Root length density is root length per unit of soil volume.
Root length can be estimated by the equation:
R = Pi AN / 2H
Where R is the total length of the roots in area A of the petri dish, and N is the number of intersections between the roots and random horizontal grid lines of total length H.
For more details and the method for developing this equation to other equations, see the pages contained in the following link:
I am doing review about plant root length but the most of papers do not provide this information. The papers usually provide root length density. So I want to calculate the root length using root length density. May you help me?