Effects of phosphate-solubilizing microorganisms on strawberry yield and nutrient concentrations

Phosphorus (P)-solubilizing bacteria and fungi can increase soil-P availability, potentially enhancing crop yield when P is limiting. We studied the effectiveness of Bacillus FS-3 and Aspergillus FS9 in enhancing strawberry (Fragaria x ananasa cv. Fern) yield and mineral content of leaves and fruits on a P-deficient calcareous Aridisol in Eastern Anatolia, Turkey. The 120 d pot experiment was conducted in three replicates with three treatments (Bacillus FS-3, Aspergillus FS9, control) and five increasing rates of P addition (0, 50, 100, 150, and 200kg P ha(-1)). Fruit yield and nutrient content of fruits and leaves and soil P pools were determined at the end of the experiment. Phosphorus-fertilizer addition increased all soil P fractions. Strawberry yield increased with P addition (quadratic function) reaching a maximum of 94 g pot(-1) at 200 kg P ha(-1) in the absence of P-solubilizing microorganisms. At this yield level, Bacillus FS-3 and Aspergillus FS9 inoculation resulted in P-fertilizer savings of 149 kg P ha(-1) and 102 kg P ha(-1), respectively. Both microorganisms increased yields beyond the maximum achievable yield with sole P-fertilizer addition. Microorganism inoculation increased fruit and leaf nutrient concentrations (NI, P, K, Ca, and Fe) with the largest increases upon addition of Bacillus FS-3. We conclude that Bacillus FS-3 and Aspergillus FS9 show great promise as yield-enhancing soil amendments in P-deficient calcareous soils of Turkey. However, moderate additions of P fertilizer (50-100 kg ha(-1)) are required for highest yield.