INTERACTIONS OF ARBUSCULAR MYCORRHIZAE, MELOIDOGYNE-ARENARIA, AND PHOSPHORUS FERTILIZATION ON PEANUT

The individual and combined effects of two arbuscular mycorrhizal fung i (AMF), Meloidogyne arenaria, and phosphorus (P) fertilization, (0, 2 5, 75, and 125 mu g/g soil) on peanut plant growth and pod yield were determined in greenhouse studies. Best growth and yield usually occurr ed at 75 or 125 mu g P regardless of inoculation treatment. Peanut gro wth and yield were generally stimulated by AMF development, and growth alone was suppressed by M. arenaria at 0 and 25 mu g P. In challenge inoculations, VAM increased peanut plant tolerance to the nematode and offset the growth reductions caused by M. arenaria at the two lower P levels. However, VAM and added P increased galling and M. arenaria eg g production/g root, thereby increasing peanut susceptibility to nemat ode attack. M. arenaria had only a minimal effect on root colonization by AMF and sporulation by the fungi.