Purpose of description

TSPM 91018 was released as Okoa in 1994 by the Ministry of Agriculture and Livestock Development, Government of Tanzania, for general cultivation in the country.

Origin and development

TSPM 91018 was developed by the Southern African Development Community (SADC)/ ICRISAT Sorghum and Millet Improvement Program (SMIP) at Matopos Research Station, Zimbabwe, f r om a local germplasm population, Halale. Eighteen accessions, including Halale, were identified in a yield trial involving 961 populations during the 1988/89 cropping season. Sibbing of selected progenies of Halale was done in an isolation block in 1989/90. In 1990, Halale was further treated as a composite population in an off-season nursery and 200 S1 progenies were selected for evaluation in a nonreplicated nursery in 1990/91. The top-yielding 7.5% (15) progenies were recombined by hand-sibbing in a diallel fashion to constitute TSPM 91018 in the 1991 off-season. TSPM 91018 was progressively improved from 1991 to 1993. Plant-to-plant crosses of high-tillering, and longpanicled synchronous-tillering plants were made in the 1992 cropping season. Bulk pollen from selected plants was crossed on to each of the plants and 300 crosses were separately harvested. During the 1992 off-season, selected plants were sown as progeny in rowsalternating w i th a bulk constituted from all progenies. Pollen from bulk rows was crossed on to plants in progeny rows and the crosses were harvested and bulked together. In 1993,harvested crosses were random-mated in isolation. Weaker plants were eliminated. Seeds of TSPM 91018 were multiplied under irrigation in an isolation block during the 1993 offseason. It took seven generations (3.5 years) of recurrent selection to constitute TSPM 91018 f r om its original germplasm population.