<i>Bacillus amyloliquefaciens</i> D203 ameliorates rice growth and resistance to rice blast disease

Abstract

This study evaluated the effects of Bacillus amyloliquefaciens D203 encapsulated in alginate-bentonite coating enriched with titanium nanoparticles on rice germination and Magnaporthe oryzae infection. Seed coating was achieved using the ionic gelation/extrusion method with modifications. The study investigated various concentrations of strain D203 on biomass and bacterial release from the beads, along with its influence on detached leaves. Results showed that treatment with a strain D203 cell suspension (2 × 107 CFU/ml) significantly enhanced root and shoot lengths, despite a slightly lower germination rate (90%) compared to the control. Treatment with a concentration of 1 × 107 proved to be optimum for growth because it maintained germination at 100% and boosted biomass growth of shoot and root by 49.57% and 16.44%, respectively. Colonization by strain D203, explored through seed coating and subsequent resuspension from roots and media, peaked in roots, indicating preferential root zone inhabitation. In vitro studies demonstrated strain D203’s efficacy against M. oryzae at 21 and 40 days, with the 1 × 107 CFU/ml spray significantly reducing disease symptoms. Strain D203 exhibited a preventive effect, especially in early growth stages. The encapsulated form of strain D203 had a control effect comparable to 40% Hexaconazole but less effective than 75% Tricyclazole. Uncoated and encapsulated B. amyloliquefaciens treatments significantly improved sterile rice plant growth over 21 days, with the encapsulated bead treatment surpassing both controls and free cell treatments by days 14 and 21, despite slower initial growth. Encapsulation presents a promising alternative, potentially matching the effectiveness of chemical fungicides, emphasizing the importance of environmentally friendly alternatives in sustainable disease management strategies.