Evaluation of municipal sewage sludge for Arbuscular mycorrhizal fungi inoculum production

Abstract

This experiment was carried out to assess the effect of soil amendment with different concentrations of municipal sewage sludge (SS) as a substrate on inoculum production of two selected arbuscular mycorrhizal fungi (AMF) i.e., Glomus mosseae and Acaulospora laevis. The experiment was a 4 × 5 factorial design with four hosts including, maize (Zea mays L.), lemon grass (Cymbopogon nardus (L.) Rendle), palmarosa (Cymbopogon martini (Roxb.) Wats.) and Sesbania (Sesbania aculeata Poir.) and the following five SS concentrations 1) no substrate, 2) 25 g, 3) 50 g, 4) 75 g and 5) 200 g pot–1) with five replications. After 90 days, the host roots and its rhizosphere soil were examined for fungal mycorrhization in terms of percent of root colonization and AMF spore quantification. Furthermore, we calculated the response of each host in terms of increase in plant height (cm), root length (cm), root, fresh shoots, and dry weight (g). Mycorrhization pattern showed moderate to abundant intraradical mycelium, extraradical mycelium, vesicles, and arbuscules in all the host plants. This pattern varied with a change in the input level of SS. The 75 g treatment obtained the maximum mycorrhization of both the AMF, while the highest input level was detrimental to AMF and host plants' survival. Among the tested hosts, lemon grass and maize had a tremendous increment in G. mosseae and A. laevis inoculum respectively. Consequently, 75 g SS with lemon grass is the most compatible host–substrate combination capable of maximum G. mosseae and A. laevis spore production and root colonization and so far, highlights the significance of an alternative, cost–effective and affordable carrier medium that can be adopted by farmers as sustainable cultural practices for on farm AMF inoculum production.