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Infection Unit Method of Vesicular‐Arbuscular Mycorrhizal Propagule Determination
Author(s) -
Franson Raymond L.,
Bethlenfalvay Gabor J.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300030020x
Subject(s) - propagule , glomus , biology , infectivity , phycomycetes , mycorrhiza , horticulture , botany , veterinary medicine , inoculation , symbiosis , bacteria , virology , virus , medicine , genetics
A method is presented for quantifying infectivity of vesicular‐arbuscular mycorrhizal (VAM) fungal inocula by directly counting infection units in roots. Inocula of five isolates of VAM fungi [ Glomus etunicatum Becker and Gerd., Glomus pallidum Hall, and Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe from California, Florida and Nevada] were assessed. Sorghum bicolor L. was grown for 14 d under controlled conditions in 100 mL growth tubes containing 48, 12, 3, or 0.75 g of each inoculum (96, 24, 6, or 1.5 for G. etuicatum ) mixed with sterile soil to provide a total growth medium of 96 g. Discrete infection units were found for all isolates at all inoculum density levels, except for G. etunicatum (no infection at lowest density) and G. mosseae ‐California (coalescing infection units at highest density). The relationship between inoculum density and discrete infection units per gram root fresh weight was linear ( P < 0.01). This relationship is particularly suitable for determining amounts of inocula of equivalent potential for use in short‐term experiments.