Production and commercial quality of lettuce fertirrigated with nitrogen and potassium in greenhouse

ABSTRACT Organic fertilization can provide most of the nutrients needed to grow lettuce crop. However, the rate of nutrient mineralization may be limiting to absorption, once complementary forms of fertilization with soluble fertilizers can be used, such as fertirrigation. The objective of this work was to evaluate the effect of the drip fertirrigation with nitrogen and potassium with organic fertilization in the production and commercial quality of the Vera lettuce cultivated in greenhouse. The cultivation period used for the experiment was between August and October 2012 (winter and spring; 67 days). The experimental design was completely randomized with three replications, in which ten treatments were evaluated, with nine of them formed by the Plan Puebla III matrix, that is, from the combination among five N (9, 54, 90, 126, and 171 kg ha-1) and five K doses (1.15, 6.90, 11.50, 16.10, and 21.85 kg ha-1), applied in topdressing, and one of them as control, which did not receive fertirrigation. The best answer to the shoot commercial fresh mass took place with the maximum dose of Si and K2O and in the zero dose of N. The commercial leaf number per plant showed their higher values in the maximum doses of N and Si and K2O. The shoot noncommercial fresh mass increment, both with the increase in N doses and with the increase in Si and K2O doses, did not harm the commercial quality.

摘要：有机肥可满足生菜生长所需的大部分养分，但其养分矿化速率可能成为植株养分吸收的限制因素，此时可采用可溶性肥料配套施肥方式，例如滴灌水肥一体化灌溉。本研究旨在评估结合有机肥施用的氮、钾肥滴灌水肥一体化模式对温室栽培维拉生菜的产量与商品品质的影响。试验栽培周期为2012年8月至10月（涵盖冬季与春季，共计67天），采用完全随机设计，设置3次重复，共设10个处理组：其中9个处理组基于普埃布拉III方案（Plan Puebla III）构建，由5个施氮水平（9、54、900、126、171 kg·ha⁻¹）与5个施钾水平（1.15、6.90、11.50、16.10、21.85 kg·ha⁻¹）组合而成并以追肥方式施用，剩余1组为不施加滴灌水肥一体化施肥的对照组。研究结果表明：地上部商品鲜重的最优响应条件为零施氮水平下最高剂量的硅（Si）与氧化钾（K₂O）组合；单株商品叶片数的最高值出现在最高施氮量与最高硅、氧化钾施用量的组合中；随施氮量、硅与氧化钾施用量提升而增加的地上部非商品鲜重增量，并未对商品品质造成负面影响。