NPK fertilization and irrigation of sunflowers in Luvisol: Vegetative behavior

The sunflower is one of the most important crops used for the production of biofuels. While the literature does contain some information, the hydric and nutritional requirements of sunflowers are still not completely defined. In order to correct this deficiency, an experiment was conducted at the Federal University of Campina Grande, Campina Grande, Paraíba State, Brazil, with the aim of evaluating the effect of nitrogen, phosphate, and potassium fertilization and available soil water (AW) on the behavior of Sunflower cv. Embrapa 122 V2000. The experiment consisted of 44 treatments with compound fertilizers using a Baconian Matrix (1: 0-0-0, 2: 0-80-80, 3: 80-80-80, 4: 100-80-80, 5: 60-0-80, 6: 60-100-80, 7: 60-120-80, 8: 60-80-0, 9: 60-80-80, 10: 60-80-100, 11: 60-80-120 kg ha-1 of N, P and K, respectively, and four difference quantities of available soil water (55, 70, 85 and 100%). The 9th compound fertilizer treatment was considered the reference since its doses are those used by the region's sunflower growers in Rio Grande do Norte State. The treatments were arranged in a completely randomized design with three replications. The height, stem diameter, number of leaves and leaf area of the plants were evaluated at 40 and 60 days after sowing. The results showed that the effects of available soil water and NPK fertilization on sunflower crop occurred independently for all variables except for the number of leaves. All variables increased linearly as a function of available soil water, except for leaf area. For the conditions studied, the doses 100, 80 and 80 kg ha-1 of N, P2O5 and K2O resulted in the highest growth rates, respectively.

向日葵是用于生物燃料生产的核心作物之一。尽管现有文献已涵盖部分相关研究成果，但向日葵的需水与营养需求仍未得到完全明确。为弥补这一研究空白，巴西帕拉伊巴州坎皮纳格兰德市坎皮纳格兰德联邦大学开展了一项田间试验，旨在评估氮肥、磷肥、钾肥配施以及土壤有效含水量（available soil water, AW）对向日葵品种Embrapa 122 V2000生长表现的影响。
本试验采用培根矩阵（Baconian Matrix）设计，共设置44个复合肥施肥处理，具体配比如下：1组为0-0-0（无氮磷钾），2组为0-80-80，3组为80-80-80，4组为100-80-80，5组为60-0-80，6组为60-100-80，7组为60-120-80，8组为60-80-0，9组为60-80-80，10组为60-80-100，11组为60-80-120 kg·ha⁻¹（分别对应氮、五氧化二磷、氧化钾的施用量），另设置4个梯度的土壤有效含水量水平（55%、70%、85%和100%）。其中第9组复合肥处理作为参照组，其施肥剂量为北里奥格兰德州当地向日葵种植户的常规用量。
试验采用完全随机设计，设置3次生物学重复。分别在播种后40天和60天，测定植株株高、茎粗、叶片数及叶面积。
研究结果表明，除叶片数外，土壤有效含水量与NPK配施对其余各生长指标的影响均相互独立。除叶面积外，其余各生长指标均随土壤有效含水量的提升呈线性增长趋势。在本试验设定的条件下，当氮、五氧化二磷、氧化钾施用量分别为100 kg·ha⁻¹、80 kg·ha⁻¹、80 kg·ha⁻¹时，植株生长速率达到最高水平。