1988 Volume 54 Issue 2 Pages 151-157
The resistance in soybean (Glycine max) and wild soybean (G. sofa) to purple seed stain (Cercospora kikuchii) was studied by using three soybean cultivars (Oshimashirome, Raiden, Hanayome) and one wild soybean line (E-1). Four phases in the infection process, rate of spore germination, elongation of germ tubes, formation of infection structure, and penetration, did not differ among the soybean cultivars. For both resistant soybean cultivar (Hanayome) and wild soybean, the growth of hyphae in pods was not stopped, but slow in speed. In this respect, the resistance in pods of soybean and wild soybean seemed to be derived from the same mechanism. The resistance that actually prevented the hyphal penetration into seeds was caused by hard-coatedness and this was identified only in the wild soybean. On the other hand, the resistance of seed itself was not observed in all the soybean cultivars tested because the fungus, when inoculated directly to seeds, could penetrate the seeds of all the cultivars almost equally. The results indicate that the apparent resistance of seeds of a soybean cultivar, e.g. Hanayome, grown under field conditions is not due to the resistance of seed but to the resistance of pod tissue.