Growth and antioxidant response of Brassica rapa var. rapa L. (turnip) irrigated with different compositions of paper and board mill (PBM) effluent

Current study presents the effect of irrigation with different compositions (0%, 20%, 40%, 60%, 80% and 100%) of PBM effluent on growth and antioxidant potential of Brassica rapa var. rapa L. plants. Seeds were exposed to different PBM effluent compositions, which resulted in significant decrease in their germination potential with elevated delay index. Significant changes in growth parameters (plant height, number of leaves and leaf area) were recorded for turnip plants at regular intervals (25, 50 and 75 d) as function of PBM effluent proportion. Response of biochemical and antioxidant constituents in different parts of turnip, against stress induced by PBM effluent, was assessed by estimating the contents of chlorophyll (a + b), carotenoids, protein, phenolics, flavonoids, ascorbic acid and malondialdehyde. Antioxidant activity was evaluated by measuring DPPH radical scavenging potential. The results of this study suggest that the impact of PBM effluent irrigation is dependent on concentration of effluent in irrigation mixture and is very clear on plant growth and antioxidant attributes. Maximum benefits were secured at 40% PBM effluent to irrigate turnip plants till maturity while higher concentrations were found useful for shorter period (25–50 d).