Effect of different NH4 +/NH4+ + NO3- ratios on some qualitative and quantitative characteristics of fruit in Gala and Golab Kohanz Esfahan apple cultivars

In this research, the effect of different nitrate to ammonium ratios was studied on qualitative and quantitative characteristics of apple fruit. The nitrate to ammonium ratios were 0.03, 0.14, 0.10, 0.07 and 0.04 meq/L-1. The pH of nutritive solution was adjusted at 6.5 ± 0.1. Experiment was carried out based on a randomized complete block design with three replications. Qualitative and quantitative characteristics of fruit including length, diameter, length to diameter ratio (L/D), weight, flesh firmness, pH, total soluble solids, titrable acidity (TA) and nitrogen, potassium and calcium concentrations were evaluated. The ratio of NH4 +/ NH4 + + NO3 - had no significant effect on total soluble solid, firmness, weight, diameter, pH, length, dry matter and (L/D) ratio of fruit. Flavour index (TSS/TA) ratio, N, K and Ca concentrations of fruit samples were influenced significantly by NH4 +/ NH4 + + NO3 - ratio. Increasing ammonium caused a significant decrease on Ca and K concentrations and (TSS/TA) ratio of apple fruit, but N concentration and TA were increased, significantly. Cultivars are also influenced by the ratio of NH4 +/ NH4 + + NO3 -, significantly and Gala often showed higher indices in comparison to Golab cultivar.