A phosphorus-dissolving Aspergillus awamori strain from sugarcane leaf compost for growth promotion of pepper

Abstract:

[Objective] Isolation of strains with high-efficiency of phosphorus-dissolving and growth-promoting functions from sugarcane leaf compost has provided available microbial resources for bio-fertilizers production. [Methods] Phosphorus-dissolving strains were screened from insoluble inorganic phosphorus media containing Ca₃(PO₄)₂ or Zn₃(PO₄)₂, and identified by morphological characteristics and ITS rDNA sequence analysis. The phosphorus-dissolving ability of the strains was determined by the halo zone and molybdenum antimony colorimetric methods, and the growth-promoting ability of the strain was analyzed by pot experiment of pepper. [Results] Strain DC30-2-P1 was screened from the compost and identified as Aspergillus awamori. The diameter of the colony of the strains (d) was 55.33 mm and 45.00 mm, the halo zone (D) was 65.33 mm and 67.67 mm, and the D/d value was 1.16 and 1.50 on the medium with Ca₃(PO₄)₂ and Zn₃(PO₄)₂, respectively. After 96 hours of cultivation in a liquid medium with Ca₃(PO₄)₂ as the phosphorus source, the available phosphorus content reached 2974 mg/L. The results indicated that strain DC30-2-P1 had a significant effect on dissolving phosphorus. The results of the pot experiment show that the inoculation of DC30-2-P1 promoted the growth of pepper. Compared with the treatment group without phosphate solubilizing fungi, the above-ground fresh and dry weight increased by 18.6% and 43.5%, the under-ground fresh and dry weight increased by 30.2% and 25%, plant height increased by 13.6%, and chlorophyll content increased by 44.9%, both plant total phosphorus content and soil available phosphorus content increased by more than 80%. [Conclusion] Strain DC30-2-P1 from sugarcane leaf compost has a high efficiency on dissolving insoluble phosphorus compounds, promoting the absorption of phosphorus and improving crop yield.