Effects of inoculation with arbuscular mycorrhizal fungi and rhizobia on growth of Medicago sativa in acidic soil

Experiments were performed to test the effects of arbuscular mycorrhizal fungi (AMF) and rhizobia on the growth of Medicago sativa (alfalfa) with a variety of soil pH in a greenhouse. Plants were inoculated with Glomus intraradices (AMF), Sinorhizobium medicae (rhizobium), both, or neither, under four different soil pH treatments (4.43, 5.06, 6.43, and 7.16). Acid stress inhibited alfalfa growth, such that plant height was decreased 1.27%~10.13% and biomass decreased 33.33%~55.56%. AMF alleviated acid stress and promoted alfalfa plant height by 244.26%~294.17%, shoot biomass by 727.78%~1 737.50%, root biomass by 1 120%~2 220%, root length by 39.85%~102.63%, root: shoot ratio by 5.71%~90.32%. Inoculation with rhizobia alone did not significantly affect alfalfa growth(P>0.05), but the co-inoculation of AMF and rhizobia significantly increased alfalfa growth(P<0.05).