Abstract

Sunflower is an important oil crop in India. The present study aims to find out the response of biofertilizers and homo-brassinolide on growth, yield and oil content of sunflower (Helianthus annuus L.). The results showed that inoculation of biofertilizers significantly affected plant height, total chlorophyll content and also significantly increased yield attributes viz., thalamus diameter, weight of thalamus, filled seeds capitulum^-1 and 1000 seed weight as well as seed yield, biological yield and oil content. The combined inoculation of Phosphate solubilizing bacteria (PSB) + Vesicular-arbuscular mycorrhizal (VAM) + Azotobacter recorded higher seed yield (3189 and 3263 kg ha^-1) over Azotobacter (1866 and 2073 kg ha^-1), PSB + Azotobacter (2269 and 2421 kg ha^-1) and VAM + Azotobacter inoculation (2545 and 2752 kg ha^-1) respectively, during the both years. Twice sprayings of homo-brassinolide at budding + flowering stages significantly recorded higher value of plant height, total chlorophyll content and yield parameters as compared to brassinolide spraying at budding stage alone. The maximum seed yield (2760 and 2917 kg ha^-1) was obtained from crop receiving both spraying of homo-brassinolide at budding + flowering stages over only one spraying at budding stage (2171 and 2337 kg ha^-1) respectively, during 2010-2011 and 2011-2012.

Key words: Azotobacter, brassinolide, phosphate solubilizing bacteria (PSB), Sunflower, vesicular-arbuscular mycorrhizal (VAM).