firmer at harvest\ud compared to fruits on other rootstocks. Fruits on MM106 produced\ud low ethylene and had less storage breakdown. Fruits\ud on M7 had lower soluble solids and dry matter than most other\ud rootstocks. Fruits with higher minerals usually had lower\ud soluble solids.\ud Higher nitrogen induced significantly greater evolved ethylene\ud after storage and retained more green color in the fruit