|Riggs, Robert - UNIVERSITY OF ARKANSAS|
|Crippen, D - UNIVERSITY OF ARKANSAS|
Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: June 8, 1999
Publication Date: December 15, 1999
Citation: Timper, P., Riggs, R.D., Crippen, D.L. 1999. Saprophytic growth of a sterile fungus (ARF) under different conditions [abstract]. Journal of Nematology. 31:575-576. Technical Abstract: A sterile fungus designated ARF is a facultative parasite of the soybean cyst nematode, Heterodera glycines. The objectives of this study were to compare saprophytic growth among isolates of ARF, and to compare growth in the presence and absence of soybean plants and soil microorganisms. ARF produces mycelial mats in soil which can be used as an indicator of saprophytic growth. Two experiments were conducted, both in the absence of H. glycines: in the first, biomass of ARF isolates was compared in heat-treated soil with and without Lee 74 soybean, and in the second, biomass of isolates was compared in heat-treated and native (nonheated) soil. The dry weight of mats extracted from soil by wet sieving was compared in the different treatments 10 days after mixing homogenized mycelium into soil. In both experiments, the isolates that were previously shown to be more effective in reducing H. glycines numbers in soil, usually produced a greater biomass of mats than did isolates that were less effective. Soybean roots had no consistent effect on the biomass of mycelial mats. Mats were sometimes associated with the rhizosphere, but most were recovered from the bulk soil. There was a positive correlation (P=0.0001, R=0.66) between the total biomass of mats and the number associated with roots indicating that isolates producing more or larger mats in soil have a greater probability of contacting roots. In the second experiment, biomass of mycelial mats was 2x greater in heat-treated than in native soil in one trial and similar in another trial. There were no isolate by plant or soil treatment interactions.