Ethiopian Durum Wheat Research Articles

Genetic diversity and population structure analysis based on the high density SNP markers in Ethiopian durum wheat (Triticum turgidum ssp. durum)

BackgroundEthiopia has been considered as a center of diversity and the second possible center of domestication of durum wheat. Genetic diversity and population structure analysis in the existing Ethiopian durum wheat germplasm have enormous importance in enhancing breeding effort and for sustainable conservation. Hence, 192 Ethiopian durum wheat accessions comprising 167 landraces collected from major wheat-growing areas of the country and 25 improved varieties released from Debre Zeit and Sinana Agricultural Research Centers, Ethiopia in different years (1994–2010) were assembled for the current study.ResultsThe panel was genotyped with a High-density 90 K wheat SNP array by Illumina and generated 15,338 polymorphic SNPs that were used to analyze the genetic diversity and to estimate the population structure. Varied values of genetic diversity indices were scored across chromosomes and genomes. Genome-wide mean values of Nei’s gene diversity (0.246) and polymorphism information content (0.203) were recorded signifying the presence of high genetic diversity within this collection. Minor allele frequency of the genome varied with a range of 0.005 to 0.5 scoring a mean value of 0.175. Improved varieties clustered separately to landraces in population structure analysis resulted from STRUCTURE, PCA and neighbor joining tree. Landraces clustering was irrespective of their geographical origin signifying the presence of higher admixture that could arise due to the existence of historical exchanges of seeds through informal seed system involving regional and countrywide farming communities in Ethiopia.ConclusionsSustainable utilization and conservation of this rich Ethiopian durum wheat genetic resource is an irreplaceable means to cope up from the recurrent climate changes and biotic stresses happening widely and thereby able to keep meeting the demand of durum productivity for the ever-growing human population.

Genome-wide association mapping for grain shape and color traits in Ethiopian durum wheat (Triticum turgidum ssp. durum)

Grain shape and color strongly influence yield and quality of durum wheat. Identifying QTL for these traits is essential for transferring favorable alleles based on selection strategies and breeding objectives. In the present study, 192 Ethiopian durum wheat accessions comprising 167 landraces and 25 cultivars were genotyped with a high-density Illumina iSelect 90K single-nucleotide polymorphism (SNP) wheat array to conduct a genome-wide association analysis for grain width (GW), grain length (GL), CIE (Commission Internationale l'Eclairage) L* (brightness), CIE a* (redness), and CIE b* (yellowness) traits. The accessions were planted at Sinana Agricultural Research Center, Ethiopia in the 2015/2016 cropping season in a complete randomized block design with three replications. Twenty homogeneous and healthy seeds per replicate were used for trait measurement. Digital image analysis of seeds with GrainScan software package was used to generate the phenotypic data. Analysis of variance revealed highly significant differences between accessions for all traits. A total of 46 quantitative trait loci (QTL) were identified for all traits across all chromosomes. One novel major candidate QTL (−lg P ≥ 4) with pleiotropic effects for grain CIE L* (brightness) and CIE a* (redness) was identified on the long arm of chromosome 2A. Eighteen nominal QTL (−lg P ≥ 3) and 26 suggestive QTL (−lg P ≥ 2.5) were identified. Pleiotropic QTL influencing both grain shape and color were identified.

Genetic variability and association of traits in Ethiopian durum wheat (Triticum turgidium L. var. durum) landraces at Dabat Research Station, North Gondar

Durum wheat (2 n = 28, AABB, Triticum turgidum L. ssp. durum) is the most commonly cultivated form of allotetraploid wheat and is grown on 8% of the world’s wheat area. The trial was conducted at D...

Screening of Diverse Ethiopian Durum Wheat Accessions for Aluminum Tolerance

Acid soils and associated Al3+ toxicity are prevalent in Ethiopia where normally Al3+-sensitive durum wheat (Triticum turgidum ssp durum Desf.) is an important crop. To identify a source of Al3+ tolerance, we screened diverse Ethiopian durum germplasm. As a center of diversity for durum wheat coupled with the strong selection pressure imposed by extensive acid soils, it was conceivable that Al3+ tolerance had evolved in Ethiopian germplasm. We used a rapid method on seedlings to rate Al3+ tolerance according to the length of seminal roots. From 595 accessions screened using the rapid method, we identified 21 tolerant, 180 intermediate, and 394 sensitive accessions. When assessed in the field the accessions had tolerance rankings consistent with the rapid screen. However, a molecular marker specific for the D-genome showed that all accessions rated as Al3+-tolerant or of intermediate tolerance were hexaploid wheat (Triticum aestivum L.) that had contaminated the durum grain stocks. The absence of Al3+ tolerance in durum has implications for how Al3+ tolerance evolved in bread wheat. There remains a need for a source of Al3+-tolerance genes for durum wheat and previous work that introgressed genes from bread wheat into durum wheat is discussed as a potential source for enhancing the Al3+ tolerance of durum germplasm.

A large nested association mapping population for breeding and quantitative trait locus mapping in Ethiopian durum wheat.

SummaryThe Ethiopian plateau hosts thousands of durum wheat (Triticum turgidum subsp. durum) farmer varieties (FV) with high adaptability and breeding potential. To harness their unique allelic diversity, we produced a large nested association mapping (NAM) population intercrossing fifty Ethiopian FVs with an international elite durum wheat variety (Asassa). The Ethiopian NAM population (EtNAM) is composed of fifty interconnected bi‐parental families, totalling 6280 recombinant inbred lines (RILs) that represent both a powerful quantitative trait loci (QTL) mapping tool, and a large pre‐breeding panel. Here, we discuss the molecular and phenotypic diversity of the EtNAM founder lines, then we use an array featuring 13 000 single nucleotide polymorphisms (SNPs) to characterize a subset of 1200 EtNAM RILs from 12 families. Finally, we test the usefulness of the population by mapping phenology traits and plant height using a genome wide association (GWA) approach. EtNAM RILs showed high allelic variation and a genetic makeup combining genetic diversity from Ethiopian FVs with the international durum wheat allele pool. EtNAM SNP data were projected on the fully sequenced AB genome of wild emmer wheat, and were used to estimate pairwise linkage disequilibrium (LD) measures that reported an LD decay distance of 7.4 Mb on average, and balanced founder contributions across EtNAM families. GWA analyses identified 11 genomic loci individually affecting up to 3 days in flowering time and more than 1.6 cm in height. We argue that the EtNAM is a powerful tool to support the production of new durum wheat varieties targeting local and global agriculture.

Identification of Stripe Rust Resistance in Ethiopian Durum Wheat by Phenotypic Screening and Kompetitive Allele Specific PCR (KASP) SNP Markers

Stripe (Yellow) rust caused by Puccinia striiformis f.sp. tritici (Pst) is one of the most devastating diseases of wheat in the highlands of Ethiopia. Improved cultivars often lose their resistance due to occurrence of new virulent races which overcome the genes and make the cultivars out of production. Therefore, identification of new sources of resistance genes helps in battling yellow rust and maximizes wheat production in Ethiopia. In this study, 300 durum wheat lines (landraces & cultivars) were screened with three virulent isolates (Pst_Is1, Pst_Is4 and Pst_Is8) for seedling resistance using Infection Type (IT) scoring method. The lines were also screened with 16 KASP-based SNP markers linked to 7 Yr genes already identified in various studies. Highly resistant infection type (IT: 0 -3) to Pst_Is1, Pst_Is4, and Pst_Is8 was exhibited by 59.3%; 67.3%; and 46.3% of the lines, respectively. 124 lines constantly exhibited high level of resistance to all three isolates. The majority (96.8%) of the resistant lines are landraces while four (3.2%) are commercial cultivars (Cocorit/71, Yerer, Obsa and Dire). In the molecular screening 12 of the markers gave clear amplifications in the controls and the tested lines. Yr7, Yr15 and YrSp were detected in 81.7%, 88.3% and 0.7% of the lines respectively while Yr1, Yr17 and Yr36 were not detected. Detection frequency was higher in landraces (58.7%) than in cultivars (32.8%). Gene combinations frequency was the highest (72.7%) for Yr7+Yr15 followed by Yr15+YrSp (0.3%). Overall, this study has resulted in detection of genes Yr15 and YrSp, which are potential candidates for marker assisted breeding for Pst resistance in wheat. Besides, it has shown that resistant source identification and detection of genes can be facilitated through combined application of phenotyping and molecular screening.

Evaluation of Ethiopian Durum Wheat Varieties and Landrace Cultivars for the Adult Plant Resistance of Wheat Leaf Rust (Puccinia triticina)

Wheat Leaf rust caused by the pathogen Puccinia triticina is a serious threat of wheat production in Ethiopia, yield loss due tothis disease reached up to 70%. A study was carried out to identify leaf rust adult plant resistance in commercial durum wheatcultivars and landraces. 35 durum wheat Varieties and 200 durum wheat landraces with three susceptible checks arranged inAugment design and evaluated against leaf rust at Debere Zeit Agricultural Research Center, Ethiopia during the 2017/18 mainseason. Terminal Rust Severity (TRS), Coefficient of Infection (CI), Area under Disease Progress Curve (AUDPC) and Disease Progress Rate (DPR) were used to measure leaf rust adult plant resistance in the test materials. Analysis of all disease parameters was carried out using SPAD software. There were highly significant differences (Pl0.01) for all disease parameters among the test cultivars. Above half of evaluated Varieties and landraces (57.9 %) showed better Adult plant resistance under high disease pressure. From the total of 235 tested Varieties and landraces, 136 had slow rusting resistance of which 14 were released varieties and the rest 122 were landraces. Four commercial Varieties (Selam, Mossobo, Bekelcha, and Utuba) and a landrace cultivar (Mcd4-32) had high levels of field resistance with very low AUDPC, ACI, and TRS with MR infection type; hence, they may carry major resistance gene (s). However, the rest 99 Varieties and landraces exhibited high to moderate level of slow rusting resistance with MS responses and may have adult plant resistance controlled by minor resistance genes. The slow rusting cultivars identified from the current study can be used for further manipulation in wheat improvement programs.

Genetic Diversity of Ethiopian Durum Wheat (Triticum durum Desf.) Landrace Collections as Reveled by SSR Markers

Genetic Diversity of Ethiopian Durum Wheat (Triticum durum Desf.) Landrace Collections as Reveled by SSR Markers

Seedling resistance of selected Ethiopian bread and durum wheat lines against dominant stem rust races

Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is one of the most important diseases of wheat in Ethiopia. It has a reputation to cause yield losses reaching up to 100% on susceptible cultivars. A study was conducted to evaluate the infection responses of 34 bread and 20 durum wheat lines at the seedling stage against four major stem rust races; TKTTF (Digalu race), TTKSK (Ug99 race), TRTTF and JRCQC. Wheat lines were artificially inoculated with urediniospores of the four Pgt races at Ambo Plant Protection Research Center in 2017, under controlled environment. Diverse seedling resistance responses were observed against the tested Pgt races. Three durum wheat lines TD56, TD393 and TD402 showed low infection types against all the races while the great majority (73%) of the tested bread wheat lines was susceptible to at least three of the races. The resistant durum wheat lines identified in this study can be used as sources of resistance in wheat breeding program.

Allelic composition and associated quality traits of the Glu-1 and Glu-3 loci in selected modern Ethiopian durum wheat varieties

Gluten protein determines the processing quality of both durum wheat and bread wheat. The glutenin subunits compositions and associated quality traits of 20 Ethiopian durum wheat varieties were systematically analyzed using SDS-PAGE and Payne numbers. A total of 16 glutenin patterns were identified. At the Glu-A1 locus, all varieties scored the null allele. The predominant glutenin alleles at the Glu-B1 locus were Glu-B1b (7+8) and Glu-B1e (20). In Glu-3, the most abundant glutenin subunits were Glu-A3a and Glu-B3c. Based on the Payne scores, the varieties Yerer, Ginchi, Candate, and Foka were identified to have allelic composition suitable for pasta making. The cluster analysis using agglomerative hierarchical clustering (AHC) method classified the varieties into four similarity classes. Based on the findings of this experiment, suggestions were made for allelic composition improvement through introgression of superior alleles from known Glu-1 and Glu-3 sources.

Allelic variation at the gliadin coding loci of improved Ethiopian durum wheat varieties

The objective of this study was to determine gliadin allele compositions of 20 improved Ethiopian durum wheat varieties using acid-polyacrylamide gel electrophoresis (A-PAGE). Each block of co-dominantly inherited polypeptides encoded by gliadin loci were identified and their genetic diversities were estimated using statistical analyses. A total of 30 electrophoretic blocks were identified at five major gliadin loci. In addition, four novel gliadin blocks were identified. Gli-B1 and Gli-A2 loci had higher numbers of gliadin alleles (nine and ten, respectively) compared to other loci. Alleles Gli-A1c on chromosome 1A, Gli-B1c on chromosome 1B, Gli-A2a, and Gli-A2o on chromosome 6A, and Gli-B2h on chromosome 6B had maximal frequencies in their corresponding loci. Varieties were classified into three main clusters and one singleton based on genetic distances of detected gliadin alleles. These results indicate that Ethiopian durum wheat varieties are genetically diverse with unique allele compositions at gliadin-coding loci.

Genome-Wide Association Study of Septoria tritici Blotch Resistance in Ethiopian Durum Wheat Landraces.

Septoria tritici blotch (STB) is a devastating fungal disease affecting durum and bread wheat cultivation worldwide. The identification, development, and employment of resistant wheat genetic material is the key to overcoming costs and limitations of fungicide treatments. The search for resistance sources in untapped genetic material may speed up the deployment of STB genetic resistance in the field. Ethiopian durum wheat landraces represent a valuable source of such diversity. In this study, 318 Ethiopian durum wheat genotypes, for the most part traditional landraces, were phenotyped for resistance to different aspects of STB infection. Phenology, yield and yield component traits were concurrently measured the collection. Here we describe the distribution of STB resistance traits in modern varieties and in landraces, and the relation existing between STB resistance and other agronomic traits. STB resistance sources were found in landraces as well as in modern varieties tested, suggesting the presence of alleles of breeding relevance. The genetic material was genotyped with more than 16 thousand genome-wide polymorphic markers to describe the linkage disequilibrium and genetic structure existing within the panel of genotypes, and a genome-wide association (GWA) study was run to allow the identification of genomic loci involved in STB resistance. High diversity and low genetic structure in the panel allowed high efficiency GWA. The GWA scan detected five major putative QTL for STB resistance, only partially overlapping those already reported in the wheat literature. We report four putative loci for Septoria resistance with no match in previous literature: two highly significant ones on Chr 3A and 5A, and two suggestive ones on Chr 4B and 5B. Markers underlying these QTL explained as much as 10% of the phenotypic variance for disease resistance. We found three cases in which putative QTL for agronomic traits overlapped marker trait association deriving from STB GWA. Our results show that the Ethiopian untapped allelic diversity bears a great value in studying the molecular basis of STB resistance and in breeding for resistance in local and international material.

Novel Sources of Stripe Rust Resistance Identified by Genome-Wide Association Mapping in Ethiopian Durum Wheat (Triticum turgidum ssp. durum).

Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici (Pst), is a global concern for wheat production, and has been increasingly destructive in Ethiopia, as well as in the United States and in many other countries. As Ethiopia has a long history of stripe rust epidemics, its native wheat germplasm harbors potentially valuable resistance loci. Moreover, the Ethiopian germplasm has been historically underutilized in breeding of modern wheat worldwide and thus the resistance alleles from the Ethiopian germplasm represent potentially novel sources. The objective of this study was to identify loci conferring resistance to predominant Pst races in Ethiopia and the United States. Using a high-density 90 K wheat single nucleotide polymorphism array, a genome-wide association analysis (GWAS) was conducted on 182 durum wheat landrace accessions and contemporary varieties originating from Ethiopia. Landraces were detected to be more resistant at the seedling stage while cultivars were more resistant at the adult-plant stages. GWAS identified 68 loci associated with seedling resistance to one or more races. Six loci on chromosome arms 1AS, 1BS, 3AS, 4BL, and 5BL were associated with resistance against at least two races at the seedling stage, and five loci were previously undocumented. GWAS analysis of field resistance reactions identified 12 loci associated with resistance on chromosomes 1A, 1B, 2BS, 3BL, 4AL, 4B and 5AL, which were detected in at least two of six field screening nurseries at the adult-plant stage. Comparison with previously mapped resistance loci indicates that six of the 12 resistance loci are newly documented. This study reports effective sources of resistance to contemporary races in Ethiopia and the United States and reveals that Ethiopian durum wheat landraces are abundant in novel Pst resistance loci that may be transferred into adapted cultivars to provide resistance against Pst.

English

The majority of Ethiopian durum wheat are farmers’ varieties. Durum wheat varieties under production in Ethiopia are less productive due to the effect of climate change and marginalism of agricultural inputs. Recognizant to these, revisiting farmers varieties, ex-situ conserved, could be among the best options to adapt these changes. This study has thoroughly characterized a set of 49 durum wheat varieties to assess the level of phenotypic diversity through multivariate approaches for traits of importance. The study was aimed at estimating the extent of genetic diversity among the genotypes and to identify traits maximally contributing to the observed phenotypic variations. The statistical analyses have confirmed that the genotypes have shown very large (p<0.001) variations for most traits considered, except for number of effective tillers. The estimated broad – sense heritability (h2) has ranged from 20% for grain yield to 78% for spike length. The genotypes were grouped into six clusters with significant inter-cluster distances (χ2=15.51, p<0.05). The clustering revealed that the landraces are genetically far from the improved varieties. Genotypes consisted in a particular cluster are superior for a trait or more compared to the other clusters. For instance, genotypes in the first cluster are superior for grain and biomass yields. Early maturing and second high yielding genotypes were consisted in the fifth cluster. The genotype – by – traits biplot analysis has explained 82% of the total variation where 65.5% was explained by PC1, indicating that most of the observed variation is inherited. It can be concluded that the landraces are quite divergent from the improved varieties and the within landraces diversity was also high indicating that they represent important gene pool for important traits. Hence, revisiting landraces, which are Ex-situ conserved, and their exploitation in durum wheat breeding programs for grain yield improvement, earliness and other traits of importance is crucial. Key words: Revisiting, ignored, Durum wheat, landrace, genetic variation, quantitative trait.

High-density molecular characterization and association mapping in Ethiopian durum wheat landraces reveals high diversity and potential for wheat breeding.

SummaryDurum wheat (Triticum turgidum subsp. durum) is a key crop worldwide, and yet, its improvement and adaptation to emerging environmental threats is made difficult by the limited amount of allelic variation included in its elite pool. New allelic diversity may provide novel loci to international crop breeding through quantitative trait loci (QTL) mapping in unexplored material. Here, we report the extensive molecular and phenotypic characterization of hundreds of Ethiopian durum wheat landraces and several Ethiopian improved lines. We test 81 587 markers scoring 30 155 single nucleotide polymorphisms and use them to survey the diversity, structure, and genome‐specific variation in the panel. We show the uniqueness of Ethiopian germplasm using a siding collection of Mediterranean durum wheat accessions. We phenotype the Ethiopian panel for ten agronomic traits in two highly diversified Ethiopian environments for two consecutive years and use this information to conduct a genome‐wide association study. We identify several loci underpinning agronomic traits of interest, both confirming loci already reported and describing new promising genomic regions. These loci may be efficiently targeted with molecular markers already available to conduct marker‐assisted selection in Ethiopian and international wheat. We show that Ethiopian durum wheat represents an important and mostly unexplored source of durum wheat diversity. The panel analysed in this study allows the accumulation of QTL mapping experiments, providing the initial step for a quantitative, methodical exploitation of untapped diversity in producing a better wheat.

Phenotypic diversity in Ethiopian durum wheat (Triticum turgidum var. durum) landraces

The phenotypic diversity of 274 Ethiopian durum wheat accessions was analyzed, taking their geographic origins into account. The aim was to assess the extent and patterns of agronomically important phenotypic variation across districts of origin and altitude classes for major qualitative traits using diversity index and multivariate methods. Eight qualitative and three quantitative traits were scored for 2740 plants and analyzed for diversity. The Shannon–Weaver diversity (H′) index was used to estimate phenotypic diversity. The estimated H′ ranged from monomorphic for glume hairiness to highly polymorphic for other traits. The highest (0.86) H′ was obtained for seed degree of shriveling, possibly indicating the differential responses of the genotypes to water deficit during later growth stages. With respect to district of origin, the highest (0.72) and lowest (0.44) H′ values were obtained for the Bale and SNNP districts, respectively. With respect to altitude, the highest (0.76) and lowest (0.62) H′ values were recorded for altitudes 1600–2000 and >3000m above sea levels, respectively. Principal components analysis explained substantial variation contributed by district of origin and altitude range. Genotypes were clustered into three groups by districts of origin and altitude class, with relatively strong bootstrap values of 57 and 62 for the former and latter, respectively. It could be concluded that Ethiopian durum wheat landraces are very diverse both within and among districts of origin and altitude classes. This wealth of genetic diversity should be exploited for wheat improvement of yield and for resistance to biotic and abiotic stresses, particularly terminal drought.

Haplotype analysis of molecular markers linked to stem rust resistance genes in Ethiopian improved durum wheat varieties and tetraploid wheat landraces

The recent emergence of wheat stem rust race Ug99 (TTKSK) and related strains threaten Ethiopian as well as world wheat production because they overcome widely used resistance genes that had been effective for many years. The major cause which aggravates the ineffectiveness of Ethiopian wheat varieties against stem rust is the narrow genetic base on which the breeding for resistance has been founded, however, little is known about the resistance genotypes of Ethiopian durum wheat varieties and tetraploid wheat landraces. The objective of the study was to identify stem rust resistance genes that are present in the Ethiopian tetraploid wheat landraces and improved durum wheat varieties using molecular markers and assess which genes are effective for current Ethiopian stem rust races of Puccinia graminis f. sp. tritici including Ug99. The investigated 58 tetraploid wheat accessions consisted of 32 (Triticum durum s.l. incl. Triticum aethiopicum Jakubz., Triticum polonicum) landraces and 22 registered T. durum varieties released in Ethiopia between 1966 and 2009 and four T. durum varieties from ICARDA. A total of 17 molecular markers (SSR, EST and InDel) linked or diagnostic for stem rust resistance genes Sr2, Sr13, Sr22 and Sr35 were used for genotyping. Haplotype analysis indicated that only few of the Ethiopian durum wheat varieties carried Sr13. The resistant variety ‘Sebatel’ showed a haplotype for Sr2 and Sr22 and variety ‘Boohai’ for Sr22, however further evaluation is needed for the diagnostic value of these haplotypes. This study is the first report on the presence of stem rust resistance (Sr) genes in Ethiopian durum wheat varieties and tetraploid wheat landraces based on linked or associated molecular markers. Thus it might help in the identification of varieties carrying resistant alleles that provide valuable genetic material for the development of new improved varieties in further breeding programmes.

Response of Ethiopian durum wheat genotypes to water deficit induced at various growth stages

Understanding the effect of water stress on yield and its components is the essential step in developing of high yielding and stable genotypes. Substantial reduction in grain yield can be caused by water deficit depending on the intensity, duration and the developmental stage at which water stress occurred. An experiment was conducted in the lathouse at Sinana Agricultural Research Center in 2006/2007 to evaluate the effect of water deficit on grain yield and yield components of eighteen durum wheat genotypes induced at different growth stages. Grain yield and other agronomic traits of all genotypes were significantly reduced and the reduction was much more pronounced under stress induced from tillering to crop maturity. Grain yield per plant was reduced by 72, 37 and 17.1% due to stress induced at tillering, flowering and grain-filling stages as compared to the well-watered treatment, respectively. Kilinto and Gerardo were found to be stable and drought tolerant genotypes whereas S17B and Boohai were highly susceptible. The most drought tolerant genotypes were found to maintain relatively high levels of kernel numbers per spike and hundred-kernel weight. Mean kernel weight was associated to the duration of grain filling and grain filling rates and these traits contributed to a greater yield under water stress conditions.

Genotypic Variability, Heritability, Genetic Advance and Associations among Characters in Ethiopian Durum Wheat (&lt;i&gt;Triticum durum&lt;/i&gt; Desf.) Accessions

A field experiment was conducted at Geregera (11&deg; 45&rsquo; N latitude and 38&deg; 45&rsquo; E longitude) in north Wollo, Ethiopia during the 2003 cropping season with the objectives of estimating genotypic variability, heritability, genetic advance and associations among yield and yield-related characters of durum wheat. Forty four randomly taken Ethiopian durum wheat accessions were evaluated using randomized complete block design in three replications. Analysis of variance showed significant differences (p &lt; 0.05) among the durum wheat accessions for all the characters considered. Genotypic coefficients of variation (GCV %) were medium for spike length (12.5%) and kernel yield plant-1 (12.3%). Broad sense heritability were high for spike length (89.2%), plant height (87.1%) and thousand kernels weight (80.2%), indicating that these characters were predominantly controlled by genetic factors. Maximum heritability in broad sense coupled with high genetic advance were exhibited for spike length, plant height and thousand kernels weight, implying that phenotypic selection could identify superior genotypes for these traits. Genotypic correlation analysis revealed that grain yield had strong positive associations (p &lt; 0.01) with kernel yield plant-1 (rg = 0.89), plant height (rg= 0.84), thousand kernels weight (rg = 0.82), biomass yield (rg = 0.80) and number of kernels spike-1(rg = 0.78), where biomass yield and harvest index exerted maximum positive direct effects on grain yield. On the other hand, days to heading had a significant negative correlation (p &lt; 0.01) with grain yield (rg = -0.75) which exerted maximum negative direct effect on grain yield. Therefore, earliness coupled with high biomass yield could be considered as an indirect selection criterion for durum wheat grain yield improvement in moisture stressed areas.Keywords: Genetic; Genetic Advance; Harvest Index; Heritability; Variability

Selection criterion for improved grain yields in Ethiopian durum wheat genotypes

Wheat (Triticum durum Desf.) is the most important cereal crop grown in the intermediate and highland areas of northeastern Ethiopia. Durum wheat dominates in these areas where water logging is the major production constraint. Because of the predominant problem of water logging coupled with other various biotic and abiotic production hobbling factors, the average productivity of wheat in the northeastern region never exceeds 8.4 ha -1, which is below the national average of 14.4 ha -1 (ECSA, 2002). Screening of wide durum wheat germplasm has been undertaken to improve durum wheat grain yield. But, selection based on the performance of grain yield alone, a polygenically controlled complex character, is usually not very efficient. An experiment was conductedat Geregera testing site of Sirinka Agricultural Research Centre, during the 2003-cropping season with the objective of estimating the associations between yield and yield-related traits and to identify direct and indirect effects of characters for durum wheat grain yield improvement. The experimental material consisted of 44 indigenous durum wheat genotypes, which are randomly taken from the indigenous germplasm collections. Mean sum of squares for all the characters considered showed highly significant differences (P