Occurrence of fungal-inhibiting Pseudomonas on caryopses of Tripsacum dactyloides L. and its implication for seed survival and agriculture application

Pseudomonas bacteria capable of inhibiting maize fungal pathogens were isolated from caryopses of three of 11 populations of eastern gamagrass ( Tripsacum dactyloides ) collected from eastern and central United States. The bacteria inhibited fungal pathogens in pure cultures and a zone of fungal inhibition 1–2 cm wide occurred around surface sterilized maize kernels that were treated with the bacteria and placed in culture dishes containing 2% maize meal agar. In cold-soil germination tests, there were no significant ( P < 0.05) differences in germination of scarified maize kernels that were treated with gum arabic (sticking agent) and one of the bacterial strains (98%) or the commercial fungicide, Captan (96%). Both of these treatments resulted in significantly higher germination than scarification (50%) or scarification and gum arabic alone (58%). Non-scarified controls had 85% germination. The results indicate that Pseudomonas may be effective in preventing invasion of damaged seeds by pathogens capable of inhibiting germination and destroying seed embryos.