Enhancement of clover growth by inoculation of P-solubilizing fungi and arbuscular mycorrhizal fungi

This study evaluated the synergism between several P-solubilizing fungi isolates and arbuscular mycorrhizal fungi to improve clover (Trifolium pratense) growth in the presence of Araxa apatite. Clover was sown directly in plastic pots with 300g of sterilized washed sand, vermiculite and sepiolite 1: 1: 1 (v: v: v) as substrate, and grown in a controlled environment chamber. The substrate was fertilized with 3 g L-1 of Araxa apatite. A completely randomized design, in 8 x 2 factorial scheme (eight P-solubilizing fungi treatments with or without arbuscular mycorrhizal fungi) and four replicates were used. The P-solubilizing fungi treatments consisted of five Brazilian P-solubilizing fungi isolates (PSF 7, 9, 20, 21 and 22), two Spanish isolates (Aspergillus niger and the yeast Yarowia lipolytica) and control (non-inoculated treatment). The greatest clover growth rate was recorded when Aspergillus niger and PSF 21 were co-inoculated with arbuscular mycorrhizal fungi. Aspergillus niger, PSF 7 and PSF 21 were the most effective isolates on increasing clover growth in the presence of arbuscular mycorrhizal fungi. Greater mycorrhizal colonization resulted in greater clover growth rate in most PSF treatments. PSF 7 was the best isolate to improve the establishment of mycorrhizal and rhizobia symbiosis.