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Academic literature on the topic 'Genotypic variance(σ2g)'
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Journal articles on the topic "Genotypic variance(σ2g)"
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Chapman, S. C., M. Cooper, D. G. Butler, and R. G. Henzell. "Genotype by environment interactions affecting grain sorghum. I. Characteristics that confound interpretation of hybrid yield." Australian Journal of Agricultural Research 51, no. 2 (2000): 197. http://dx.doi.org/10.1071/ar99020.
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Past sorghum hybrid trials in north-eastern Australia have detected substantial genotype by environment (G×E) interactions for yield in sampling a variable target population of environments (TPE) that is affected by spatial and seasonal differences in crop water supply. Three datasets, comprising yields of commercial and final stage experimental hybrids and covering 9–17 years (Y) and up to 30 locations (L), were analysed to quantify variance components for trial error, genotypic (σ2g), and G×E (σ2gl, σ;2gy, and σ2gly) interaction effects. Whereas trial means varied 2–3-fold across seasons, a greater range was estimated for variance components of trial error (range of 0.05–0.5), G (0–>0.3), and G×L interaction (0.05–>1.0). There was substantial seasonal variation in the ratio of σ2g to (σ2g +σ2gl), and in two datasets, 73% of the seasonal σ2gl was due to poor genetic correlations among locations. This implies that any given set of hybrids in a random set of locations would be ranked differently from season to season. Analysis of locations over years detected 90% of the total G×E interaction as G×L×Y, rather than G×L or G×Y, although this was reduced by accounting for genotype maturity. To achieve repeatabilities of >80%, trials would need to be conducted over at least 5 years and 20 locations per year. The variable and unpredictable nature of much of the G×E interaction in the region implies that broad adaptation to different water regimes is required, unless prior knowledge of the seasonal weather can be used to choose ‘narrowly adapted’ cultivars. With current approaches, a large sample of environments is needed to identify such hybrids, and testing across locations and years is equally important. Alternative breeding strategies based on classifying environment types are discussed.
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Hamza, A.M., E.C. Okolo, S.G. Ado, I.S. Usman, and Collins Agho. "Estimates of Components of Variances for Bunch Traits in Date Palm Crosses (Phoenix dactylifera L)." Greener Journal of Agricultural Sciences 3, no. 7 (2013): 563–68. https://doi.org/10.15580/GJAS.2013.3.061013663.
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A field experiment was carried out at Nigeria institute for Oil Palm Research date palm Research substation Dutse, Jigawa state during 2004-2005 flowering season. Biparental progenies derived from 60 crosses replicated twice were subjected to analysis of variance using nested design for the purpose of estimating additives, genetic and dominance components of variances of the seven bunch traits. Significant variation was observed for the traits studied. The male components of variances (σ2m) for all the traits were negative, indicating that the estimates were not different from zero or were very small. Positive estimates were recorded for females within male variance (σ2f/m), while Non-significant negative additive variances (σ2A) were obtained for all the traits. Dominance variance (σ2D) showed significant positive values for number of fruits, spikelets, aborted fruits and unfertilized florets. Positive estimates were recorded for environmental variance (σ2e), genotypic variance (σ2g) and phenotypic variance (σ2ph). In allcases phenotypic variance was much larger than the genotypic variance. Low environmental variance were obtained for the traits indicating that the environmental condition where the experiment was carried out is homogenous and the material could perform considerably well under similar environmental conditions. The means performance of the males indicates that variability exists between the males; Males 6R3 and 1R7 are good combiners with female 12R3 for number of fruits while males 1R12 and 5R2 are good combiners with female 12R3 for number of fruits. Female 2R8 is poor general combiners for number of fruits. Males 1R12 and 5R2 are good combiners with female 1R27 for weight of fruit while male 6R3 and 1R7 are good combiners with female 12R3 for fruit weight. Recurrent and backcross selection are recommended for further date palm improvement programs.
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Zala, K. R., S. M. Makwana, V. S. Patel, and K. S. Solanki. "Genetic Variability Analysis, Correlation Coefficient and Path Coefficient Analysis of Dahlia (Dahlia variabilis L.) Varieties in Saurashtra Region of Gujarat, India." International Journal of Plant & Soil Science 35, no. 21 (2023): 259–66. http://dx.doi.org/10.9734/ijpss/2023/v35i213972.
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Identification of genotypes better suited for particular region and their improvement is of immediate task to exploit their full potential. The improvement can be brought out after confirming the association among the most important growth with quality attributes. Hence, varietal evaluation becomes necessary to find out suitable variety for a particular region. Experiment was conducted with 20 different decorative types of dahlia varieties at Jambuvadi Farm, College of Horticulture, Junagadh Agricultural University, Junagadh which falls under South Saurashtra Agro-climatic Zone during 2021-22. The analysis of variance revealed significant differences among the genotypes for eleven characters in dahlia viz., plant height, number of leaves per plant, number of branches per plant, stem girth, days taken to first bud initiation, diameter of flower, stalk length, vase life, anthocyanin content, chlorophyll content and flower yield which indicated the existence of variability in the experimental material. The estimates of genotypic (σ2g) and phenotypic variances (σ2p) of each character were carried out.
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Talas, Firas, Rasha Kalih, and Thomas Miedaner. "Within-Field Variation of Fusarium graminearum Isolates for Aggressiveness and Deoxynivalenol Production in Wheat Head Blight." Phytopathology® 102, no. 1 (2012): 128–34. http://dx.doi.org/10.1094/phyto-06-11-0162.
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Fusarium head blight (FHB), caused by Fusarium graminearum sensu stricto (s.s.), causes tremendous annual yield losses in wheat worldwide. Variation of aggressiveness of isolates from individual field populations in terms of FHB infection and deoxynivalenol (DON) concentration in the host are important population parameters reflecting parasitic ability. Our main objective was to estimate the variation of both traits within three populations of F. graminearum s.s., each consisting of 30 single-spore isolates collected from small wheat fields in Germany, and to compare it with 11 isolates of a collection (F. graminearum collection) from four countries. The same isolates were characterized using 19 single-sequence repeat markers. All isolates were spray inoculated on a moderately resistant spring wheat cultivar at two field locations over 2 years (i.e., in four environments). The genotypic proportion of phenotypic variance (σ2G) within populations was significant (P < 0.01) for both traits, and the σ2G × environment interaction was even more important for mean FHB severity. Ranges in mean FHB severity and DON concentration in the host were only slightly smaller for the field populations than for the F. graminearum collection. Both traits were significantly (P < 0.05) correlated within and across populations. A further partitioning of σ2G revealed 72% of σ2G within and 28% of σ2G across populations for both traits. Molecular variance of the three populations was similarly distributed (73.6% within versus 26.4% between populations). In view of this high within-field variation for traits of parasitic ability and selection, neutral molecular markers, multiple resistance genes of different origin should be employed in wheat breeding programs to obtain a long-term stable FHB resistance.
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Rasel, Md, Lutful Hassan, Md Injamum Ul Hoque, and Setu Rani Saha. "Estimation of genetic variability, correlation and path coefficient analysis in local landraces of rice (Oryza sativa L.) for the improvement of salinity tolerance." Journal of the Bangladesh Agricultural University 16, no. 1 (2018): 41–46. http://dx.doi.org/10.3329/jbau.v16i1.36479.
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Twenty eight local rice landraces were assessed for eleven morphological traits for the improvement of salt tolerance ability of rice genotypes. Genotypic variance (σ2g), phenotypic variance (σ2p), phenotypic co-variance (PCV), genotypic co-variance (GCV), heritability, genetic advance, genetic advance as a percentage of mean, correlation coefficient and path coefficient were estimated. For all the traits, PCV was higher than the GCV indicating that they were controlled by non-additive gene action and selection for the improvement of these traits would be promising. Among the traits, survival rate of plant exhibited high estimates of PCV (460.72) and GCV (324.73) indicated wide range of variability for these traits where lowest phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) where low PCV and GCV were observed for root dry weight (0.17 & 0.12) followed by shoot dry weight (0.31 & 0.16) and total number of roots (0.61 & 0.34) indicating lack of inherent variability and limited scope for improvement through selection for these traits among the genotypes. Highest heritability had observed in all traits except chlorophyll content and root length and maximum value of heritability was noticed for shoot length (75.96%). High heritability along with high genetic advance was noticed for survival rate of plant (31.14%) followed by live leaves percentage (11.98) and the lowest genetic advance was found in root dry weight (0.58) and shoot dry weight (0.58). Correlation study revealed that significant negative correlations at both phenotypic and genotypic level exist between standard evaluation score (SES) and survival rate (%), root length, shoot length, root fresh weight, root dry weight and shoot dry weight at the seedling stage further confirmed the importance of these parameters as useful selection criteria for screening for salt tolerance rice genotypes. Path analysis revealed that the root length (0.487), root dry weight (0.394) and shoot dry weight (0.047) had direct positive effect on standard evaluation score at genotypic level where live leaves (%) per plant (0.168), total number of roots (0.006), chlorophyll content (0.243) and shoot fresh weight (0.102) had direct positive effect on standard evaluation score at phenotypic level. From the correlation and path analysis it can be concluded that root length, root dry weight and shoot dry weight would be more promising for the improvement of salt tolerance in rice genotypesJ. Bangladesh Agril. Univ. 16(1): 41-46, April 2018
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Asungre, Peter Anabire, Richard Akromah, Alexander Wireko Kena, and Prakash Gangashetty. "Genotype by Environment Interaction on Grain Yield Stability and Iron and Zinc Content in OPV of Pearl Millet in Ghana Using the AMMI Method." International Journal of Agronomy 2021 (November 8, 2021): 1–10. http://dx.doi.org/10.1155/2021/9656653.
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Twenty-two open-pollinated varieties (OPVs) of pearl millet (Pennisetum glaucum) genotypes were tested in two locations for three seasons in Ghana to estimate the magnitude of genetic variability, heritability, and stability for grain yield and related traits and grain micronutrients among the varieties. General analysis of variance within and across locations and years revealed very highly significant variability ( p < 0.01 ) among the genotypes. The additive main effects and multiplicative interaction (AMMI) analyses revealed significant genotype × environment interaction (GEI) that influenced the relative ranking of genotypes across the environments. Genotypic variance ( σ 2 g ) contributed a greater proportion of the phenotypic variance (σ2p) for plant height (530.31) and grain Fe content (34.72). Broad-sense heritability ( h b s 2 ) varied widely from 24.82% for grain yield to 77.53% in days to flower. Phenotypic coefficient of variation (PCV) was higher than genotypic coefficient of variation (GCV) for all traits, indicating strong play of environment on trait expressions. 11 out of the 22 OPVs were stable for grain yield and micronutrients across environments for the three-year period and included GB 8735 and ICMV 221 Wbr and SOSAT-C88.
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B., Aishwarya, Patil B. R., Patil R. S., Hegde M. G., and Rao M. S. L. "Assessment of combining ability and genetic parameters for yield and fiber traits in upland cotton (Gossypium hirsutum L.) using Line × Tester analysis." Electronic Journal of Plant Breeding 16, no. 1 (2025): 133–42. https://doi.org/10.37992/2025.1601.010.
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Seed cotton yield and fiber quality are two critical parameters that fundamentally define the economic and industrial value of cotton. The present work focused on improving cotton genotypes both for yield and quality parameters through intraspecific crosses. Estimation of combining ability parameters for forty-five Gossypium hirsutum genotypes employed the Line × Tester mating design. Significant (p≤0.01) differences in mean squares values were observed across all studied traits for the genotypes. Regarding parental lines, P2-103 and P1-190 demonstrated the highest positive general combining ability (gca) effects for seed cotton yield per plant, boll weight, and number of bolls per plant, thereby being identified as exceptional combiners. From the comprehensive set of forty-five crosses, P1-62×Suraksha and P2-36×Subiksha emerged with notable positive specific combining ability (sca) effects across multiple traits. Non-additive genetic variance (σ2D) predominantly exceeded additive genetic variance (σ2A) for most traits, suggesting potential exploitation of superior cross combinations through heterosis breeding strategies. Keywords: Cotton, Line x Tester, combining ability, GCA, SCA
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Abd El-Hady, M. E. E., A. A. Hamed, M. A. I. Youssif, and H. E. M. A. Ismail. "Genetic Studies for some Bean Traits in Relation to Stability and Insect Infestations." IOP Conference Series: Earth and Environmental Science 1213, no. 1 (2023): 012069. http://dx.doi.org/10.1088/1755-1315/1213/1/012069.
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Abstract This research was carried out at a private farm located at Qaha, Qalyubia Governorate, Egypt during the two successive summer seasons of 2018 and 2019 to estimate the stability parameters of ten dry bean (Phaseolus vulgaris L.) genotypes for yield, insect infestation and some economic traits under different planting densities as well as to assess the annual variation of some insect pests through different growing densities and seasons in relation to certain climatic factors, synchronization of plant age with insect infestation percentage on plant due to insect activity. There were significant genotype × densities interactions for the studied bean’s traits, i.e., number of days to flowering, pod length, 100-seeds weight, number of pods/plant, yield/feddan and insect infestation. Combined analysis of variance revealed significant differences among genotypes for all studied traits. Pooled deviation mean squares for number of days to flowering, yield/fed. and insect infestation were not significant suggesting the consistency of the genotypes yielding ability under environmental conditions tested. The high yielding genotypes G6, G1 and G10 produced high yielding performance based on wide adaptation and stability of performance over all environments. Genotypes G3, G5, G7 and G10 were insensitive to environmental changes and could be recommended for cultivation under all conditions. Genotype G8 also had minimum aphid infestation over range of environments showed below regression coefficients for yield/fed. and insect infestation and low deviation from regression, indicated specific adaptability of this genotype to unfavorable environments. Genetic variation (σ2g) was large in magnitude compared to error one (σ2e) in all studied traits of all cases except pod length in all densities of 2nd season (Env. 5-8) and number of pods under 10 cm/2 rows of Env.8, reflecting the genetic differences among genotypes for all studied traits except of those two cases. The population of both leaf miners (Melanogromyza phaseoli) and aphid (Aphis craccivora Koch) was observed from the third week of March (5th week after planting date) and continued till to 3rd week of May (14th week after planting) and reached to a peak level 55.2 and 85.9% for aphid and leaf miners during 9th and 11th weeks after planting date, respectively, i.e. 2nd and 4th week of April. Genotype G8 interacted with planting space of (5 cm ×2 rows) were explained the lowest Melanagromyza phaseoli (Tryon) and Aphis craccivora Koch, infestations (18.8% and 12.6%, respectively) followed by G1 and G5 with the same planting space for leaf miners (29.6%) and aphid (15.3%) infestations, respectively.
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N. Dudhatra, Kuldeep, Mukesh P. Patel, and Mihir M. Pandya. "Elucidation of gene action and estimation of combining ability effects for fruit yield attributes and biochemical traits in brinjal (Solanum melongena L.)." Electronic Journal of Plant Breeding 15, no. 3 (2024): 612–20. http://dx.doi.org/10.37992/2024.1503.067.
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Abstract The present investigation was undertaken in brinjal (Solanum melongena L.) to estimate combining ability and gene action following a half diallel mating design using ten parents. The ratio of genetic variance components, σ2gca/σ2sca and σ2D/σ2A, showed dominant gene action, indicating the presence of non-additive genetic variance for days to 50% flowering, fruit yield per plant, total phenol, antioxidant activity and total soluble sugar. The traits fruits per plant, fruit girth, and fruit weight showed additive genetic variance. Among the parental genotypes, AB 15-08, ABSR 2 and AB 20-13 were found to be good general combiners for fruit yield, fruits per plant, and total soluble solids. The three highest-ranking hybrids were AB 15-08 × AB 20-13, AB 15-08 × AB 20-03 and AB 20-07 × GP BRJ 224. The above hybrids would be rewarding for harnessing heterosis. Keywords: Diallel cross, brinjal, combining ability, fruit yield, antioxidant activity
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Vedanchiya, K. K., N. V. Soni, R. M. Patel, et al. "Hybrid Vigour and Combining Ability in Biofortified Maize (Zea mays L.)." International Journal of Bio-resource and Stress Management 14, Aug, 8 (2023): 1204–13. http://dx.doi.org/10.23910/1.2023.3592c.
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The study was conducted during winter season of 2020–2021 and rainy season of 2021 at Maize Research Station, Sardarkrushinagar Dantiwada Agricultural University, Bhiloda, Gujarat, India. The aim of the study was to assess magnitude of heterosis and combining ability of forty-five single cross hybrids developed by half-diallel mating design involving ten parents and two standard checks. The field experiment was laid out in randomized block design with three replications. The heterosis, combining ability and components of genetic variance were studied for diverse thirteen characters. The analysis of variance revealed that mean square values of genotypes were significant for all the characters which indicated the existence of considerable amount of genetic variation in genotypes for all the characters. Among single crosses, IMR-76×IMR-58 exhibited maximum mean and desired SCA effect and standard heterosis for β-carotene and IMR-53×IMR-72 for kernel yield. The general and specific combining ability variances observed highly significant for all traits except days to tasseling (only additive gene action), anthesis-silking interval and shelling percentage (only non-additive gene action). The σ2A/σ2D ratio indicated that preponderance of non-additive gene action for the inheritance of these characters suggesting due weightage should be given to heterosis breeding for genetic improvement of these traits. The crosses namely IMR-52×IMR-72 and IMR-51×IMR-58 presented significant heterosis for days to maturity, grain yield, iron and β-carotene content.