Hydroponic design influences morphophysiology and mineral uptake in kale (Brassica oleracea var. acephala).

Hydroponic system architecture plays a pivotal role in optimizing plant growth under controlled environment conditions. This study assessed the effects of two hydroponic designs—a vertical tower and a three-layer horizontal platform—on the growth performance, physiological traits, and nutrient uptake of two curly kale cultivars, Oldenbor F1 and Redbor F1. A total of 26 morphological, physiological, and colorimetric traits were evaluated. Nested ANOVA revealed that system architecture significantly influenced biomass accumulation, plant height, root collar diameter, leaf morphology, and pigment traits (p < 0.001). SPAD chlorophyll index and leaf nitrogen content also varied significantly between systems. Colorimetric differences (L*, a*, b*) were attributed to microclimatic conditions and cultivar-specific responses. Macronutrients (N, P, Mg) were predominantly concentrated in shoots, whereas micronutrients (Fe, Mn, Zn, Cu) were more abundant in roots, especially in the vertical system. Principal component analysis (PCA) accounted for 66.61% of total variation, effectively separating morphological and pigment-related traits by system and cultivar. These findings underscore the importance of aligning hydroponic system design with cultivar selection to enhance morphophysiological performance and nutrient efficiency in soilless vertical farming systems. The results offer actionable insights for cultivar-system matching to improve yield, nutrient use, and sustainability.