Responses of Lentil to Co-Inoculation with Phosphate-Solubilizing Rhizobial Strains and Arbuscular Mycorrhizal Fungi

ABSTRACT

The purpose of this study was to evaluate the responses of lentil (Lens culinariscv. ‘Ziba’) to co-inoculation with arbuscular mycorrhizal (AM) fungi and some indigenous rhizobial strains varying in phosphorus (P)-solubilizing ability in a calcareous soil with high pH and low amounts of available P and nitrogen (N). A factorial experiment with completely randomized block design was conducted under controlled greenhouse conditions. The treatments consisted of (1) three inoculants of Rhizobium leguminosarum bv. viciae strains and a mixed rhizobial inoculant with an effective P-solubilizer strain of Mesorhizobium ciceri, (2) two AM fungal species, Glomus mosseae and Glomus intraradices, (3) two P sources, superphosphate and phosphate rock. Four replications were prepared for each treatment and a related control. After the growth period of three months, the dry matter of shoots plus seeds, their P and N contents, and percent of root colonized by AM fungus were measured. The results showed that the effects of AM fungi, rhizobial strains, and P fertilizers were highly significant (p < 0.01) for all the characteristics studied. The rhizobial strain with P-solubilizing ability showed a more beneficial effect on plant growth and nutrient uptake than the strain without this ability, although both strains had similar effectiveness for N₂-fixation in symbiosis with lentil. Synergistic relationships were observed between AM fungi and some rhizobial strains that related to the compatible pairing of these two microsymbionts. The P-uptake efficiency was increased when P fertilizers were applied along with AM fungi and/or P-solubilizer rhizobial strains.

Keywords:

• co-inoculation
• phosphate-solubilizing rhizobial strains
• arbuscular mycorrhizal fungi (AMF)
• lentil

ACKNOWLEDGMENTS

Financial support for this investigation provided by grants from the Iranian Ministry of Science, Research and Technology, the Center of Excellence in Soil Science, and the “Studies and Researches Between Universities” program is gratefully acknowledged.

Notes

∗HD: halo diameter (mm) and CD: colony diameter (mm).

∗,∗∗Significant at 0.05, 0.01 probability level, respectively.

∗∗Significant at 0.01 probability level.