Effect of Arbuscular Mycorrhizal fungus inoculation and phosphorus chemical fertilizer on growth characteristics of two annual medics

Endo-mycorrhizal fungi are useful soil microorganisms, which can be used as a biological fertilizer for providing nutrient requirements for plants (particularly phosphorus). Two field experiments were carried out in research farm of Shahrood University of Technology to investigate the effects of one species of arbuscular mycorrhizal fungi (Glomus intraradices) on growth and forage production of two annual medics (Medicago polymorpha and M. scutellata) in different conditions of soil phosphorus. Each experiment was arranged in a factorial randomized complete block design with two treatments of mycorrhizae (with inoculation and without inoculation) and phosphorus fertilizer (0 and 65 kg P/ha) with 4 replications. The results were shown that inoculation of Medicago polymorpha and M. scutellata with Glomus intraradices had positive and significant effect on root colonization, shoot and root dry weight, but had no significant effect on root and shoot length, dry weight and number of sheath. On the basis of the results of this study, mycorrhizal inoculation increased 30% of forage production in both annual medic species Medicayo polymorpha and M. scutellata Application of phosphorous chemical fertilizer also increased forage production as the same amount as mycorrhizal inoculation, but it decreased root mycorrhizal colonization in both plants significantly. With due attention to positive effects of mycorrhizal fungi on forage production of Medicago polymorpha and M. scutellata, it seems that mycorrhizal fungi can be used as a biological fertilizer instead of phosphorus chemical fertilizer, which have no environmental problems compared with phosphorus chemical fertilizer in sustainable agriculture.