Effect of natural farming practices on physiological and biochemical traits of cabbage (Brassica oleracea var. capitata) under mid-hill conditions of Himachal Pradesh

Natural farming helps in improving sustainability; and it is imperative to know at which concentration of its inputs the crops respond best. Therefore, the field experiment was conducted to evaluate the effect of natural farming practices on cabbage (Brassica oleracea L. var. capitata) in the mid-hill region of Himachal Pradesh during two consecutive seasons (2023–24 and 2024–25). Six treatments, consisting of a control and five concentrations of jeevamrit (10%, 20%, 30%, 40% and 50%) were evaluated for physiological parameters including chlorophyll content, carotenoids, photosynthetic rate, transpiration rate, leaf area index as well as stomatal traits and biochemical characteristics such as total phenolics, flavonoids and antioxidant activity. The results revealed that all doses of jeevamrit significantly improved these parameters over control. Among various treatments, 40% dose recorded maximum chlorophyll content, higher transpiration rates, secondary metabolite accumulation and enhanced antioxidant activity. A reduction in values at 50% suggested that the response had surpassed the optimum concentration. Principal Component Analysis (PCA) and correlation analysis showed strong positive associations between phenolic compounds, flavonoids and antioxidant capacity (DPPH), as indicated by high correlation coefficients (r = 0.97–0.99) and close vector alignment in the PCA biplot. Phenolic and flavonoid levels were significantly correlated with antioxidant capacity at optimal levels, suggesting enhanced physiological performance and tolerance to stress conditions. In general, these results indicated that 40% jeevamrit is the most effective concentration for improving physiological performance and biochemical quality of cabbage under natural farming conditions.