Acquisition of Cu, Zn, Mn and Fe by mycorrhizal maize (Zea mays L.) grown in soil at different P and micronutrient levels

Sustainability of soil-plant systems requires, among other things, good dev elopment and function of mycorrhizal symbioses. The effects of P and micron utrient levels on development of an arbuscular mycorrhizal fungus (AMF) and uptake of Zn, Cu, Mn and Fe by maize (Zen mays L.) were studied. A pot exp eriment with maize either inoculated or not with Glomus intraradices was co nducted in a sand:soil (3:1) mix (pH 6.5) in a greenhouse. Our goal was to evaluate the contribution of mycorrhizae to uptake of Cu, Zn, Mn and Fe by maize as influenced by soil P and micronutrient levels. Two levels of P (10 and 40 mg kg 1 soil) and three levels of a micronutrient mixture: 0, 1X an d 2X (1X contained, in mg kg(-1) soil, 4.2 Fe, 1.2 Mn, 0.24 Zn, 0.06 Cu, 0. 78 B and 0.036 Mo), were applied to pots. There were more extraradical hyph ae at the low P level than at the high P level when no micronutrients were added to the soil. Root inoculation with mycorrhiza and application of micr onutrients increased shoot biomass. Total Zn content in shoots was higher i n mycorrhizal than non-mycorrhizal plants grown in soils with low P and low or no micronutrient addition. Total Cu content in shoots was increased by mycorrhizal colonization when no micronutrients were added. Mycorrhizal pla nts had lower Mn contents than non-mycorrhizal plants only at the highest s oil micronutrient level. AMF increased total shoot Fe content when no micro nutrients were added, but decreased shoot Fe when plants were grown at the high level of micronutrient addition. The effects of G. intraradices on Zn, Cu, Mn, and Fe uptake varied with micronutrient and P levels added to soil .