Physiological, Biochemical, Growth, and Yield Responses of Radish (Raphanus sativus L.) Plants Grown on Different Sewage Sludge–Fly Ash Mixture (SLASH) Ratios

Abstract

Agricultural utilization of sewage sludge (SS) and fly ash (FA) can be explored as an alternative and sustainable waste management option to recycle valuable plant nutrients present in both the wastes. A pot experiment was carried out to assess the effects of different sewage sludge–fly ash mixture (SLASH) ratios on physiological, biochemical, growth, and yield responses of Radish (Raphanus sativus L.) plants. The study comprised of four mixtures prepared by mixing sewage sludge and fly ash in four different ratios denoted as A [4(SS): 1(FA)], B [4(SS): 2(FA)], C [4(SS): 3(FA)], and D [4(SS): 4(FA)], respectively, and agricultural farm soil which served as control. Experimental results revealed a significant increase in total chlorophyll and carotenoid content in plants grown at all the four SLASH mixture ratios as compared to control plants. Different biochemical parameters such as protein, proline, phenol and thiol content, and lipid peroxidation and peroxidase activity also increased significantly at both the ages of observation [45 and 65 days after sowing (DAS)] in plants grown at different SLASH mixtures as compared to control plants. The test plant also showed positive morphological response to different SLASH mixture ratios as evident by significant increment in root and shoot length, number of leaves, leaf area, root, shoot, and total biomass in comparison to control plants. Similarly, yield also increased significantly in all the SLASH mixtures with maximum increment of 87.8% shown by SLASH mixture A followed by C (87.5%) and B (84.8%). The results of the study suggest that SLASH mixtures A, B, and C may be a good option to utilize as a fertilizer supplement or soil amendment for Radish as shown by increased chlorophyll and protein content along with antioxidant levels, indicating toward strong antioxidant defense which resulted in enhanced growth parameters, biomass accumulation, and yield of plants.