Broad-sense Heritability Estimates Research Articles

Genetic Variation and Heritability for Hydrogen Cyanide in Fresh Cassava Roots: Implications for Low-Cyanide Cassava Breeding.

Breeding for low-hydrogen-cyanide (HCN) varieties is a major objective of programs targeting boiled cassava food products. To enhance the breeding of low-HCN varieties, knowledge of genetic variation and trait heritability is essential. In this study, 64 cassava clones were established across four locations and evaluated for HCN using three HCN assessment methods: one with a 1 to 9 scale, on with a 0 ppm to 800 ppm scale, and a quantitative assay based on spectrophotometer readings (HCN_Spec). Data were also collected on the weather variables precipitation, relative humidity, and temperature. Highly significant differences were observed among clones (p < 0.001) and locations (p < 0.001). There was also significant clone-environment interactions, varying from p < 0.05 to p < 0.001. Locations Arua and Serere showed higher HCN scores among clones and were associated with significantly higher (p < 0.001) mean daily temperatures (K) and lower relative humidity values (%) across 12 h and 18 h intervals. Within locations, HCN broad sense heritability estimates ranged from 0.22 to 0.64, while combined location heritability estimates ranged from 0.14 to 0.32. Relationships between the methods were positive and strong (r = 0.75-0.92). The 1 to 9 scale is more accurate and more reproducible than either the 0 to 800 ppm scale or spectrophotometric methods. It is expected that the information herein will accelerate efforts towards breeding for low-HCN cassava varieties.

Evaluation of non-additive genetic effects on carcass and meat quality traits in Korean Hanwoo cattle using genomic models

The traditional genetic evaluation methods generally consider additive genetic effects only and often ignore non-additive (dominance and epistasis) effects that may have contributions in genetic variation of complex traits of livestock species. The available dense single nucleotide polymorphisms (SNPs) panels offer to investigate the potential benefits of including non-additive genetic effects in the genomic evaluation’s models. Data from 16,971 genotyped (Illumina Bovine 50K SNP chip) Korean Hanwoo cattle were used to estimate genetic variance components and prediction accuracy of genomic breeding values (GEBV) for four carcass and meat quality traits: carcass weight (CWT), eye muscle area (EMA), back fat thickness (BFT) and marbling score (MS). Five different genetic models were evaluated through including additive, dominance and epistatic interactions (additive by additive, A×A; additive by dominance, A×D and dominance by dominance, D×D) successively in the models. The estimates of additive genetic variances and narrow sense heritabilities (ha2) were found similar across the evaluated models and traits except when additive interaction (A×A) was included. The dominance variance estimates relative to phenotypic variance ranged from 1.7 to 3.4% for CWT and MS traits, whereas, they were close to zero for EMA and BFT traits. The magnitude of A×A epistatic heritability (haa2) ranged between 14.8 and 27.7% in all traits. However, heritability estimates for A×D and D×D epistatic interactions (had2 and hdd2) were quite low compared to haa2 and were contributed only 0.0 to 9.7% of the total phenotypic variation. In general, broad sense heritability (hG2) estimates were almost twice (ranged between 0.54 and 0.68) the ha2 for all of the investigated traits. The inclusion of dominance effects did not improve the prediction accuracy of GEBV but improved 2.0 to 3.0% when epistatic effects included in the model. More importantly, rank correlation revealed that partitioning of variance components considering dominance and epistatic effects in the model would enable to re-rank of top animals with better prediction of GEBV. The present result suggest that dominance and epistatic effects could be included in the genomic evaluation model for better estimates of variance components and more accurate prediction of GEBV for carcass and meat quality traits in Korean Hanwoo cattle.

Morpho-agronomıc varıabılıty, herıtabılıty and genetıc advance studıes ın sesame (sesamum ındıcum L.) In nıgerıa

The study explored morpho-agronomic and biochemical traits to assess variability level and the degree of genetic diversity in 15 Sesame accessions. Data were subjected to analysis of variance, multivariate analyses, and genetic parameters were estimated. Significant differences (P &lt; 0.05) existed among the accessions in all the characters. Four components with a cumulative variation of 85.7% were extracted. Substantial broad sense heritability estimates and high genetic gain were observed in secondary branches (97.8%; 719.4%), primary branches (96.1%;142,5%), capsules per plant (97.8%; 141.1%), single plant seed yield (86.87%; 46.03%), capsule length (99.16%; 32%), and 500 seed weight (95.15%; 34.12%). It may be inferred that a considerable level of variability existed among the accessions studied and charcters like branching habit, capsules per plant, capsule length and single plant seed yield  could be considered for selection in breeding for superior genotypes. Bangladesh J. Bot. 53(1): 75-81, 2024 (March)

Genetic analysis of cassava brown streak disease root necrosis using image analysis and genome-wide association studies.

Cassava brown streak disease (CBSD) poses a substantial threat to food security. To address this challenge, we used PlantCV to extract CBSD root necrosis image traits from 320 clones, with an aim of identifying genomic regions through genome-wide association studies (GWAS) and candidate genes. Results revealed strong correlations among certain root necrosis image traits, such as necrotic area fraction and necrotic width fraction, as well as between the convex hull area of root necrosis and the percentage of necrosis. Low correlations were observed between CBSD scores obtained from the 1-5 scoring method and all root necrosis traits. Broad-sense heritability estimates of root necrosis image traits ranged from low to moderate, with the highest estimate of 0.42 observed for the percentage of necrosis, while narrow-sense heritability consistently remained low, ranging from 0.03 to 0.22. Leveraging data from 30,750 SNPs obtained through DArT genotyping, eight SNPs on chromosomes 1, 7, and 11 were identified and associated with both the ellipse eccentricity of root necrosis and the percentage of necrosis through GWAS. Candidate gene analysis in the 172.2kb region on the chromosome 1 revealed 24 potential genes with diverse functions, including ubiquitin-protein ligase, DNA-binding transcription factors, and RNA metabolism protein, among others. Despite our initial expectation that image analysis objectivity would yield better heritability estimates and stronger genomic associations than the 1-5 scoring method, the results were unexpectedly lower. Further research is needed to comprehensively understand the genetic basis of these traits and their relevance to cassava breeding and disease management.

Genetic Diversity and Structure of Terminalia bellerica (Gaertn. Roxb.) Population in India as Revealed by Genetic Analysis.

In this study, an extensive exploration survey of wild progeny was conducted which yielded 18 candidate plus trees (CPTs) of Terminalia bellerica. Seeds of these CPTs were collected from diverse locations between 10°54' and 28°07' E longitude, and 76°27' and 95°32' N latitude, covering 18 different locations across 5 states of the Indian subcontinent. The objective of the progeny trial was to assess genetic associations and variability in growth and physio-chemical characteristics. Significant variations (p < 0.05) were observed among the growth traits, encompassing plant height, basal diameter, girth at breast height and volume, as well as physio-chemical characteristics such as leaf length, width, area and chlorophyll content, carotenoids, and protein in the progeny trial. Broad-sense heritability (h2b) estimates were consistently high, exceeding 80% for all growth and physiological related traits under investigation except for plant height, leaf length, and girth at breast height. A correlation study revealed that selecting based on plant height, leaf area, and girth at breast height effectively enhances T. bellerica volume. A moderate genetic advance in percent of the mean (GAM) was observed for most traits, except leaf length, leaf width, girth at breast height, and plant height. Across all 13 traits, phenotypic coefficient of variation (PCV) surpassed genotypic coefficient of variation (GCV). Utilizing principal component analysis (PCA) and dendrogram construction categorized the genotypes into seven distinct groups. In conclusion, the study has demonstrated that targeting girth at breast height and plant height would be a highly effective strategy for the establishment of elite seedling nurseries and clonal seed nurseries for varietal and hybridization programs in the future.

Genetic dissimilarity, attributes association, and path analysis of sweet peppers

The present investigation was conducted on genetic diversification, character connections, and their direct and indirect effects using 21 sweet pepper genotypes to identify superiors owing to developing variety (es) and/or utilizing the pertinent genotypes in the hybridization program. It was found that, except fruit length (FL), all of the features had larger phenotypic coefficients of variation (PCV) than genotypic variation coefficients of variation (GCV), and the gap between PCV and GCV was rather small. Except for FL (24.98%) and seed number per fruit (24.76%), all traits had a high estimation of broad sense heritability of more than 75.00%, indicating significant improvement is possible by employing standard selection procedures. High genetic advance as a percentage of the mean was observed for all the characters. Genotypic and phenotypic correlation analyses showed that there was a strong positive correlation between fruit yield per plant with fruit yield/plot and yield (t/ha) (r = 1.00**). In addition, the importance and close correlation of characters to enhance yield or to use as selection catalogues were demonstrated by the fact that the genotypic direct impacts utilized by the yield component traits were fairly bigger than their equivalent phenotypic effects.

Evaluation of shoot-growth variation in diverse carrot (Daucus carota L.) germplasm for genetic improvement of stand establishment.

Carrot (Daucus carota L.) is a high value, nutritious, and colorful crop, but delivering carrots from seed to table can be a struggle for carrot growers. Weed competitive ability is a critical trait for crop success that carrot and its apiaceous relatives often lack owing to their characteristic slow shoot growth and erratic seedling emergence, even among genetically uniform lines. This study is the first field-based, multi-year experiment to evaluate shoot-growth trait variation over a 100-day growing season in a carrot diversity panel (N=695) that includes genetically diverse carrot accessions from the United States Department of Agriculture National Plant Germplasm System. We report phenotypic variability for shoot-growth characteristics, the first broad-sense heritability estimates for seedling emergence (0.68 < H2 < 0.80) and early-season canopy coverage ( 0.61 < H2 < 0.65), and consistent broad-sense heritability for late-season canopy height (0.76 < H2 < 0.82), indicating quantitative inheritance and potential for improvement through plant breeding. Strong correlation between emergence and canopy coverage (0.62 < r < 0.72) suggests that improvement of seedling emergence has great potential to increase yield and weed competitive ability. Accessions with high emergence and vigorous canopy growth are of immediate use to breeders targeting stand establishment, weed-tolerance, or weed-suppressant carrots, which is of particular advantage to the organic carrot production sector, reducing the costs and labor associated with herbicide application and weeding. We developed a standardized vocabulary and protocol to describe shoot-growth and facilitate collaboration and communication across carrot research groups. Our study facilitates identification and utilization of carrot genetic resources, conservation of agrobiodiversity, and development of breeding stocks for weed-competitive ability, with the long-term goal of delivering improved carrot cultivars to breeders, growers, and consumers. Accession selection can be further optimized for efficient breeding by combining shoot growth data with phenological data in this study's companion paper to identify ideotypes based on global market needs.

Genetic variability and heritability studies in sunflower inbred lines

The experiment was conducted at Oilseeds Research Centre, Dr. PDKV, Akola during Kharif 2020-2021, to study the Genetic Variability studies in Sunflower Inbred Lines. The experiment consisted of 24 sunflower inbred lines were evaluated with three checks (DRSF 108, DRSF 113 and Phule Bhaskar) respectively and was laid out in Randomized Block Design. The study illustrated, the existence of wide ranges of variations for most of the characters among the sunflower inbred lines. Analysis of variation indicated that the mean squares of the genotypes were highly significant for all the characters taken under study. The range of variation, as well as genotypic and phenotypic coefficient of variations were high for seed yield/plant, plant height and test weight indicating the scope of improvement through simple selection procedure for obtaining high yield. Broad-sense heritability estimate was maximum for plant height (98.5), while that for seed yield g/plant (97.4) and head diameter (95.6). Hence, higher heritability estimates for these traits indicated that environmental factors did not greatly affect phenotypic variation of these characters.

Genetic Variability and Heritability of Medium Maturity Group’s Soybean (Glycine max (L.)) Genotypes at Oromia, Ethiopia

Field experiment was conducted to assess the extent of genetic variability and heritability in soybean genotypes for yield and its related traits. A total of thirty six soybean genotypes were evaluated using simple lattice design at Fedis eastern Ethiopia. Data were recorded for major quantitative traits and analyzed using appropriate statistical R-software. Analysis of variance revealed that the genotypes were highly significant for all the traits studied, indicating the existence of considerable magnitude of variability. High broad sense heritability estimate coupled with relatively high genetic advance as percentage of mean were computed for pods/plant, plant height, grain yield and primary branches/plant. Moderate to high genetic advance as percent of mean was estimated from the present result days to maturity, primary branches/plant, plant height, pods/plant, seeds/pod, hundred seeds weight and grain yield were recording  high genetic advance as percent of mean, while days to flowering and secondary branches/plant estimated moderate genetic advance as percent of mean. High values of phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), broad sense heritability (H2), and genetic advance as percent of mean (GAM) were estimated for plant height, primary branches per plant, pod per plant, seeds per pod, and grain yield indicating the ease of direct selection for the improvement of these traits. Hence, selection for these traits is likely to be effective as high heritability values were associated with high genetic advance as percent of means in the improvement of the performance of the soybean genotypes. As a result breeder can improve the tested soybean genotypes through plant height, number of pods/plant, number of primary branches/plant and grain yield.

Screening for High-Yielding Barley Genotypes with Adequate Foliar Disease Resistance in North Delta of Egypt

In addressing the global impact of fungal foliar diseases on barley yield; namely powdery mildew, net blotch and leaf rust, this study undertakes a robust phenotypic and genotypic evaluation. A set of 132 barley genotypes, were evaluated under conditions of elevated pathogenic stress. Multivariate analyses revealed statistically significant inter-genotypic variances for all measured agronomic and pathological traits, concomitant with noticeable seasonal effects. In a nuanced observation, the genotype-by-season interaction elicited significant impacts across a plethora of traits, with the exception of spike length and thousand grain weight. From a quantitative genetics perspective, broad-sense heritability estimates were remarkably high: 97.2% for powdery mildew, 89.3% for net blotch, and 97.5% for leaf rust. Concurrently, genetic advance estimates for biological yield, grain yield, powdery mildew, net blotch, and leaf rust registered in the high to very high categories. Correlational analyses substantiated a positive linear relationship between grain yield and maturity date, plant height and biological yield. Using biplot analysis, 12 genotypes were identified that showed high yield and resistance to powdery mildew, net blotch, and leaf rust. Thus, investigation illuminates the possibility of deploying high-yielding, disease-resistant barley cultivars as an effective strategy for mitigating the deleterious effects of fungal foliar pathogens on barley production in Egypt.

Genotype × environment interaction and stability analysis for seed yield and yield components in sesame (Sesamum indicum L.) in Benin Republic using AMMI, GGE biplot and MTSI

Increasing production requires the development of high yielding cultivars adapted to various environments. Multi-environment trials (MET) remains the best approach to assess the performance of accessions across environments. The objective of this study was to select the best performing and stable accessions of sesame across different environments in Benin Republic. Nineteen sesame accessions were evaluated across eight environments using a randomized complete block design with four replicates. The accessions were evaluated for three traits: days to 50% flowering (D50F), thousand-seed weight (TSW), and seed yield (SY) during 2020 growing season. The stable and top-performing accessions across environments were determined using AMMI (Additive main effects and multiplicative interaction), GGE (Genotype main effect and genotype × environment interaction), and MTSI (Multi-trait stability index). AMMI analysis of variance showed a significant difference across environments for the three traits. The accessions were affected by environmental conditions for the three traits. The broad-sense heritability estimates were high (>0.60) for all the traits, indicating the improvement is achievable through selection. AMMI1 and AMMI2 biplots identified G10 and G13 as high seed yielding accessions adapted to environments E1, E2. The GGE biplot showed two mega-environments for TSW and three mega-environments for D50F and SY. For SY, G11 and G13 were the best accessions in the first mega-environment, G10 the best accession in the second mega-environment; G3 and G8 were the best accessions in the third mega-environment. AMMI and GGE analyses identified G10, G5, G12 as high seed yielding and stable accessions across environments. GGE biplot revealed that E1 and E2 were the most suitable environments for multi-location trials based on their discriminating ability and representativeness. MTSI indicated G10, G13, G19 as promising germplasm to be recommended for breeding program.

Assessment of yield performances for grain sorghum varieties by AMMI and GGE biplot analyses

Grain sorghum is an exceptional source of dietary nutrition with outstanding economic values. Breeding of grain sorghum can be slowed down by the occurrence of genotype × environment interactions (GEI) causing biased estimation of yield performance in multi-environments and therefore complicates direct phenotypic selection of superior genotypes. Multi-environment trials by randomized complete block design with three replications were performed on 13 newly developed grain sorghum varieties at seven test locations across China for two years. Additive main effects and multiplicative interaction (AMMI) and genotype + genotype × environment (GGE) biplot models were adopted to uncover GEI patterns and effectively identify high-yielding genotypes with stable performance across environments. Yield (YLD), plant height (PH), days to maturity (DTM), thousand seed weight (TSW), and panicle length (PL) were measured. Statistical analysis showed that target traits were influenced by significant GEI effects (p &amp;lt; 0.001), that broad-sense heritability estimates for these traits varied from 0.40 to 0.94 within the medium to high range, that AMMI and GGE biplot models captured more than 66.3% of total variance suggesting sufficient applicability of both analytic models, and that two genotypes, G3 (Liaoza No.52) and G10 (Jinza 110), were identified as the superior varieties while one genotype, G11 (Jinza 111), was the locally adapted variety. G3 was the most stable variety with highest yielding potential and G10 was second to G3 in average yield and stability whereas G11 had best adaptation only in one test location. We recommend G3 and G10 for the production in Shenyang, Chaoyang, Jinzhou, Jinzhong, Yulin, and Pingliang, while G11 for Yili.

Genetic variation and correlations for some physiological characters and seed yield in Indian mustard (Brassica juncea L.) under rainfed conditions

An experiment was conducted with 42 Indian mustard genotypes in Randomized Complete Block design to estimate genetic parameters and correlations of some physiological characters and seed yield under rainfed conditions. Specific leaf area, transpiration rate and relative water content were recorded at 30 (vegetative stage), 45-50 (50% flowering stage) and 60-65 days aftersowing (full flowering stage). Total drymatter, harvest index, pod intensity, pod area on main and primary branches, seed : husk ratio and seed yield were recorded at the time of harvest. The analysis of variance indicated highly significant differences among the genotypes for all the characters studied. The maximum phenotypic and genotypic variability was observed for transpiration rate at full flowering stage. Heritability estimates in broad-sense were high for all the characters except relative water contents (RWC) at all the 3 stages, pod area of main and primary branches and pod intensity on main shoot. High heritability combined with high genetic advance was observed for specific leaf area at all the 3 stages, transpiration rate at 50%and fullflowering and total drymatter/plant suggested scope for selection for these characters owing to predominance of additive effects in the expression of these characters. Seed yield/plant had significant and positive correlations with harvest index (r = 0.581**), total drymatter/plant (r = 0.869**), pod intensity on main shoot (r = 0.467**), pod area of main (r = 0.536**) and primary branches ((r = 0.317*) and RWC at all the 3 developmental stages. Thus, selection for high harvest index, total dry matter/plant and pod intensity coupled with low transpiration rate at flowering stage, resulting in maintenance of high RWC in leaves, should be emphasized to increase yield under rainfed conditions.

Identification of superior clones of Satureja rechingeri Jamzad. using progeny test

Satureja rechingeri is a precious plant for the pharmaceutical, feed and food industries due to the high content of antimicrobials in essential oil, mainly carvacrol. As a part of domestication and introduction into the cultivation program, a poly cross design was performed to evaluate genetic parameters and the general combining ability of 58 promising clones of S. rechingeri. Half-sib family seeds were grown in an RCBD with ten replications, and plants were assessed for their quantitative and essential oil traits. General combining ability and genetic parameters, phenotypic and genotypic correlations were estimated for all assessed traits. Analysis of variance revealed significant variation among entries of all the characters, indicating the possibilities of exploiting the available variability for further genetic improvement. Estimates of the genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were highest for essential oil yield (98.38% and 213.95%) and essential oil content (91.60% and 135.14%) in 2021 and 2022, respectively. Broad sense heritability estimates for various traits ranged from 16.68 for leaf width to 91.88 for growth type. Essential oil traits showed a high and positive phenotypic and genotypic correlation with plant height, leaf width, number of lateral branches, plant fresh weight, plant dry weight, and growth type. The growth type, number of lateral branches, plant fresh weight, plant dry weight, leaf width, and number of main branches were identified as influential factors in increasing the quantity of S. rechingeri target traits essential oil traits, and dry weight. Based on general combining ability estimates of principal traits, half-sib families of S. rechingeri clones of ‘Z19′, ‘G48′, ‘Z16′, ‘K48′, ‘F3′, ‘K5′, ‘E41′, ‘G27′ and ‘F71′ showed the highest performance. These clones can be selected as parents of synthetic varieties or new genetic sources to select superior genotypes.

Genotypic variability and genetic parameters for root yield, dry matter and related traits of cassava in the Guinea Savannah ecological zone of Ghana

The aim of this study was to assess the agronomic performance and genetic parameters governing storage root yield and related traits in cassava genotypes in order to identify superior genotypes. The study involved 18 elite cassava genotypes which were arranged in a randomized complete block design with three replications and assessed for storage root yield and yield components (12 months after planting) in the Guinea savannah ecology of Ghana for three seasons. Analysis of variance indicated significant (p &lt; 0.05) genotype and year main effects for fresh and dry root yields, dry matter content, starch yield and harvest index. Genotype × year effect was significant (p &lt; 0.05) for fresh root yield, dry root yield and starch yield. Estimates of the variance components revealed greater genotypic influence for starch yield, fresh and dry root yields implying the potential for genetic gain with selection for these traits among the genotypes. Relatively high (69 %) broad sense heritability estimate was observed for dry storage root yield indicating the depth of genetic influence. Path coefficient analysis revealed a direct positive effect of dry matter content on dry storage root yield whilst dry storage root yield had direct positive effect on starch yield suggesting the possibility of indirect selection for starch yield through dry storage root yield. The study revealed ample genotypic variability among the cassava genotypes to warrant selection. Four genotypes, IBA 070134, IBA 419, IBA 950289 and IBA 980581 were identified for high and stable fresh and dry root yields for multilocational testing.

Assessment of genetic parameters in periwinkle through diallel analysis

Estimation of genetic variability assists in determining the contribution of various plant parameters inexhibiting the improvement of genotypes under a specific set of environmental factors. Genetic analysis allows us to clearly understand various morphological, physiological, and genetic traits, in addition to the type and extent of their role in the advancement of cultivars. The present investigation was carried out to evaluate six inbred lines of periwinkle (Vi-15-1, Vi-13-2, Vi-16, Vi-15-2, Vi-29, Vi-14-3), and their cross combinations in the full diallel fashion for ornamentally important characters. Analysis of variance revealed highly significant variations for all the parameters in all the inbred lines utilized in the study. The highest broad sense heritability estimates were observed for the number of seeds/follicles (H= 97.77 %) in the parents, whereas plant height had the highest heritability in the cross combinations (H= 98.73%). The high values of phenotypic and genotypic coefficient of variation in parents (PCV=34.41; GCV=34.02) and crosses (PCV=25.49; GCV=24.93) were recorded for thenumber of seeds/follicles. In the present study, moderate to high heritability together with a high percentage of genetic advance was recorded for seeds/follicle, follicle length, primary branches/plant, plant height, internode length and plant spread, suggesting that the additive gene action controlled these characters. Therefore, the results suggested the existence of variability for studied traits in these periwinkle inbred lines, which should be improved in future breeding.

Planting Density Does Not Affect Root Shape Traits Associated with Market Class in Carrot

Carrot (Daucus carota var. sativus) cultivars with common root shape, appearance, and end-use are grouped and commercialized in market classes. The shape of the carrot storage root is the result of growth and development, which is highly influenced by genotype; however, the extent to which planting density affects root shape traits and its interaction with genotype remains unexplored. To observe the effects of market class and density on carrot root shape characteristics, five cultivars classified in five different market classes, including Imperator, Nantes, Danvers, Chantenay, and Ball, were each grown at five planting densities ranging from 0.5 million to 4.5 million plants/ha. A generalized complete block design with a two-way factorial treatment arrangement of the two factors, density and genotype, was used in three environments. Roots were phenotyped using a digital imaging pipeline and scored for root size (length, maximum width) and compound root shape traits including traits derived from the principal component analysis of root contour profiles like root fill and tip and shoulder curvature. The results suggest that planting density had minimal impact on the shape of carrot roots, and the expected shape for each market class was maintained regardless of planting density; however, the analysis was constrained by the presence of interactions among genotype, density, and environment, which influence the contribution of main effects to shape. For the Nantes, Danvers, Chantenay, and Imperator market classes, planting density influenced the size of the carrot root, with size decreasing by up to 50% in length and width at high planting densities. We found high estimates of broad-sense heritability for traits that determine the shape of the carrot root, such as root fill and length-to-width ratio, which capture size-independent variation of the storage root. Although environmental signals play a role, our results suggested that the shape of the carrot root is primarily determined by genotype, and that planting density generally does not have a significant effect on its shape.

Diversity Assessment of Winged Bean [Psophocarpus tetragonolobus (L.) DC.] Accessions from IITA Genebank

The capability of winged bean to support food and nutrition security in sub-Saharan Africa is recurrently being affected by several constraints, which include a lack of genetic improvement. The dearth of adequate information on the level of available genetic diversity in winged bean germplasm has been a major setback in planning appropriate improvement programs. Fifteen winged bean accessions were assessed for genetic diversity using 10 quantitative traits and 10 simple sequence repeat (SSR) markers. The accessions were laid out in RCBD with three replicates for two growing seasons. Leaf samples were obtained from 10 plants representing each accession for SSR marker genotyping. The accessions exhibited significant (p &lt; 0.05) differences for measured traits. Broad-sense heritability estimates varied from 10.31% for days to first plant maturity to 72.67% for pod weight. Pod weight had a positive and significant correlations with pod length (0.53, p &lt; 0.05), pod width (0.70, p &lt; 0.01), and number of seeds per pod (0.64, p &lt; 0.01). However, the number of seeds per pod was negatively correlated with days to maturity (−0.71, p &lt; 0.01). Number of seeds per pod was positively predicted by pod weight, seed thickness, and days to maturity. Cluster analysis delineated the accessions into two distinct groups. Average number of alleles of 4.2, gene diversity of 0.25, and polymorphic information content of 0.22 were recorded. Analysis of molecular variance revealed intra-accession variation of 95% as compared to inter-accession variation of 5%. Two primary genetic groups were identified and only three accessions, namely TPt-6, TPt-126, and TPt-48, showed genetic purity. The results of this study provide the basis for exploiting the existing diversity for winged bean improvement.

Genetic studies on iron and zinc concentrations in common bean (Phaseolus vulgaris L.) in Ghana

Iron and zinc deficiencies cause high health risk to young children and expectant mothers in sub Saharan Africa. The development of biofortified common bean (Phaseolus vulgaris L.) varieties could address the acute micronutrient deficiencies with associated improvement in the nutrition and health of women, children and adults. The objective of this study was to determine the mode of gene action and genetic advance in iron and zinc levels in common bean. Field experiment was carried out using six generations of two populations made of crosses between pairs of low iron, low zinc and high iron, moderate zinc genotypes (Cal 96 ˣ RWR 2154; MCR-ISD-672 ˣ RWR 2154). Each generation (P1, P2, F1, F2, BC1P1 and BC1P2) was evaluated on the field in a randomized complete block design with three replications. Generation mean analysis were performed for each trait measured in each of the crosses while iron and zinc levels were quantified by x-ray fluorescence. The study showed that both additive and non-additive gene effects were important in determining the expression of high iron and zinc levels. Iron concentration in the common bean seeds ranged from 60.68 to 101.66 ppm while zinc levels ranged from 25.87 to 34.04 ppm. Broad sense heritability estimates of iron and zinc were high in the two crosses (62–82% for Fe and 60–74% for Zn) while narrow sense heritability ranged from low to high (53–75% for Fe and 21–46% for Zn). Heritability and genetic gain were used as selection criteria for iron and zinc, and it was concluded that doing so would be beneficial for future improvement.

Molecular mapping of quantitative trait loci for resistance to early blight in tomatoes.

Early blight (EB), caused by Alternaria linariae (Neerg.) (syn. A. tomatophila) Simmons, is a disease that affects tomatoes (Solanum lycopersicum L.) throughout the world, with tremendous economic implications. The objective of the present study was to map the quantitative trait loci (QTL) associated with EB resistance in tomatoes. The F2 and F2:3 mapping populations consisting of 174 lines derived from NC 1CELBR (resistant) × Fla. 7775 (susceptible) were evaluated under natural conditions in the field in 2011 and in the greenhouse in 2015 by artificial inoculation. In all, 375 Kompetitive Allele Specific PCR (KASP) assays were used for genotyping parents and the F2 population. The broad-sense heritability estimate for phenotypic data was 28.3%, and 25.3% for 2011, and 2015 disease evaluations, respectively. QTL analysis revealed six QTLs associated with EB resistance on chromosomes 2, 8, and 11 (LOD 4.0 to 9.1), explaining phenotypic variation ranging from 3.8 to 21.0%. These results demonstrate that genetic control of EB resistance in NC 1CELBR is polygenic. This study may facilitate further fine mapping of the EB-resistant QTL and marker-assisted selection (MAS) to transfer EB resistance genes into elite tomato varieties, including broadening the genetic diversity of EB resistance in tomatoes.