Effect of Inoculation With Endomycorrhizal Fungi(VAM) and Rhizobium mililoti on Nodulation,Nutrition and N2-fixation of Alfalfa Grown on Calcareous Soil

Abstract

The effect of dual inoculation with endomycorrhizae and Rhizobium mililoti on the nodulation,nutrients uptake and symbiotic N2-fixation of alfalfa grown on calcareous soil was studied in a pot experiment under different levels of phosphate sources( either superphosphate or rock-phosphate). Results have shown that inoculation with both Rhizobium mililoti and VA-mycorrhizae significanly increased the nodulation, N2-ase activity,plant growth, P and miconutrients uptake and nitrogen contents of the plants. Application of rock-phosphate rather than superphosphate stimulated the abovementioned parameters. Superphosphate depressed the root-colonization with VAM and affected the nodulation and the symbiotic N2-fixation to some extent compared with rock-phosphate. Application of micronutrients namely Fe+++ and Mo has no observed effect on the nodulation and N2-fixation of alfalfa plants inoculated with both endomycorrhizae and Rhizobium , while it has stimulatory effect on those not-treated with VAM. Therefore,mycorrhization of alfalfa plants together with R. mililoti -inoculation are highly recommended when such plants are grown in arid calcareous soil to improve the nodulation,plant growth, P uptake and consequently the symbiotic N2-fixation.