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

H. Tefera  K. Assefa  F. Hundera  T. Kefyalew  T. Teferra 《Euphytica》2003,131(1):91-96

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.  相似文献   

Breeding tef [Eragrostis tef (Zucc.) trotter]: conventional and molecular approaches     

M. Zeid  G. Belay  H. Tefera  M. E. Sorrells 《Plant Breeding》2011,130(1):1-9

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Surface crystallization in a liquid AuSi alloy     

Shpyrko OG  Streitel R  Balagurusamy VS  Grigoriev AY  Deutsch M  Ocko BM  Meron M  Lin B  Pershan PS 《Science (New York, N.Y.)》2006,313(5783):77-80

X-ray measurements reveal a crystalline monolayer at the surface of the eutectic liquid Au82Si18, at temperatures above the alloy's melting point. Surface-induced atomic layering, the hallmark of liquid metals, is also found below the crystalline monolayer. The layering depth, however, is threefold greater than that of all liquid metals studied to date. The crystallinity of the surface monolayer is notable, considering that AuSi does not form stable bulk crystalline phases at any concentration and temperature and that no crystalline surface phase has been detected thus far in any pure liquid metal or nondilute alloy. These results are discussed in relation to recently suggested models of amorphous alloys.  相似文献   

Genetic analysis and phenotypic associations for drought tolerance in Hordeum spontaneum introgression lines using SSR and SNP markers     

Berhane Lakew  Robert J. Henry  Salvatore Ceccarelli  Stefania Grando  Jason Eglinton  Michael Baum 《Euphytica》2013,189(1):9-29

Associations between markers and drought related traits were investigated on a set of 57 advanced barley breeding lines, carrying various levels of introgression from Hordeum spontaneum lines 41-1 and 41-5, the best sources of drought tolerance in the ICARDA barley breeding program, using 74 simple sequences repeats (SSR) and 20 single nucleotide polymorphism markers. The 57 lines were evaluated for grain yield and drought related traits for three years (2003/04, 2004/05, 2005/06) in nine Mediterranean low rainfall environments. A high level of polymorphism was found with SSR markers, and the mean polymorphism information content and gene diversity values were 0.67 and 0.71, respectively. The number of alleles per locus varied from 2 to 11, with an average of 5.8 alleles per marker. Considering all the 57 lines, the linkage disequilibrium (LD) analysis was significant at a comparison-wise P?<?0.01 level in nearly 9 % of the SSR marker pairs used and a decay of LD was observed to a value of r ²?<?0.2 at a genetic distance of 40?cM. The association analysis revealed a total of 147 significant marker?Ctrait associations for grain yield and drought related traits. A total of 72 (49 %) marker?Ctrait associations showed favorable effects of the exotic germplasm where the H. spontaneum lines contributed to an improvement of the trait under drought stress conditions. The number of significant marker?Ctrait associations per trait were: 12 for growth habit; 2 for growth vigor; 11 for peduncle extrusion; 5 for number of grains per spike; 20 for peduncle length; 16 for days to heading; 20 for plant height; 8 for spike length; 17 for thousand kernel weight; 30 for grain yield; 4 for harvest index and 2 for biological yield. The phenotypic variation explained by individual marker?Ctrait associations ranged from 7.6 % to 36.2 %. The identification of genomic regions associated with grain yield and drought related traits is useful for the genetic improvement of cultivars better adapted to drought stress environments. Thus, the present study is encouraging in identifying significant marker?Ctrait associations through LD based association mapping analysis, which could complement and augment previous quantitative trait loci information for the potential use of Marker Assisted Selection for drought.  相似文献   

Communal farmers’ ecological knowledge and perceptions of grasses in the central Eastern Cape province,South Africa: similarities with field studies and scientific knowledge and their implications     

Solomon Tefera  Ayanda Kwaza 《African Journal of Range and Forage Science》2019,36(2):85-94

The local ecological knowledge (LEK) and perceptions of grasses were investigated in six semi-arid communal areas in the central Eastern Cape province, South Africa, and compared with field studies and scientific knowledge. Of the total of 21 grasses identified in the field survey, communal farmers had vernacular names only for 11 species. Respondents rated Digitaria eriantha and Pennisetum clandestinum to have the highest (p < 0.05) grazing value. Respondents’ ratings of Eragrostis obtusa and Sporobolus africanus as having similar (moderate) grazing values to Themeda triandra is against the established knowledge. Respondents’ ratings of T. triandra and S. africanus as having higher (p = 0.01) ecological value than the other grasses concur with the scientific knowledge, whereas their nomination of E. obtusa and D. eriantha as providing less ecological benefits than Aristida conjesta disagrees with some ecologists. The study hinted at the complementarity and discrepancies between LEK and scientific knowledge that need ratification. The respondents’ lack of detailed knowledge is suggestive of a gradual eroding of LEK among the local communities that will adversely impact the local people’s ability to implement sustainable rangeland utilisation practice. The current study also recognised farmers’ familiarity as well as training needs that would expound their knowledge and management of grasses.  相似文献   

Risk factors for bovine mastitis with the isolation and identification of Streptococcus agalactiae from farms in and around Haramaya district,eastern Ethiopia     

Lakew  Biniam Tsegaye  Fayera  Taresa  Ali  Yimer Muktar 《Tropical animal health and production》2019,51(6):1507-1513

Tropical Animal Health and Production - A cross-sectional study was carried out to determine the prevalence and risk factors of bovine mastitis caused by Streptococcus agalactiae from farms in and...  相似文献   

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

Kebebew Assefa  Seyfu Ketema  Hailu Tefera  Henry T. Nguyen  Abraham Blum  Mulu Ayele  Guihua Bai  Belay Simane  Tiruneh Kefyalew 《Euphytica》1999,106(1):87-97

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.  相似文献   

The potential contribution of wild barley (Hordeum vulgare ssp. spontaneum) germplasm to drought tolerance of cultivated barley (H. vulgare ssp. vulgare)     

B. Lakew  J. Eglinton  R.J. Henry  M. Baum  S. Grando  S. Ceccarelli 《Field Crops Research》2011

Improving drought tolerance has always been an important objective in many crop improvement programs and is becoming more important as one way of adapting crops to climate changes. However, due to its complexity, the genetic mechanisms underlying the expression of drought tolerance in plants are poorly understood and this trait is difficult to characterize and quantify. This study assessed the importance of the wild progenitor of cultivated barley, Hordeum spontaneum C. Koch, in contributing developmental and yield-related traits associated with drought tolerance and therefore its usefulness in breeding for improved adaptation to drought stress conditions. Fifty-seven fixed barley lines derived from crosses with two H. spontaneum lines (41-1 and 41-5) were evaluated in Mediterranean low rainfall environments with 10 improved varieties and three landraces for grain yield, developmental and agronomic traits. The study was conducted for three years (2004–2006) in a total of nine environments (location–year combinations), eight in Syria and one in Jordan, which were eventually reduced to seven due to a large error variance in two of them. There was significant genetic variation among the genotypes for most of the traits measured, as well as differential responses of genotypes across environments. Traits such as peduncle length, peduncle extrusion and plant height were positively correlated with grain yield in the dry environments. Differences in phenology were small and not significantly correlated with differences in grain yield under stress. Performances at the three highest yielding environments were much more closely correlated than those at the four stress environments. The GGE biplot analysis allowed identification of genotypes consistently best adapted to the lowest yielding environments and confirmed the existence of unique environments for identifying better adapted genotypes in the low rainfall environments of Syria. The top yielding lines in the driest of the seven environments derived mostly from crosses with H. spontaneum 41-1, while most of the improved varieties showed a positive genotype by environment (GE) interaction with the highest yielding environments. The results of the field experiments indicated that there was variation for grain yield under drought stress among barley genotypes, and that some of the lines derived from H. spontaneum had consistently superior specific adaptation to the range of severe stress conditions used in this study. The usefulness of H. spontaneum in breeding programs for stress conditions is likely to increase in view of the predicted increase in the occurrence of high temperatures and droughts.  相似文献   

Crop water stress mapping for site-specific irrigation by thermal imagery and artificial reference surfaces     

M. Meron  J. Tsipris  Valerie Orlov  V. Alchanatis  Yafit Cohen 《Precision Agriculture》2010,11(2):148-162

Variable-rate irrigation by machines or solid set systems has become technically feasible, however mapping crop water status is necessary to match irrigation quantities to site-specific crop water demands. Remote thermal sensing can provide such maps in sufficient detail and in a timely way. In a set of aerial and ground scans at the Hula Valley, Israel, digital crop water stress maps were generated using geo-referenced high-resolution thermal imagery and artificial reference surfaces. Canopy-related pixels were separated from those of the soil by upper and lower thresholds related to air temperature, and canopy temperatures were calculated from the coldest 33% of the pixel histogram. Artificial surfaces that had been wetted provided reference temperatures for the crop water stress index (CWSI) normalized to ambient conditions. Leaf water potentials of cotton were related linearly to CWSI values with R ² = 0.816. Maps of crop stress level generated from aerial scans of cotton, process tomatoes and peanut fields corresponded well with both ground-based observations by the farm operators and irrigation history. Numeric quantification of stress levels was provided to support decisions to divide fields into sections for spatially variable irrigation scheduling.  相似文献   

Seroepidemiological study of bovine viral diarrhea (BVD) in three agroecological zones in Ethiopia     

Zelalem Nigussie  Tariku Mesfin  Tefera Sertse  Tadele Tolosa Fulasa  Fekadu Regassa 《Tropical animal health and production》2010,42(3):319-321

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