Estimation of plant root lengths during growth
Department of Agricultural and Bioresource Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
Stereological Research Laboratory, University Bartholin Building, University of Åarhus, Århus 8000 C, Denmark
Résumé
The method of “total vertical projections” was applied to develop a non-destructive, unbiased method for estimating total root length from 2D projections of 3D structure in young developing plants. No assumptions regarding the isotropy or randomness of root structure and branching are required. To illustrate the procedures, crested wheat grass plants (Agropyron cristatum L.) were grown in polycarbonate magentas containing a transparent tissue culture medium. Estimates of root length, diameter, and branching were obtained over a four week period at approximately three day intervals. The method of estimating total lengths from vertical projections was found to be very robust with estimated sampling coefficients of error generally less than 5% for 50-100 grid intersection counts. Biological coefficients of variance for total length were between 30-70%, and were largely attributable to variation in the degree of secondary root branching.