Predominance Of Additive Gene Action Research Articles

Multivariate analysis of phenotypic diversity elite bread wheat (Triticum aestivum L.) genotypes from ICARDA in Ethiopia

Wheat is an important crop for food security, providing a source of protein and energy for the growing population in Ethiopia. However, both biotic and abiotic factors limit national wheat productivity. The availability of genetically diverse wheat genotypes is crucial for developing new wheat varieties that are both high-yielding and resilient to stress. Therefore, this field trial aimed to assess phenotypic variation and relationship among ICARDA-derived bread wheat genotypes using multivariate analysis techniques. The trial was conducted at three locations: Enewari, Wogere, and Kulumsa using an alpha lattice design with two replications during the main cropping seasons of 2022 and 2023. Phenotypic data on eight agronomic traits and the severity of yellow rust were collected and R programming was used for data analysis. Individual and combined location data analysis of variance showed significant differences (p ≤ 0.05) among genotypes for most of the studied traits. The highest heritability and genetic advance as a percentage of the mean were observed in days to heading (90.8, 21.29), plant height (72.4, 28.6), seeds per spike (61.7, 28), thousand kernel weight (61.9, 12), and area under the disease progress curve (67, 39.8), suggesting a predominance of additive gene action. Grain yield showed a strong positive correlation with days to maturity, plant height, spike length, spikelet per spike, and thousand kernel weight for each location. Dendrogram and phylogenetic tree methods were used to group genotypes into four genetically distinct clusters. Cluster II and III had the greatest inter-cluster distance, indicating higher diversity among their genotypes. This study identified new candidate genotypes with superior agronomic performance, high grain yield traits, and robust resistance to yellow rust, making them valuable for both current and future wheat breeding programs. Additionally, the comprehensive dataset produced in this study could facilitate the identification of genetic variations influencing desirable traits through genome-wide association analysis.

Genetic Variability and Diversity Analysis in Yard Long Bean [Vigna unguiculata (L.) walp subsp. sesquipedalis (L.) verdcourt] Accessions under Coastal Saline Ecosystem

Background: Yard long bean despite being highly nutritive summer legume vegetable crop, it is not cultivated on large scale due to seasonal constraints with progressing research activities, Tamil Nadu is yet to came up with a suitable commercial variety of yard long bean with higher yield and superior pod quality. Considering this, the present study with 30 yard long bean germplasm accessions was undertaken to estimate the genetic parameters and deciphering the extent of genetic divergence for nine quantitative traits in yard long bean. Methods: The genetic material comprising 30 different sources of germplasm accessions were evaluated for various quantitative traits in randomized block design (RBD) with triplicate replication at the Garden land, Department of Horticulture, Faculty of Agriculture, Annamalai University during 2022. TNAUSTAT and R Software has been used for data analysis. Result: Analysis of variance exhibited significant differences among the accessions for all the nine quantitative traits indicating the presence of genetic variability. The magnitude of high phenotypic and genotypic coefficient of variation was obtained for all the traits except days to maturity and days to fifty per cent flowering. High heritability coupled with genetic advance per cent as mean was observed for pod yield per plant followed by number of pods per plant, test weight, pod girth, number of seeds per pod, plant height and pod length indicating the predominance of additive gene action. Direct selection for above indicate traits could be valuable for yield improvement programme. Further, genetic divergence analysis revealed that seven clusters could be identified from 30 genotypes. The cluster I was largest having twelve genotypes. The maximum inter cluster distance was found between cluster I and cluster VII followed by cluster I and IV and the intra cluster distance was noted in cluster III followed by cluster I. Among the yield contributing traits, maximum contribution towards genetic divergence existed for pod length followed by test weight, days to maturity and pod yield per plant. Hence, hybridization between cluster VII (IC-630381), V (IC-630379), IV (IC-630383) and I (IC-626143) could be utilized for superior recombinants with desirable traits in segregating generations of yard long bean.

Diallel analysis, maternal effect and heritability in groundnut for yield components and oil content

BackgroundGroundnut is one of the world's major food and oil crops. Being sources of nutrition and vegetable oil, rich in affordable and digestible protein, it is a strategic crop in Burkina Faso for food security, nutrition, and cash income. Understanding the nature of gene effect and genetic variation affecting yield and yield component traits will contribute to designing appropriate breeding methods for groundnut improvement and increase selection efficiency in Burkina Faso. MethodsIn 2018, a total of 30 F2 progenies were generated through a 6 x 6 full diallel mating using six different and contrasting varieties. In 2019, parents and progenies were evaluated in a lattice square design in 3 replications at ICRISAT-Mali experimental field to assess the general combining ability (GCA) and specific combining ability (SCA) effects, the inheritance and the maternal and reciprocal effects for yield component traits (YCT) and oil content (OC). ResultsSignificant variabilities were observed among the parental genotypes and their F2 progenies for DTH, PSR, HPW, PL, PWD, SL, SWD, and OAC. Mean performance of the six parents were HPW (117.05g), HSW (57.24 g), PYH (1914.76), SYH (1312.73), PL (2.52), PWD (1,19), SL (1.38), SWD (0.83), OC (49.43), OAC (50.43) and LAC (33.61). Parent QH243C presented the highest value for SWD (1.02 cm) and OAC (60.76) while the parent ICGV09195 had the highest value of OC (50.36). Chalimbana presented the highest value of HPW (169.61 g), PL (2.98 cm), PWD (1. 41 cm), and SL (1.57 cm) while CG7 presented the highest value for HSW (75. 14 g), and SYH (1639.28 kg). Both YCT and OC are controlled by additive and non-additive gene effects with a predominance of additive gene action for HSW, SL, and SWD, whereas HPW, PL, PWD, and OAC were found to be more controlled by non-additive gene effects. Maternal effects as well as nuclear and cytoplasmic interaction effects were observed for both YCT and OC indicating that YCT and OC are influenced by a combination of genetic factors from both the maternal parent and the nuclear genome, as well as cytoplasmic factors such as mitochondrial DNA. Broad sense heritability ranged from 3.76 % to 91.56 %, and higher broad sense heritability values were recorded for pod length (91.56 %), hundred pod weight (83.71 %) and pod width (80.95 %). ConclusionThe study yields valuable insights into the inheritance of YCT and OC. The parents, Chalimbana and CG7, showed promise as good combiners for both yield component traits and oil content when used as male parents while TE3, Sh470P and QH243C can be used as female for the oil content and its components (oleic and linoleic content).

Breeding Strategies for Simultaneous Improvement in Anthracnose Disease Resistance and Economically Important Traits in French Bean

Background: French bean (Phaseolus vulgaris L.) production in the tropics is threatened by heavy incidence of anthracnose disease causing substantial crop loss when infection is at the early growth stages. Breeding strategies for tolerance against anthracnose disease along with enhanced productivity, and high pod protein content are to be formulated. Methods: Genotypes having broad genetic base and phenotypic diversity in 5 bush and 1 pole types were crossed in a 6 × 6 half diallel mating design to estimate combining ability, mode of gene action, and extent of heterosis for 11 quantitative traits. Result: The additive genetic effect was evident for percent disease index (PDI) of anthracnose and 10 pod weight. Rapid genetic gain can be achieved due to predominance of additive gene action in their control and can therefore be selected in early generation through simple breeding methods. Rest of the economic traits controlled by additive and non-additive gene effects could be improved through biparental mating, reciprocal recurrent selection, or diallel selective mating. Anthracnose disease tolerant and high yielding cultivars of might be developed utilizing parents, ‘Laxmi’, ‘Arka Sharath’ and ‘Vaishnavi-264’ with high gca effects. Although two cross combinations ‘Arka Sharath × Lakshmi’ and ‘Arjun × Arka Sharath’ showed significant heterobeltiosis in desired direction for PDI of anthracnose and other desirable horticultural traits but could not be exploited at commercial level due to complexity in hybridization. Identifying pure lines with tolerance against anthracnose disease and favorable horticultural attributes could be accomplished in segregating generations of the prospective hybrids.

Insights into Genetic Variability Parameters and Character Association among Agro-morphological and Biochemical Traits in Little Millet (Panicum sumatrense Roth. Ex. Roem and Schultz)

A set of 64 little millet genotypes was evaluated for their genetic variability parameters, principal components, and their contribution to total variance using seven agro-morphological and four biochemical traits in alpha lattice design with two replications. The mean performance revealed the presence of substantial variability for the characters studied. The phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) estimated ranged from 18.28% to 43.75% and 10.06% to 42.75%, respectively. Even though PCV was found to be significantly greater than GCV for the number of tillers, a slightly higher PCV over GCV was observed for all the other traits, suggesting a limited environmental influence for the majority of the traits. High heritability was observed for all agro-morphological and biochemical traits (84.00-94.00%), except for the number of tillers (42.00%), which exhibited moderate heritability. Genetic advance as a percentage of mean (GAM) was high for most of the traits, viz., days to 50% flowering, plant height, panicle length, single plant yield, test weight, grain protein, iron, zinc, and calcium contents. suggesting the predominance of additive gene action and the greater possibility of genetic improvement through simple phenotypic selection. Majority of the contribution towards the total divergence by days to 50% flowering, days to maturity, plant height, number of tillers, panicle length, single plant yield, and grain calcium content coupled with significant and positive correlations of majority of grain yield components with grain yield suggested that these traits are the key drivers of variability that could be exploited through a little millet improvement program.

Estimates of Genetic Variability, Association Studies and Per se Performance of Tomato Genotypes for Growth and Yield Parameters Under Drought Stress Conditions

Aims: Drought tolerance is a complex phenomenon, influenced by the coordinated activity of many genes. Breeding for drought tolerance is the need for contemporary research under the present climate change scenario. Further, the estimates of variability and degree of association among the traits would facilitate the selection for yield under drought conditions as it is highly influenced by environmental factors. This study aimed for the enhancement of selection capacity for drought stress tolerance in tomato based on the measures of genetic variability parameters and extent of association among traits which in turn used to identify drought tolerant genotypes. Methodology: The experiment was conducted with 39 tomato genotypes with 2 replications under normal and drought stress condition (15 days irrigation interval) following a Randomized Block Design during summer, 2020 at Department of Biotechnology and Crop Improvement, Kittur Rani Channamma College of Horticulture, Arabhavi. Results: High heritability along with moderate to high GAM was recorded for all the characters under study in both control and drought stress condition, indicating predominance of additive gene action for these traits. Yield per plant had positive and strong association with plant height, stem girth, number of primary branches, number of fruits per plant and average fruit weight. Further, path analysis revealed high desirable direct effect of average fruit weight and number of fruits per plant on yield per plant. Thus, there is ample of scope for improving these traits through selection. The genotypes viz., EC-634394, EC-638519 and Kashi Anupama shown superior performance for yield along with other yield attributing traits and also exhibited less percent reduction in these traits under drought condition.

Genetic Parameters and Association Studies for Yield and Grain Quality Traits in Rice Genotypes Derived from Distant Crosses

In the current study, 49 rice genotypes were studied for thirteen yield and grain quality traits to estimate the variability parameters and character associations. Number of filled grains per panicle and grain yield/plant recorded high phenotypic and genotypic coefficients of variation and most of the characters studied manifested high heritability estimates except for ear bearing tillers/plant and kernel breadth. Grain yield/plant exhibited high estimates for all genetic parameters indicating the predominance of additive gene action in the inheritance of this trait. The results of correlations revealed that, days to 50% flowering, plant height, ear bearing tillers/plant, number of primary branches/panicle, number of filled grains/panicle and test weight exhibited positive and significant correlation with grain yield. The outcome of path coefficient analysis concluded that days to 50% flowering, plant height, ear bearing tillers/plant, number of primary branches/panicle, number of filled grains/panicle and test weight manifested positive direct effects as well as significant positive association with grain yield, and hence direct selection of these traits would improve grain yield/plant.

Genetic variability studies of yield, its attributing traits and oil content in RHAlines of sunflower (Helianthus annuus L.)

Sunflower inbred lines (RHA) derived from different sources with Rf gene were evaluated during 2018- 2020.Genetic variability, phenotypic and genotypic coefficients of variation, heritability and genetic advance were assessed for seven traits related to seed yield, its attributing traits and oil content in 50 RHA lines of sunflower. The analysis of variance revealed highly significant differences for all the characters among the RHA lines. The magnitude of differences between PCV and GCV was relatively low for all the traits, indicating less environmental influence. The estimates of GCV and PCV were high for seed yield/plant. High heritability in broad sense estimates (>90%) were recorded for all the traits under study indicating, the predominance of additive gene action and selection of RHA lines based on these characters would be more valid and selected RHA lines are likely produce high yielding hybrids. Effective for target plant selection in early generation.

Genetic variation and response to selection of photosynthetic and forage characteristics in Kentucky bluegrass (Poa pratensis L.) ecotypes under drought conditions.

Evaluation of the effects of water-limited conditions on the photosynthetic characteristics and forage yield is important for enhancing the forage productivity and drought tolerance in Kentucky bluegrass (Poa pratensis L.). In the present study, 100 P. pratensis ecotypes collected from different geographical areas in Iran were assessed under well-watered and drought stress conditions. Genetic variation and response to selection for the photosynthetic characteristics [i.e., net photosynthesis rate (A), stomatal conductance (gs), transpiration rate (Tr), chlorophyll content (Chl), and photochemical efficiency (Fv/Fm)] and forage yield [fresh forage yield (FY) and dry forage yield (Dy)] traits were analyzed during the 2018 and 2019 growing seasons. Drought stress had negative effects on evaluated photosynthesis parameters and significantly reduced dry and fresh forage yields. On average, FY with a 45% decrease and gs with a 326% decrease under drought stress conditions showed the highest reduction rate among forage yield and photosynthesis traits, respectively. Genotypic coefficients of variation (GCV) for FY were lower under drought stress. The estimates of heritability, genetic advance, and genetic advance as percentage of mean showed the predominance of additive gene action for the traits. Overall, the results showed that "Ciakhor", "Damavand", "Karvandan", "Basmenj", "Abr2", "Abrumand", "Borhan", "Hezarkanian", "LasemCheshmeh", "Torshab", and "DoSar" have higher forage yield production with little change between two irrigation regimes, which makes them promising candidates for developing high-yielding drought-tolerant varieties through breeding programs.

Estimation of Genetic Variability, Correlation and Path Analysis for Yield and Some Yield Contributing Traits in Bread Wheat (Triticum aestivum L.)

A study was conducted at the Student Instruction Farm, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur, during the rabi season of 2022–2023, to estimate the genetic variability, correlation, and path coefficient analysis of yield and its contributing traits in cross combination. Ten wheat cultivars were grown in a randomized block design with three replications. The analysis of variance revealed that the treatments were highly significant for all the characters. The higher magnitudes of genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were recorded for grain yield, biological yield, harvest index and plant height. The high heritability in broad sense was estimated for all the characters except for day to 50% heading, flag leaf area (cm2), number of leaves/main tiller, number of spikelets/ear and protein content (%).A high value of heritability suggests that it could be due to a higher contribution of genotypic components. High heritability associated with high genetic advantage as a percentage of the mean was found for plant height, harvest index, biological yield, and grain yield, indicating a predominance of additive gene action in the inheritance of these traits. The estimated correlation coefficients showed high direct genotypic and phenotypic correlations for days to 50% flowering, days to maturity, plant height, productive tillers/plant, test weight, biological yield, and harvest index. In contrast, flag leaf area (cm2), number of leaves/main picks, number of kernels/spike, and seed hardiness were negatively correlated with grain yield. Path analysis showed that biological yield had the largest direct positive effect on grain yield, followed by harvest index, ear length, plant height, and days to 50%, indicating that these factors were the largest contributors to grain yield.

Genetic Studies in Advanced Sugarcane Mid-Late Clones through Yield and Quality Traits

Sugarcane varietal development is frequently aimed at increasing yield and sucrose quality. Effective crop genetic evolution requires knowledge of the numerous traits that contribute to the present diversity by genetic analysis. Keeping in view, this experiment was conducted using a randomized block design with three replications and the trial consisted of nine mid-late sugarcane genotypes. Data on cane yield and quality traits were used to estimate the genetic variability parameters, heritability, and genetic advance (GA). Analysis of variance revealed highly significant and significant differences for all studied traits. Evaluated characters exhibited different levels of variability, heritability, and genetic advance among the studied genotypes. Low to high phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were recorded. The moderate GCV and PCV values were found particularly for Sugar Yield at harvest (18.09% and 21.64%) and Cane Yield at harvest (16.62% and 20.14%) respectively, whereas the lowest GCV and PCV (1.43% and 2.26% respectively) manifested for Purity at the 12 months stage. The highest broad sense heritability value manifested for Pol in juice at 12 months stage (%) (86.47%) followed by CCS at 12 months stage (%) (85.43%), while the lowest heritability (35.00%) revealed only for Germination % at 30 DAP. In the present study, high heritability and genetic advance as a percentage of the mean (>50) was recorded for Millable canes at harvest (000/ha) and single cane weight at harvest (kg) indicating a predominance of additive gene action for these characters. Therefore the result of this study suggests the existence of variability for cane yield and quality traits in these sugarcane genotypes, which should be exploited in future breeding.

Influence of Genetic Variability Parameters, Character Association and Path Analysis for Grain Yield and its Attributing Traits in Kodo Millet Improvement

A set of 64 genotypes of kodo millet comprising of germplasm accessions and released varieties were evaluated for their genetic variability, heritability, genetic advance as per cent of mean, character associations and path coefficients using 11 agro-morphological traits during kharif 2022 in an Alpha Lattice Design with two replications. The analysis of variance revealed the presence of significant variations among the genotypes for all the traits evaluated. High PCV and GCV were observed for the traits viz., plant height, number of tillers, panicle length, peduncle length, thumb length, grain yield, and fodder yield. It indicated the presence of substantial variability and a low environmental influence on these traits. High heritability combined with high genetic advance as per cent of mean (GAM) was observed for plant height, peduncle length, panicle length, and fodder yield, which indicated the predominance of additive gene action and selection based on these traits would be more reliable. Grain yield exhibited significant and positive correlation with days to 50% flowering, number of tillers, panicle length, number of racemes, test weight and fodder yield. Genotypic path analysis revealed that highest direct positive effect on grain yield was exhibited by days to 50% flowering, number of tillers, panicle length, test weight and fodder yield. Hence, the above-mentioned traits exhibiting positive significant correlation and positive direct effect on grain yield could be considered as important traits to be included in the selection criteria to achieve genetic improvement of grain yield in kodo millet.

Mutation induction in aromatic Joha rice of Assam for improvement of morpho-agronomic traits through M1 to M3 generation

Purpose The popular Joha rice cultivar Kon Joha, cultivated throughout the state, was used to induce mutations. Kon Joha is short-grain aromatic rice with excellent cooking quality. The cultivar is tall and late maturing with an average yield of less than 2 tons ha−1 and is susceptible to lodging Materials and methods The investigation through M1 to M3 generation aimed at improving the morpho-agronomic traits of the popular Joha rice cultivar Kon Joha. The experiments were carried out during the Sali season (winter rice) from 2017 to 2019 at Instruction-cum-Research (ICR) Farm of Assam Agricultural University, Jorhat (Assam). Dry uniform seeds of Kon Joha were subject to irradiation with 100–400 Gy of gamma rays from a 60Co source. The M1 generation used a randomized complete block design with four replications during Sali 2017. A total of 5998 M1 plant progenies were subject to screening in the M2 during Sali 2018. The M3 included 662 morpho-agronomic variants raised in the plant rows during Sali 2019, and 66 mutants were confirmed. Results The M1 of Kon Joha registered a reduction in germination, seedling height, pollen/spikelet fertility and plant survival at 400 Gy. All the traits showed highly significant differences among the doses in the M2 generation. The shift in trait means was in both directions as influenced by the genotype and mutagen dose. The 66 mutants exhibited significant differences for all traits in the M3 generation. Fifty mutants were shorter than the parent Kon Joha. The GCV and PCV estimates were high (>20%) for grain yield, biological yield, productive tillers, filled grains, and average panicle weight. All the traits except panicle length exhibited high heritability coupled with high genetic advance, suggesting the predominance of additive gene action and the effectiveness of simple selection. Grain yield showed a significant positive correlation with plant height, panicle length, filled grains, spikelet fertility, the average panicle weight and harvest index in the mutant population. Conclusions Thus, mutation induction in Kon Joha proved useful in inducing desirable changes in plant architectural traits. The study further emphasized the short stature high yielding mutants with strong aroma for wide-scale testing in the state.

Assessment of Genetic Variability for Yield, Yield Attributing and Quality Traits of Promising Genotypes of Cluster Bean [Cyamopsis tetragonaloba L. Taub.

The present study was conducted to evaluate twenty four (24) genotypes along with 1 check variety (Pusa Navbahar) of cluster bean during kharif, July–September, 2019 at College of Horticulture, Rajendranagar, Sri Konda Laxman Telangana State Horticultural University, Telangana, India to estimate variability, broad sense heritability and genetic advance for pod yield and yield attributing traits. The observations were recorded on various growth, yield and quality parameters. High estimates of GCV and PCV were recorded for plant height, number of branches plant-1, pod length, pod weight and number of pods plant-1. Protein content, gum content and fibre content recorded moderate to high PCV and GCV. High heritability coupled with high genetic advance as % of mean was observed for plant height, number of branches plant-1, number of clusters plant-1, days to maturity, number of pods plant-1, pod length, pod girth, pod weight, number of seeds pod-1, pod yield plant-1, pod yield ha-1, protein content, gum content and fibre content. High variability in conjunction with high genetic advance as % of mean indicating the predominance of additive gene action. These traits could be exploited through manifestation of dominance and epistatic components through heterosis breeding. The overall assessment showed that there was wide variability among cluster bean genotypes which has important implication for selection of cluster bean genotypes for yield and quality attributes.

Genetic variability of rice genotypes under screening of normal and flash flood condition

The present study was undertaken to expose the flash flood tolerance of rice germplasm for some important quantitative traits with genetic variability existing in the 30 rice genotypes. The coefficients of variation at phenotypic and genotypic levels were marginally high for number of grains per panicle, grain yield per plant, grain breadth, 100-grain weight and number of productive tillers per plant and moderate for the traits viz., days to 50% flowering, plant height, panicle length and grain length for both normal and flash flood condition. From the results, high heritability coupled with high genetic advance of per cent of mean was observed for grain yield per plant, panicle length, number of productive tillers per plant, number of grains per panicle and 100-grain weight in both normal and flash flood condition, which indicated the predominance of additive gene action, in controlling these traits, early and simple selection could be exercised due to fixable additive gene effects.

Genetic variability study in advanced mutant lines of cluster bean [Cyamopsis tetragonoloba (L.) Taub.

Advanced cluster bean mutant lines developed by treating seeds of Pusa Navbahar variety with gamma radiation were evaluated in randomised complete block design with two replications to study the genetic variability. The analysis of variance revealed highly significant differences among the mutant lines of cluster bean for all the characters studied. The GCV and PCV values were high (>20 %) for number of vegetable pods per plant, pod yield per plant, pod yield per plot, pod weight, dry pod yield per plant, seed yield per plant and seed yield per plot indicating the existence of broad genetic base, which would be amenable for further crop improvement. High heritability (>60 %) coupled with high genetic advance over mean (>20 %) were observed for characters viz., plant height, number of vegetable pods per plant, number of pods per cluster, pod yield per plant and seed yield per plant which indicated predominance of additive gene action for these traits and hence direct selection would be more effective in improving these traits.

Studies on gene action and combining ability in rice (Oryza sativa. L) hybrids

The study was carried out to learn about the nature of gene action and combining ability in rice hybrids for grain yield and its component traits. For this, eight lines were crossed with four testers in an L x T mating design. The analysis of variance revealed significant variance for all the characters studied among the parents and hybrids. GCA variances were higher than SCA variances for most of the characters, indicating the predominance of additive gene action, while SCA variances were higher than GCA variances for number of productive tillers per plant, pollen fertility, hulling, milling, head rice recovery and grain yield per plant, indicating the predominance of non-additive gene action. The testers JMS 13A (3.91) and CMS 59A (2.46), as well as the lines MTU 1153 (9.52), RNR 28355 (3.26) and RNR 26085 (3.09), were the best combiners for grain yield and important yield components due to positive GCA effects. Based on SCA effects and corresponding mean performance for grain yield and its component traits, the hybrids CMS 59Ax RNR 26015, CMS 23A x JGL 25960, CMS 64Ax RNR 26015 and JMS 13Ax MTU 1153 were identified as the best specific combiners. These hybrids could be tested in multi-environment trials for commercial use. Keywords:  CMS lines, Gene action, Combining ability, GCA, SCA, Line x Tester &nbsp

Genetic variability and relatedness among yield characters in rice landraces and improved varieties

Sixty-nine cultivars of rice were examined for fourteen biometrical characteristics to study the degree of genetic divergence, heritability and genetic gain as a percentage of mean, character relationship and path coefficient analysis. Yield per plant reported the highest estimate of PCV and GCV followed by the total effective tillers per plant, hundred seed weight, number of filled seedsper panicle and flag leaf length indicating that these traits may be given importance while exercising selection. Plant height, panicle length,total tillers, total effective tillers per plant, flag leaf length, grain length, grain L/B ratio, the number of filled seeds per plant, hundred seed weight and yield per plant exhibited remarkable genetic gain and high heritability, implying a predominance of additive gene action. Hence, genetic advancement through simple selection would be more beneficial. Among the yield traits examined, days to 50% flowering,total tillersper plant, the number of effective tillers per plant, flag leaf breadth, the number of filled seeds per panicle, and hundred-seed weight recorded a positive significant correlation with direct effects on yield per plant asserting that these traits were the most efficient and promising selection criteria. Keywords: Rice, PCV, GCV, heritability, genetic gain, correlation and direct effects&nbsp

Genetic Variability Analysis for Agro-morphological and Seed Yield Component traits of Soybean (Glycine max (L.) Merrill) Genotypes under Mid Hill Zone of Himachal Pradesh

Aim, Design and Methodology: A research with 21 soybean genotypes including three checks was carried out in kharif 2021 at Research Farm of Genetics and Plant Breeding, CSK HPKV Palampur to estimate the genetic variation, heritability and genetic advance for 13 agro-morphological & seed yield component traits that can be used as selection criteria in breeding programmes. RBD design was used to set up the experiment with a plot size of 3 × 1.35=4.05 m2 and replicated three times.
 Results and Conclusion: The results of the analysis of variance revealed that the genotypes varied considerably for days to 50 percent flowering, days to 75 percent maturity, plant height (cm), number of nodes per plant, inter-nodal length (cm), number of branches per plant, number of pods per plant, pod length (cm), number of seeds per pod, seed yield per plant (g), 100-seed weight (g), biological yield per plant (g) and harvest index (%) showing the genetic divergence of the planting materials from one another. According to the estimates of genetic variability, the phenotypic coefficient of variation for all the traits were greater than the genotypic coefficient of variation explaining the important role played by environmental factors in the manifestation of the traits. Higher values of PCV coupled with moderate GCV values were detected for harvest index (27.93%, 11.84%) indicating the presence of sufficient genetic variation for selection in such traits. High heritability estimates along with high genetic advance (as percent of mean) were recorded for plant height and 100-seed weight which could be ascribed to predominance of additive gene action and high selective index and therefore, selection pressure could be applied profitably to such traits for genetic modification in soybean.

An Assessment of Genetic variability and association studies for yield and its components of soybean MAGIC population lines (Glycine max (L.) Merrill.)

In the present investigation, 565 soybean MAGIC population lines along with 6 checks were evaluated in augmented design in 5 blocks at Agricultural Research Station, Adilabad during kharif, 2019-20 to study genetic parameters, character association and the direct and indirect effects of the traits on seed yield. Based on range, all the traits exhibited huge amount of variability. In the present study, the estimate of PCV was higher than GCV indicating the important role of environment in the expression of the characters under study. The highest genotypic and phenotypic coefficient of variation observed for the traits number of branches per plant (PCV- 33.53 %, GCV-20.15 %), number of pods per plant ( PCV- 32.35 %, GCV-21.11 %), net plot yield( PCV- 36.36 %, GCV-27.27 %) and seed yield per plant (PCV- 31.67 %, GCV-22.30 %) which indicates selection can be applied on these traits to isolate more promising line. The broad sense heritability was lower to higher for all the traits ranged from days to 50% flowering (20.02%) to days to maturity (75.87 %) while high genetic advance was recorded in all traits under study except, days to 50% flowering (2.99 %) and days to maturity (9.47 %).Among all the characters, high heritability along with high genetic advance as percent of mean was observed for plant height and net yield indicating predominance of additive gene action and a limited role of environment in the expression of these traits. Hence, these traits are fixable in nature and selection on the basis of these traits would be effective. Correlation studies indicated that number of branches/plot, number of pods/plant, net yield/plot, 100 seed weight and number of nodes/plant had significant and positive correlation with seed yield/plant.