Thesis

GENETIC VARIABILITY and ASSOCIATION of YIELD and YIELD COMPONENT TRAITS of BREAD WHEAT (Triticum aestivum L.) GENOTYPES in NORTH GONDAR, ETHIOPIA

Mon, 01 Jan 2024 00:00:00 GMT

GENETIC VARIABILITY and ASSOCIATION of YIELD and YIELD COMPONENT TRAITS of BREAD WHEAT (Triticum aestivum L.) GENOTYPES in NORTH GONDAR, ETHIOPIA Adane, Mestawut Bread wheat variety development plays vital role in enhancing productivity and product quality in Ethiopia, which could be achieved by the information generated from the pre-breeding activity. To achieve this, the study aimed to assess genetic variability, heritability, genetic advance, correlation and path analysis among 49 bread wheat genotypes for 17 quantitative traits. The experiment was conducted at Dabat and Debark research stations of Gondar Agricultural Research Center during the main cropping season of 2022, using a 7 x 7 simple lattice design. The genotypes showed significant variation for most traits, both within and across locations, according to the analysis of variance. The average grain yield of the genotypes varied from 2.3 to 4.37 ton/ha in the two locations. The combined analysis showed that the genotypic coefficient of variation (GCV) ranged from 0.77% for days to maturity to 18.33% for thousand-kernel weight. The phenotypic coefficient of variation (PCV) ranged from 2.41% for starch content to 29.85% for grain yield. The broad-sense heritability (H2b ) ranged from 4.81% for the number of spiklets spike-1 to 89.47% for starch content. The genetic advance as a percentage of mean (GAM) ranged from 0.36% for days to maturity to 23.37% for thousand kernel weight in the combined locations. Grain yield had positive and highly significant genotypic and phenotypic correlations (p≤0.01) with harvest index, hectoliter weight, starch content, thousand kernel weight, number of kernels spike-1, days to maturity, grain filling period and number of spiklets spike-1. The genotypic path analysis showed that grain filling period had the highest positive direct effect on grain yield (0.975), followed by biomass yield (0.373). At the phenotypic level, harvest index had the highest positive direct effect on grain yield (0.787), followed by grain protein content (0.610). The cluster analysis divided the 49 genotypes into five clusters, with cluster III having the highest intra-cluster distance (D2=4.73). The largest inter-cluster distance was between cluster III and V (D2=17.91). Principal components (PCs) with Eigen values >1 explained 79.00% of total variation among genotypes. This research showed the existence of genetic variations among bread wheat genotypes for yield, indicating the potential use in future breeding programs.

Enetic Variability and Association of Traits Among Sorghum [Sorghum Bicolor(L.) Moench] Genotypes Northeastern Ethiopia

Sat, 01 Jun 2024 00:00:00 GMT

Enetic Variability and Association of Traits Among Sorghum [Sorghum Bicolor(L.) Moench] Genotypes Northeastern Ethiopia Tadesse Ayalew vi Sorghum is an important food and feed crop in the semiarid regions of the world. Hence, this study was conducted to evaluate genetic variability and traits associations among 81 Sorghum genotypes Northeastern Ethiopia during the 2023 cropping season, using a 9x9 simple lattice design. Quantitative data analysis was computed by using R software. Analysis of variance revealed highly significant (P<0.001) differences among genotypes for days to 50% flowering, leaf length, leaf area index, plant height, panicle, length, head weight, biological yield, harvest index, thousand kernel weight, and grain yield. This result indicates the presence of sufficient genetic variation. The differences in PCV and GCV were small for days to 50% flowering, days to maturity, plant height, head weight, panicle length, thousand kernel weight, and grain yield, suggesting that the environment had minimal influence on the expression of these traits. High broad sense of heritability coupled with high genetic advance as a percentage of the mean were exhibited for head weight, biological yield, thousand kernel weight, and grain yield. Days to 50% flowering, days to maturity, plant height, head weight, leaf length, leaf width, leaf area index, panicle length, biological yield, thousand kernel weight, and grain yield had positive and highly significant genotypic and phenotypic correlations with grain yield. Days to 50% flowering, leaf length, leaf width, plant height, biological yield, harvest index, and thousand kernel weight had positive direct effect at genotypic level on grain yield, implying that a breeding strategy for increasing grain yield and promising genotypes could be selected based on these traits. The first four principal components accounted for 80.11% of the total variation among sorghum genotypes. The most important traits that explained the greatest variation on the PCA was grain yield, head weight, biological yield, leaf length, leaf area, plant height, harvest index, thousand kernel weight, and days to maturity. The maximum intercluster distance was found between clusters I and IV, followed by clusters I and, III and IV and clusters II and III, indicating good opportunity for hybrid crosses between clusters rather than with in clusters. The result of this

Genetic Variability and Association of Yield and Yield Component Traits in Faba Bean (Vicia Faba L.) Genotypes in Debre Tabor, North Western Ethiopia

Mon, 01 Jan 2024 00:00:00 GMT

Genetic Variability and Association of Yield and Yield Component Traits in Faba Bean (Vicia Faba L.) Genotypes in Debre Tabor, North Western Ethiopia Solomon Sharie Faba bean, a globally important pulse, offers genetic variation for plant breeders, although information on this variability is scarce in Ethiopia. Therefore, the study was conducted to assess the genetic variability and association between yield and yield components of genotypes at the Debre Tabor research site using 49 genotypes with 7 x 7 simple lattice designs. Analysis of variance revealed that there were highly significant differences among forty-nine genotypes for all studied traits (days to flowering, days to maturity, grain filling period, number of branch, plant height, pod per plant, seed per pod, biomass yield, harvest index, hundred seed weight, chocolate spot and seed yield). High GCV and PCV was observed in pod per plant and chocolate spot both at genotypic and phenotypic level including number of branch at phenotypic level. Moderate to high heritability estimates were observed in all studied traits. A high genetic advance in percent of mean was observed in the number of branches per plant, the number of pods per plant, grain yield, seed weight, and chocolate spot. The study found that pod per plant, harvest index, and biomass yield all have a significant correlation with grain yield, with biomass yield and harvest index having the most positive effects. Path coefficient analysis showed biomass yield and harvest index exerted the highest positive direct effect on grain yield at genotypic and phenotypic levels. The faba bean genotypes were grouped into six clusters, with the highest inter-cluster distance in clusters III and VI (365.76), and PCA explaining 72.53 percent of the total variation. The study found that the ET 07013-1 and ET 07005-1 genotypes are potential for future breeding programs, but further experimentation across locations and seasons is needed. It is recommended to give much attention to traits with high heritability and GAM, which include the number of branches per plant, the number of pods per plant, grain yield, hundred seed weight, and chocolate spot. It is also important to consider biomass yield and harvest index, as they exert the highest positive direct effect on grain yield and crossing members of highly divergent clusters.

GENETIC DIVERSITY and TRAIT ASSOCIATION in BARLEY (Hordeum Vulgare L.) GENOTYPES in ADET and DEBARK, ETHIOPIA

Mon, 01 Jul 2024 00:00:00 GMT

GENETIC DIVERSITY and TRAIT ASSOCIATION in BARLEY (Hordeum Vulgare L.) GENOTYPES in ADET and DEBARK, ETHIOPIA Sefinew Wale Genetic diversity is valuable for barley breeding programs, as it allows for the selection of desirable traits for further improvement. Compared to the genetic resources available in the gene bank and the ever-changing weather conditions, previous genetic diversity studies on barley have not been sufficient. This study was therefore, conducted to assess the extent of genetic variability and association of agronomic traits in barley genotypes at Adet and Debark experimental stations during the 2023 main cropping season. Eighty-one barley genotypes were evaluated using a 9x9 simple lattice design. The analysis of variance revealed a high level of variability among barley genotypes. In Adet, all traits exhibit high heritability. In Debark, traits like days to heading, grain filling period, plant height, spike length, number of seeds per spike, thousand seeds weight, and leaf rust severity had high heritability. Genotypic correlations showed a highly significant positive association of grain yield with harvest index, aboveground biomass, grain filling period, and thousand seeds weight at both locations. However, days to heading and leaf rust severity had also a highly significant negative correlation with grain yield at both locations. The path coefficient analysis in this study revealed high and favorable direct effects of aboveground biomass and harvest index on grain yieldand days to heading and leaf rust severity had also negative indirect effects throughgrain filling period, aboveground biomass and harvest index on grain yield at both locations. In this study at Adet, the first four principal components with eigenvalues greater than one accounted for 78.4% of the total variations among genotypes and the first five principal components with eigenvalues greater than one accounted for 80.5% of the variation across the 14 traits under study at Debark. Using hierarchical cluster analysis, the genotypes were grouped into five clusters at each location, each with specific trait compositions. At Adet, cluster II and IV showed the highest inter-cluster distance (75.0) followed by cluster II and III (59.35), and cluster IV and V (59.2). Whereas at Debark, the highest inter-cluster distance was observed between cluster III and V (103.98) followed by cluster III and IV (82.14), and cluster I and III (71.84). The higher inter-cluster distance observed in this study indicatesthe genetic diversity among the barley genotypes.This study also identified highyielding genotypes (5, 9, 18, 32, 41, 50, 51, 53, 54, 60, 65, 68, 75) with a grain yield potential from2681.2Kg/ha to 7291.6 Kg/ha at Debark and 80.5 kg/ha to 4631.8 kg/h at Adet. These genotypes could be selected as potential varieties through selection and evaluation or as parents for hybridizationprogram. Since it is a one-year result, however, it is necessary to repeat the field experiment over years and across locations.