No abstract

Tef [Eragrostis tef (Zucc.) Trotter] is an important food staple cereal crop in Ethiopia. Despite its importance in the Ethiopian agriculture, there are constraints that need to be addressed through scientific research. The major constraints are low yield of landrace cultivars under widespread cultivation, susceptibility to lodging and a lack of knowledge concerning the genetic control of agronomic traits. Conventional tef breeding efforts started in the late 1950s, and since then a total of 24 varieties have been developed and released. Yield gain from tef breeding has been linear with an average annual increase of 0.8%. Tef genomics has provided much molecular genetic information on important agronomic traits. More than 1500 PCR-based molecular markers have been developed and several genetic linkage maps based on intra-and inter-specific crosses have been constructed. Results from quantitative trait loci studies have provided information necessary for marker-assisted selection. Lodging is the number one cause of yield loss in tef. Recently, molecular breeding techniques and biotechnologies are being employed to understand the genetic control of lodging.

One hundred and twenty tef Eragrostis tef (Zucc.) Trotter, germplasm lines from eight regions of Ethiopia were field evaluated in two randomized complete blocks at Debre Zeit and Melkassa during the 1995/96, and at Debre Zeit and Alem Tena during the 1996/97 main seasons. The objectives were to assess the extent and pattern of their diversity with respect to 17 pheno-morphic and agronomic traits, and to obtain an insight into the broad sense heritability (H) and genetic advance (GA) expectations of the various traits. Discernible (p < or = 0.05) variability among regions and among genotypes within regions were observed in seven and nine of the traits, respectively. In the combined analysis of variance over environments, genotypes showed substantial (p < or = 0.05) variation in all traits, and genotypes and environments interacted significantly on nine of the traits. The phenotypic and genotypic coefficients of variation varied in that order from about 3% for days to maturity to 28% for grain yield/plant, and from less than 2% for days to maturity to 15% for number of fertile tillers/plant. Estimates of H were lowest for shoot phytomass/plant (17%) and highest for panicle length (75%). The minimum GA expectations were for days to maturity (2%) and the maximum was for number of fertile tillers/plant (23%). About 67% of the gross phenotypic diversity in the germplasm was explained on the basis of four principal components (PCs). Up to 28% of the variance extracted by the first PC was due mainly to variations in the second and first basal culm internode diameters, culm and panicle length, days to panicle emergence, and number of panicle branches and fertile tillers/plant. Largely variations in the length of the two basal culm internodes and grain yield/plant contributed to 19% of the whole variance accounted for by the second PC. Generally, the study showed that there is ample genetic variation in the genotypes evaluated and this presents a valuable base for use in the improvement work.

A yield potential experiment was conducted with one farmers' variety and 10 improved varieties released over the periods 1960-1995 to estimate the progress made in improving grain yield potential and to determine changes produced on agronomic traits associated with genetic yield potential improvement. The experiment was conducted at the Debre Zeit Agricultural Research Center, Debre Zeit, Ethiopia, on two soil types in the 1997 main cropping season, using a randomized complete block design with three replications. Evaluation of cultivars from different eras in a common environment has been used to estimate breeding progress. Optimum levels of fertilizers and full weed and bird control programs were used. Netting was used to prevent lodging. Data on grain yield and its attributes were determined. Grain yield of tef was estimated to have risen for 35 years of breeding from 3425 to 4599 kg/ha. Biomass yield and kernel weight per main panicle were greater in newer cultivars, highly and linearly related to cultivar age, and positively and significantly correlated to grain yield. Number of spikelets per panicle is also greater in newer cultivars and significantly and positively correlated with grain yield. Improved plant height, panicle length and kernels per panicle were a feature of most modern genotypes. However, no change occurred in harvest index and 100-kernel weight. Results of a stepwise regression analysis of grain yield on selected yield components revealed that biomass yield was the single most important yield attribute, which accounted for 56.7% of the variation in grain yield.

Tef, Eragrostis tef (Zucc.) Trotter, is the main Ethiopian cereal grown on 2.5 million ha annually, and serving as a staple food grain for more than 50 million people. The major constraints in tef husbandry are low productivity (average about 1 t ha 21 ) and lodging. Scientific research on tef began in the late 1950s and over the years a number of improved varieties and management practices have been developed. However, the research outputs have, until recently, been little adopted by farmers. This paper gives an overview of new and impactful technological, institutional and partnership innovation undertaken by Debre Zeit Agricultural Research Centre with a new tef variety called Quncho. Quncho was developed from an intra-specific hybridization between two improved pure line selection varieties (DZ-01-974 and DZ-01-196). The variety DZ-01-974 is high yielding, but because of the seed colour (pale white) its preference by farmers was limited. On the other hand, the variety DZ-01-196 has been popular for its very white seed colour, but its productivity has been relatively low (1.6 -1.8t ha 21 ). Hence, a targeted cross to bring together the high-yielding traits of DZ-01-974 with the seed quality of DZ-01-196 was made in 2000. Quncho was then developed as an F 2 -derived recombinant inbred line (RIL) through a singleseed descent breeding method. Officially released in 2006, the Quncho variety is presently attracting farmers and seed growers.