It is my pride to express my sincere gratitude and profound appreciation to Professor Dr. Durga Mani Gautam, Department of Horticulture, IAAS, Rampur for his invaluable guidance, suggestions, support, constant encouragement and continuous cooperation throughout the entire course of the investigation and his constructive comments and assistance for preparing this dissertation. I extend my heartiest sense of admiration and gratitude to the members of my advisory committee, Prof. Dr. Moha Dutta Sharma (Department Horticulture), IAAS, Prof. Dr. Resham Bahadur Thapa (Department of Entomology), IAAS and Principal Scientist Dr. Krishna Prasad Paudyal (Horticulture Research Division), NARC for their technical guidance, support and constructive suggestions during the research work and preparation of this dissertation. I would like to express my deepest thanks to my beloved wife Bhabani Pandey, son Sandeep Pandey and daughter Sangeeta Pandey for their patience, sacrifices, continuous encouragement and inspiration in me which were great motivations to complete this whole research and publication work.