Maize response to phosphate rock and arbuscular mycorrhizal fungi in acidic soil

Plants grown in acidic soils often have reduced productivity because of lim ited mineral nutrients. For plants to obtain adequate nutrients under these conditions, some source of fertilizer is commonly added or a method to mak e nutrients more available to plants, such as mycorrhiza, is needed. Maize (Zea mays L.) was grown in acidic soil (pH, 4.7, soilwater, 1:1) with added phosphate rock (PR) and the arbuscular mycorrhizal fungus (AMF) Glomus cla rum to determine the effectiveness of AMF and PR for supplying nutrients, e specially P. Plants were grown in a growth chamber and harvested when plant s had grown in treated soil 15, 22, 29, and 36 d. Plant dry matter (DM) was greatly enhanced by PR, and even more at each harvest when roots were colo nized with AMF (AMF+PR). Shoot DM increased more than root DM with PR (PR a nd AMF+PR) treatments. Total root length (RL) was greater for plants grown with PR and AMF+PR compared to the Control (no added P or AMF) and AMF plan ts. Colonization of roots by AMF was higher for AMF+PR than for AMF plants. Acquisition of P followed the sequence of AMF+PR > PR much greater than AM F > Control. Other nutrients commonly limiting in acidic soil [e.g., calciu m (Ca), magnesium (Mg), and potassium (K)] were greatly enhanced in AMF com pared to nonmycorrhizal (nonAMF) plants. The AMF plants had 2-3-fold greate r inflow rates [inflow = mug nutrient m(-1) RL day(-1)] of Ca, Mg, copper ( Cu), zinc (Zn), and boron (B) than nonAMF plants. The application of PR and /or AMF colonization decreased the concentrations of iron (Fe), manganese ( Mn), and aluminum (Al) in the shoots. The lower specific accumulation rate [SAcR= mug nutrient g(-1) shoot DM day(-1)] of Fe, Mn, and Al in the shoots indicated a possible precipitation or/and formation of metal-organic compl exes in the roots. Application of PR to this acidic soil did not inhibit ma ize response to AMF, and both PR and AMF were important for optimal growth of maize in this acidic soil.