Y. Izumi et al., TIMECOURSE CHANGES IN 2 DIFFERENT TOPOLOGICAL INDEXES WITH SEMINAL ROOT-SYSTEM DEVELOPMENT OF RICE, Nippon Sakumotsu Gakkai Kiji, 65(2), 1996, pp. 303-308
For the topological analysis of plant root systems, two sets of topolo
gical indices have been proposed; the ratios of measured altitude (a)
and total external pathlength (Pe) to the expected value of the respec
tive parameter when lateral root branching is assumed to occur randoml
y {a/E(a), PelE(Pe)} and to the maximum value of the respective parame
ter when all lateral roots emerge from the main root axis (herringbone
type) {a/Max(a), Pe/Max (Pe)}. We traced the timecourse changes in th
ese indices with root system development of two rice cultivars grown w
ith the excised root tip culture method, and evaluated their adaptabil
ity for the actual complexity of the branching pattern. The a/E(a) and
Pe/E(Pe) did not adequately express the progress of complication with
root growth and the difference between cultivars in branching pattern
because root system size substantially affected the values. On the ot
her hand, changes in a/Max(a) and Pe/Max(Pe) showed close correlation
with those in several root developmental characters such as the number
and mean branching order of lateral roots (MBO). Thus, we conclude th
at a/Max(a) and Pe/Max(Pe) are better indices than a/E(a) and PelE(Pe)
for the topological characterization of morphology in the development
al study of rice root systems.