Assessment of genetic variability, heritability and genetic components for yield traits in soybean (Glycine max (L.) Merrill)

Introduction

The soybean (Glycine max (L.) Merrill), 2n = 40, belongs to the Leguminosae or Fabaceae family and the Papilionoideae subfamily. It is believed to have originated in Eastern Asia, particularly in North and Central China. Since 2006, soybean has maintained its prominent status as a leading oilseed crop in India, significantly contributing to the country's vegetable oil supply and bolstering the national economy through substantial foreign exchange earnings from soymeal exports. The United States of America is the world's largest soybean producer, accounting for 55% of global production and 45% of the soybean-growing area. It is also grown in Brazil, Argentina, China and India. Soybean is known as the "Golden Bean" and the "Miracle Crop" because of its dual properties of high protein and oil content, making it one of the most important crops of the 21st century. It contributes significantly to meeting the world's current and future protein and edible oil demands. Soybean seeds contain 37-42% high-quality protein, 6% ash, 29% carbohydrates and 17-24% oil (Kumari et al., 2022) [7] .

Materials and Methods

The present experimental material comprised five generations i.e., P₁, P₂, F₁, F₂ and F₃ of each of the seven crosses, viz., NRC 127 × KDS 11-49, NRC 127 × RSC 10-46, NRC 127 × NRC 12, NRC 127 × RSC 10-52, NRC 127 × RSC 11-42, PS 1689 × RSC 10-46 and PS 1689 × RSC 11-42. The parental plants were grown and the crossing programme was carried out during Kharif 2022. Thereafter, the F₁ seeds along with their parents were sown during Rabi 2022-23 and observations on the characterization of F₁ and parental lines were recorded. During Rabi 2022-23, F₂ seeds were produced. These F₂ seeds, along with their parents, were sown during Kharif 2023. During Rabi 2023-24, the P₁, P₂, F₁, F₂ and F₃ generations were grown and observations were recorded. The observations were taken from 12 yield attributing traits.

Results and Discussion Genotypic and phenotypic coefficient of variation

The estimation of phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) indicates the existence of significant variability among the genotypes studied for different traits. The GCV and PCV values are categorized as low (less than 10%), moderate (10-20%) and high (more than 20%), as suggested by Sivasubramanian and Madhavamenon (1973).

Days to 50% flowering

In all seven crosses, the phenotypic coefficient of variation (PCV) was slightly higher than the genotypic coefficient of variation (GCV). The PCV and GCV percentages were observed to be below 10% (low) in all seven crosses. The maximum PCV (6.87%) and GCV (5.30%) were observed in the cross NRC 127 × RSC 11-42. These findings are in accordance with the reports of Jain et al. (2017) [6] , Guleria et al. (2019) [4] , Sonkamble et al. (2020) [10] and Jandong et al. (2020) [5] .

Days to maturity

Similarly, PCV and GCV percentages were observed to be low (less than 10%) in all seven crosses for days to maturity. The maximum PCV (6.45%) and GCV (6.11%) were observed in the cross NRC 127 × NRC 12. These findings are in accordance with the reports of Jandong et al. (2020) [5] and Bairagi et al. (2023) [2] .

Moderate to high (more than 20%) PCV and GCV percentages were observed among the seven crosses. The crosses NRC 127 × KDS 11-49, NRC 127 × RSC 10-46, NRC 127 × NRC 12 and NRC 127 × RSC 10-52 showed high PCV and GCV values (more than 20%), while the remaining crosses exhibited moderate values. These findings are in accordance with the reports of Bairagi et al. (2023) [2] , Susanto et al. (2023) [11] , Singh et al. (2023) [12] and Paulos and Kindie (2025) [9] .

No. of primary branches per plant

All crosses showed high PCV and GCV percentages (i.e more than 20%), except for the cross NRC 127 × RSC 10-46 which exhibited a moderate range of variation. These findings are in accordance with the reports of Sonkamble et al. (2020) [10] , Jandong et al. (2020) [5] , Bairagi et al. (2023) [2] and Susanto et al. (2023) [11] .

No. of Pods Per Plant

All crosses fell within the moderate range of PCV and GCV percentages (10-20%) except for the cross NRC 127 × RSC 11-42 which was categorized as high, with PCV (20.91%) and GCV (20.39%). These findings are in accordance with the reports of Sonkamble et al. (2020) [10] , Jandong et al. (2020) [5] , Bairagi et al. (2023) [2] and Susanto et al. (2023) [11] .

The only cross NRC 127 x RSC 10-52 showed high range of PCV and GCV % that is 22.12 and 21.73 respectively, remaining crosses fell in low to moderate category. These findings are in accordance with the work of Jandong et al. (2020) [5] , Bairagi et al. (2023) [2] , Susanto et al. (2023) [11] and Singh et al. (2023) [12] .

Number of seeds per pod

All crosses exhibited a low range of PCV and GCV %. These findings are in accordance with the reports of Jain et al. (2017) [6] , Bairagi et al. (2023) [2] , Susanto et al. (2023) [11] and Singh et al. (2023) [12] .

No. of Seeds per Plant

The crosses exhibited moderate to high PCV and GCV percentages. The maximum values were observed in the cross NRC 127 × RSC 10-46 with PCV and GCV of 30.00% and 29.51%, respectively. These findings are in accordance with the reports of Jandong et al. (2020) [5] , Bairagi et al. (2023) [2] , Susanto et al. (2023) [11] and Singh et al. (2023) [12] .

The PCV and GCV percentages in all crosses were low, except for the cross NRC 127 × NRC 12 which exhibited a moderate range of variation, with PCV and GCV values of 13.38% and 13.12% respectively. These findings are in accordance with the reports of Jain et al. (2017) [6] , Guleria et al. (2019) [4] , Susanto et al. (2023) [11] and Singh et al. (2023) [12] .

All crosses showed very low PCV and GCV percentages which fall under the low variability category. These findings are in accordance with the reports of Jain et al. (2017) [6] and Guleria et al. (2019) [4] .

Similar to protein content, oil content also exhibited a low category of PCV and GCV percentages (less than 10%). Among the crosses PS 1689 × RSC 11-42 and PS 1689 × RSC 10-46 exhibited the maximum values with PCV and GCV ranging from 5.24% to 4.18% and 4.87% to 4.72% respectively. These findings are in accordance with the reports of Bairagi et al. (2023) [2] , Susanto et al. (2023) [11] , Singh et al. (2023) [12] and Paulos and Kindie (2025) [9] .

The crosses exhibited moderate to high PCV and GCV percentages (10-20%) and above 20%). The maximum PCV and GCV values were observed in the cross NRC 127 × RSC 10-46 (PCV 31.00% and GCV 27.31%) followed by the cross PS 1689 × RSC 10-46 (25.83% and 25.27% respectively). These findings are in accordance with the reports of Jain et al. (2017) [6] , Guleria et al. (2019) [4] , Susanto et al. (2023) [11] , Singh et al. (2023) [12] and Paulos and Kindie (2025) [9] .

Heritability

Assessment of heritability is one of the most important genetic parameters used in breeding programmes. It is a statistical measure that indicates the proportion of total variation within a population that is attributable to genetic differences rather than environmental factors. Heritability values range from 0 (entirely environmental influence) to 1 (entirely genetic influence). It reflects how much of the observed variation in a trait is due to genetic differences, not how much of the trait itself is determined by genes. Heritability values are categorized as low (<30%), moderate (30-60%) and high (>60%) as suggested by Johnson et al. (1955). Heritability is useful in the selection of elite genotypes from homozygous populations and can be estimated from parental and segregating generations based on total genetic variance.

Days to 50% flowering

A high heritability estimate (81.09%) was observed for the cross NRC 127 × KDS 11-49, whereas the lowest estimate (13.81%) was observed for the cross PS 1689 × RSC 10-46. Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] .

Days to maturity

The highest heritability value (89.69%) was recorded in the cross NRC 127 × NRC 12 whereas the lowest value (19.02%) was recorded in the cross NRC 127 × RSC 10-52. Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] . [7] , Saicharan et al. (2022) [13] and Kalamkhede et al. (2025) [8] .

Plant height

Number of primary branches/plants

All the crosses showed high heritability values. Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] .

No. of pods/plant

All crosses showed high heritability values. Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] .

Pod bearing length

All crosses showed high heritability values, except for the cross PS 1689 × RSC 10-46 (52.34%). Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] and Tandekar et al. (2023) [15] .

Number of seeds per pod

The crosses PS 1689 × RSC 10-46 (87.12%) and NRC 127 × KDS 11-49 (73.33%) exhibited high heritability estimates, whereas NRC 127 × RSC 10-52 (15.18%) showed the lowest heritability value. Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] and Tandekar et al. (2023) [15] .

No. of seeds/plant

All crosses exhibited high heritability values. The cross NRC 127 × NRC 12 showed the maximum value (97.26%). Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] . 100 seed weight (g) All crosses exhibited high heritability values. The cross NRC 127 × NRC 12 showed the maximum value (96.15%). Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] .

The crosses NRC 127 × RSC 10-46 (78.79%) and PS 1689 × RSC 11-42 (67.68%) exhibited high heritability, whereas the remaining crosses showed low to moderate heritability. Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] and Tandekar et al. (2023) [15] Oil content (%) A high heritability estimate was observed for the cross PS 1689 × RSC 10-46 (94.11%), whereas the lowest value (7.02%) was observed for the cross NRC 127 × RSC 10-46. Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] .

All crosses exhibited high heritability estimates except for the cross NRC 127 × RSC 11-42 (26.32%). Similar findings were reported by Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] and Kalamkhede et al. (2025) [8] .

Genetic advance as % of mean

Days to 50% flowering

The observations recorded for this trait in all seven crosses exhibited low genetic advance as a percentage of the mean. High heritability coupled with low GAM was recorded only in the crosses NRC 127 × KDS 11-49 and NRC 127 × RSC 10-46. This suggests that non-additive gene action or epistasis governs the trait in these two crosses. Similar findings were also reported by Sidramappa et al. (2019) [14] , Bhuva and Babariya (2020) [1] .

Days to maturity

Similar to days to 50% flowering low GAM was observed in all seven crosses, except for the cross NRC 127 × NRC 12, where it was moderate. High heritability coupled with low GAM was observed in the crosses NRC 127 × RSC 10-46, NRC 127 × RSC 11-42 and PS 1689 × RSC 11-42. In contrast the cross NRC 127 × NRC 12 exhibited high heritability coupled with moderate GAM. Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] , Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

This trait showed high GAM in all seven crosses. High heritability coupled with high GAM was observed in all crosses, indicating the role of additive gene action in controlling the trait. Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] , Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

Number of primary branches per plant

High genetic advance as a percentage of the mean was observed in all seven crosses. In all crosses, high heritability coupled with high GAM was observed, indicating the role of additive gene action in controlling the trait. Tandekar et al. (2023) [15] , Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

Number of pods per plant

Similar to the number of primary branches per plant, high GAM values were recorded for this trait in all seven crosses, except for the cross NRC 127 × NRC 12. High heritability coupled with high GAM was also observed in all crosses except NRC 127 × NRC 12, indicating the influence of additive gene action in controlling the trait. Similar findings were reported by Tandekar et al. (2023) [15] , Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

Moderate to high GAM values were observed among the crosses. The crosses NRC 127 × RSC 10-46, NRC 127 × NRC 12, NRC 127 × RSC 10-52 and NRC 127 × RSC 11-42 exhibited high GAM values, whereas the remaining crosses showed moderate GAM values. In the crosses NRC 127 × NRC 12, NRC 127 × RSC 10-46, NRC 127 × RSC 10-52 and NRC 127 × RSC 11-42, high heritability coupled with high GAM indicated that the trait is predominantly controlled by additive gene action. Similar findings were reported by Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

Number of seeds per pod

Low GAM values were observed in six crosses, whereas the cross PS 1689 × RSC 10-46 exhibited a moderate GAM value. High heritability coupled with low GAM was observed in the crosses NRC 127 × KDS 11-49 and PS 1689 × RSC 11-42, indicating that the trait in these crosses is governed by non-additive gene action. In contrast, the cross PS 1689 × RSC 10-46 exhibited high heritability coupled with moderate GAM. Similar findings were reported by Tandekar et al. (2023) [15] , Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

Number of seeds per plant

The important yield-contributing trait, i.e. number of seeds per plant, exhibited both high GAM and high heritability estimates in all seven crosses, indicating the effective role of additive gene action in controlling this trait. This trait can be selected from all crosses for further improvement in the breeding programme. Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

The 100-seed weight is another important trait influencing yield. The results revealed that only two crosses, namely NRC 127 × NRC 12 and NRC 127 × RSC 12, exhibited high GAM values. In both these crosses, high heritability was coupled with high GAM, indicating the important role of additive gene action in controlling the trait. Similar findings were reported by Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

The results for this quality trait revealed that very low GAM values were observed in all seven crosses, indicating that there is little scope for improvement in progenies over the population mean. The cross NRC 127 × RSC 10-46 showed the involvement of non-additive gene action in controlling this trait, as high heritability was coupled with low GAM. Similar findings were reported by Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

Observations of this trait revealed low GAM values in all seven crosses, whereas non-additive gene action was found in the crosses PS 1689 × RSC 10-46, PS 1689 × RSC 11-42, NRC 127 × NRC 12 and NRC 127 × KDS 11-49. Similar findings were reported by Kalamkhede et al. (2025) [8] and Fufa and Nepir (2025) [3] .

Seed yield per plant one of the most important economic traits revealed that high GAM values were observed in six crosses. In these crosses, high heritability was coupled with high GAM, indicating the important role of additive gene action in controlling this trait. Only the cross NRC 127 × RSC 11-42 exhibited low GAM and low heritability. Similar findings were reported by Sidramappa et al. (2019) [14] , Bhuva and Babariya (2020) [1] , Sharmila et al. (2022) [7] , Saicharan et al. (2022) [13] , Tandekar et al. (2023) [15] .

Conclusion

The study revealed considerable genetic variability among the evaluated crosses for several important yield and yieldrelated traits. The phenotypic coefficient of variation (PCV) was generally slightly higher than the genotypic coefficient of variation (GCV), indicating minimal environmental influence and a predominant role of genetic factors in trait expression. Moderate to high genetic variation was observed for plant height, number of primary branches per plant, number of pods per plant, pod bearing length, number of seeds per plant, 100-seed weight, and seed yield per plant in most crosses. However, traits such as days to 50% flowering, days to maturity, number of seeds per pod, protein content and oil content exhibited low to moderate variability, reflecting limited genetic diversity. High heritability coupled with high genetic advance as a percentage of mean was recorded for major yieldcontributing traits, suggesting the predominance of additive gene action and the effectiveness of direct selection. Therefore, these traits can be reliably improved through selection to develop high-yielding and genetically superior genotypes.

Acknowledgement

AcknowledgementThe authors are thankful to the Department of Genetics and Plant Breeding, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya, Raipur, (C.G.) for its valuable support during entire research.

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