Potential Microbial Consortium for Plant Growth Promotion of Sunflower (Helianthus annuus L.)

Bioinoculants are formulations of beneficial microorganisms used to promote plant growth. Their mode of action includes nutrient solubilisation, phytohormone production and antifungal activity, etc. In the recent years there is a steady increase in demand for these bioinoculants as a means to reduce use of chemical fertilizers and pesticides. This study was conducted to evaluate Azospirillumbrasilense (ASP20), Azotobacterchrococcum (AZB 29), Bacillusmegaterium var. phosphaticum (PSB037) and Trichodermaviride (CRITV01) for their ability to solubilise nutrients and to develop a microbial consortium for plant growth promotion in sunflower. B. megaterium var. phosphaticum showed 29.6, 49.3, 6.7, and 14.1 % solubilisation in vitro in agar medium amended with tri-calcium phosphate, potassium aluminium silicate, zinc oxide and zinc carbonate. Similar solubilisation potential was also observed in broth cultures amended with the same substrates. Liquid consortium formulation showed better shelf life (4.8 to 8.6 × 108 cfu ml−1) after 60 days of formulation than other formulations. However, macro-encapsulated bioinoculants showed significant growth promotion in sunflower after 60 days of sowing. © 2014, The National Academy of Sciences, India.