In vitro evaluation of bacterial antagonists in controlling seed borne fungi associated with four oilseeds in Bangladesh

Abstract

Effect of bacterial antagonists was assessed using blotter incubation method of seed health testing. Four oilseeds in Bangladesh viz., mustard var. Binasorisha-4, soybean var. Binasoybean-3, sesame var. Binatil-3 and peanut var. Binachinabadam-4 and three bacterial bioagents, Bacillus subtilis, Bacillus thuringiensis and Pseudomonas fluorescens were used in this study. Besides these antagonists, Vitavax 200 was used as a positive check treatment along with an untreated control. Among the tested antagonists, in comparison to control treatment, B. subtilis increased the germination of Soybean (91.67%), Sesame (94.0%) and Peanut (83.33%). In case of mustard, highest germina- tion (96.0%) was observed in seed treated with P. fluorescens. Nine fungal mycoflora were recorded from the four non-treated control oilseed samples viz., Fusarium oxysporum, Aspergillus flavus, A. niger, Colletotrichum truncatum, Macrophomina phaseolina, Cercospora personata, Curvularia lunata, Penicillium sp., and Rhizopus sp. The highest number of seed borne fungi was detected in untreated control. According to the observation, B. subtilis, B. thuringiensis and P. fluorescens significantly inhibited seed borne fungi of tested seeds over control treatment. However, Vitavax 200 was found highly effective to inhibit the seed borne fungi. Among the bioagents, B. subtilis suppressed highest number of seed borne fungi such as A. niger (mustard) and Aspergillus flavus (sesame), whereas B. thuringiensis suppressed the highest number of seed borne fungi such as F. oxysporum (Peanut), Aspergillus flavus (Peanut), C. lunata (Sesame) and Penicillium sp.(Peanut). P. fluorescens was found highly effective to inhibit different seed borne fungi such as F. oxysporum (Mus- tard), Aspergillus flavus (Soybean and Mustard), Penicillium sp. (Mustard and Sesame), C. truncatum (Soybean), C. personata (Soybean) and M. phaseolina (Soybean). In most cases, inhibition of seed borne fungi by P. fluorescens was statistically similar to Vitavax 200. Thus, all of the three tested bioagents were effective to control seed borne fungi associated with oil seed crops. Specifi- cally, P. fluorescens was found to be the most effective bioagent in controlling seed-borne fungi.