The effect of canola (Brassica napus) as a biofumigant on soil microbial communities and plant vitality: A pot study

Abstract

Canola (Brassica napus) may be incorporated into soil as a biofumigant for control of pathogens such as Sclerotinia sclerotiorum. Yet, the effect of biofumigants on natural microbial communities required to maintain soil functions is still unclear. A pot experiment with sunflowers as the crop plant was conducted to assess the biofumigation effect of canola on the soil microbial community. The study consisted of 32 pots containing four treatments of eight replicates each. Each pot contained one sunflower plant. The treatments included (1) soil only, (2) soil incorporated with canola, (3) soil incorporated with canola and inoculated with S. sclerotiorum, and (4) soil inoculated with S. sclerotiorum. Microbial community function and structure were assessed through assays of dehydrogenase activity, substrate utilisation profiles and signature biomarker analysis. Chlorophyll a fluorescence measurements were performed as a measure of sunflower vitality. Canola incorporation brought about transient changes in the soil microbial community, none of which were detrimental. Plant vitality showed no negative effects due to the biofumigant or the inoculated pathogen. Canola can be suitable as a biofumigant, without having harmful effects on the indigenous soil microbial community. Copyright © 2013 Combined Congress Continuing Committee.