plant growth-promoting activities of bacillus subtilis mbi 600 (integral®) and its compatibility with commonly used fungicides in rice sheath blight management

摘要

Sheath blight (ShB) of rice caused by Rhizoctonia solani is an economically important disease, causing significantudyield losses. In this study, the growth promoting activities of commercial formulation of a bioagent, Bacillus subtilis MBI 600ud(Integral®) and its compatibility with rice fungicides were evaluated. Integral was evaluated for growth promotion in rice onudfour cultivars (Cocodrie, Catahoula, Neptune, and Trenasse) under in vitro conditions. Treated rice seeds were incubated forud7 days, and the shoot and root lengths were measured. Rice cv. Cocodrie seeds were treated with strain MBI 600 at variousudconcentrations and seeded in pots containing field soil in GH in a randomized complete block design. Germination andudseedling lengths were measured at 7 and 15 days after sowing (DAS). The strain MBI 600 was found to produceudsiderophores. Seed treatment with Integral significantly increased shoot and root lengths at all concentrations in cvs.udCocodrie, Catahoula, and Trenasse under in vitro conditions. The shoot lengths ranged from 39 to 42 mm at a concentrationudof 2.20 x 109 cfu/ml in all CV’s. At 2.20 x 109 cfu/ml, the root lengths ranged from 47 to 69 mm. The shoot and root lengths ofudcontrol seedlings were each up to 20 mm. Seed treatment with 2.20 x 108 and 2.20 x 109 cfu/ml significantly increasedudseedling emergence (81 to 89%) compared to 2.20 x 106 and 2.20 x 107 cfu/ml, and control (61%) under GH conditions.udSimilarly, seed treatment with 2.20 x 109 cfu/ml of MBI 600 resulted in the highest shoot and root lengths (335 and 166 mmudrespectively). Integral has good tolerance to hexaconazole, propiconazole, and validamycin; moderate tolerance toudtricyclazole; and poor tolerance to benomyl and mancozeb at 1000 ppm. Integral showed compatibility to carbendazim andudazoxystrobin up to 400 ppm. Overall, our results suggest that Integral produces siderophores, promoted rice seedlingudemergence and growth, and is compatible with rice fungicides.