Effect of single and dual inoculations of arbuscular mycorrhizas on soil phosphatase, growth, and root colonization of tomato

Soil phosphatase, growth and root colonization of tomato treated with two strains of arbuscular mycorrhizal fungi (AMF) - Rhizophagus irregularis and Rhizophagus intraradices in single and dual inoculations were investigated. The experiment was set up in a completely randomized design with four treatment groups: R. irregularis (R.irr), R. intraradices (R.int), R.irr+R.int, and uninoculated (control), for six weeks in a greenhouse, after which the plants were harvested. The data collected on soil acid phosphatase, root colonization, growth indices and shoot phosphorus (P) concentrations were analyzed using one-way ANOVA at 95% probability level. Soil acid phosphatase and shoot P concentrations were significantly (p < 0.05) increased by AMF inoculation, with higher phosphatase values in dual inoculation (0.43 μg g−1) compared to the single inoculation of R.irr (0.32 μg g−1) and R.int (0.34 μg g−1), and the control (0.14 μg g−1). Compared to the control, R.irr and R.irr+R.int significantly increased the shoot fresh weights and total dry weights, while plant lengths and number of leaves were highest in dual inoculation. However, the intensity of mycorrhizal colonization (41.32%, 20.57% and 38.18%) recorded for R.irr, R.int, and R.irr+R.int, respectively, and the corresponding growth responses (30.99%, 24.56% and 27.48%), were not significantly (p > 0.05) different between single and dual inoculated plants. Although a significant synergistic effect on host colonization and biomass indices was not obtained, dual inoculation of R. irregularis and R. intraradices induced more soil phosphatase production in tomato rhizosphere than single inoculation.