| Summary: | Greenhouse evaluation of 42 accessions/cultivars of Capsicum spp. to bacterial wilt caused by Ralstonia
solanacearum revealed that the Malaysian local cultivar 'Kulai' was highly resistant. Three accessions, namely
CO 1969, CO 1970 and CO 1553, were moderately resistant; all other accessions were susceptible to highly
susceptible. Anatomical study of resistant and susceptible cultivars indicated significant differences in certain
anatomical characters. The number of vascular strands per root was fewer, the cortex was thicker, and the length
of xylem elements was shorter in the roots of resistant cultivars than the susceptible cultivar. The average number
of vascular bundles per plant and the number of xylem elements per vascular bundle were fewer and the length
and diameter of xylem elements were shorter in the mid-stem of resistant cultivars. These anatomical characters
of resistant plants may contribute to limit or slow down the infection process, movement and multiplication of
the pathogen. Multiplication ofR. solanacearum at mid-stem, collar and tap root in stem-inoculated susceptible
and resistant chilli cultivars revealed that in susceptible cultivars the bacterial population did not differ at all
sites tested, but it differed significantly between cultivars at similar sampling sites. These findings show that the
mechanism of resistance to the disease is mainly due to the reduced rate of multiplication of the pathogen within
the resistant host.
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