Techniques for Determining Root Length Infected by Vesicular‐arbuscular Mycorrhizae

Abstract

Abstract Techniques were adapted and combined to estimate root lengths and total root length with vesicular‐arbuscular (VA) mycorrhizal infection. Steps include separating roots quantitatively from known volumes of soil, cutting roots into short segments to allow subsampling and mounting, clearing tissue in 10% KOH, staining fungi with trypan blue, subsampling root segments suspended in glycerol by using a syringe, spreading root segments in a counting/observation chamber (made easily from 80 × 100 mm lantern‐slide cover glasses), and line‐intersection counting of segments during microscopic examination. Root lengths with and without fungal infection are calculated from the counts. Root hairs, tips, branching, diameters, cell outlines, and condition of the cortex and stele are microscopically visible in the cleared, stained roots. Consequently, the method offers potential for quantifying several important root characteristics. Data collected from roots of Festuca arundinacea Schreb. are presented as an example.