Evaluation of mycorrhizal fungus and phosphate rock effectiveness on growth and uptake of phosphorous in soybean (Glycine max (L.) Merr.)

It is necessary to use the phosphate rock (PR) because of the globally increasing chemical phosphate fertilizers price and huge resources of domestic PRs. There is a negligible knowledge on mycorrhizal fungi and native PRs sources influence on phosphorous uptake. Therefore a pot experiment was carried out to investigate the effect of mycorrizal fungi on enhancement of phosphate uptake from native PRs sources in soybean in 2010. Experiment was factorial with four replicates. Factors were included none-inoculation (M0) and inoculation (M1) to mycorrhizae plus five sources of phosphate (B1: control without phosphate amendment, B2: standard phosphate fertilizer from triple superphosphate, B3: Yazd rock phosphate, B4: Yasouj rock phosphate and B5: Gafsa rock phosphate from Tunisia). Results showed Gafsa PR produced the highest phosphorous concentration of root and shoot, shoot nitrogen and dry matter among the applied PRs. In the Gafsa rock phosphate inoculated by mycorrhiza phosphorous uptake was higher than other PRs. Gafsa inoculated to mycorrhiza, had the maximum relative agronomic effectiveness based on phosphorus uptake (60.54%) and relative agronomic effectiveness based on shoot dry matter (39.65%). Mycorrizal colonization index in Gafsa was higher than other PRs. Generally, mycorrhiza markedly increased phosphorus uptake from Gafsa PR more than the domestic PRs.