Kumar, BijendraMaurya, Nimsha2024-08-242024-08-242023-07Theses of M.Sc.https://krishikosh.egranth.ac.in/handle/1/5810213695Rice (Oryza sativa L.) is the major crop cultivated all around the world and considered as the staple food. The cultivation is impeded by a number of insect-pests and diseases causing a huge economic loss. Brown spot of rice caused by Bipolaris oryzae (teleomorph : Cochliobolus miyabeanus) is one of the major fungal disease leading to significant reduction in quality and quantity of produce. The present investigation was carried to study the variability in the pathogen, in-vitro and field management of the disease and activity of defence related enzymes in response to application of bio-agents. The morphological and molecular variability was studied in isolates obtained from different tehsils of Udham Singh Nagar district. A significant variability was resulted from the isolates of the pathogen in a district. For the management of disease, seven fungicides and four biocontrol agents were tested both under in-vitro and field conditions. Among the fungicides, Tebuconazole 25.9%EC resulted to be the best by inhibiting the maximum mycelial growth under in-vitro conditions and leading to maximum reduction of disease index under field conditions. However, under in-vitro conditions T. harzianum (Pant bioagent-1) was found to the most effective bioagent followed by P. fluorescens (Pant bioagent-2) and under field conditions, the minimum disease index and maximum yield was obtained with the combination of T. harzianum and P. fluorescens (Pant bioagent-1 and Pant bioagent-2). The activity of three defence related enzymes i.e., Phenylalanine ammonia lyase (PAL), Peroxidase (POD) and Polyphenol oxidase (PPO) was found to be maximum in the treatment with spray application of T. harzianum. An integrated management approach with use of effective bioagents and fungicides should be recommended for the disease management.EnglishThesis