Phenotypic Coefficient Of Variation Research Articles

Multi-locus genome-wide association studies reveal genetic loci and candidate genes for leaf angle traits in cut chrysanthemum

Chrysanthemum (Chrysanthemum morifolium Ramat.), one of the four most popular cut flowers in the world, occupies a large share of global floriculture trade. Leaf angle (LA) is an important factor affecting plant architecture, photosynthesis and yields of cut chrysanthemum. However, the genetic basis and related genes underlying LA remain largely unknown. In this research, phenotypes of five LA-related traits in 200 cut chrysanthemum accessions were investigated across two consecutive years (Y2020 and Y2021), and their broad-sense genetic heritabilities ranged from 68.91% to 84.70%. Leaf orientation value (LOV) exhibited the maximum phenotypic coefficient of variation of 35.66% in Y2020 and 32.34% in Y2021. A new methodological framework named 3VmrMLM was applied for multi-locus genome-wide association study (GWAS) based on a set of 330,710 single nucleotide polymorphisms (SNPs) to explore the genetic loci and candidate genes of LA. As a result, 303 quantitative trait nucleotides (QTNs) in single-environment, 120 QTNs and 75 QTN × environments interactions (QEIs) in multiple-environments were identified. Among the genes around these QTNs and QEIs, 26 known genes were considered to be associated with LA, including ARF16, IBH1, AN3, etc. Furthermore, the haplotype analysis of ARF16 revealed four accessions with elite LA. Our findings provide a fundamental understanding to the genetic architecture of LA and contribute to further gene cloning and molecular improvement of chrysanthemum plant architecture.

Genetic Variability and Correlation Studies in High-yielding Varieties of Rice (Oryza sativa L.)

Rice is the major staple food crop of India and there is an anticipated high demand due to increasing population. Information on yield contributing traits and the level of heritable variation in these traits is essential for establishing the genotype’s potential for future breeding programmes. The study was conducted to evaluate the variability in yield contributing traits and their correlation in a set of released rice varieties from ICAR – Indian Institute of Rice Research, Hyderabad. The objective of the study was to estimate the genotypic and phenotypic coefficient of variation, heritability and genetic advance of yield and related traits using thirty-two rice cultivars. For all evaluated traits, the phenotypic coefficient of variation was found to be significantly higher than the genotypic coefficient of variance, implying that the expression of these traits is influenced by the environment. High heritability coupled with high genetic advance was observed for panicle weight whereas low heritability coupled with low genetic advance over per cent mean was recorded for productive tiller number. The traits viz., tiller number, productive tiller number, flag leaf width, panicle weight, number of grains per panicle, number of filled grains per panicle and test weight exhibited a positive association, whereas the number of unfilled grains per panicle and plant height exhibited negative association with grain yield.

Role of Genetic Variability and Their Associated Character on Yield Attributing Traits in Castor (Ricinus communis L.) Germplasm Lines

Castor (Ricinus communis L.) is an industrially important non-edible oil seed crop with limited genetic variation. It is consequently important to diversify the genetic base to utilize the diversity. The primary objective of this study was to assess the extent and significance of variability among castor genotypes concerning yield and its associated traits. A study with two hundred germplasm lines along with four checks on genotypes on variability, correlation, and path coefficient was carried out for nine traits. The genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) values indicated the presence of broad variation for all characters except for days to 50 percent flowering, days to maturity, number of nodes, and oil content. However, high heritability coupled with high genetic advance as percent mean was observed for plant height, days to 50 percent flowering, days to maturity, number of nodes, total length of the primary spike, number of effective spikes, seed weight, and total yield. The character's plant height, number of nodes, total length of the primary spike, number of effective spikes, seed weight, and oil content show a positive significant correlation with the total yield. The path coefficient analysis indicates that the utmost positive direct effect on total yield was exerted by a number of effective spikes per plant. Hence it was concluded that selection for traits total length of the primary spike, number of effective spikes, and 100 seed weight beneficial in yield improvement programs of castor.

Characterization and Trait Association Analysis of 27 Pearl Millet Landraces in Southern Tunisia

Pearl millet (Pennisetum glaucum (L.) R. Br., 2n = 2x = 14, Poaceae), is a cross-pollinated, warm-season crop grown worldwide. To select genotypes for breeding pearl millet cultivars that adapt to drought condition in southern Tunisia, we evaluated the grain yield (GY) and yield-related traits using a set of 27 landraces at two locations in southern Tunisia for two grown seasons (2019 and 2020). The genetic variability, phenotypic and genotypic association, and path coefficient (PC), based on grain yield (GY) and different yield-related agronomic traits, were evaluated. Analysis of variance and BLUPs value revealed a wide range of variability and the possibility of genetic selection for traits that are advantageous. Broad sense heritability (H) for all the traits ranged from 24.10% for grain yield (GY) to 57.11% for spike length (SL), indicating low to moderate inheritability. Genetic advance as a percentage of the mean (GAM) ranged from high (29.56%) for principal panicle weight (PPW) to moderate for all the traits except from plant high (PH) (7.31%). For all the traits, the phenotypic coefficient of variation (PCV) was higher than genotypic coefficient of variation (GCV), indicating the magnitude of environmental conditions. GY was significantly correlated with all the traits at the genotypic and phenotypic level. According to the path coefficient, the traits PPW and SL displayed the highest direct effects on GY. Heatmap analysis demonstrated a clear segregation between the early and late genotypes based on their geographic origin. Based on the cluster analysis and FAI-BLUPS analysis, genotypes G11, G13, G12, G17 and G18 were selected as the best-performing genotypes with the shortest cycle.

Assessment of Genetic Variability for Yield and Yield Contributing Characters in Rice (Oryza sativa L.)

The study was conducted at the department of Genetics and Plant Breeding, Patuakhali Science and Technology University, Bangladesh during the period from April 2018 to August 2018 to study variability, heritability, genetic advance, interrelationship among 14 important characters among the 15 popular rice genotypes of Bangladesh. Significant variation in plant height of BRRI dhan43, in 50% flowering BRRI dhan42 and BRRI dhan43, for days to maturity BRRI dhan42 and BRRI dhan43, for number of unfilled grain per panicle BRRI dhan48, for flag leaf length Lakhi Lata, for flag leaf width Lohar Gura, for panicle plant-1 BRRI dhan27, for number of filled grain per panicle Kalo Jamvi, number of filled grain per panicle Lakhi Lata, for 100-grain weight BRRI dhan48, for yield plant-1 BRRI dhan48 were found. Besides, yield per plant and 100-grain weight showed high genotypic and phenotypic co-efficient of variation while other characters showed moderate genotypic and phenotypic co-efficient of variation, except days to 50% flowering, days to maturity, panicle length, flag leaf length, flag leaf width, dry matter, and harvest index. All but, plant height and spikelet per panicle, all other characters studied in this experiment showed high heritability and high genetic advance in percent of mean. Panicle per plant, no. of filled grain, 100-seed wt., and harvest index are positively correlated. Yield per plant is also significantly and positively correlated with flag leaf length at the genotypic level but non-significant at phenotypic level. Grain yield showed non-significant positive association with flag leaf width and panicle length. Above information suggests that yield per plant would increase with increase of these characters. Path co-efficient analysis suggested that flag leaf length, panicle per plant, and flag leaf width showed moderate to low direct effect, but 100-seed weight showed highest positive direct effect toward yield per plant. Plant height showed a low negative direct effect on grain yield per plant while days to maturity, panicle length, no. of filled grain, no. of unfilled grain per panicle and dry matter had considerable negative direct effect on grain yield per plant and showed a negligible indirect effect. Thus, selection based on maturity period, number of panicles per plant, panicle length and higher number of filled grains per panicle might be effective for improving yield of rice.

Estimation of Genetic Variability among Sorghum Genotypes for Different Morphological and Biochemical Traits

Fifty diverse genotypes of sorghum were evaluated for different metric traits to assess the genetic diversity during kharif 2018-19 for yield and its associating traits. Less difference between the estimates of GCV and PCV implying the minimal influence of environmental agencies and importantly, improvement through selection seems feasible. The coefficients of variation (GCV and PCV) for panicle length without peduncle, 100-grain weight, green fodder production, crude protein yield, and other variables were found to be high. Whereas, low genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were recorded for traits, crude protein, height up to flag leaf, plant height, stem diameter, stem diameter and time of panicle emergence. Leaf breadth, panicle length without peduncle, dry matter%, 100-grain weight, green and dry fodder yield, HCN and tannin content, crude protein all had high heritability and genetic advance.

Genetic Variability, Heritability and Genetic Advance of Newly Developed Soybean (Glycine Max) Genotypes Based on Yield and Yield-Related Traits

This study aimed to estimate important genetic parameters such as genotypic coefficient of variance (GCV), phenotypic coefficient of variance (PCV), heritability (h2) and expected genetic advance (EGA) for newly developed soybean (Glycine max) genotypes based on yield and yield-related traits. Fifteen genotypes collected from the University of Agriculture Makurdi were studied. The results showed that there was sufficient variability in the material for all the studied traits, with high heritability estimates coupled with high expected genetic advance observed for number of leaves (4, 6 and 8) weeks, plant height (4, 6 and 8) weeks, leave length (6 and 8) weeks and yield per plant.

Estimates of Genetic Variability, Correlation and Path Analysis in Indian Mustard [Brassica juncea (L.) Czern & Coss

The Present investigation was undertaken to study the genetic variability, correlation and path analysis of twelve quantitative traits in Twenty Indian mustard (Brassica juncea L.) lines. The experiment material was evaluated in a randomized block design with three replications. The analysis of variance showed significant difference among genotype for all the characters. Results from the study indicated that heritability was high for all traits studied. Genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were low to medium for all the traits studied and genetic advance as percent of mean showed low to high values for most of the traits studied. Path coefficient at phenotypic and genotypic level revealed direct positive effect on seed yield per plant for about 50% of the traits studied. The significance for these results and their basis for selection of improved Indian mustard lines for further breeding in the program were discussed.

Genetic Variability, Heritability and Genetic Advance for Yield and Yield Contributing Characters in Bitter Gourd (Momordica charantia L.) Genotypes

Twenty diverse genotypes were evaluated at Horticulture research centre of SVP university of Agriculture & Technology, Meerut during spring season, 2022. The experiment was laid out in Randomized block design with three replications. The analysis of variance revealed significant among all the genotypes for all the characters under study. The high percentage of Genotypic coefficient of variation and phenotypic coefficient of variation for fruit diameter, fruit yield per plot, number of fruits per plant, fruit yield per hectare, node number to first male flower, average fruit weight while, moderate were found for node number to first female flower and TSS and lowest in days to germination, number of leaves per plant, vine length, number of primary branches per plant, days to first male flower, days to first female flower and days to first fruit harvest which estimated that high degree of variability in these traits. The highest heritability recorded for fruit diameter 99.45% followed by number of fruits per plant, fruit yield per plot, fruit length, node number to first female flower, average fruit weight, number of leaves per plant, node number to first male flower, days to first male flower, fruit yield per hectare, days to first fruit harvest, TSS, days to germination, vine length, days to first female flower and number of primary branches per plant. Genetic advance as percent of mean was highest for fruit diameter, fruit length, fruit yield per plot, number of fruits per plant, fruit yield per hectare, node number to first male flower, average fruit weight, node number to first female flower. Which indicate that above characters may be most potential for further improvement.

Study of Genetic Variability for Yield and Yield Attributes and Bran Oil Content in Maintainer Lines of Rice (Oryza sativa L.)

The present investigation was carried out during kharif, 2016 (June to October) at Regional Agricultural Research Station, Jagtial, Telangana, India to study the phenotypic coefficient of variation and genotypic coefficient of variation, heritability (bs), and genetic advance (GA) for yield contributing characters of 40 maintainer lines of rice. The experiment was designed in RBD replicated twice. Analysis of variance revealed significant differences among rice lines for 15 quantitative traits. The phenotypic coefficient of variation (PCV) value was higher than the genotypic coefficient of variation (GCV), indicating a negligible environmental influence in the phenotypic expression of traits. The PCV and GCV values were highest for the grains panicle-1 and moderate for bran oil percentage, indicating that these two characteristics have a higher variability within and between populations than other characteristics. All of the characters had high heritability. The range of bran oil content in the 40 maintainer lines used to assess the range of bran oil content was from 11.87% in line B11 to 19.35% in line JMS17B.The genetic advancewas greatest for number of grains panicle-1 (87.86%) and modest for bran oil %. The high and moderate estimations of genetic advance show that traits such as the number of tillers plant-1, test weight, L/B ratio, plant height, bran oil percentage, kernal breadth, grain yield plant-1 and kernal length were selected. The genetic advance obtained from the high and moderate estimates indicate that the selection for these characters can be used to improve the yield of the crop.

Genotypic Variability and Character Associations of Kabuli Chickpea (Cicer artietinum L.) Genotypes for Yield and Yield Related Traits at Arsi-Robe, Southeastern Ethiopia

The study was conducted at Arsi-robe, Southeast Ethiopia during August–December, 2020 to understand the extent of genetic variability and association for yield and yield related traits among Kabuli chickpea genotypes. Forty-nine Kabuli chickpea genotypes were evaluated for 11 traits at Arsi-robe using 7×7 simple lattice designs. The analysis of variance showed significant differences among genotypes. The phenotypic variances of the traits were higher than the genotypic variances, implying the influence of environment on the expression of the traits. Genotypic coefficient of variation (GCV) ranged from 1.28 for days to maturity to 41.74% for grain yield and phenotypic coefficient of variation (PCV) ranged from 1.47 to 44.06% for days to maturity and grain yield, respectively. High heritability was recorded from grain yield. High broad-sense heritability coupled with high genetic advance was observed for grain yield, number of secondary branches and hundred seed weight. Grain yield showed highly significant and positive genotypic correlations with grain filling period, number of seed plant-1 and plant height. Genotypic path coefficient analysis showed that days to maturity, number of pods plant-1, number of seed plant-1, plant height and hundred seed weight had positive direct effects on grain yield. Number of pods plant-1 exhibited a maximum positive direct effect on grain yield. The observed variations indicate the possibility for further improvement of grain yield and associated traits by utilizing selected parental genotypes and targeted crossing schemes in breeding programs.

Genetic variability, heritability, and genetic advance for quantitative traits of sorghum [Sorghum Bicolor (L.) Moench] genotypes at Fedis, Eastern Ethiopia

Sorghum is the second most important food crop after teff in Ethiopia. The objective of the study was to estimate the genetic variations, heritability, and expected genetic advances in the selected sorghum genotypes. Sixty-four sorghum genotypes were evaluated for 17 quantitative traits in 8x8 simple lattice designs at the Boko research site. The analysis of variance revealed highly significant differences among genotypes for all traits. The Phenotypic Coefficient Of Variation (PCV) ranged from 4.74% for days to flowering to 24.74% for panicle width, while Genotypic Coefficients Of Variation (GCV) ranged from 3.58% for leaf length to 20.33 % for panicle width. The highest PCV and GCV values were recorded for panicle width, head weight, and harvest index. Moderate PCV and GCV were recorded for grain filling period, grain filling rate, plant height, panicle length, and grain yield; indicating the effectiveness of selection based on the phenotypic performance of the genotypes. Broad sense heritability (H2) ranged from 24.74 % for biomass yield to 96.6% for head weight, whereas GAM ranged from 4.8% for biomass yield to 41.95% for panicle width. High H2 coupled with high GAM was observed for grain filling rate, panicle length, panicle width, head weight, grain yield, and harvest index; indicating that these characters are controlled by additive gene action and phenotypic selection for these characters will be effective. However, the information generated in the current study it can be useful for breeders who want to improve yield and yield contributing traits of sorghum.

Hybrid evaluation for yield and yield attributes in Okra (Abelmoschus esculentus L. Moench) during monsoon season

The present investigation aimed to evaluate Okra hybrids for growth and yield characteristics during the monsoon season in the dry and humid regions of Telangana. The experiment was conducted under augmented design with nineteen numbers of checks over 335 okra hybrids. The analysis of variance showed significant differences for all the traits under adjusted and unadjusted treatment effect and moreover checks also, except the number of days for flowering. The comparative mean performance deduced the hybrids like 21A014, 21A046, 21A064, 21A077, 21A079, 21A095, 21A112, 21A121, 21A181, 21A235, 21A252 and Check-12 has performed well under monsoon condition for various characters. The genetic parameter revealed that the traits like number of branches, stem internode distance (cm), average fruit weight (g), seed count, yield per plant (g/plant) and yield per hectare (t/ha) resulted in moderate Phenotypic Coefficient of Variation (PCV), Genotypic Coefficient of Variation (GCV), with high broad sense heritability coupled with high Genetic Advance over Mean (GAM). The selected hybrids can be potentially evaluated for the summer season in various locations for yield prospective and viral tolerance.

Study on Genetic Variability, Heritability and Genetic Advance in Spinach Beet under Garhwal Region of Uttarakhand

An investigation was carried out at the Vegetable Research and Demonstration Block, College of Horticulture, Veer Chandra Singh Garhwali, Uttarakhand University of Horticulture and Forestry, Bharsar Pauri (UK) during September, 2021 to evaluate diverse germplasm of spinach beet under temperate conditions of Garhwal region of Uttarakhand. The experiment was laid out in RCBD with three replications. In this study, fifteen genotypes including one check cultivar Pusa Harit were evaluated for different horticultural traits. Eight genotypes viz., Genotype-4, Arka Anupama, All Green, Palak Haryali, Genotype-1, Genotype-10, Genotype-2 and Genotype-7 performed better yield attributing traits and recorded higher than check cultivar. These genotypes need further testing to be released as a substitute of already existing spinach beet varieties or they can be involved in further breeding program for development of superior varieties in spinach beet. Genetic analysis indicated that phenotypic coefficient of variance (PCV) was higher than genotypic coefficient of variance (GCV) in all the attributes studied. The phenotypic coefficients of variance (PCV) and the genotypic coefficients of variance (GCV) were found high in total leaves weight per plot, the least was found in dry matter content. High heritability estimates coupled with high genetic gain were found highest for the character average leaves weight per plant and lowest for dry matter content, indicated that these traits are under additive gene effects and are more reliable for effective selection.

Genetic diversity of Ethiopian durum wheat (T. turgidum subsp. durum) landraces under water stressed and non stressed conditions

Ethiopia, being a major center of origin and diversity for durum wheat, possesses a highly variable genetic pool with diverse agroecological adaptations. Wheat landraces are an important source of genetic variation for breeding programs. This study was conducted to study the genotypic diversity of Ethiopian durum wheat genetic resources under two contrasting environments namely drought-stressed and non-stressed. It was carried out on 100 landraces and 4 local checks using an augmented design. Data were collected on 13 traits comprising yield and yield components, phenology, and canopy condition. The analysis of variance revealed significant differences between landraces for different traits with different sources of variation. Several landraces were found to outyield the checks at both environmental conditions. Intermediate to high estimates of the phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability in a broad sense (h2b), and genetic advance in percent of the mean (GAPM) were observed for all the studied traits except for days to flowering at normal, thousands seed weight at stress, and days to maturity, leaf chlorophyll concentration measurement, and canopy temperature measurement at both conditions. The estimation of variability parameters showed that genotypic variation was higher than environmental variation for most traits. The number of tillers, spike length, kernel per spike, and grain yield indicated higher values for h2b and GAPM (74.42% and 20.86; 83.2% and 28.24; 70.79% and 28.0; and 89.54% and 74.71) at normal and (97.87% and 98.22; 71.27% and 28.51; 75.52% and 43.9; and 90.04% and 103.68) at the stressed condition, respectively. Spikelets per spike, kernel per spike, and thousands seed weight were positively correlated with grain yield. Grain yield exhibited a weak negative correlation with days to heading and days to maturity. Principal components analysis revealed that six traits were the major loadings on the first two principal components that describe 37.9% and 41.0% of the total morphological variance at normal and stressed conditions, respectively. Cluster analysis grouped the landraces into six clusters, with each cluster showing variation in performance for different traits under normal and stressed conditions. The intracluster distance was maximum in cluster I (D2 = 7.68) and (D2 = 8.19) at normal and stressed conditions respectively and the intercluster distance was found to be maximum between clusters I and IV (D2 = 11.02) and clusters I and II (D2 = 10.33) at normal and stressed conditions respectively. The presence of significant genetic variability among the evaluated durum wheat landraces suggests an opportunity for improvement of grain yield through the hybridization of genotypes from different clusters and subsequent selection. Genotypes with superior agronomic traits that outperform the best checks are identified as potential parents for yield improvement programs for moisture stress.

Correlation, Genetic Variability, Heritability And Genetic Advance For Some Morphological Traits In Red Cabbage Lines (Brassica oleracea L.var. capitata subvar. rubra)

Genetic variability, heritability, genetic advance, genetic gain and correlation for seven different traits were studied in 22 genotypes of red cabbage. The genotypes were evaluated for seven quantitative characters such as head weight, head diameter, head length, core length, head volume, head density and head shape index. Analysis of variance showed significant variation among the genotypes for all the studied yield and yield contributing characters. Head weight of the lines was highly significant positively correlated with head length, head diameter, core length and head volume. The phenotypic coefficient of variation were observed to be higher than the corresponding genotypic coefficient of variation for all the characters studied, indicated that the traits were influenced by environment. The high phenotypic and genotypic coefficient (PCV and GCV) was observed for head density (30.61 and 20.06) followed by head volume (24.72 and 20.49), core length (15.68 and 14.99) and head weight (10.66 and 9.65). Heritability was high for majority of the traits. High heritability (broad sense) values were recorded for traits such as for head length (91.56%), core length (91.38%) and head diameter (82.24%). The highest genetic advance as percent of mean was shown by head volume (35.0 %) followed by core length (29.52%) and head density (27.09%). As a result, high heritability coupled with high genetic advance was observed head length, head diameter, head volume and head density which are governed by additive gene and could be effectively used as selection criteria in the breeding programme of red cabbage varieties with high yield.

GENETIC DIVERSITY OF DIFFERENT RADISH (RAPHANUS SATIVUS L.) CULTIVARS UNDER THE BASTAR PLATEAU OF CHHATTISGARH, INDIA

The presented study, held at the Research cum Instructional Farm of the College of Horticulture and Research Station, Jagdalpur, Chhattisgarh, India, ran during the Rabi season of 2021, to investigate superior radish cultivars for selection having high yield potential and better quality root for Bastar plateau. The experiment, laid out in randomized block design (RBD), had 15 treatments and three replications. Observing high genotypic and phenotypic coefficient of variation was for the following traits: dry and fresh weights of roots, plants, and leaves; root and leaf yields; days to 50% germination; the diameter and length of the root, North-South and East-West spread of the plant; plant height, and the number of leaf plant-1, having recorded significant heritability and high genetic advance. Similarly, high heritability showed for root yield and fresh and dry weights of roots. Moderate heritability levels appeared for the traits, viz., the plant’s dry weight and the root diameter. The genetic gain resulted high for characters, viz., root yield and fresh and dry weights of roots. High heritability followed by high genetic advance indicates that selection may be effective for improving such characteristics. Root yield (t ha-1) exhibited a highly significant positive correlation with the fresh weight of the plant at the phenotypic and genotypic levels, followed by dry weight of roots, dry weight of the plant, East-West spread of the plant, the diameter of the root, and leaf yield plot-1 . The fresh weight of roots had the maximum positive direct effect on root yield in the genotypic path, followed by the dry weight of roots and the plant, the East-West spread of the plant, the diameter of the root, and leaf yield in radish. The selection of these characters can benefit in improving the yield of radishes.

Inheritance Studies in Segregating Population of Bread Wheat (Triticum aestivum L.)

The experimental material of present study comprised of 127 treatments and 4 check varieties in augmented design conducted during rabi season (2022) in research field of Genetics and Plant Breeding, Lovely Professional University, Phagwara, India. Observations were recorded for days to 50% heading, days to maturity, plant height, number of productive tillers per plant, ear length, number of spikelets per ear, ear weight, number of grains per ear, test weight, biological yield per plant, harvest index, chlorophyll content and grain yield per plant. Analysis of variance disclosed that treatments and check varieties are highly significant for all the characters. Phenotypic coefficient of variation noted higher magnitude than genotypic coefficient of variation for all the traits. Heritability combined with genetic advance as percent of mean is noted high for grain yield per plant, biological yield per plant, number of productive tillers per plant, ear weight, harvest index, test weight, ear length, number of spikelets per ear, number of grains per ear and plant height. The correlation coefficient assessed positive and highly significant for biological yield per plant, number of productive tillers per plant, harvest index, ear weight, plant height, test weight and ear length. Grain yield per plant recorded positive significant association with biological yield per plant (0.7816), number of productive tillers per plant (0.7051), harvest index (0.527), ear weight (0.4076), plant height (0.3632), test weight (0.3222), and ear length (0.2439), whereas negatively significantly associated with days to 50% heading (-0.4019) and days to maturity (-0.4019). The findings from path analysis unveiled that the maximum direct effect was noted for biological yield per plant, harvest index, number of spikelets per ear, number of productive tillers per plant, ear weight, days to 50% heading, test weight and days to maturity. Out of thirteen traits, eight traits exhibited direct positive effect on grain yield such as biological yield per plant (0.8282), harvest index (0.6061), number of spikelets per ear (0.107), number of productive tillers per plant (0.0191), ear weight (0.0138), days to 50% heading (0.011), test weight (0.0088), and days to maturity (0.0001).

Studies on PCV, GCV, Heritability, and Genetic Advance in Rice Genotypes for Yield and Yield Components

The present experiment was carried out in twelve genotypes including IRRI introgression lines and a Japonica cultivar to analyse the genetic variability, heritability, and genetic gain. Significant differences were observed among the genotypes. All the traits under study recorded a high phenotypic coefficient of variation (PCV) than the genotypic coefficient of variation (GCV) indicating the presence of environment controlling the traits. But, the less difference between PCV and GCV implies that the involvement had a negligible role in the trait expression. High PCV and GCV were observed for the characters plant height, number of productive tillers, 1000 grain weight, L/B ratio, protein content, phenol content, and reducing sugar, representing that these characters in genotypes are contributed by additive gene action and the direct selection will improve the trait easily. Among the traits studied, high heritability and genetic advance were obtained for plant height, number of days to 50% flowering, panicle length, number of grains per panicle, grain breadth, L/B ratio, protein content, phenol content, and ascorbic acid, representing that these characters are predominant in additive gene action.

ASSESSMENT OF GENETIC VARIABILITY, HERITABILITY AND CORRELATION IN SPRING RICE GENOTYPES (Oryza sativa L.) AT RATNANAGAR, CHITWAN IN 2022

The stagnant yield of rice in Nepal can be improved by development of genotypes with improved traits through breeding for which estimates of genetic parameters are essential. Hence, a field experiment was carried out from February to June in the year 2022 with the objectives to evaluate the genetic variability, heritability, genetic advance and character association among yield traits in spring rice genotypes in order to provide valuable insights for rice breeders for the development of high-yielding spring rice varieties. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications comprising 10 genotypes. Various quantitative characters were recorded to estimate variability and correlation coefficient. Analysis of variance indicated significant differences for all traits among the assessed genotypes, indicating the presence of variability among evaluated genotypes. A lower genotypic coefficient of variation than the phenotypic coefficient of variation revealed the presence of environmental influence on the expression of these traits, being higher in fertility percentage and grain yield. High heritability was estimated for all the traits except fertility percentage, harvest index and grain yield. High heritability along with the high genetic advance was reported by the number of filled grains per panicle, thousand grain weight, and straw yield while remaining traits showed moderate to high heritability with low to moderate genetic advance as a percent of the mean. The number of panicles per hill, fertility percentage, biological yield and straw yield exhibited a significant positive association with grain yield indicating the chance of improvement in yield if a selection is applied in favor of those traits among these genotypes. Therefore, the results highlight the potential for selection among these genotypes for traits such as number of filled grains per panicles, number of panicles per hill and straw yield for higher productivity and performance.