Arbuscular mycorrhizal fungal isolate effectiveness on growth and root colonization of Panicum virgatum in acidic soil

Arbuscular mycorrhizal fungi (AMF) can enhance plant ability to grow and wi thstand acidic soil induced stresses. Panicum virgatum L. (switchgrass) was grown in pH(Ca) 4 and 5 (soil:10 mM CaCl2, 1:1) soil (typic Hapludult) ino culated with eight isolates of AMF [Glomus (G.) clarum, G. diaphanum, G. et unicatum, G. intraradices, Gigaspora (Gi.) albida, Gi. margarita, Gi. rosea and Acaulospora (A.) morrowiae] to determine the effects of these isolates on plant growth and root colonization. Compared to nonmycorrhizal (nonAMF) plants, mycorrhizal (AMF) plants had as high as 52-fold increases in dry m atter (DM) in pH(Ca) 4 soil and as high as 26-fold increases in DM in pH(Ca ) 5 soil; G. clarum and G. diaphanum plants had the highest DM and Gi. rose a plants had the lowest DM. The AMF plants grown in pH(Ca) 4 soil had highe r DM than in pH(Ca) 5 soil. Root DM decreased more than shoot DM for plants grown in pH(Ca) 5 compared to pH(Ca) 4 soil, which was reflected in shoot- to-root DM ratio changes. Total root length (RL) was similar for plants gro wn in pH(Ca) 4 and 5 soil and varied considerably depending on AMF isolate. Specific RL was higher for AMF plants grown in pH(Ca) 5 than in pH(Ca) 4 s oil. Root colonization [determined as vesicles or arbuscules in root cells (VA), roots with hyphal infections (HI) and total colonization (VA or HI)] varied extensively with AMF isolate. Although percentage root colonization was not directly related to amount of DM, good enhancement of DM did not oc cur unless total colonization was >20%. Some AMF isolates were highly effec tive in overcoming acidic soil constraints and good growth of switchgrass i n acidic soil may depend on root-AMF symbiosis. Published by Elsevier Scien ce Ltd.