Broad-sense Heritability Estimates Research Articles

Multiple-trait, random regression, and compound symmetry models for analyzing multi-environment trials in maize breeding.

An efficient and informative statistical method to analyze genotype-by-environment interaction (GxE) is needed in maize breeding programs. Thus, the objective of this study was to compare the effectiveness of multiple-trait models (MTM), random regression models (RRM), and compound symmetry models (CSM) in the analysis of multi-environment trials (MET) in maize breeding. For this, a data set with 84 maize hybrids evaluated across four environments for the trait grain yield (GY) was used. Variance components were estimated by restricted maximum likelihood (REML), and genetic values were predicted by best linear unbiased prediction (BLUP). The best fit MTM, RRM, and CSM were identified by the Akaike information criterion (AIC), and the significance of the genetic effects were tested using the likelihood ratio test (LRT). Genetic gains were predicted considering four selection intensities (5, 10, 15, and 20 hybrids). The selected MTM, RRM, and CSM models fit heterogeneous residuals. Moreover, for RRM the genetic effects were modeled by Legendre polynomials of order two. Genetic variability between maize hybrids were assessed for GY. In general, estimates of broad-sense heritability, selective accuracy, and predicted selection gains were slightly higher when obtained using MTM and RRM. Thus, considering the criterion of parsimony and the possibility of predicting genetic values of hybrids for untested environments, RRM is a preferential approach for analyzing MET in maize breeding.

Study of heat stress memory related to acquired thermo-tolerance in wheat

Wheat is one of the important plants frequently suffer by effects of heat stress. In the present study, heat priming for the first generation studied on heat tolerance of the successive generations in seedling and maturity stages under high temperature stress. Under high-temperature stress condition during seedling stage, the progeny of heat-primed (PH) genotypes shown significantly higher chlorophyll a and b content and percent tetrazolium chloride (%TTC) reduction than the progeny of the non-heat primed (NH) genotypes. At maturity stage, higher grain yield per plant was obtained for PH genotypes than NH genotypes under heat stress condition, which was mainly associated with the higher grain weight for PH than NH genotypes. The greater grain weight could be resulted from the higher percent cell membrane thermo-stability (%CMS) in the PH genotypes than in the NH genotypes. Estimation of variance components and broad sense heritability were higher in PH genotypes than observed in NH genotypes for most studied traits at seedling and maturity stages. Based on morpho-physiological traits, the highest genetic distance was recorded between G9 genotype of heat-primed plants and G9 genotype of non-primed plants, which gave highly significant differences between PH plants and NH plants for all studied traits. The heat priming for the parents may induce heat tolerance for offspring, and this might be an effective method to cope with severe heat stress during some the different growth stages in wheat.

Field pea (Pisum sativum L.) shows genetic variation in phosphorus use efficiency in different P environments

Field pea is important to agriculture as a nutritionally dense legume, able to fix nitrogen from the atmosphere and supply it back to the soil. However, field pea requires more phosphorus (P) than other crops. Identifying field pea cultivars with high phosphorus use efficiency (PUE) is highly desirable for organic pulse crop biofortification. This study identified field pea accessions with high PUE by determining (1) the variation in P remobilization rate, (2) correlations between P and phytic acid (PA), and (3) broad-sense heritability estimates of P concentrations. Fifty field pea accessions were grown in a completely randomized design in a greenhouse with two replicates under normal (7551 ppm) and reduced (4459 ppm) P fertilizer conditions and harvested at two time points (mid-pod and full-pod). P concentrations ranged from 332 to 9520 ppm under normal P and from 83 to 8473 ppm under reduced P conditions across all tissues and both time points. Field pea accessions showed variation in remobilization rates, with PI 125840 and PI 137119 increasing remobilization of P under normal P conditions. Field pea accessions PI 411142 and PI 413683 increased P remobilization under the reduced P treatment. No correlation was evident between tissue P concentration and seed PA concentration (8–61 ppm). Finally, seed P concentration under limited P conditions was highly heritable (H2 = 0.85), as was mid-pod lower leaf P concentrations under normal P conditions (H2 = 0.81). In conclusion, breeding for PUE in field pea is possible by selecting for higher P remobilization accessions in low P soils with genetic and location sourcing.

Study on genetic analysis for yield and its components and YVMV resistance in okra {Abelmoschus esculentus (L.) Moench}

The Genotypes Verma (240.18g) and 6.23 t ha-1) was recorded highest mean performance for fruit yield plant-1 and fruit yield t ha-1). The genotypic coefficient variance value were categorized as low (0-10%), moderate (10-20%) and high (20% and above). In the present study the heritability estimates in broad sense were classified into 3 groups such as high (>75%), moderate (60% - 75%), low (

Detailed Genetic Analysis for Identifying QTLs Associated with Drought Tolerance at Seed Germination and Seedling Stages in Barley.

Drought induces several challenges for plant development, growth, and production. These challenges become more severe, in particular, in arid and semiarid countries like Egypt. In terms of production, barley ranks fourth after wheat, maize, and rice. Seed germination and seedling stages are critical stages for plant establishment and growth. In the current study, 60 diverse barley genotypes were tested for drought tolerance using two different treatments: control (0-PEG) and drought (20%-PEG). Twenty-two traits were estimated for seed germination and seedling parameters. All traits were reduced under drought stress, and a significant variation was found among genotypes under control and stress conditions. The broad-sense heritability estimates were very high under both control and drought for all traits. It ranged from 0.63 to 0.97 under the control condition and from 0.89 to 0.97 under drought, respectively. These high heritabilities suggested that genetic improvement of drought tolerance in barley at both stages is feasible. The principal component analysis revealed that root-related parameters account for the largest portion of phenotypic variation in this collection. The single-marker analysis (SMA) resulted in 71 quantitative trait loci (QTLs) distributed across the seven chromosomes of barley. Thirty-three QTLs were detected for root-length-related traits. Many hotspots of QTLs were detected for various traits. Interestingly, some markers controlled many traits in a pleiotropic manner; thus, they can be used to control multiple traits at a time. Some QTLs were constitutive, i.e., they are mapped under control and drought, and targeting these QTLs makes the selection for drought tolerance a single-step process. The results of gene annotation analysis revealed very potential candidate genes that can be targeted to select for drought tolerance.

Combining ability analysis of yield and resistance to late blight disease caused by Phytophthora infestans in Uganda

Breeding for resistance to late blight disease caused by Phytophthora infestans (Mont.) de Bary in potato is the most economically, effective and ecologically sustainable method to control the disease and boost productivity. The study estimated combining ability effects of yield, yield related traits, late blight resistance and gene action controlling resistance to Phytophthora infestans. Eighteen F1 families generated from two sets of 12 parents, using a North Carolina Design II, were evaluated for relative area under disease progress curve (rAUDPC), yield and yield related traits in two late blight hotspot locations of Kachwekano and Kalengyere research stations. Trials were established using an alpha lattice design (6 x 5) with two replications. Both additive and non-additive genetic effects were important in controlling yield and late blight resistance. However, additive gene action was dominant. The general combining ability (GCA) to specific combining ability ratio (SCA); (GCA/SCA) for total tuber weight and late blight resistance was 0.53 and 0.62 respectively. Broad-sense heritability estimates were 0.78 for total tuber weight and 0.68 for relative area under disease progress curve (rAUDPC). This study showed some evidence of maternal effects for rAUDPC (1.45) and average tuber weight (ATW) (1.56), although these were not significant at P<0.05. Parents Kinigi, 392657.8, 396034.103, 396038.107, 395011.2, NKRK19.17, NKRN59.58 and 395017.14 had good GCA effects for both late blight resistance and yield related traits. Crosses of 392657.8 x 395017.14 and 396038.107 x NKRN59.58 had the highest SCA effects for yield related traits, while families Kinigi x NKRK19.17and 392657.8 x NKRN59.41 had the lowest SCA effects for rAUDPC. The relatively high heritability estimates and predominant additive genetic effects imply that genetic advances in resistance to Phytophthora infestans and tuber yield among these genotypes can be realized by selecting superior clones.

Development of a genetic framework to improve the efficiency of bioactive delivery from blueberry

In the present study, we applied a novel high-throughput in vitro gastrointestinal digestion model to phenotype bioaccessibility of phenolics in a diverse germplasm collection representing cultivated highbush blueberries. Results revealed significant (P < 0.05) differences between accessions, years, and accession by year interaction for relative and absolute bioaccessibility of flavonoids and phenolic acids. Broad sense heritability estimates revealed low to moderate inheritances of relative and absolute bioaccessibility, suggesting that besides environmental variables, genetics factors could control bioaccessibility of phenolics. Acylated anthocyanins had significantly higher relative bioaccessibility than non-acylated anthocyanins. Correlation analysis indicated that relative bioaccessibility did not show significant association with fruit quality or raw concentration of metabolites. The study also identified accessions that have high relative and absolute bioaccessibility values. Overall, combining the bioaccessibility of phenolics with genetic and genomic approaches will enable the identification of genotypes and genetic factors influencing these traits in blueberry.

Accuracy of genomic selection and long-term genetic gain for resistance to Verticillium wilt in strawberry.

Verticillium wilt, a soil-borne disease caused by the fungal pathogen Verticillium dahliae, threatens strawberry (Fragaria × ananassa) production worldwide. The development of resistant cultivars has been a persistent challenge, in part because the genetics of resistance is complex. The heritability of resistance and genetic gains in breeding for resistance to this pathogen have not been well documented. To elucidate the genetics, assess long-term genetic gains, and estimate the accuracy of genomic selection for resistance to Verticillium wilt, we analyzed a genetically diverse population of elite and exotic germplasm accessions (n=984), including 245 cultivars developed since 1854. We observed a full range of phenotypes, from highly susceptible to highly resistant: <3% were classified as highly resistant, whereas>50% were classified as moderately to highly susceptible. Broad-sense heritability estimates ranged from 0.70-0.76, whereas narrow-sense genomic heritability estimates ranged from 0.33-0.45. We found that genetic gains in breeding for resistance to Verticillium wilt have been negative over the last 165 years (mean resistance has decreased over time). We identified several highly resistant accessions that might harbor favorable alleles that are either rare or non-existent in modern populations. We did not observe the segregation of large-effect loci. The accuracy of genomic predictions ranged from 0.38-0.53 among years and whole-genome regression methods. We show that genomic selection has promise for increasing genetic gains and accelerating the development of resistant cultivars in strawberry by shortening selection cycles and enabling selection in early developmental stages without phenotyping.

Assessment of Genetic Diversity for Some Egyptian Wheat Varieties based on Morphological Characters and SSR Markers

The genetic diversity estimates can be useful in important genotypes selection for plant breeders. Eight durum and three bread wheat cultivars were used to study and compare morphological traits with molecular study using SSR technique based genetic diversity estimates. Significant and highly significant differences among wheat genotypes were observed for all traits except flag leaf attitude and outer glume pubescence. Highly significant differences were obtained between durum and bread wheat genotypes for most studied traits. Moderate to low broad-sense heritability estimates were obtained for morphological studied traits. Positive and high significant correlation was found for ear density with foliage color (r= 0.51), waxiness of flag leaf sheath (r= 0.57), waxiness of peduncle (r= 0.60) and peduncle length (r= 0.53), whereas a negative correlation was found between ear density and plant height (r= -0.52, P

Selection Efficiency and Environmental Sensitivity for Agronomic Traits in A Bread Wheat Population under Normal and Late Sowing Dates Conditions کفاءة الإنتخاب والحساسیة للبیئة للصفات المحصولیة فی عشیرة من قمح الخبز تحت ظروف میعادی الزراعة العادی والمتأخر

The present study was carried out during seasons, i.e. 2017/18 to 2019/20 at Shandaweel Agric. Res. Stat., Sohag Governorate, Egypt. Two cycles of pedigree selection for grain yield plant-1 and number of spikes plant-1 from F2 to F4 generations were practiced under normal and late sowing dates. The genotypic variance was slightly less than the phenotypic variance under both environments and generally decreased from (F2) to F4 generation. After two cycles of pedigree selection, broad sense heritability estimates were 90.27% and 73.83% for grain yield plant-1 and 88.21% and 82.47% for no. of spikes plant-1 under normal and late sowing dates, respectively. Evaluation of the selected families for high grain yield plant-1 under normal sowing date showed significant differences 18.33% and 9.31% when selection was practiced under normal sowing date, and 20.60% and 11.83% when selection was under late sowing date from the bulk sample and the better parent, respectively. The average observed gains of the selected families for high no. of pikes plant-1 under normal sowing date and evaluated under both conditions were 13.53% and 17.74% from the bulk sample and 9.67% and 11.51% from the better parent under normal and late sowing dates, respectively. While when selection was under late sowing date were 12.68% and 17.80% from the bulk sample and 8.78% and 11.57% from the better parent under normal and late sowing dates, respectively. The antagonistic and the synergistic selection nearly have the same effect on the sensitivity to heat stress under the two selection criteria.

Genotypic Variability in Some Morpho-Physiological Traits in Different Environments and Their Relationship with Cassava (Manihot esculentaCrantz) Root Yield

Cassava root yield under diverse environments is influenced by morpho-physiological traits that are in turn influenced by genotype, environment, and genotype × environment interaction (GEI). Most GEI analyses in cassava have been limited to root yield with less emphasis on stability of other yield-related traits. This study was carried out to assess the effect of GEI on some morpho-physiological traits in cassava and key traits that are useful for selection in different environments. The study utilized 20 cassava genotypes evaluated in six environments, namely, Fumesua 2013 and 2014, Nyankpala 2013 and 2014 (irrigation), and Nyankpala 2013 and 2014 (no irrigation). The genotypes were arranged in a randomized complete block design (RCBD) with three replications and assessed for a number of morpho-physiological traits, root yield and yield components. The data were subjected to analysis of variance using SAS statistical package. Subsequently, the GGE biplot was used to carry out genotype × environment, genotype × trait, and environment × trait interaction analyses to determine the specificity of genotypic performance and traits linked to particular environments. The results indicated significant (P&lt;0.05) GEI effect on all traits except leaf temperature. The genotype × trait biplot analysis revealed closely related traits and those associated with root yield and genotypes that show weakness in these traits. Both environment × trait biplot and principal component analyses identified traits with higher discriminatory power among genotypes in various environments particularly in the dry environments. These can be used as secondary traits to select drought-tolerant genotypes. From this study, the GGE biplot was useful in identifying traits associated with specific genotypes in different environments to aid in selection. Moderate broad-sense heritability estimates werefound for storage root yield, harvest index, plant height, ratio of storage rootlength to girth, and cassava mosaic disease score indicating that progresscan be made through selection for these traits.

Culture selected somaclonal variants showing low-ODAP and high protein content in nineteen grass pea (Lathyrus sativus L.) genotypes

To develop low-ODAP grass pea genotypes with high protein content, in vitro tissue culture techniques were used for inducing somaclonal variation through internode explants that was cultured on B5 medium containing 2 mg L− l α-naphthaleneacetic acid and 1 mg L− l 6-benzylaminopurine of 19 grass pea genotypes. The selected somaclones (R3 and R4 generations) were evaluated for variation in ODAP, protein, and quantitative agronomic traits. The results showed statistically significant (P < 0.001) genotypic differences for ODAP %, Protein %, 100-seed weight (HSW) and pod width (PODW) in the R4 somaclones under field conditions. The somaclones showed broad-sense heritability estimate of 0.14 ± 0.064 for ODAP%, 0.87 ± 0.015 for protein, 0.78 ± 0.025 for HSW and 0.13 ± 0.062 for PODW. Among the 270 somaclones, Sel462-5 was significantly superior to the parent and other somaclones in terms of ODAP content (0.13%), protein content (28.47%) and pod width (1.43 cm). The correlation coefficients between parents and somaclones for pod width with 100-seed weight, ODAP-clones and protein-clones were positive and significant. The superiority of somaclones for ODAP, protein, 100-seed weight and pod width in R4 generation opened the possibility for grass pea improvement through somaclonal variation. Induction of somaclonal variation in grass pea is an alternate approach to introduce new and desirable genetic variability in the cultivated gene pool.

Assessing genetic variation for Fusarium wilt race 4 resistance in tetraploid cotton by screening over three thousand germplasm lines under greenhouse or controlled conditions

Cotton (Gossypium spp.) is the most widely-grown natural fiber crop used by the textile industry. Fusarium wilt, caused by Fusarium oxysporum f. sp. vasinfectum (FOV) comprised of eight nominal pathogenic races, is one of the most destructive diseases in cotton. FOV race 4 (FOV4) is an emerging threat to cotton production in the US. In this study, a total of 3258 lines including 3080 Upland (G. hirsutum) and 178 Pima (G. barbadense) germplasm lines were evaluated in 21 tests under greenhouse or temperature-controlled conditions for resistance to FOV4. A total of 2224 lines from 13 tests were screened in a commercial potting soil in the greenhouse under higher temperature (HT) conditions (24–32 °C), while 1204 lines from 8 tests were screened in a naturally FOV4-infected farm soil at a lower temperature (LT) setting (20–21 °C), both with artificial inoculations. The 170 Pima lines were evaluated in both temperature regimes. The results showed that, at 30 days post inoculation, both temperature regimes produced similar disease incidence (81.2% for HT vs. 86.8% for LT), but LT caused significantly higher disease severity ratings (DSR, 3.86 vs. 1.94) and plant mortality (81.7% vs. 7.5%) than did HT. DSR and morality rate were highly significantly correlated (r = 0.849–0.941) at LT. Significant genotypic variations in DSR were detected in all studies except two, and the broad-sense heritability estimates for DSR were 0.59–0.83 with an average of 0.70 at HT and 0.61–0.72 with an average of 0.69 at LT, indicating that 70% the phenotypic variation in FOV4 resistance was determined by genetic variation. Using the naturally FOV4-infected farm soil and LT to screen 1034 Upland and 170 Pima germplasm lines (with 20–40 plants for each line) with artificial inoculations, 48% showed 100% mortality; 22% had a mortality rate between 70 and 99%; 5% had mortality below 30%; and 0.5% (6 lines) did not display any apparent FOV4 symptoms. The results indicated that many existing available germplasm lines may be heterogeneous for FOV4 resistance and pedigree selection within germplasm may increase frequencies of resistant plants. This study represents one of the first publicly reported large-scale screenings of cotton for FOV4 resistance in the US and provides useful information for breeding cotton with resistance to FOV4.

A multiethnic genome-wide analysis of 44,039 individuals identifies 41 new loci associated with central corneal thickness

Central corneal thickness (CCT) is one of the most heritable human traits, with broad-sense heritability estimates ranging between 0.68 to 0.95. Despite the high heritability and numerous previous association studies, only 8.5% of CCT variance is currently explained. Here, we report the results of a multiethnic meta-analysis of available genome-wide association studies in which we find association between CCT and 98 genomic loci, of which 41 are novel. Among these loci, 20 were significantly associated with keratoconus, and one (RAPSN rs3740685) was significantly associated with glaucoma after Bonferroni correction. Two-sample Mendelian randomization analysis suggests that thinner CCT does not causally increase the risk of primary open-angle glaucoma. This large CCT study explains up to 14.2% of CCT variance and increases substantially our understanding of the etiology of CCT variation. This may open new avenues of investigation into human ocular traits and their relationship to the risk of vision disorders.

Effects of drought on agronomic and fiber quality in an introgressed backcross inbred line population of Upland cotton under field conditions

Upland cotton (Gossypium hirsutum) is the most important fiber crop and an important oilseed crop in the world. Developing drought tolerant cultivars is important to sustainable cotton production in arid and semi-arid regions. However, there is a lack of information on genetic variation for drought tolerance in breeding populations. In this study, a backcross inbred line (BIL) Upland population with germplasm introgression from a more drought-tolerant American Pima cotton (G. barbadense) parent was evaluated in multiple field environments under well-watered (WW) and water-limited (WL) conditions at the flowering stage. Drought at the flowering stage reduced seedcotton yield (SCY), lint yield (LY), boll weight (BW), fiber length (FL), and fiber strength (STR) but increased lint percentage (LP), micronaire (MIC), neps per size, nep per gram, seedcoat nep size, and seed coat fragment count by gram. Significant genetic differences in the BIL population were detected for most agronomic and fiber quality traits and drought susceptibility index (DSI) for these traits. DSI of SCY and LY ranged from 0.01 to 1.5 and 0.1–1.45, respectively, reflecting the tolerance level of the BILs under WL conditions. The broad-sense heritability estimates were moderate for most agronomic traits and moderate to high for most fiber quality traits. Results indicated that highly positive correlation was detected for agronomic and fiber quality traits between WW and WL conditions, with the highest correlations for SCY, LY, UHM, SCY, and MIC. Promising BILs with drought tolerance were identified. This study has provided a line of evidence that field drought tolerance was transferred from the more drought tolerant Pima line to Upland cotton.

SELECTION AMONG SOME MELON STRAINS FOR TOLERANCE TO THE TWO-SPOTTED SPIDER MITE, Tetranych usurticae koch

This study was conducted during the period from 2016 to 2018. Seven different strains of melon (Cucumis melo L.) were tested for their response to Tetranychus urticae. Data revealed that, all plant growth parameters were affected significantly with infestation of T. urticae; leaf area which considered the main source of mite feeding was the most affected one. However, (L5) had the lowest leaf area (24.98 cm2 ) while (L7) recorded the highest leaf area (41.26 cm). Also, accumulated moving stages in (L2) showed the lowest population density with an average of 1.70 individual /in2 during 4 weeks, of season 2016. During season 2017, the highest leaf area was in hybrids (L4×L1) and (L4×L2) with an average 62.93 and 61.86 cm2 . All hybrids explained three levels of infestation; high level was observed in hybrids (L6×L2), (L5×L2) and (L7×L1) and accumulated the population density of moving stages with an average of 80.70, 70.60 and 61.40 individual /in2 . While medium level was recorded in hybrids (L5×L1 and L7×L2) and the third, low level of infestation was recorded in hybrids (L6×L1, L4×L1, L3×L2, L3×L1 and L4×L2) and moving stages average were 2.70, 3.30, 3.70, 3.90 and 5.30 individual /in2 so these hybrids were resistant to infestation of T .urticae . Regarding horticultural characters obtained data on total yield ranged from 4015.0 to 2185.0 g/plant; (L4) gave the highest value of total yield. Estimates of broad sense heritability were high for all studied traits indicating minor role of the environment. The results showed significant and highly significant mean squares for both general combining ability and specific combining ability in all studied traits, indicating the important role of both additive and non-additive gene effects in the expression of these traits. Highly significant SCA effects in all studied traits were recorded for the crosses (L3×L2), (L5×L2), (L6×L2) and (L3×L1).

Combining Ability Analysis of Dry Matter Content, Reducing Sugars and Yield of Potato (Solanum tuberosum L.) Genotypes in Uganda

Potato (Solanum tuberosum L.) in Uganda is a major food and cash crop mainly grown in the highland regions by small-scale farmers. The increasing importance of potato as a processed product requires new varieties possessing quality processing attributes with acceptable yield. The objectives of this study were to estimate the combining ability effects for dry matter content, reducing sugars, and yield related traits in potato. Nineteen F1 families generated from eight parents using a half diallel mating design were evaluated for dry matter content, reducing sugars, average weight per tuber and total tuber yield at Kachwekano research station. Additive genetic effects were predominant for dry matter content while non-additive effects for the other traits. The GCA/SCA ratios were 0.58, 0.28, 0.17 and 0.44 for dry matter content, reducing sugars, average weight per tuber and total tuber yield respectively. Broad sense heritability estimates were 50.6% for dry matter content, 77.8% for reducing sugars, 90.3% for average weight per tuber and 29.5% for total tuber yield. Parents NAROPOT 3 and 395096.2 had desirable GCA effects for both dry matter content and reducing sugars. Families of nkrk19.17 x Rutuku had desirable SCA effects for dry matter content while Rutuku x 393077.54 and nkrk19.17 x 392657.8 had desirable SCA effects for reducing sugars. Additive genetic effects for dry matter content imply that, genetic gains can be achieved through different selection methods and trait transferred to the respective progenies. The selected parents and families will be subjected to further clonal evaluation and selection.

Mixed models and multivariate approach applied to maize breeding: A useful tool for biofortification

Biofortification and bioactive compounds enrichment of maize genotypes is a great alternative for mitigating micronutrients deficiency in human and animal diet, and also for improving the benefits of maize for human health. This work aimed to estimate variance components and genetic parameters of bioactive compounds and micronutrients to predict superior maize hybrids from different genetic bases, and to apply the RELM/BLUP methodology to multivariate techniques. The inbreed lines were crossed and the F1 hybrids were grown for evaluations in 2014/2015 and 2015/2016 growing seasons, respectively. Then, micronutrients and bioactive compounds related traits were evaluated. The variance components and genetic parameters were estimated by REML methodology. The BLUP methodology was employed to predict genetic values and to verify the percentages of genetic gain with selection. The predicted genetic values were applied to estimate genetic distances by the Mean Euclidean Distance. The relative contribution of each trait to genetic divergence was evaluated and the principal components analysis determined, proposing the genotypes that are potentially capable to increase a given trait. The presence of genetic variability was evidenced among genotypes, while some of them presented potential for increasing specific traits. The top cross hybrid L64XAS1590 showed the highest estimates for increasing antioxidant-responsible traits, and micronutrients contents such as manganese, cooper, iron and zinc. In general, there was the possibility of achieving genetic gains with selection under application of biofortified and bioactive compounds to enhance maize hybrids through conventional breeding. However, it does not applicable for iron content due to its low estimate of broad sense heritability.

Genetic Variability, Heritability and Genetic Advance Among Bread Wheat Genotypes at Southeastern Ethiopia

The knowledge of nature and magnitude of variation existing in available breeding materials is great importance for successful selection of varieties. This study was conducted to generate information on the extent of genetic variability in advanced bread wheat lines. Thirty bread wheat genotypes were tested at Sinana and Agarfa, Southeastern Ethiopia, in alpha lattice design with three replications. Combined over locations ANOVA was carried out for yield and yield related traits. There were highly significant differences among genotypes for all traits. Highly significant location effects at P < 0.01 were observed for yield and yield related except for harvest index which showed significant effect at P < 0.05 and grain yield non-significant location effect. This indicates the presence of variability for these characters among the tested genotypes. In combined analysis, grain yield had high PCV (27.1%) and moderate GCV was observed for biomass weight, grain yield and harvest index. Phenotypic coefficient of variance (PCV) moderate for biomass weight and harvest index. Heritability estimates in broad sense (H2) was very high for most of the characters except for grain yield (52.3%) and number of kernel per spike (73.2%). However, low GAM was observed for most of the characters except moderate GAM was observed for harvest index (15.9%). Finally, the presence of variability among the genotypes, performance of heritability and GAM in the tested traits of the genotypes confirmed possibility to increase wheat productivity. Hence, selection and hybridization on those genotypes can be recommended for farther yield improvement of bread wheat.

Genetic control of traits related to maturity in cowpea

Abstract The aim of this study was to investigate genetic control of the traits number of days to flowering (NDF) and number of days to maturity (NDM) in a cowpea cross. Genetic parameters were estimated in segregating and non-segregating generations of a cross between two contrasting cowpea genotypes (MNC05-828C-1-9-1 × MNC04-792F-146). No evidence for maternal effect was found for either trait. Broad and narrow sense heritability estimates were above 50%, allowing genetic gains from selection of plants in the F2 generation. High significance of additive gene effects and low contribution of dominance and epistatic effects were detected for both traits. The estimated number of genes controlling the traits was around 4 for NDF and 5 for NDM. The results suggest that early-maturing cowpea self-fertilized cultivars can be developed through standard breeding approaches, meeting the demands of modern agricultural systems for more crop seasons per year and mechanized harvesting.