Effect of Cover Crops On the Microbial Community and Its Ability to Suppress Disease and Acquire Nutrients.

Cover crops are able to provide a field with a microbial biomass that is able perform important ecological functions for that field. Studies show that cover crops are able to increase soil microbial biomass, suppress disease and weeds, and improve soil and water quality. Siderophores are an important mechanism by which bacteria obtain nutrients for themselves and host plants while making those same nutrients unavailable to other microbial species. Here we aim to address the ability of 4 different cover crops to support a disease suppressive microbiome. Canola, Mustard, Honeysweet and Sordan 79 were grown in potato fields for two consecutive years. One hundred microbial isolates were obtained from the soil of each cover crop each year. Total siderophore content was measured from each soil as well as siderophore production of the field bacterial isolates. Bacterial isolates were also tested for antagonistic activity against three potato pathogens, Rhizoctonia solani, Fusarium solani, Phytophthora erythroseptica. The top siderophore producing bacteria were identified and their inhibition of the three pathogens was indexed. Four species of microbes were common among all cover crops, however siderophore production as well as pathogen inhibition index varied within the same bacterial species. The Sudan 79 soil had the greatest siderophore production and had the highest total number of isolates which were able to suppress pathogen growth. This indicates that while different cover crops may support a genetically similar set of microbes, there exists strain specificity in conjunction with these cover crops that may provide better disease suppression and nutrient acquisition.