Estimation of Genetic Parameters and Selection Potential in Groundnut (Arachis Hypogaea L.) Genotypes

Introduction

Arachis hypogaea L. represents a significant economic oilseed crop on the international stage, positioning itself as the 13 th most important food crop globally. The crop functions as humanity's fourth primary oil resource and third major supplier of plant-based proteins. From a botanical perspective, this species constitutes an annual herb within the Fabaceae (Leguminosae) family. The scientific nomenclature originates from Greek terminology, where Arachis signifies a pulse crop and hypogaea translates to "subterranean," highlighting the distinctive trait wherein pod maturation takes place underground. Chromosomally, groundnut exhibits an allotetraploid configuration (2n = 4x = 40) with a fundamental chromosome value of x = 10 (Stalker, 1991) [23] . The plant demonstrates cleistogamous pollination mechanisms, which results in predominantly self-fertilizing characteristics (Knauft and Wynne, 1995) [11] . Diverse geographical regions assign different terminologies to this legume. North American regions favour the "peanut," though numerous alternative appellations exist including African nut, Chinese nut, Manila nut, Kipper nut, Hawk's nut, Jar nut, Earth chestnut, Monkey nut, Goober pea, Ground pea and Ground bean (Johnson, 1964). Within India, the crop receives the traditional name mungphali. Its substantial commercial importance has earned it the prestige title "King of Oilseeds." This legume thrives across tropical, subtropical and warm temperate zones between approximately40° N and 40° S latitude bands. Historical evidence from phylogenetic and geographic analyses indicates the species originated in southern Bolivia along with northern Argentina (Kochert et al. 1996) [12] . The genus Arachis demonstrates its highest genetic variation across South America, particularly throughout western Brazil, Bolivia, Paraguay and northern Argentina, where wild relatives and ancestral variants are naturally distributed. The country's low groundnut production is mostly attributable to a lack of adoption of better varieties and uneven performance in a variety of locations, notably rainfed situations. Therefore, the creation of high-yielding cultivars with wide adaptability, fertilizer responsiveness and resistance to biotic and abiotic challenges, together with short seed dormancy, is crucial to increase output. It also has many health benefits including weight gain control (Petersen et al., 2022) [14] ., prevention of cardiovascular diseases (Feldman, 2002) [7] ., protection against Alzheimer's disease (Vaishnavi et al., 2023) [25] . and cancer inhibition (Wang et al., 2021) [26] . Groundnuts contain 21 -36.4% protein, 18% carbohydrates, 36-54% fat and 100-120 grams of fibre per kg of kernels (Bonku and Yu, 2020) [3] . Genetic variability parameters such as genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) developed by Burton and De Vane (1953) [4] ., broad-sense heritability (h²bs) and genetic advance expressed as percentage of mean (GAM) formulated by Johnson et al. (1955) [10] ., are essential statistical measures in plant breeding to assess genetic variation and predict selection effectiveness. The classification criteria for these parameters, established by Sivasubramanian and Menon (1973) for GCV and PCV, and Johnson et al. (1955) [10] . for heritability and GAM, enable breeders to identify traits amenable to direct phenotypic selection. Traits exhibiting high values for all four parameters indicate substantial, stable, and heritable variation suitable for improvement through conventional breeding. Understanding these genetic variability parameters is essential for developing evidence based breeding strategies and identifying priority traits for improvement in crop improvement programs, particularly in oilseed crops such as groundnut where yield and oil percent enhancement is a major breeding objective.

Materials and Methods

The research utilized 70 peanut accessions sourced from the Main Oilseed Research Station at Junagadh Agricultural University, Junagadh procured during the Summer-2026. A Randomized Block Design framework incorporating three replications formed the basis of this experimental setup. Individual genotypes were sown in solitary rows measuring 2.0 m in length with 30 cm intervals between rows and 10 cm spacing between individual plants. Standard agronomic protocols and protective measures against pests and diseases were implemented throughout the cultivation period. Data collection focused on pod yield per plant alongside various associated parameters including days to 50% flowering, days to maturity, plant height (cm), number of primary branches per plant, number of mature pods per plant, 100-pod weight (g), kernel yield per plant (g), 100kernel weight (g), shelling percentage (%), sound mature kernel (%), biological yield per plant (g), harvest index (%), oil content (%) and subsequent correlation analysis along with path coefficient investigation. Oil content was determined using Nuclear Magnetic Resonance methodology. Five plants from each genotype per replication were assessed for trait evaluation, with the exception of days to 50% flowering and days to maturity which were measured at the plot level rather than individual plant basis.

Weight of kernels (g) Weight of pod samples (g) ×100

Sound mature kernel (SMK %) = Number of well mature kernels Total number of kernels × 100

Harvest index (%) = Pod yield per plant (g) Biological yield per plant (g) × 100

Variance analysis following the randomized complete block design (RCBD) framework was performed for each trait utilizing the statistical approach detailed by Panse and Sukhatme (1995) [13] . Genotypic, phenotypic and environmental variances were estimated from the analysis of variance table following Johnson et al. (1955) [10] . and genotypic and phenotypic coefficients of variation (GCV and PCV) were computed and classified according to Sivasubramanian and Menon (1973) into low (<10%), medium (10-20%) and high (>20%) categories. Broad-sense heritability (h²bs) was estimated following Johnson et al.

(1955) [10] . and classified as low (0-30%), medium (30-60%) and high (≥60%), while genetic advance expressed as percentage of mean (GAM) was calculated using Johnson et al. (1955) [10] . with categories of low (0-10%), medium (10-20%) and high (≥20%). All statistical computations were performed utilizing R-Studio statistical software.

Results and Discussion

Analysis of variance

During the Summer-2026 season, a comprehensive evaluation of seventy groundnut genotypes including eight control varieties was executed using a Randomized Complete Block Design (RCBD). Analysis of variance (ANOVA) was performed across all fourteen quantitative and qualitative traits to assess the significance of variation among the genotypes, as detailed in Table 1. Excluding days to maturity, the mean sum of squares attributed to genotypes was highly significant for all evaluated parameters, indicating the presence of extensive genetic diversity within the experimental material across the studied traits. This substantial variability offers significant scope for developing superior, high yielding breeding lines through targeted selection for key agronomic and economic attributes.

Genotypic coefficient of variation

The genotypic coefficients of variation (GCV) for different characters are presented in 1973), is presented in Table 3 and Figure 1. [5] ., Gali et al. (2021) [8] ., Shrotri et al. (2021) [20] , Ragiri et al. (2023) [16] . and Yami and Abtew (2025) [28] , who also observed high GCV and PCV for these traits in groundnut.

Heritability (h 2 bs)

phenotypic variance that is attributable to genetic variance and is generally expressed as a percentage. It represents the extent to which phenotypic variation is governed by genetic factors and therefore, reflects the likelihood of transmitting a trait from parents to their offspring. High estimates of broad-sense heritability indicate that phenotypic performance is a reliable measure of genetic potential, thereby enhancing the effectiveness of selection for quantitative traits. The broad-sense heritability estimates for the different characters in the present study are presented in Table 4.2. Highest heritability estimate was recorded for harvest index (94.53%) followed by 100 kernel weight (86.05%), sound mature kernel (82.74%), 100 pod weight (79.93%), days to 50 % flowering (69.38%), oil content (67.81%), shelling percentage (61.01%), biological yield per plant (60.17%) and mature pod per plant (60.03%). The findings were akin to Solanki et al. (2019) [21] , Sridevi et al. (2022) [22] , Ragiri et al. (2023) [16] ., Reddy et al. (2023) [18] ., Vaishali et al. (2023) [24] , Yadav et al. (2023) [27] , Poojitha et al. (2024) [15] ., Rajput et al. (2024) [17] . for high heritability in 100 kernel weight. High heritability for oil content was reported by Devarakonda et al. (2024) [6] . and Yami and Abtew (2025). Broad-sense heritability is defined as the proportion of total [10] .

Classification Characters 0-30 Low Days to maturity 30-60 Medium Kernel yield per plant, number of primary branches per plant, plant height and pod yield per plant 60 and above High harvest index, 100 kernel weight, sound mature kernel, 100 pod weight, days to 50 % flowering, oil content, shelling percentage, biological yield per plant and number mature pod per plant

The genotypic coefficient of variation (GCV) alone cannot reveal how much of the observed variation is inherited genetically. Therefore, estimating heritability is essential to determine the likely effectiveness of selection and the expected genetic improvement in quantitative traits. When GCV is considered together with heritability, it provides a clearer understanding of the genetic potential of a trait and its probable response to selection. Burton (1952) [1] . emphasized that the combined evaluation of GCV and heritability offers a more reliable basis for identifying traits that can be effectively improved through selection in plant breeding programmes. H 2 (bs) estimates were recorded for nine characters: oil content, shelling percentage, biological yield per plant, harvest index, 100-kernel weight, sound mature kernel, 100-pod weight, days to 50% flowering and number of mature pods per plant. High broad-sense heritability suggests that a significant amount of the observed variance is genetically determined and that these qualities are less affected by environmental influences. These findings imply that the attributes have significant genetic variability and may react well to selection in groundnut breeding programs since the current study calculated broad-sense heritability, which encompasses both additive and non-additive gene effects.

Genetic advance expressed as per cent of mean (gam)

Genetic advance expressed as a per cent of mean for different characters is presented in Table 2. Harvest index (54.09%) had the largest genetic progress as a percentage of the mean, followed by 100-kernel weight (31.27%), biological yield per plant (30.44%), number of ripe pods per plant (27.28%), 100-pod weight (25.02%) and kernel yield per plant (23.48%). The significant genetic diversity that may be exploited is shown by the high genetic progress seen for these qualities, which implies that selection-based improvement would be successful. The current results are supported by similar findings for high genetic progress, especially for harvest index, which were also reported by Abubakar et al. (2024) [2] . and Yami and Abtew (2025) [28] . [10] . [10] ., evaluating heritability and genetic advancement together yields a more accurate prediction of the anticipated response to selection than evaluating heredity alone. Therefore, these characteristics are helpful in identifying features that may be effectively increased through breeding. For harvest index, 100-kernel weight, biological yield per plant and number of ripe pods per plant, the current study found significant broad-sense heritability combined with high genetic progress as a percentage of the mean. This combination reveals that environmental influences have less of an impact on these qualities and shows the prevalence of additive gene action. According to Panse (1957), direct phenotypic selection for these variables is thus anticipated to be successful in enhancing groundnut production and its contributing attributes.

GA as per cent of mean

Conclusion

The study revealed extensive genetic diversity in seventy groundnut genotypes with significant heritable variation suitable for crop improvement. Five traits-harvest index, biological yield per plant, kernel yield per plant, number of mature pods per plant and pod yield per plant exhibited high GCV and PCV values with favourable selection potential.

Harvest index emerged as the most promising trait, combining the highest heritability (94.53%) and genetic advance (54.09%). Nine traits displayed high broad-sense heritability (>60%), indicating predominance of additive gene action and minimal environmental influence. Harvest index, 100-kernel weight, biological yield per plant and number of mature pods per plant are reliable targets for direct phenotypic selection and rapid genetic gain. Traits with low GCV and heritability (days to maturity, oil content, shelling percentage) require alternative breeding strategies such as hybridization or molecular approaches. The identified genetic diversity provides excellent opportunity for groundnut improvement through phenotypic selection.

Multi-location evaluation and correlation analysis are recommended for future studies.

Acknowledgement

AcknowledgmentsI wish to express my profound gratitude to Dr. R. B. Madariya, serving as the major advisor, along with the members of my advisory committee for rendering valuable scholarly direction throughout this investigative endeavour. I further extend sincere appreciation to Junagadh Agricultural University for facilitating the provision of essential facilities and infrastructure that contributed significantly to the successful completion of this research undertaking.

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