The Effect of Different Water Levels on Yield, Quality, and Biochemical Properties of Red Cabbage (Brassica oleracea f. rubra)
Abstract
This study was conducted under field conditions in Canakkale Province, Türkiye, during the 2021–2022 growing seasons and investigated the effects of different irrigation levels on the yield, quality, and biochemical properties of red cabbage (Brassica oleracea f. rubra). Four irrigation regimes were applied: 100% (I1.0: full irrigation), 70% (I0.7: mild stress), 30% (I0.3: severe stress), and 0% (I0.0: rainfed only). Morphological, physiological, and biochemical responses of plants to water stress were examined, with particular emphasis on the accumulation of flavonoids, anthocyanins, and phenolic compounds to evaluate adaptive capacity and nutritional quality. The data showed that yield decreased significantly as water deficit increased. The highest yields were obtained under full irrigation, with 1514.2 g plant⁻¹ in 2021 and 1252.6 g plant⁻¹ in 2022, demonstrating the positive effect of adequate water supply on productivity. The lowest yields were recorded under non-irrigated (rainfed) conditions. In contrast to yield trends, water restriction increased the accumulation of bioactive compounds. As irrigation decreased, flavonoid, phenolic, and anthocyanin contents as well as antioxidant activity (measured by DPPH and CUPRAC assays) increased significantly. The highest anthocyanin content (1.31 mg g⁻¹) and antioxidant activity were found under severe stress in the second experimental year. These findings indicate that water stress negatively affects yield but strongly stimulates secondary metabolite synthesis, thereby enhancing the nutritional and functional quality of the crop. Therefore, controlled or moderate water stress can be strategically used as a sustainable agricultural practice to improve the biochemical quality of red cabbage, particularly in water-limited farming systems. The results highlight the importance of effective irrigation management and adaptive strategies to sustain crop yield and quality under future climate change scenarios.