Purpose: Floating hydroponic system for lettuce greenhouse production consists of plants inserted in styrofoam platform floating in a 15 cm-tall nutrient solution, which is aerated by some growers while others maintain the solution static. The present investigation had the objective of determining the effect of ${\mathrm{N}\mathrm{O}}_3^{-}$-N and K in Romaine lettuce cultivated in floating hydroponic system and the impact of nutrient solution aeration. Materials and methods: Plants were transplanted into 34 L rigid plastic containers with aerated or non-aerated solutions containing either 15/7, 12/8.5 or 12/2.85 meq L⁻¹ of ${\mathrm{N}\mathrm{O}}_3^{-}$/K concentration. Results: Aeration of the nutrient solution promoted plant growth, leaf K, P, and Mg, and water uptake, however, photosynthesis and transpiration rates were enhanced under non-aeration conditions. Decreasing N did not affect leaf N uptake and accumulation; however, decreasing K markedly decreased leaf P and K in aerated plants. Despite the higher transpiration and stomatic conductance in non-aerated plants, water uptake was higher in aerated plants. Non-aerated plants exhibited decreased leaf K accumulation. Conclusions: non-aeration or reduction of K concentration of the nutrient solution may be a strategy to reduce leaf K in lettuce; leaf N concentration was unaffected by aeration.

目的：用于莴苣温室生产的漂浮水培系统由插入泡沫聚苯乙烯平台的植物组成，漂浮在15厘米高的营养液中，某些种植者对其充气，而另一些则保持溶液静态。本调查的目的是确定${\mathrm{ñ}\mathrm{Ø}}_3^{-}$漂浮水培系统中长叶莴苣中的-N和K以及养分溶液通气的影响。材料和方法：将植物移植到装有充气或非充气溶液的34 L刚性塑料容器中，该溶液含有15 / 7、12 / 8.5或12 / 2.85 meq L ^-1的${\mathrm{ñ}\mathrm{Ø}}_3^{-}$/ K浓度。结果：营养液的通气促进了植物的生长，叶片钾，磷和镁的吸收以及水分的吸收，但是在非通气条件下，光合作用和蒸腾速率得到了提高。减少氮肥不会影响叶片氮素的吸收和积累。但是，降低K会显着降低充气植物的叶片P和K。尽管在非充气植物中蒸腾和气孔导度较高，但在充气植物中吸水量较高。未充气的植物表现出减少的叶片钾积累。结论：不通气或降低营养液中钾的浓度可能是减少莴苣叶片中钾含量的一种策略。叶片氮浓度不受通气影响。