Effect of Phosphorus Application and Arbuscular Mycorrhizal Fungi Inoculation on the Growth of American Jointvetch and Greenleaf Desmodium

Corresponding Author: Manabu Tobisa Faculty of Agriculture, University of Miyazaki, Miyazaki, 889-2192 Japan Email: [email protected] Abstract: This study examined the growth and Arbuscular Mycorrhizal (AM) colonization of two tropical forage legumes, namely, American jointvetch (Aj) and Greenleaf desmodium (Gd), at two phosphate application rates (0 or 10 g P m −2 yr −1 ; -P or +P), with or without AM (+AM or -AM) in a pot experiment. AM inoculation and P application promoted the growth of both species. AM inoculation in the early growth stages promoted colonization in both species, but P application did not. Nitrogen and phosphorus concentrations were affected by neither AM inoculation nor P application. Nitrogen uptake in both Aj and Gd, however, was affected by both AM inoculation and P application. Phosphorus uptake was affected by AM inoculation in Aj and by P application in Gd. The results suggest that both P application and AM promoted legume growth and AM colonization was not suppressed by P application. Nevertheless, plant responses to the treatments varied with species and growth stage.