Grain yield variation and association of major traits in brown-seeded genotypes of tef [Eragrostis tef (Zucc.)Trotter]
© Jifar et al.; licensee BioMed Central. 2015
Received: 26 November 2014
Accepted: 8 May 2015
Published: 16 June 2015
Tef [Eragrostis tef (Zucc.) Trotter] is the major cereal crop of Ethiopia where it is annually cultivated on more than three million hectares of land by over six million small-scale farmers. It is broadly grouped into white and brown-seeded type depending on grain color, although some intermediate color grains also exist. Earlier breeding experiments focused on white-seeded tef, and a number of improved varieties were released to the farming community. Thirty-six brown-seeded tef genotypes were evaluated using a 6 × 6 simple lattice design at three locations in the central highlands of Ethiopia to assess the productivity, heritability, and association among major pheno-morphic traits.
The mean square due to genotypes, locations, and genotype by locations were significant (P < 0.01) for all traits studied. Genotypic and phenotypic coefficients of variations ranged from 2.5 to 20.3 % and from 4.3 to 21.7 %, respectively. Grain yield showed significant (P < 0.01) genotypic correlation with shoot biomass and harvest index, while it had highly significant (P < 0.01) phenotypic correlation with all the traits evaluated. Besides, association of lodging index with biomass and grain yield was negative and significant at phenotypic level while it was not significant at genotypic level. Cluster analysis grouped the 36 test genotypes into seven distinct classes. Furthermore, the first three principal components with eigenvalues greater than unity extracted 78.3 % of the total variation.
The current study, generally, revealed the identification of genotypes with superior grain yield and other desirable traits for further evaluation and eventual release to the farming community.
KeywordsBrown seeded Eragrostis tef Heritability Traits Variation Yield
Tef [Eragrostis tef (Zucc) Trotter] is the most important cereal crop in Ethiopia where it is annually cultivated by 6.3 million small-scale farmers on more than 30 % of the total area allocated to cereal crops . The importance of tef in Ethiopia is mainly due to its preference by both farmers and consumers. Farmers, above all, grow tef due to its tolerance to several biotic and abiotic stresses especially to the poorly drained vertisols, a dominant soil type in the central highlands where other cereals can hardly survive without the use of proper drainage system. Over 50 million people in Ethiopia consume tef as staple food due to the better quality bread called “injera” made from it compared to that from other cereals. The absence of gluten in its grain  makes tef a healthy food such that people allergic to gluten can safely consume tef products. Compared to the straw from other cereals, the straw from tef is more nutritious and palatable for livestock feed [3, 4].
Despite its huge importance in the economy and being the favored crop by growers and consumers, the productivity of tef is relatively low compared to other cereals. In 2013, the national average yield for tef was only 1.4 t/ha compared to 2.1 t/ha for wheat and 3.1 t/ha for maize . The major yield limiting factors in tef are lodging and drought . Lodging, the displacement of the plant from the upright position due to wind and rain, contributes for 17 % yield loss in tef .
Based on the color of the grain, tef is broadly grouped into two classes as white- and brown-seeded types; however, grains with intermediate color between these also exist. Earlier, the National Tef Breeding Program in Ethiopia focused on improving the white-seeded tef based on consumers’ preferences [7, 8]. The brown-seeded tef genotypes have been given less attention due to relatively lower market preferences and prices as compared to the white grain ones. As a result, only 4 out of the total of 35 improved tef varieties in Ethiopia are from the brown type . Although brown grain tef is traditionally consumed by the farming community, recently, an increasing number of urban dwellers are becoming interested in this type of tef due to nutritional benefits especially high iron content . The two tef types are mostly cultivated under similar environmental conditions, though the white type is vastly grown at an intermediate altitude below 2400 m a. s. l. while the brown type at altitudes above 2200 m a. s. l. However, farmers often claim that the brown-seeded types perform better under less favorable conditions of fields and cultural practices than do the white-seeded types . The present study was, therefore, carried out to examine the performance of brown tef types for productivity and major agronomic traits at three locations in the central highlands of Ethiopia as well as to identify a new brown variety of tef for future release to the farming community.
Materials and methods
Experimental sites and materials
Environmental descriptions of the three experimental locations in Ethiopia
Altitude (m a. s. l.)
Mean annual rain fall (mm)
Mean annual temperature (°C0)
List of tef genotypes or accessions used in the study
Name of genotype/pedigree
Area of collection
Name of genotype/pedigree
Area of collection
Data on days to panicle emergence, grain filling period, days to maturity, shoot biomass, grain yield, harvest index, and lodging index were assessed on plot basis. Harvest index was calculated as a ratio of grain yield to shoot biomass. On the other hand, plant height, panicle, and culm length were recorded on previously selected and tagged five random samples of plants from the central parts of each plot. Mean values of the five random samples of plants per plot were then used for the analyses of data collected on individual plant basis.
All the collected data were subjected to analysis of variance (ANOVA) using the SAS software , and variance effects were considered as significant and highly significant at P < 0.05 and P < 0.01, respectively.
The total phenotypic variance of each trait was partitioned into genetic and nongenetic factors using the variance component method based on the combined analyses over the three test locations as per the method suggested by Assefa et al. . Phenotypic (PCV) and genotypic (GCV) coefficients of variation were calculated following the method of . Broad sense heritability (H) was calculated as a ratio of genotypic variance to phenotypic variance according to Allard . Genetic advance (GA) was expected, assuming selection of the superior 5 % of the genotypes were estimated following the procedure elaborated by Singh and Chaudhury .
Phenotypic and genotypic correlation coefficients were computed from the components of variance and covariances based on the method described by Singh and Chaudhury  using the CANDISC procedure of SAS system .
Multivariate analyses such as cluster analysis (CA) and principal component analysis (PCA) were made based on the mean values for the ten traits and 36 tef genotypes over the three locations. CA was made using the PROC CLUSTER of SAS Version 9  following the average linkage cluster analysis, and the determination of the number of clusters was made based on the Pseudo-F and Pseudo-T2 options. PCA, on the other hand, was made using the PROC PRINCOMP of SAS version 9  to identify the traits that contributed to the large part of the total variation among the genotypes. In principal component analysis, eigenvalues greater than unity were considered important to explain the observed variability.
Results and discussions
Analysis of variance
Mean squares from ten traits of 36 tef genotypes evaluated at three locations in the central highlands of Ethiopia in 2013
L × G
(DF = 2)
(DF = 1)
(DF = 35)
(DF = 10)
(DF = 70)
(DF = 97)
Mean values of 10 traits for 36 brown-seeded tef genotypes evaluated at three locations in the central highlands of Ethiopia in 2013
Days to panicle emergence
Days to maturity
Grain filling period (days)
Plant height (cm)
Panicle length (cm
Culm length (cm)
Shoot biomass (t/ha)
Grain yield (t/ha)
Plant height which has direct relation with lodging index was significantly taller at Ginchi while panicle length which corresponds to grain yield of tef was significantly longer at Holetta than the two other locations. However, both grain and shoot biomass yields were significantly higher at Holetta than at Ginchi and Adadi mainly due to the lodging caused by unexpected rainfall during the grain filling stage especially at Ginchi.
The widely cultivated farmers’ variety currently used as a local check at Holetta was among high yielders, only surpassed by HO-TFS-5458B1 and HO-TFS-5499B1. This could most probably be due to the fact that farmers themselves have developed such a high-yielding cultivar through years of selection and cultivation. The presence of this farmers’ cultivar could also be the probable reason for a less adoption rate of the three so far nationally released brown-seeded varieties in the area. The two genotypes performed better than the farmers’ cultivar in the current study, have a great potential to be released, and are accepted in the future by the farming community in the area.
Estimates of coefficients of variation, heritability, and genetic advance
Estimates of genotypic (GCV) and phenotypic (PCV) coefficient of variation, broad sense heritability (H), and genetic advance as percent of the mean for 10 traits in 36 brown tef genotype evaluated in the central highlands of Ethiopia in 2013
Days to panicle emergence
Days to maturity
Days to grain filling
On the other hand, the highest broad sense heritability value of 97 % was estimated for days to panicle emergence followed by culm length, panicle length, and plant height, while the lowest value of 37 % was recorded for grain filling period. This indicates that traits with high heritability can easily be selected based on phenotype. High heritability was also reported for panicle length  and for days to panicle emergence [21, 22] though the values for each trait were lower than those from the present findings.
The estimated genetic advance values in the present study ranged from 3.4 % for grain filling period to 39.1 % for grain yield. Seven of the 10 traits (grain yield, panicle length, plant height, harvest index, culm length, shoot biomass, and lodging index) have shown relatively high estimates of GA, indicating their amenability for improvement through selection. The GA estimates in the current study are much higher than those in most previous findings which ranged from less than 1 to 21 % , less than 2 to 23 % , and less than 1 to 15.8 %  for other tef genotypes.
Genotypic (upper diagonal) and phenotypic (lower diagonal) correlations among traits for 36 brown-seeded tef genotypes
0.2 1 ns
−0.2 1 ns
0.1 6 ns
−0.3 1 ns
Means for 10 different traits of 36 brown-seeded tef genotypes grouped into seven clusters
Means of clusters
Days to panicle emergence
Days to maturity
Days to grain filling
Principal component analysis
Eigenvectors and values of the first three principal components for 36 tef test genotypes evaluated in the central highlands of Ethiopia in 2013
Days to panicle emergence
Days to maturity
Grain filling period
Percent of variance accounted for
Cumulative variance accounted for (%)
Considerable grain trait variations were observed among the 36 tef genotypes evaluated at the three locations. There was also substantial genotype by environment interactions for all traits evaluated indicating that the test genotypes had differential performance at diverse locations. Besides, the test locations also showed substantial effects on all the traits studied indicating that the locations were adequately diverse to reveal the performance of the tef genotypes. The positive genotypic association between the grain yield, shoot biomass, and harvest index is a good opportunity to simultaneously improve those important agronomic traits. All phenologic traits including days to panicle emergence, days to maturity, and grain filling period, and other traits like shoot biomass and harvest index are positively correlated with grain yield; these traits can be used as selection criteria for increased yield. On the other hand, of the three height-related traits including total plant height, culm length, and panicle length, the former two are negatively correlated and only panicle length is positively correlated with grain yield. Consequently, panicle length which has already been in use as indicator of high yield in the tef breeding program can still be used as useful selection criteria for yield. Cluster analysis had grouped the test genotypes into seven distinct classes with the larger number of genotypes (56 %) fall under cluster I. Based on means of the clusters, different tef genotypes can be selected for improvement of traits of agronomic importance. For instance, tef genotypes in cluster IV can be used for improvement of grain yield and total biomass, while short stature plants for improving lodging resistance as well as for earliness traits can be made from genotype in cluster VII. Furthermore, the first three principal components with eigenvalue greater than one have contributed for 78 % of the entire variation.
In general, the current study revealed the possibility of identifying lines with superior grain yield and other desirable traits for further evaluation and eventual release to the farming community. To this end, the materials would be valuable as a source of breeding materials for improved brown-seeded tef varieties which are expected to be in high demand, apart from use for domestic consumption, particularly in view of the presently burgeoning global popularity and export potential for tef and tef products.
analysis of variance
days to maturity
days to panicle emergence
Ethiopian Biodiversity Institute
Ethiopian Institute of Agricultural Research
genotypic coefficient of variation
grain filling period
phenotypic coefficient of variation
The authors would like to acknowledge the Ethiopian Institute of Agricultural Research (EIAR) for financing the field research. We also thank the technical staff of the Tef Breeding Section at Holetta Agricultural Research Centers for the execution of the field experiments.
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