Effects of field management practices on plant health and rhizosphere microbial community structure
Creators:Benitez, Maria Soledad
Advisor:McSpadden Gardener, Brian B.
Contributors:Baysal Tustas, Fulya
Kleinhenz, Matthew D.
Miller, Sally A.
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Series/Report no.:Plant Pathology. Graduate student poster competition, 2006
Farming practices can have profound effects on soil properties including physical, chemical and biological characteristics. In this study, we characterized the influence of soil management practices on soil borne disease suppressiveness and soil microbial population structure in an organic cropping system. Four transitional management strategies, with and without compost amendments, were considered: mixed hay, tilled fallowing, open-field vegetables and high tunnel vegetables. The effects of compost addition on soil characteristics varied with transition strategy, with the greatest effects being observed in the soils coming from the mixed hay and high tunnel treatments. The effects of treatments on plant health were assayed in growth chambers using Edamame soybean (cv. Sayasume). In general, disease severity increased with the addition of the compost amendments, and the mixed hay treatment was less conducive to disease development. In addition, tilled fallow and vegetable cropping systems had the highest disease. Microbial populations are being studied through culture-dependent and culture-independent strategies. In Edamame soybeans, compost amendments led to higher rhizosphere colonization rates of various Pseudomonas spp. under all cropping strategies. In addition, soil and rhizosphere bacterial community profiling using terminal restriction fragment length polymorphism (T-RFLP) revealed at least seven terminal restriction fragments specifically associated with different cropping systems. Characterization of selected ribotypes would lead to the identification of novel microbial populations associated with disease suppressiveness in these fields.