Effects of rootstocks and K and N fertilizers on seasonal apple fruit mineral composition in a high density orchard

Abstract

Seasonal mineral composition of ‘Starkspur Golden Delicious’ apple fruit (Malus domestica Borkh.) grown on six rootstocks: Mailing (M) 1, M 7, M 26, Mailing Merton (MM) 106, OAR 1 and seedling rootstocks in a high density orchard with two levels of K (K₂SO₄) and two levels of N (urea) soil fertilization were studied in 1980 and 1981. The concentrations (dry weight basis) of all minerals declined in fruits of all treatments as the season progressed. However, fruit from OAR 1 stock generally had about 15% lower N, P, K, Mg, Fe, and Cu, but about 17% higher B, whereas fruit from M 7 had about 10% higher concentrations of N, K, Fe and Cu than most other rootstocks. Fruit on M 26 had about 6% lower concentrations of B than most other stocks in both seasons. Scion fruit on OAR 1 had the lowest mineral content (total mineral per fruit) except for B which was about 11% higher for this rootstock than most other rootstocks. Crop load was found to affect mineral contents particularly fruit of light cropping trees on M 26 in which higher contents (up to about 20%) of N, P, K, and Mg were observed due to the larger size of fruit. Higher K fertilizer decreased fruit B concentrations with little effect on other elements. Whereas higher applications of N increased fruit N concentrations, total N content per fruit and nitrogen on fresh weight basis but decreased fruit P and K concentrations.

Key words:

• Malus domestica
• Seedling
• M 1
• MM 106
• M 7
• OAR 1
• M 26
• Plant nutrition

Notes

Graduate Research Assistant, Oregon State University; National Technical Advisor for Clonal Germplasm; Associate Professor of Horticulture, Oregon State University; Associate Dean, School of Agriculture, Pennsylvania State University, respectively.