Evaluation of amplified fragment length polymorphism markers in tef, Eragrostis tef (Zucc.) Trotter, and related species

Tef is an important cereal crop in Ethiopia. This study was conducted to investigate (1) genetic diversity within and among three Eragrostis species (E. tef, E. pilosa and E. curvula), and (2) the relationship between E. tef, E. pilosa and E. curvula. A total of 529 AFLP markers were obtained, out of which 58% (368) were polymorphic, using 10 primer, combinations. The three species were separated distinctly using amplified fragment length polymorphism (AFLP), However, diversity revealed at the morphological trait level was not commensurate with that observed for AFLP. This was due to the small number of morphological traits available and their interaction with the environment. Within tef, ‘Rubicunda’ and DZ‐01‐1093 were found to be distantly related to the rest of the tef accessions. The diversity within species was such that E. pilosa was the most diverse followed by E. curvula and E. tef. Moreover, E. pilosa was more closely related to E. tef than E. curvula. Therefore, further study is needed of E. pilosa accessions and of ‘Rubicunda’ and DZ‐01‐1093 in a crossing programme to generate a population for selection and/or genetic mapping. A total of 19 cultivars or accessions had one or more unique fragments using one or more AFLP primers, indicating the potential of the technology in fingerprinting tef in a breeding or seed multiplication programme.     

Heritability and genetic advance in recombinant inbred lines of tef (Eragrostis tef)

Recombinant inbred lines (RILs) of the tef cross Kaye Murri × Fesho were evaluated for nine quantitative traits at three locations in the central highlands of Ethiopia during the 1998/99 main season in order to estimate the genetic coefficient of variation (GCV), heritability and genetic advance expected from selection. Highly significant differences were obtained among the RILs for all traits studied. Grain yield, panicle weight and yield per panicle showed a relatively high GCV (12–16%). A comparatively high heritability was obtained from days to heading (31%) followed by panicle length (25%) and grain yield (23%). Moderate amounts of heritability values were obtained for panicle weight and yield per panicle. High genetic advance as percent of the mean were obtained from grain yield (16%), yield per panicle (12%) and panicle weight (10%) at5% selection intensity, which indicated the possibility of improving these traits. Several RILs were identified that have exceeded the better yielding parent at all locations. Grain yield showed a strong positive association (r = 0.26–0.70) with shoot biomass, lodging index, panicle length, plant height, panicle weight and yield per panicle. Overall, the present results showed a) the availability of genetic variance for some useful traits in the RILs for exploitation through selection, b) the existence of significant genotype × location interaction that indicated the need to test inbred populations in more environments, and c)the availability of superior inbred lines for further breeding work. This revised version was published online in August 2006 with corrections to the Cover Date.     

Diversity among germplasm lines of the Ethiopian cereal tef [ Eragrostis tef (Zucc.) Trotter]

Three hundred twenty germplasm lines of the major Ethiopian cereal, tef, [ Eragrostis tef (Zucc.) Trotter], were evaluated for 20 morphological, phenological and agronomic characters in two-replicated randomized complete blocks at Debre Zeit and Melkassa Agricultural Research Centers in Ethiopia during the 1995 main season. The objectives were to assess the diversity of the lines, and to estimate the broad sense heritability (H) and genetic advance (GA) of the various characters. The mean squares of genotypes were highly significant (p ≤ 0.001) for all the traits. The phenotypic and genotypic coefficients of variation ranged in that order from about 6–40% and 3–23% for days to maturity and grain yield/plant, and days to maturity and number of spikelets/main shoot panicle, respectively. The cluster analysis grouped the genotypes into 14 major complexes consisting of one to 183 lines. Of the 19 principal components involved in explaining the entire variation among the genotypes the first five which had eigenvalues of more than one explained about 73.8%. The first principal component which accounted for about 34% of the total variance was due chiefly to plant height, culm and panicle length, diameters of the two basal culm internodes, main shoot panicle mass and grain yield, number of main shoot panicle branches and spikelets, and days to panicle emergence and maturity. Estimates of H varied from about 22% for length of the lowest main shoot stem internode to 74% for number of main shoot panicle branches. Values of GA (expected from selection of the superior 5% of the lines and expressed relative to the means) ranged from about 3% for days to maturity to 36% for number of spikelets/main shoot panicle. Overall, the study indicated the existence of trait diversity in tef germplasm and this can be exploited in the genetic improvement of the crop through hybridization and selection. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetics of grain yield and other agronomic characters in t'ef (Eragrostis tef Zucc Trotter). II. The triple test cross

The normal and selfed families of the triple test cross were employed to detect gene action in t'ef for grain yield and other useful agronomic characters in the breeding programme. Cultivars Kay Murri and Fesho were used as L₁ and L₂ testers, respectively. Eight randomly selected cultivars and two released varieties (DZ-01-354 and DZ-01-196) were crossed with the testers L₁, L₂ and L₃ (the F₁ of L₁ × L₂). In the case of the selfed families, 14 cultivars and two released varieties were used for crossing with the testers. The normal families were grown on an Inceptisol developed from volcanic ash whilst the selfed families were grown on a pellic Vertisol at the Debre Zeit Agricultural Research Centre, Ethiopia. The rainfall during the experimental season was 463 mm. Epistasis was detected for grain yield, yield per panicle, panicle weight, plant weight, harvest index, tiller number, panicle length, culm diameter, days to heading and days to maturity in the normal families of the triple test cross (TTC) of t'ef. Similarly the characters grain yield, yield per panicle, panicle weight, plant height, panicle length, days to heading and days to maturity showed epistasis in the selfed families of the TTC. Epistatic interaction was not important for shoot biomass and for harvest index (for the transformed data) in this family. Therefore, both the normal and selfed families of the TTC were in agreement with regard to detecting epistasis for grain yield, yield per panicle, panicle weight, panicle length, days to heading and days to maturity. Significant additive (D) and dominance (H) components were estimated for the characters in both families, although the magnitudes might have been inflated due to epistasis. The dominance component for panicle length was unimportant in both families of the TTC and as a result the additive components were not biased. In general, the additive, dominance and epistatic components were important in t'ef. Since the crop is self-fertilized only the additive and additive × additive terms are important to develop pure breeding varieties. Therefore, selection for superior segregants should start in advanced generations as homozygosity increases. This revised version was published online in July 2006 with corrections to the Cover Date.     

Allelopathic Effects of Parthenium hysterophorus Extracts on Seed Germination and Seedling Growth of Eragrostis tef

The present study was conducted to investigate the allelopathic effects of Parthenium hysterophorus weed on seed germination and seedling growth of tef. Flower, stem, root and leaf aqueous extracts of Parthenium at 0, 1, 5, and 10 % concentrations were applied to determine their effect on tef seed germination and seedling growth under laboratory conditions. Increasing concentrations of aqueous extracts of Parthenium from leaf and flower inhibited seed germination and complete failure of seed germination was recorded when the extract concentration from the leaf part was 10 %. In contrast, aqueous extracts from stem and root had no effect on tef seed germination. Roots appeared more sensitive to allelopathic effect than shoots. Extracts from flower, root and stem had a stimulatory effect on shoot length at all concentration levels, as against an inhibitory effect of leaf extracts. Root extracts at low concentration (1 %) greatly promoted root length but aqueous extracts from leaf and flower inhibited root length.     

Smoke-Water and a Smoke-Isolated Butenolide Improve Germination and Seedling Vigour of Eragrostis tef (Zucc.) Trotter under High Temperature and Low Osmotic Potential

The seeds of Eragrostis tef are often exposed to high temperatures and low water availability during unfavourable climatic conditions. This affects germination and seedling stand establishment of the crop. Smoke is currently widely studied for its stimulatory role in seed germination. The effect of smoke-water and a smoke-isolated butenolide was investigated on E. tef seed germination and seedling growth at different temperatures, light conditions and osmotic potentials. Treating E. tef seeds with smoke-water and butenolide increased the percentage germination relative to the control at all tested temperatures. These treatments significantly improved seedling length and the vigour index at 25, 30, 35 and 40 and 30/15 °C. Smoke-water and butenolide increased percentage imbibition from high to low osmotic potential. In comparison with the control, smoke-water- and butenolide-treated seeds of E. tef showed higher percentage germination with decreasing osmotic potential. Smoke-water treatment exhibited significantly longer and more vigorous seedlings than the control between 0 and −0.30 MPa osmotic potential. The findings of this study suggest the possibility of using smoke treatments for minimizing E. tef seedling losses at elevated temperatures and water stress.     

Diversity for osmotic adjustment and root depth in TEF [Eragrostis tef (Zucc) Trotter]

Osmotic adjustment (OA) and deep roots were shown to be important drought resistance mechanism in many crop plants. In this study, geno types systematically selected from an Ethiopian endemic tef [Eragrostis tef (Zucc) Trotter] germplasm pool were evaluated for osmotic adjustment and root depth in greenhouse in several experiments. The association of these traits with other plant characters was also studied. Osmotic adjustment was investigated in two experiments. Experiment 1 was conducted using nine genotypes for two seasons (spring and fall 1996), and experiment 2 was undertaken in the spring of 1997 with 45 genotypes. In experiment 1, there were significant genotype effects on OA. Though there was also significant genotype by season interaction for OA, some of the extreme lines gave consistently high (Ada and DZ-01-99) and low (DZ-01-354 and Trotteriana) OA values across seasons. There was a significant variation among genotypes for OA in experiment 2. Osmotic adjustment was not associated with the altitude of the region of origin of the particular tef genotype. In both experiments, OA was significantly correlated across tef genotypes with delayed wilting and the maintenance of higher relative water content (RWC) under conditions of soil moisture stress. Three experiments were conducted to evaluate the phenotypic diversity for root depth. In all experiments tef genotypes differed significantly for root depth as measured at flowering time. The late maturing genotypes tended to have greater root depth as compared to early maturing genotypes. Root depth was not associated with the altitude of the region of origin of the tested genotypes. There was no association between root depth and OA across genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic diversity in tef [Eragrostis tef (Zucc) Trotter] and its relatives as revealed by Random Amplified Polymorphic DNAs

Tef is one of the staple cereal crops in Ethiopia. To evaluate genetic diversity of tef and its relatives, 47 accessions of tef, three accessions of E. pilosa, and six accessions of E. curvulawere analyzed using random amplified polymorphic DNA (RAPD) markers. The level of polymorphism among the wild species was extremely high, while low polymorphism was detected among tef accessions. All cultivars and wild species under study could be distinguished with the help of different primers, thereby indicating the potential of RAPD in the genetic fingerprinting of tef. Accessions from E. curvula and E. pilosa can be differentiated by a single selected primer. In spite of low polymorphism within tef, accessions under study could be distinguished by a combination of selected primers. Cluster analysis indicated that tef is a very closely related species to E. pilosa with 45%similarity, supporting the hypothesis that tef originated from E. pilosa based on morphological data. Given that RAPD are relatively quick, simple to use, and are not subjected to environmental influences, they provide a valuable new approach for the genetic fingerprinting and study of genetic diversity in tef. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetics of grain yield and other agronomic characters in t'ef (Eragrostis tef Zucc. Trotter). I. Generation means and variances analysis

Quantitative genetics of grain yield and other agronomic characters of t'ef (Eragrostis tef) were studied using the F₁, F₂, BC₁, and BC₂ of the cross Fesho × Kay Murri. The study was carried out to estimate gene effects controlling the inheritance of grain yield and related agronomic characters. Significant additive [d] and dominance × dominance [l] interaction effects were detected for grain yield. The variations of yield per panicle and panicle weight were explained in terms of [d], dominance [h], and additive × additive [i] interactions. Non-allelic gene interactions were also detected for kernel weight, harvest index, tiller number, plant height, days to heading and days to maturity. The simple additive-dominance model explained the variation for panicle length, culm diameter and plant weight, allowing unbiased estimates of additive (D) and dominance (H) variance components. Large dominance variances (H) were estimated for grain yield, yield per panicle, and panicle weight. The additive variances for plant height, panicle length, days to heading and days to maturity were higher than the respective dominance variances. High narrow-sense heritability (h²) values (> 0.50) were estimated for plant height, panicle length, days to heading and days to maturity. The lowest h² (0.09) was obtained for kernel weight for which there was little variability. Since grain yield and several important agronomic characters of t'ef are influenced by non-allelic gene interaction, it is advisable to delay selection for yield to later generations with increased homozygosity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phosphorus Response Studies on Some Varieties of Durum Wheat (Triticum durum Desf.) and Tef (Eragrostis tef (Zucc.) Trotter) Grown in Sand Culture

The response of four varieties each of durum wheat (DZ-04-118, DZ-320, DZ-918 and TOB-2) and tef (DZ-01-354, DZ-01-787, DZ-01-1445, and DZ-Cr-37) to P application levels was examined in a sand culture study conducted in a glasshouse for 4 weeks. Results showed that plant height, shoot and root dry weights, and plant P uptake were increased by increasing levels of P application from 0 to 5 (tef) and 0 to 10 mg P 100 g⁻¹ (wheat). Varietal differences were also observed in all parameters, except in shoot dry weight of the four durum wheat varieties. In general, all modern varieties of the two crops showed better growth and P uptake than the corresponding traditional varieties. The short period study proved that variations generally existed in the P responses of durum wheat and tef varieties which may be confirmed by long-term study up to maturity. Inclusion of more populations in similar studies may help to identify P efficient genotypes.     

Genetic variation in F<Subscript>2</Subscript> populations and their potential in the improvement of grain yield in tef (<Emphasis Type="Italic">Eragrostis tef</Emphasis>)

Tef is a staple cereal of Ethiopia in high demand by consumers. In order to cope up with this high consumer demand, productivity per unit of land must increase through the development and use of high-yielding varieties. To this effect, the National Tef Research Project has long been striving towards the development of high yielding varieties through direct selection from germplasm and concentrating favourable alleles through hybridization and selection, despite the tedious crossing technique. The objective of this study was to assess the degree of genetic variation in F₂ populations of tef as a basis for improving grain yield. F₂ populations from 12 crosses and their parents were grown at the Debre Zeit Agricultural Research Center, Ethiopia, and assessment was made on eight traits on individual plant basis. Eleven of the 12 crosses showed substantial genetic variation for grain yield and its components, indicating the potential for improvement through selection. Moreover, grain yield, plant weight and yield related traits showed moderate to high heritability values (17–80%). In all the crosses, tiller number, panicle weight, yield per panicle and panicle length showed significant (P ≤ 0.05) and positive association with grain yield. Considering the degree of genetic variation and heritability values, emphasis should be given to selected crosses in an effort to developing high-yielding tef varieties.     

Technology generation to dissemination: lessons learned from the tef improvement project

Indigenous crops also known as orphan crops are key contributors to food security, which is becoming increasingly vulnerable with the current trend of population growth and climate change. They have the major advantage that they fit well into the general socio-economic and ecological context of developing world agriculture. However, most indigenous crops did not benefit from the Green Revolution, which dramatically increased the yield of major crops such as wheat and rice. Here, we describe the Tef Improvement Project, which employs both conventional- and molecular-breeding techniques to improve tef—an orphan crop important to the food security in the Horn of Africa, a region of the world with recurring devastating famines. We have established an efficient pipeline to bring improved tef lines from the laboratory to the farmers of Ethiopia. Of critical importance to the long-term success of this project is the cooperation among participants in Ethiopia and Switzerland, including donors, policy makers, research institutions, and farmers. Together, European and African scientists have developed a pipeline using breeding and genomic tools to improve the orphan crop tef and bring new cultivars to the farmers in Ethiopia. We highlight a new variety, Tesfa, developed in this pipeline and possessing a novel and desirable combination of traits. Tesfa’s recent approval for release illustrates the success of the project and marks a milestone as it is the first variety (of many in the pipeline) to be released.     

Gene action controlling yield and yield‐related traits among tef (Eragrostis tef [Zucc.] Trotter) populations under drought‐stressed and nonstressed conditions

This study was aimed to determine gene action for grain yield and yield‐related traits of newly developed tef populations under drought‐stressed and nonstressed conditions to improve drought tolerance. Ten crosses, along with the parents, were evaluated in the F₂ generation under drought‐stressed conditions at Hastebo and Adigdad sites in 2015 and Dura site in 2016 and under nonstressed conditions at Dura site in 2016. Additive gene action predominantly controlled the inheritance of the grain yield and majority of the yield‐related traits under drought‐stressed and nonstressed conditions. Under both test conditions, the genotypes DZ‐Cr‐387 and 9415 were the best general combiners for increased grain yield and morphological traits. Conversely, genotype 222076 was the best general combiner for reduced maturity period only. The selected parents are novel genetic materials for tef breeding programmes to improve grain yield and morphological traits with reduced days to maturity for drought tolerance breeding. The family of the cross DZ‐Cr‐387 × 222076 was selected for high grain yield and early maturity in both the drought‐stressed and nonstressed environments.     

7份云南野生画眉草属植物种子产量及萌发特性研究

以云南分布较为广泛的7份野生画眉草属植物材料为研究对象,以弯叶画眉草为对照,对种子产量及萌发特性进行初步研究,以确定云南野生画眉草属植物的结实性能和发芽规律.结果表明,供试材料均表现出较好的开花结实性能,种子产量以弯叶画眉草最高,达525.4 kg/hm2,黑穗画眉草次之,知风草最低;种子千粒重为弯叶画眉草＞知风草＞黑穗画眉草;种间相比较,弯叶画眉草的发芽势和发芽率均最高,分别为91.7％和93.0％,显著高于黑穗画眉草和知风草(p＜0.01);种内相比较,5份黑稳画眉草间的发芽势和发芽率差异较大(p＜0.01或p＜0.05),2份知风草间差异不显著(p＞0.05).     

Early generation genetic variation and heritability of yield and related traits among tef populations

The extent of genetic variation and heritability of a trait are among the major determinants of selection gains in plant breeding programs. The aim of this study was to determine the magnitude of genetic variation and inheritance of grain yield, and component traits of newly developed tef populations under moisture-stressed and non-stressed conditions for drought tolerance breeding. Seventeen crosses along with the parents were evaluated in the F2 generation under moisture-stressed and non-stressed conditions in northern Ethiopia during 2015 and 2016. There were marked genotypic and phenotypic variation among the crosses in the F2 generation for plant height, panicle length, peduncle length, number of productive tillers per plant, main shoot panicle seed weight, biomass yield, and grain yield under both test conditions, important for successful selection and genetic advancement. The families of DZ-Cr-387 x 207832 and DZ-Cr-387 x 222076 were high grain yielders with early maturity under both test conditions.     

Qualitative trait variation in Tef [Eragrostis tef (Zucc.) Trotter] germplasm from Western and Southern Ethiopia

Three thousand tef [Eragrostis tef (Zucc.) Trotter] single panicle derived lines representing 60 populations from western and southern parts of Ethiopia were characterized for panicle form, pigmentation of lemma and anther, caryopsis color, number of main shoot culm internodes, and counts of florets/spikelet at the basal, middle and apical parts of the panicle at Debre Zeit Agricultural Research Center during the 1999 main season. The objectives were to assess the diversity patterns of the germplasm with respect to regions and altitude zones. Among the eight characters, high Shannon-Weaver diversity indices (H’) were noted for anther color (0.71) and number of apical spikelet florets (0.68), and the lowest occurred for panicle form (0.40). Monomorphism (H’ = 0.00) was observed for panicle form, lemma color and number of middle spikelet florets each in three different populations. The overall diversity index for all populations was 0.53. In the analysis of variance of H’ estimates, substantial (p <0.05) regional differences were obtained for lemma color, number of culm internodes, and counts of middle and basal spikelet florets. Clinal variation was significant for panicle form, lemma and seed color, and for the overall mean of traits. Over all traits, mean H’ values declined from 0.60 to 0.46 with an increase in the altitude zone of origin from below 1800 to over 2400 meters above sea level. Overall, the study showed substantial diversity in the test tef germplasm. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic improvement in grain yield potential and associated agronomic traits of tef (<Emphasis Type="Italic">Eragrostis tef</Emphasis>)

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.     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.