2017 ASHS Annual Conference

This research work is concerned with the effect of Bacillus amyloliquefaciens Y1 on the control of Fusarium wilt disease and the growth promotion of tomato. The results of the dual culture assay clearly showed that the strain Y1 strongly inhibited the growth of Fusarium oxysporum f.sp. lycopersici on all the tested media. The strain Y1 produced Indole 3 Acetic Acid (IAA) in both the presence and absence of tryptophan. When Y1 culture was applied to the tomato seeds, over 96% of germination rate was observed in all treatments where Y1 culture in the absence of tryptophan showed the greatest root length (5.40cm) and shoot lengths (5.15cm). However, the Y1 culture broth in the presence of tryptophan (1g/L) had the lowest root elongation with 2.22cm, but promoted the development of the root system with many root hairs as compared to the control root. To control the Fusarium wilt disease under in vivo conditions, three types of treatments; BW medium (BW), BW medium along with the commercial fungicide (BW+F) and Y1 culture in BW medium (Y1) were used. The tomato seedlings showed yellowing symptoms on the lowest leaves at 2DAI in all treatments and some of the control (BW) plants wilted at 8 DAI. Application of Y1 culture or fungicide significantly reduced the disease incidence as compared to the BW where the Y1 treated plants had higher shoot height, fresh and dry weights in roots and shoots than BW and BW+F treated plants. To examine the competent effect of Y1 growth on the total bacterial and fungal populations, the rhizospheric soil of both Y1 treated and untreated plants were collected at 7DAI, 14DAI and 21DAI. The survival colonies of Y1 (8.6x10⁴ CFUg^-1soil at 7DAI, 2.1x10⁵ CFUg^-1soil at 14DAI and 1.3x10⁵ CFUg^-1soil at 21DAI) were observed from the Y1 treated plants. Although there was no difference in fungal populations between treatments, it was clearly found that the survival of Y1 in the rhizosphere greatly reduced the populations of other bacteria. Therefore, the results of our study demonstrated that Y1 can be used as the effective agent for not only the wilt disease suppression but also the enhancement of the plant growth in tomato cultivation.