Effect of irrigation and nitrogen fertilization on orange (<em>Citrus sinensis</em> Osbeck vr. Pêra) tree yield

Abstract

The experiment was conducted at the Centro Técnico de Irrigação da Universidade Estadual de Maringá, in Maringá, PR, Brazil, in order to study the effect of irrigation and nitrogen fertilization on orange (Citrus sinensis Osbeck vr. Pêra) yield. The experimental design was entirely randomized with seven rates of irrigation (W₀ = 0; W₁ = 1.440; W₂ = 2.880; W₃ = 4.320; W₄ = 5.760; W₅ = 7.200 and W₆ = 8.640l water/tree) and five rates of nitrogen (N₀ = 0; N₁ = 107,5; N₂ = 215; N₃ = 322,5; N₄ = 430 and N₅ = 537.5g N/tree). Irrigation was performed through a microsprinkler and controlled according to the evapotranspiration of the crop, estimated by a “class A” pan. Water was applied whenever the evapotranspiration reached 7,3mm. For the nitrogen fertilization, diluted urea was divided into 43 applications at a weekly rate. The production of boxes of fruits per tree presented quadratic relationship in function of the application of nitrogen and water, reaching the maximum of 3,2 boxes (40,8kg) per tree with the application of 5,095.6l of water and 345.9g of N per tree.