Objective To explore how the symbiosis between the phosphorus-solubilizing fungus PDRF3 (Lecanicillium huhutii) and P. edulis promotes the growth of P. edulis under phosphorus-limited conditions in southern red soil regions.

Methods Pot experiments were conducted under controlled conditions, with different phosphorus sources (calcium phytate and tricalcium phosphate), phosphorus concentration levels (2.5~25.0 mg·kg⁻¹), inoculation frequencies (5 times), and fungal treatments (PDRF3 inoculation:+PDRF3; non-inoculated control: −PDRF3). The colonization of PDRF3 in P. edulis roots was quantified using qPCR technology. The effects of each treatment on the growth indices of P. edulis were analyzed. Weighted correlation analysis, range analysis, and response surface methodology were employed to screen and optimize the optimal infection conditions, and the optimized conditions were then used in a subsequent controlled pot experiment to explore the effects of the PDRF3-P. edulis symbiotic relationship on root growth and phosphorus utilization under different phosphorus conditions.

Results (1) PDRF3 rapidly established a symbiotic relationship with P. edulis, promoting increases in seedling height, root growth, internal phosphorus content, and soil available phosphorus content; (2) the optimal infection conditions were determined to be two inoculations at a phosphorus concentration of 10 mg·kg⁻¹; (3) the PDRF3 symbiosis significantly enhanced root activity and phosphorus content in P. edulis (p < 0.05), with maximum increases of 199.60% and 210.48%, particularly under low- phosphorus conditions (2.5 mg·kg⁻¹, 5 mg·kg⁻¹; p < 0.05).

Conclusion The rapid establishment of the symbiotic relationship between PDRF3 and P. edulis improves root activity, promote root elongation, effectively alleviate soil phosphorus limitations, and enhances P. edulis growth.