GENETIC IMPROVEMENT OF SORGHUM [SORGHUM BICOLOR (L.) MOENCH] FOR RESISTANCE TO [COLLETOTRICHUM SUBLINEOLIUM (P.) HENN] ANTHRACNOSE DISEASE IN BURKINA FASO
ABSTRACT
Studies were undertaken to ascertain the challenges that cause the low grain yield of sorghum in Burkina Faso, to assess the genetic diversity of the targeted germplasm, to assess the virulence of the biotype of C. sublineolium, to screen for stable resistance to anthracnose across the country, to transfer the resistant genes by introgression into farmers’ preferred varieties and to evaluate the elite progeny for yield performance in two agro ecological zones.
Group discussions and questionnaires were administrated to farmers across 19 provinces covering six regions in the country to assess the major constraints linked to sorghum production and farmers’ varietal preferences. One hundred and twenty accessions were screened in the screen house and field to assess for resistance to Colletotrichum sublineolium. The virulence traits disease incidence, severity index, incidence index and the area under disease progress curved were used to select the resistant genotypes. Also, F1 hybrids were developed by crossing 10 susceptible lines and two stable resistant genotypes. Single seed descent was used to generate seven families of F2 derived F5 progenies (F2:5) that were evaluated in an alpha lattice design with three replications at Kouaré and Saria for yield potential. The results showed that sorghum is a staple food crop for 90% of the farmers surveyed and the cropping systems are mainly monoculture (47%) or associated with cowpeas (46%). Farming is predominantly manual. The main abiotic constraint is drought and 71.3% of the farmers indicated that diseases which mainly appear during the vegetative growth stage were very important. Among the diseases, sorghum anthracnose was ranked first and as second important biotic constraint after Striga. The majority of the farmers (66%) rogued diseased plants as a method of control. Most of the farmers (91%) preferred high yielding varieties with medium maturity, good taste for “tô” (76.7%), white grain colour (79.5%); resistant to disease with good storability of the grains. The accessions evaluated exhibited significant variability for resistance to C. sublineolium virulent pathotypes. Broad sense heritability for grain yield and disease rating was low for the progeny. There is a need to further screen other progeny for disease resistance and for yield stability across more environments.