ISHS Acta Horticulturae 448: III International Symposium on Mineral Nutrition of Deciduous Fruit Trees
OPTIMUN NUTRIENT VALUES FOR PEAR TREES AT DIFFERENT TIMES OF THE GROWING SEASON |
| Authors: | M. Sanz, J. Val, L. Montañés-Millán, E. Monge, L. Montañés |
| Keywords: | Foliar diagnosis, leaf macronutrients, nutrient variations, nutritional status, pear, Pyrus communis L., reference values, sampling times |
| Abstract:
Pear is one of the most important deciduous fruit trees growing in the irrigated lands of NE Spain, occupying more than 26000 ha. The aim of this study was to offer some graphic tools in order to make possible, in this area, the interpretation of the leaf mineral analysis at any time of the growing season. This possibility is offered for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and all their ten binary ratios. The study was conducted during two growing seasons on 340 pear trees (cvs ‘Limonera’ and ‘Blanquilla’) distributed in several full bearing orchards, representative of the usual agro-climatic environment of this area, under good management practices and giving high yields. Leaf samples were taken from the trees at 30, 60, 90, 120, 150 and 180 days after full bloom (DAFB). They were analysed for N, P, K, Ca and Mg. The corresponding ten binary ratios between element concentrations (N/P, N/K, N/Ca, N/Mg, K/P, Ca/P, Mg/P, K/Ca, K/Mg and Ca/Mg) were calculated. At harvesting, the yield was measured on every of the 340 selected trees. The values of nutrient concentrations and binary ratios which best correlated with maximum yield at each of the leaf sampling times were considered as the optimum and therefore, as reference values for diagnostic purposes. These data allowed, as a conclusion, to elaborate the graphs representing the variations of the nutritional values throughout the vegetative cycle which allow a continuous diagnosis of the nutritional status for the pear tree. | |
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