Kushal RajSangwan, Pooja2022-11-142022-11-142019-12https://krishikosh.egranth.ac.in/handle/1/5810189868Pearl millet is a valuable staple food in semi-arid regions of the world. Pearl millet is affected by many diseases among them, downy mildew incited by oomycetes pathogen Sclerospora graminicola (Sacc.) Schroet is the most widespread and destructive disease of pearl millet. Endophytes play an important role in metabolism and physiology of the host plants. They provide multifarious benefits such as growth promotion, suppression of pathogens and nitrogen fixation. In the present study, roots and stubbles were collected from sick plot area of Bajra Pathology after the harvest of the pearl millet crop during Kharif 2016 and 2017. A total of 30 pearl millet root bacterial endophytes (PMRBE1- PMRBE 30) were retrieved from crushed roots of pearl millet streaked on Nutrient agar plates. Ten endophytic bacterial isolates were retrieved from roots of kharif 2016 crop and other twenty isolates from roots of kharif 2017 crop. All endophytic bacterial isolates were assessed for biocontrol activities. Amongst 30 pearl millet root bacterial endophytes, sixteen isolates were positive for siderophore production, three isolates viz. PMRBE6, PMRBE25 and PMRBE28 were found positive for HCN production, 30% of the bacterial endophytes showed good growth on ACC supplemented plates and cellulolytic activity was found in bacterial endophyte PMRBE18. The isolates PMRBE1, PMRBE4, PMRBE5, PMRBE6, PMRBE7 PMRBE17, PMRBE18, PMRBE20, PMRBE23 and PMRBE24 which showed maximum germination, seedling vigour index I & II and germination speed of three pearl millet cultivars HHB226, HHB67 Imp and 7042 S under in vitro conditions were selected for seed treatment as well as for foliar spray under screen house and field conditions. Amongst various pearl millet root bacterial endophytes, maximum germination, minimum downy mildew incidence at 30 and 60 DAS, better growth and yield of pearl millet cultivars were found on treatment with isolate PMRBE6, PMRBE18 and PMRBE23. On the basis of biochemical characterization and partial 16S rRNA sequencing pearl millet root bacterial endophytic isolates PMRBE6, PMRBE18 and PMRBE23 were identified as Bacillus subtilis strain PD4 (Accession no. MN400209), Serratia sp. and Alcaligenes faecalis strain HX2016003 (Accession no. MN400208). Promising root endophytes may be used for IPM of downy mildew in pearl millet after field trials.EnglishThesis