Onion productivity in relation to irrigation water depths and nitrogen doses

ABSTRACT Onion is considered the third most important vegetable in terms of economic value in Brazilian horticulture. The factors of production which most limit the productivity of the species are water and nutrients; so, irrigation and soil fertility control are determinant criteria for crop success. The aim of this study was to evaluate the influence of different water depths and nitrogen doses on the productivity of onion, Aquarius hybrid. Five water depths [(0, 75, 100, 125 and 150% of crop evapotranspiration (ETc)] and five nitrogen doses (0, 120, 180, 240 and 300 kg ha-1, urea form), arranged in a scheme of subdivided plots, in a completely randomized design with four replicates. We used sprinkler irrigation system. Irrigation management and water depths were estimated using Irrigameter. Plants were harvested when more than 60% of them completed the vegetative period. The water depth corresponding to 150% of the crop evapotranspiration provided higher total and commercial onion productivities, applying doses of 226.8 and 229.8 kg ha-1 of nitrogen, respectively.

摘要 洋葱在巴西园艺产业中的经济价值位列第三大蔬菜作物。限制该作物产量的核心生产因素为水分与养分，因此灌溉与土壤肥力调控是作物种植成功的决定性条件。本研究旨在探究不同灌水量与氮肥施用量对Aquarius杂交洋葱（Aquarius hybrid）产量的影响。试验设置5个灌水量梯度（分别为作物蒸发蒸腾量（ETc）的0、75%、100%、125%和150%）与5个氮肥施用量梯度（分别为0、120、180、240、300 kg·ha⁻¹，肥料形式为尿素），采用裂区设计并以完全随机方式布置，设置4次重复。本试验采用喷灌系统，灌溉管理与灌水量通过灌溉监测仪（Irrigameter）进行估算。当超过60%的植株完成营养生长期后进行收获。当灌水量为作物蒸发蒸腾量的150%时，分别配合226.8 kg·ha⁻¹与229.8 kg·ha⁻¹的氮肥施用量，可获得更高的洋葱总产量与商品产量。