Population growth of a rhabditid nematode on plant growth promoting bacteria from potato tubers and rhizosphere soil.

Nine bacterial isolates from the rhizosphere and(or) tubers of potato (Solanum tuberosum cv. Kennebec) at a field site on Prince Edward Island were assessed as food sources for a bacteria-feeding nematode species tentatively identified as Diplogaster lheritieri. This species was the most common rhabditid nematode recovered from soil around potato roots at the same site. In laboratory feeding trials, an isolate of Comamonas testosteroni recovered from soil was an excellent food source for D. lheritieri. This bacterial isolate also increased the fresh weight and number of microtubers of tissue culture plantlets in the laboratory. Two endophytic bacterial isolates recovered from potato tubers, an Agrobacterium sp. and Pseudomonas fluorescens, were also good nutritional sources for the nematode. Diplogaster lheritieri spread bacteria over agar surfaces in petri plates.