Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: October 11, 2013
Publication Date: July 1, 2013
Citation: Mazzola, M., Strauss, S.L. 2013. Changes in rhizosphere microbiome associated with orchard soil resilience in response to Brassicaceae seed meal amendment. Phytopathology. 103:S2.92. Technical Abstract: Pyrosequencing analysis of the apple rhizosphere microbiome was conducted two years post-planting at an orchard replant trial which included a no treatment control, 1,3-dichloropropene-C17 pre-plant fumigation, and pre-plant soil incorporation of a Brassicaceae seed meal (SM) formulation. SM treated soils exhibited resilience to re-infestation by Pratylenchus penetrans and Pythium spp., which was correlated with superior tree growth and yield in SM treated soil relative to that observed in fumigated soils. After two years, the rhizosphere microbiome in fumigated soils was similar to that detected in the no-treatment control, while the rhizosphere of trees established in SM treated soil possessed unique bacterial and fungal profiles. Overall diversity of the rhizosphere was demontrably reduced in the SM treatment compared to the control or fumigation treatments, suggesting that enhanced "biodiversity" was not instrumental in achieving enhanced system resilience and/or pathogen expression. Relative resistance of the orchard soil system to pathogen re-infestation was, in part, rootstock genotype-dependent and was associated with differences in bacterial phyla detected in the rhizosphere. In addition, abundance and diversity of potenial foliar and fruit pathogens was significantly lower in SM amended soils demonstating that an understanding of below ground/above ground interactions may enhance orchard sustainability.