Combine selection for earliness and yield in pedigree developed sorghum (sorghum bicolor l. Moench) progenies in eritrea

Thirteen progenies of sorghum (Sorghum bicolor L. Moench) crosses (Amal and ICSV 91078) that selected using pedigree breeding method, were evaluated along with their parental checks to obtain information on yield potential, earliness, genetic and morphological diversity. The genotypes were evaluated in randomized block design with three replications for three years (2007-2009) at Halhale research center. Significant mean squares were obtained for almost all characters in the individual analysis of variance as well as the combined analysis across seasons, suggesting that, these sorghum genotypes were highly variable for almost all the characters studied, therefore, would respond to selection. Mean values for the combined analysis of the progenies showed that Hal-1-1, Hal-4-9, Hal-13-33, Hal-11-30 and Hal-9-24 were promising cultivars in terms of grain yield and earliness. Combined analyses also showed most characters had relatively higher genotypic and phenotypic variance components and little difference between phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) indicating their variation has a genetic origin that can be exploited for further breeding programs. The genotypes also exhibited varying degrees of heritability estimates. Characters such as plant height, days to 50 % flowering and grain yield responded positively to selection because of high broad sense heritability estimates. High heritability and genetic advance was noted for plant height and days to 50% flowering indicating that these parameters were under additive gene effect and responded well for genetic improvement. However, grain weight showed high heritability with low genetic advance indicating that the trait has non additive gene action and might respond well due to its heterosis

Marker-assisted introgression improves Striga resistance in an Eritrean Farmer-Preferred Sorghum Variety

The parasitic weed Striga hermonthica hampers the production of sorghum, the most important cereal crop in Eritrea. This weed has a complex mode of infestation that adapts to many hosts and environments, complicating conventional breeding for resistance, which is the only form of crop improvement available to Eritrean breeders, but has failed. This study aimed at improving resistance against this parasite by transferring 5 Striga resistant Quantitative Trait Loci (QTLs) from resistance donor N13 to Striga susceptible Farmer-Preferred Sorghum Variety (FPSV) Hugurtay from Eritrea. The method involved backcrossing using marker-assisted selection (MAS) and evaluation of the best introgressed lines for Striga resistance in artificially infested fields. Foreground selection was performed with up to 11 polymorphic simple sequence repeat (SSR) markers linked to Striga resistance QTLs, while background selection was conducted in the BC3F2 generation with 27 polymorphic unlinked SSR markers to identify the best recovery of the recurrent parent (RP) genetic background. Out of 84 BC3F3 lines, L2P3-B, L1P5-A and L2P5P35 performed best with respect to both grain yield and reduced Striga infestation. These lines were more resistant to Striga than Hugurtay, but less resistant than N13. The three lines yielded twice as much as N13, with Area Under Striga Number Progression Curve (AUSNPC) values on average 18% higher than that of N13 and 38% lower than that of Hugurtay. This suggests that the introgressed QTLs conferred significant Striga resistance and yield advantage to these BC3F3 backcross progenies under Striga pressure. These lines have good potential for future release and demonstrate that when MAS is available to conventional breeders, even in countries with no genotyping facilities, it is a useful tool for enhancement, expediency and precision in crop improvement