The present work was directed towards evaluating the potential of Nostoc entophytum and Oscillatoria angustissima as biofertilizers for barley seedlings, with emphasis on their substitution of the costly chemical fertilizer in pot experiments. Inoculation of a suspension of both species and their combination of the two species did not change the germination percentage (100%) of barley seedlings and significantly stimulated the other measured growth parameters and photosynthetic pigments. Addition of 1% Nostoc entophytum combined with 100% chemical fertilizer induced the highest stimulation in all pigment fractions (chl.a, chl.b and carotenoids), protease and amylase activities. However, the combination between cyanobacterial mixture and the recommended dose or half the recommended dose of chemical fertilizer produced the highest stimulation in carbohydrates (D.R.V. and T.R.V.), nitrogen and phosphorus content of barley seedlings. Biofertilization combined with half the recommended dose of the chemical fertilizer was usually more effective than the addition of the full rate of chemical fertilizer, which may save 50% of the costly chemical fertilizer. Analysis of the two tested cyanobacteria showed that nitrogen fixation capacity, production of exopolysaccharides, contents of auxin and cytokinin were higher in N. entophytum than O. angustissima, whereas the latter contained more gibberellins. These data may explain the different influences of the two cyanobacteria on growth of barley seedlings.
Key words: Barley, Biofertilizers, Cyanobacteria, Plant growth, Phytohormones
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