J. Sci. Agri. Technol. (2023) Vol. 4 (1): 14 – 19
DOI: https://doi.org/10.14456/jsat.2023.3
Abstract
Rice cultivation in Thailand faces challenges in achieving high yields due to diseases. This research aims to develop a spray-dried powder containing Bacillus amyloliquefaciens strain C2-1 for control economically damaging rice diseases caused by Xanthomonas oryzae, Fusarium moniliforme, Pyricularia grisea, and Bipolaris oryzae. The B. amyloliquefaciens strain C2-1 was cultured in 3 different media, including 1) medium contained nutrient broth with glucose (NB), 2) medium contained beef extract, molasses, K2HPO4 and KH2PO4 (BM), and 3) medium contained yeast extract, molasses, K2HPO4, and KH2PO4 (YM). The results showed that YM medium gave the highest concentration of bacteria at 1.30×1016 cfu/ml, followed by BM medium at 9.88×1012 cfu/ml, and NB medium at 5.3x1012cfu/ml. Therefore, YM medium was selected as the optimal culture medium. Subsequently, the B. amyloliquefaciens strain C2-1 was produced into a spray-dried powder using the spray-drying technique. Tapioca starch and carboxymethyl cellulose were used as spray-drying carriers in a ratio of 10:1. The optimal spray-drying conditions included a hot air inlet temperature of 90°C, a hot air outlet temperature of 70°C, and a feed rate of 10-15 ml/min, resulting in the highest survival rate at 2.8×1012 CFU/g-1. The efficacy of B. amyloliquefacien strain C2-1 powder was then tested against rice diseases. The inhibition of X. oryzae was assessed using the paper disc diffusion method, while the inhibitions of F. moniliforme, P. grisae, and B. oryzea were evaluated using dual culture assay. The results demonstrated that B.amyloliquefacien strain C2-1) powder exhibited strong inhibitory effects against X. oryzae, with clear zone measuring 5.5, 5.7, and 5.7 mm at 24, 48, and 72 h, respectively. Regarding inhibiting F. moniliforme, P. grisae, and B. oryzea, B. amyloliquefaciens strain C2-1 demonstrated effective control of these rice pathogenic fungi, resulting in inhibitions of 73.0%, 68.72%, and 48.42% at 7 days, respectively. These findings strongly suggest that the B.amyloliquefacien strain C2-1 obtained from spray drying serves as a promising biocontrol agent against bacterial leaf blight disease, bacterial blight, bakanae disease, rice blast disease, and brown spot disease caused by F. moniliforme, P. grisae, and B. oryzea, respectively.
Keywords: Antagonist bacteria, B.amyloliquefacien, biological control, rice disease, spray drying
Received: December 10, 2022. Revised: March 7, 2023. Accepted: March 14, 2023.
