Effect of Nitrogen Form on the Effectiveness of a Phosphate-Solubilizing Fungus to Dissolve Rock PhosphateMitiku Habte1 and Nelson Walter Osorio2*
- *Corresponding Author:
- Nelson Walter Osorio
Universidad Nacional de Colombia
Calle 59A No. 63-20, Of. 14-216, 050034, Medellín, Colombia
E-mail: [email protected]
Received date: September 11, 2012; Accepted date: October 16, 2012; Published date: October 18, 2012
Citation: Habte M, Osorio NW (2012) Effect of Nitrogen Form on the Effectiveness of a Phosphate-Solubilizing Fungus to Dissolve Rock Phosphate. J Biofertil Biopestici 3:127. doi:10.4172/2155-6202.10000127
Copyright: © 2012 Habte M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
An in vitro experiment was carried out to evaluate the effect of nitrogen (N) form (NH4+ and/or NO3-) on the dissolution of rock phosphate (RP) by a phosphate solubilizing fungus (PSF) identified as Mortierella sp. In the presence of NH4Cl or NH4NO3, the solution of pH significantly decreased from an initial value of 7.6 to 3.4 and 3.7 respectively. In the presence of KNO3, the pH went down only to 6.7. As a result, significantly more P was detected in solution in the presence of NH4Cl (129.65 mg/L) than in the presence of NH4NO3 (109.25 mg/L). The concentration of P in solution in the presence of KNO3 was only 0.08 mg/L. The excess of NH4+ adversely affected the growth of Mortierella sp. However, this may have promoted a more active H+-pumping that decreased solution’s pH. In the presence of NO3- as the only source of N, Mortierella sp. not only dissolved a small amount of Pi from the RP but also immobilized most of it into its mycelia. In contrast, in the presence of NH4Cl, Mortierella sp. was effective to dissolve RP and the Pi released remaining in solution while only a little portion was immobilized by the fungal mycelia.