Susceptibility to ergot in Zimbabwe of sorghums that remained uninfected in their native climates in Ethiopia and Rwanda uri icon

abstract

  • Forty-four local Ethiopian and Rwandan sorghums (Sorghum bicolor) were observed to remain free ofergot, or had only low incidence, in their natural equatorial latitudes and were potentially of interest, inthe design of male-sterile lines for F| hybrid breeding, if they possessed a physiologically based resistancemechanism. These sorghums were therefore also investigated under natural and artificial diseasepressures in Zimbabwe where unadapted development and inappropriate long daylengtb preventedflowering in 18 accessions. Of the remaining 16 Ethiopian and 10 Rwandan accessions which flowered,only one from each country remained free of ergot. The susceptibility expressed was ascribed to observedasynchrony of stigma exsertion with anthesis. In the Rwandan accession that persistently remained freeof ergot in Zimbabwe, histology of ovules showed pollination before floret gaping, so that a generalprinciple of disease escape due to efficient pollination is proposed for the Ethiopian and Rwandansorghums in their native climates. The findings emphasize that cleistogamy is a desirable character foravoiding ergot infection in self-fertile sorghums and suggest that the Ethiopian and Rwandan sorghutnsmay not generally be useful for breeding ergot-resistant male-sterile female lines. However, a fewaccessions deserve more detailed study as a potential genetic resource, before a firm conclusion that allapparent resistance is disease escape owing to efficient pollination

publication date

  • 1994
  • 1994