Effect of composted agricultural and industrial wastes on the growth of vegetable seedlings and suppression of their root diseases.
Three agricultural and industrial wastes including spent forest mushroom compost (SFMC), spent golden mushroom compost (SGMC) and papermill sludge (PMS) were used to formulate culture media for the cultivation of watermelon (Citrullus vulgaris), tomato, pepper (Capsicum annuum var. grossum) and cabbage (Brassica oleracea var. botrytis) seedlings. SFMC or SGMC mixed with 5-25% (v/v) PMS was optimal for growth of vegetable seedlings. However, SFMC or SGMC mixed with >50% (v/v) PMS was unfavourable for vegetable seedling growth and significantly reduced their fresh weight. SFMC, SGMC and Bas Van Burren No.4 peat moss (BVB No.4) were respectively mixed with 25% PMS to formulate the culture media SFMC75, SGMC75 and BVB75. The culture media of SFMC, SFMC75, SGMC, SGMC75, BVB No.4, BVB75 and PMS were inoculated with Fusarium oxysporum f.sp. niveum, Plasmodiophora brassicae, F. conglutinans, Rhizoctonia solani AG-4, Meloidogyne incognita and Pythium myriotylum, respectively. Germinated seeds of watermelon, tomato, Capsicum and cabbage were respectively sown in these media in the greenhouse. The results indicated that SGMC, SGMC75, SFMC, SFMC75 and PMS media inhibited the occurrence of watermelon fusarial wilt, cabbage clubroot, root-knot nematode disease of watermelon, tomato and pepper and Pythium root rot of tomato and watermelon. These media were not, however, able to suppress Rhizoctonia damping-off of cabbage, watermelon and pepper.