Effects of Nitrate:Ammonium Ratios on Vegetative Growth and Mineral Element Composition in Leaves of Apple

Evaluations of vegetative growth and leaf concentrations of nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe) were made of apple (Malus domestica Borkh. cvs. Granny Smith, Gala, and Golab) grown with five treatments of NO₃^?:NH₄⁺ ratios in pot culture. The concentrations of NO₃^?:NH₄⁺ ratios were 2.5:0.1, 6:0.3, 6:0.5, 6:0.7, and 6: 1 meq L^?1. Regression analysis showed that growth parameters of main stems and branches were not affected by increases of NH₄⁺ in the ratios. Granny Smith, Gala, and Golab differed in some of these parameters. Concentrations of N and Fe increased as NH₄⁺ increased, whereas K and Ca decreased and Mg was not affected significantly. Generally, the treatment of 2.5:0.1 produced leaves with lower N but higher K, Ca, and Mg concentrations than the other treatments. This research showed that vegetative growth was not affected by NH₄⁺ concentration whereas elemental composition was affected.