In vitro Evaluation of Bacterial Endophytes for Biocontrol of Pythium aphanidermatum and Plant Growth Promotion in Setaria italica L. Grown in Seedling Trays

An investigation study was carried to test the ability of endophytic bacteria isolated from small millets as a biocontrol agent against the fungal pathogen Pythium aphanidermatum, the causal organism of sheath blight in foxtail millet (Setaria italica L.) grown in seedling trays under greenhouse conditions. In total twelve bacterial endophytes were isolated out of which six isolates produced β -1, 3 glucanases, 11 isolates produced chitinases and 12 isolates produced siderophores under in-vitro conditions. All these bacterial endophytic isolates inhibited mycelial growth of Pythium aphanidermatum in plate assay and liquid culture and the highest percent inhibition of mycelium was recorded in KMS5 (44.44%) followed by KMS1 (38.89%). In seedling trays, BMR7 and KMS5 (81.66%) had recorded the highest percent germination followed by KMS1 (79.62%) and KMS1 and KMS5 took 10.85 and 10.55 days respectively for 50% seed germination compared to control (13.50 days) which was treated with pathogen alone. Lowest pre-emergence disease incidence was noticed in KMS5 (14.03%) followed by KMS1 (16.18%) whereas T1 (Control) recorded maximum pre-emergence disease incidence (39.82%) was observed. Least post-emergence disease incidence (11.36) and biocontrol efficacy (68.74%) was recorded with KMS5. Apart from showing antagonistic activity, KMS5 had recorded a significantly higher seedling vigor index (2712.97), root length (18.12 cm), shoot length (15.10 cm), root dry weight (0.158 g) and shoot dry weight (0.76 g) compared to other bacterial endophytic isolates.