Marker assisted introgression of strigaresistance into Farmer preferred Sorghum variety (ochuti)
Abstract
Sorghum is the second most important cereal crop in East Africa and the 4th most
important cereal crop worldwide. Striga is the key biotic constraint of sorghum and millet
in this region with reported yield reductions of up to 100%. Efforts to control Striga
through agronomic practices such as mechanical weeding, use of cover crops and trap
crops, use of chemicals, early planting have proved futile. Breeding for resistance using
conventional methods has also been used with limited success. There have been advances
in breeding with the utilization of molecular markers tightly linked to Striga resistance
quantitative trait loci (QTL) in marker assisted selection (MAS). In this study, Striga
resistance was introgressed from a resistant sorghum variety, N13 into a farmer preferred
sorghum variety in Kenya, Ochuti. This was introgressed into two backcross line 11 and
34 of BC2F3 generation. Nine plants were identified having one QTL in BC2F3, these
materials were advanced to BC3F1 through MAS and four plants were identified each
having one QTL. The number of plants advanced from one generation into the next was
considerably low. This may have been the reason why there were fewer plants being
identified with the Striga resistance. On station trials were carried out in Alupe and Kibos
which are the hot spots for Striga in Kenya. Area under Striga Number progressive Count
(AUSNPC) was used as a measure of resistance. The backcross genotypes gave lower
Striga scores as compared to the susceptible check Ochuti. Line 34 however performed
better than line 11. Yield was negatively correlated with AUSNPC. This correlation
however was of -0.4 to -0.5. Of interest were factors such as stand count, host damage
rate, plant height and plant tillering which varied significantly between the genotypes and
the locations.
Citation
Masters of Science Plant Breeding and genetics degreePublisher
University of Nairobi Department of Plant Science and Crop Protection
Description
A thesis submitted in partial fulfillment of the requirements for the
award of a Masters of Science Plant Breeding and genetics degree,
University of Nairobi