* To whom all correspondence should be addressed. E-mail: meshilpa99@gmail.com JOURNAL OF PURE AND APPLIED MICROBIOLOGY, Sept. 2015. Vol. 9(3), p. 2591-2596 Effect of Microbial Inoculants on Growth and Yield Parameters in Sunflower (Helianthus annuus) M.E. Shilpa 1 , B. Latha 1 , G. Dakshayini 1 , H.M. Vikas 2 and M. Srikantaiah 1 1 Department of Agricultural Microbiology UAS, GKVK, Bangalore India. 2 Department of Horticulture, UAHS, Bagalkot, India. (Received: 12 April 2015; accepted: 06 May 2015) Sunflower (Helianthus annuus) is an annual species crop for its edible oil and edible fruits used as bird food, as livestock forage as meal or silage plant, and in some industrial applications. Application of Azotobacter chroococcum, Bacillus megaterium, Trichoderma viride as soil application with 100 per cent NPK and Foliar spray of Trichoderma viride has showed maximum germination percentage, increased plant height, number of leaves, stem girth and less number of days to 50 per cent flowering at all the four stages of plant growth viz., 30, 60, 90 DAS and at harvest. Similar trend was also noticed in head diameter, seed yield per hectare, 100 seed weight, and seed volume weight, oil content and residual NPK status of soil. The results of this study has clearly recorded that conjunctive use of Azotobacter chroococcum, B. megaterium and T. viride as soil application and foliar spray of T. viride is advantageous for the growth of Sunflower and to obtain higher crop yields. Key words: Sunflower, Foliar spray, microbial inoculants. Sunflower ( Helianthus annuus ), is belonging to the family of Compositae, is a major oilseed, used for the production of edible oil. At present in India, it is grown in an area of 7.22 lakh hectares with a annual production of 5.00 lakh tones having productivity of 692 kg/ha. Sunflower oil is a source of fatty molecules that can be used as reagents for chemical modifications. Sunflower oil also has excellent nutritional properties. It is practically free of significant toxic compounds and has a relatively high concentration of linoleic acid. This polyunsaturated fatty acid is an essential fatty acid (not synthesized by humans), and is the precursor of gamma-linolenic and arachidonic acids (Seiler 2007).The composition of fattyacids is a main determinant of the oil quality in sunflower. Organic agricultural practices aim to enhance biodiversity, biological cycles and soil biological activity so as to achieve optimal natural systems that are socially, ecologically and economically sustainable (Samman et al. 2008). Soil microbes play an important role in many critical ecosystem processes, including nutrient cycling and homeostasis, decomposition of organic matter, as well as promoting plant health and growth as bio-fertilization (Han et al., 2007). In recent years, biofertilizers have emerged as a promising component of integrating nutrient supply system in agriculture. Our whole system of agriculture depends in many important ways, on microbial activities and there appears to be a tremendous potential for making use of microorganisms in increasing crop production. Microbiological fertilizers are an important part of environment friendly sustainable agricultural practices (Bloemberg et al., 2000).