VATIS UPDATE Article

In a study conducted by a team of researchers from Nanjing Normal University, China, Reductive soil disinfestation (RSD) with incorporation of various organic matters under flooding conditions combined with plastic mulching were applied to suppress FOC and prevent banana Fusarium wilt disease. The biological properties of the soil during the RSD process were investigated using quantitative real-time PCR and denaturing gradient gel electrophoresis. Besides, high performance liquid chromatography was used for investigating the role of organic acids in the mechanisms of RSD.

The results showed that the values of soil redox potential significantly decreased by >800 mV in the RSD treatments incorporated with rice straw and bagasse under flooding conditions compared with untreated soil. The lowest soil pH (5.36) and a significant decline in the F. oxysporum population to 2.79% of untreated soil were obtained in flooded soil with the highest amount (1.2%, w/w) of rice straw (C/N, 46.0). Incorporation of bagasse (C/N, 129.6), pig manure (C/N, 12.8), and lime also significantly decreased the populations of F. oxysporum, but were less effective than rice straw.

Application of rice straw under flooding conditions significantly decreased fungal diversity and increased soil bacterial diversity, and the increased bacteria, such as Clostridium spp. regarded as organic acids producers, were considered to have an antagonistic effect on F. oxysporum. In a field experiment, a wilt disease control efficiency of 82.3% was obtained in flooded soil incorporated with 0.5% (w/w) rice straw compared with untreated soil. Besides, four kinds of toxic organic acids to F. oxysporum were detected in soil solutions of RSD treatments. Acetic acid and butyric acid were the primary organic acids, followed by small amounts of isovaleric acid and propionic acid.