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