Mineral composition of leaves and growth of ‘Fuji’ apple trees in response to nitrogen and potassium fertilization

Abstract

Foliar diagnosis is an important tool to assess the nutritional status of apple trees. Nutrient concentrations on leaves vary with both sampling time and fertilization practice. The aim of this paper was to evaluate the effects of nitrogen and potassium fertilizations on growth parameters and mineral concentration on leaves of apple trees in two periods of sampling. The experiment was conducted in São Joaquim, State of Santa Catarina, Brazil, from 1998 to 2006. A factorial arrangement was used with N and K annual fertilizer rates (zero, 50, 100, 200kg/ha of N and K
2O). Chemical analyses of leaves collected in two sampling periods, from January 15 to February 15 (for all growth seasons), and in the second half of November (only for 2004/05 and 2005/06 growth seasons) were conducted. The growth of the plants was assessed by measuring the trunk. The nutrient concentrations of the leaves were modified,
mainly by nitrogen fertilization, which increased N, Ca and Mg, and reduced K and P concentrations. Mg and Ca concentration on the leaves was reduced by K fertilization. The plant growth was affected by N fertilization. The chemical foliar analysis has shown that November sampling was useful in predicting the macronutrient concentration reached by the leaves in January/February.