Allelopathic effect of aqueous extracts of six Crotalania species on w
heat root growth at early growing stage was examined by using a seed p
ack growth pouch. There was a significant difference in total root len
gth of wheat with application of the extract of each species compared
with control at 21 days after planting. C. juncea and C. pallida suppr
essed the length by approximately 40% based on the control. Remarkable
suppression of root growth could be clarified by image-processing of
the root system which appeared on the surface of the pouch. A signific
ant reduction in the length of the longest root was also observed, and
C. juncea and C. spectabilis showed severe reduction. Definite inhibi
tion was observed with the leaf extract compared with the stem extract
in C. spertabilis, and the inhibition was remarkable as the concentra
tion of the extracts increased. Dry weights of both top and root of wh
eat were not influenced by application of C. brevidens, C. juncea, C.
lanceolata and C. pallida. With application of C. spectabilis, however
, top dry weight was restricted to a low value compared with the contr
ol. Fractal dimension of the profile of root system ranged in value fr
om 1.27 to 1.35, and it was not necessarily influenced by the applicat
ion of extract of each species. These results indicated that wheat roo
t growth was inhibited by application of the aqueous extract of Crotal
atia, and the seed pack growth pouch techique might be applied to the
evaluation of allelopathy.