Screening of potential gibberellin producing Fusarium strains for the hybrid rice production

Nineteen Fusarium strains were screened to select potential strains for the production of gibberellin in the culture media in flasks. Quantitative estimation of gibberellin from different strains of Fusarium was done spectrophotometrically which showed presence of gibberellin in variable amounts. Range of gibberellin production varied between 0.66 to 600 mg g(-1) dry weights of the mycelium. However, most of the strains produced 50-180 mg gibberellin on mycelium dry weight basis. Fungal strains were classified as low producer ((3)100 mg), moderate producer (100-250 mg) and high producer (<250 mg). Thin layer chromatography and high performance liquid chromatographic separation confirmed the presence of GA(3), GA(4) and GA(7) in the sample. Effect of culture filtrate of the three isolates, one from each category (low, moderate and high) showed significant increase in the second leaf length of rice (Pusa 5A CMS Line) and it could be used to produce droopy leaves in male sterile lines for more hybrid rice production.