Assessment of genetic variability, heritability and genetic divergence for yield and yield contributing traits in Mungbean (Vigna radiata L. Wilczek)

Introduction

Mungbean (Vigna radiata (L.) Wilczek) is recognized as the third most important pulse crop in India after chickpea and pigeonpea (red gram). It represents a self-pollinated legume Taxonomically placed in the family Fabaceae and the subgenus Ceratotropis of the genus Vigna. The crop is a diploid species (2n = 22) with an estimated genome size of 579 Mb (Arumuganathan and Earle, 1991) [4] . Mungbean is recognized as an excellent source of highquality protein and plays a significant role in improving nutritional security, particularly in developing countries. The seeds contain high levels of lysine, leucine, and threonine, including essential minerals and vitamins, although they contain relatively lower amounts of methionine, tryptophan, and tyrosine. During germination, the synthesis of ascorbic acid (vitamin C) increases along with enhanced levels of riboflavin and thiamine. Owing to its nutritional value and easy digestibility, mungbean is consumed in various forms such as dal, sprouts, snacks, sweets, and several traditional food preparations (Datta et al., 2012) [6] .

According to the latest agricultural statistics, mungbean occupies covering nearly 35.43 lakh hectares in India, recording a production of 16.07 lakh tonnes with an average yield of 453 kg/ha. In Gujarat, the crop is cultivated over approximately 66.48 thousand hectares, producing 35.18 thousand tonnes with an average productivity of 529.09 kg/ha (Anonymous, 2024-25). The crop is believed to have originated in India and Central Asia, which were identified as primary centres of diversity by Vavilov (1939) [20] . Mungbean is a warm-season crop that requires about 90-120 frost-free days for successful growth and development. A characteristic feature of mungbean is its indeterminate growth habit, resulting in non-synchronous flowering and pod maturity. Consequently, harvesting is generally recommended when approximately 50-70 percent of the pods have matured, at which time the seed moisture content is usually between 13 and 15 percent. Genetic divergence is a useful technique in selecting diverse parents for purposeful hybridization programme. A successful breeding program requires careful consideration of the genetic factors influencing multiple quantitively traits. This involves evaluating genetic parameters such as the genotypic coefficient of variance (GCV), phenotypic coefficient of variance (PCV), genetic advance (GA) along with genetic advance as a percentage of the mean (GAM) in mungbean germplasm under the arid South Gujarat so that promising genotypes could be identified for a breeding program to enhance the development of high-yielding varieties of mungbean for South Gujarat. Also, find out the pattern of genetic divergence among mungbean germplasm so that suitable divergent parents may be use for breeding programme to enhanced high yield.

Materials and Methods

The experimental material for the current study includes 27 mungbean genotypes viz., AM-15-3-2, AM-15-7-2, AM-15-8-1, AM-15-26-1, AM-15-48-4, AM-15-48-11, AM-15-52-1, AM-K18-6, AM-K18-11, AM-K18-14, AM-K18-16, AM-K18-19, AM-K18-22, AM-K18-23, AM-S19-1, ANDGG 1804, ANDGG 1805, ANDGG 1807, ANDGG 1808, ANDGG 1810, ANDGG 2011, ANDGG 2020, ANDGG 2029, AM-S22-9, AM-S22-10, GAM 5 and GAM 6. These genotypes were evaluated for different quantitative traits in RBD (Randomized Block Design) during late Kharif-2025 with spacing 45 x 15 cm in three replications at College Farm, College of Agriculture, Navsari Agricultural University, Bharuch. All the recommended agronomic and crop management practices were uniformly followed throughout the crop growth period until harvest. At physiological maturity, observations were recorded on five randomly selected plants from each genotype in every replication for days to 50% flowering, days to maturity, plant height (cm), branches per plant, clusters per plant, pods per cluster, pods per plant, seeds per pod, pod length (cm), 100-seed weight (g), crude protein content (%), and seed yield per plant (g). Standard statistical procedure was used for the analysis of variance (Panse and Sukhatme, 1978) [12] , phenotypic and genotypic coefficient of variation (Burton, 1952) [5] , heritability and genetic advance (Allard, 1960), genetic advance as percent of mean (Johnson et al., 1955) [8] , Mahalanobis D 2 (Rao, 1952) [16] analysis was performed in variability and Biotool package in R Studio software.

Results and Discussion

The success of any crop improvement programme primarily depends on the availability of adequate genetic variability in the breeding material. A wider range of genetic variation provides greater opportunities for effective selection and the identification of superior genotypes with desirable traits. In the present investigation, the mungbean genotypes exhibited substantial variation in their mean performance for all the characters evaluated. This variability was further validated by the analysis of variance, which revealed highly significant differences among the genotypes for all the traits studied (p<0.05), indicating the existence of considerable genetic diversity within the experimental material (Table 1). Through Assessment of par se performance of mean data it was showed that the evaluated twenty seven genotypes, ANDGG 2011, ANDGG 2029, ANDGG 1808 and AM-15-26-1 were high yielding genotypes and ANDGG 1808, ANDGG 1807 and ANDGG 2020 were identified as most promising early genotypes based on days to 50% flowering while AM-K18-23, AM-15-48-11 and AM-K18-22 were found early for maturity. Plant height (cm) was superior in genotypes GAM 6, AM-S22-10 and ANDGG 2029. Branches per plant was high in genotypes ANDGG 2011, ANDGG 1808 and AM-15-48-4 while genotypes AM-15-26-1, ANDGG 1808 and ANDGG 2011 reported maximum clusters per plant. Maximum pods per cluster was recorded in genotypes AM-K18-6, AM-S22-10 and ANDGG 1810 while highly pods per plant in genotypes AM-15-26-1, ANDGG 2029 and AM-15-3-2. High seeds per pod was recorded by ANDGG 2011, AM-15-3-2 and ANDGG 2029 while longest pod length ANDGG 2029, ANDGG 1810 and AM-15-7-2. Genotypes ANDGG 2011, AM-K18-11 and ANDGG 1807 were superior in respect of 100-seed weight. AM-15-48-4, GAM 6 and AM-15-48-11 were high in protein content. Moderate to high estimates of genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were recorded for branches per plant, clusters per plant, pods per cluster, pods per plant, and 100-seed weight. Comparable findings for branches per plant, pods per cluster, and pods per plant by Yoseph et al. (2022) [21] and Rahangdale et al. (2023) [14] . For cluster per plant by Tabasum et al. (2010) [19] . While, Nalajala et al. (2022) [10] observed similar results for 100 seed weight. Low estimates of genotypic and phenotypic coefficient of variation were observed for the traits like days to 50% flowering, days to maturity, plant height, seeds per pod, pod length and crude protein content. Similar results were observed by Ahmad et al. (2014) [1] for days to 50% flowering, days to maturity and plant height. For seeds per pod and crude protein content similar results were observed by Joshi et al. (2021) [9] and Salman et al. (2023) [17] for pod length. Traits seed yield per plant was recorded low genotypic and moderate phenotypic coefficient of variation. Similar results were observed by Ahmad et al. (2014) [1] . (Table 2) High estimates of heritability were recorded by branches per plant (76.60%), clusters per plant (87.41%), pods per cluster (85.35%), pods per plant (89.80%) and 100-seed weight (76.64%). Whereas, moderate amount of heritability was recorded by days to 50% flowering (55.51%), plant height (44.95%), seeds per pod (39.80%), pod length (46.40%), crude protein content (52.48%) and seed yield per plant (51.68%). While, low amount of heritability was observed on days to maturity (27.99%). The high genetic advance expressed as percent of mean was obtained for branches per plant (24.95%), clusters per plant (39.11%), pods per cluster (40.24%), pods per plant (50.80%) and 100-seed weight (22.03%). seed yield per plant (14.12%) reported moderate genetic advance expressed as percent of mean. Whereas the low genetic advance expressed as percent of mean was recorded for characters days to 50% flowering (5.34%), days to maturity (1.97%), plant height (8.73%), seeds per pod (6.05%), pod length (8.27%) and crude protein content (4.82%). High heritability accompanied by high genetic advance as a percentage of the mean was observed for branches per plant, clusters per plant, pods per cluster, pods per plant, and 100seed weight. These results indicate that additive gene effects predominantly control these traits, making them highly amenable to improvement through direct selection. The present results align with observations made by Rahangdale et al. (2023) [14] for branches per plant, clusters per plant, pods per cluster and pods per plant and Prasanna et al. (2013) [13] for 100-seed weight. Seed yield per plant showed moderate heritability coupled with moderate genetic genetic advance as percent of mean. Similar findings were earlier reported by Singh et al (2021) [18] . Moderate estimates of heritability accompanied by low genetic advance as a percentage of the mean were observed for days to 50% flowering, plant height, seeds per pod, pod length, and crude protein content. These findings imply that the expression of these traits is largely governed by nonadditive gene effects and environmental influences, thereby limiting the effectiveness of selection in the early generations. These findings are consistent with the observations of Salman et al. (2023) [17] for days to 50% flowering, Alom et al. (2014) [2] for plant height, Pandey et al. (2007) for seeds per pod, Jagdhane et al. (2017) [7] for pod length and Joshi et al. (2021) [9] for crude protein content. While low heritability with low genetic advance as% of mean were observed in characters days to maturity. Earlier studies by Yoseph et al. (2022) [21] and Salman et al. (2023) [17] . (Figure 1 & 2; Table 3) Results of the present investigation showed that 27 genotypes of mungbean were distributed among eight different clusters using Tocher's clustering method. 27 genotypes combined to produce eight clusters. Table 4 lists the clusters' composition and Figure 3 represent the eight clusters and inter and intra cluster distance among them (Table 5). Rao et al. (2006) [15] carried out similar type related to genetic divergence study on 60 mungbean genotypes and grouped them into eight distinct clusters using Tocher's method. With 10 genotypes, Cluster I emerged as the largest cluster, whereas Cluster II was the second largest, comprising eight genotypes. Cluster III included three genotypes, indicating moderate divergence from the other clusters, while cluster IV contained only two genotypes, representing the most genetically distinct group among all the clusters. There was only one genotype present in each of the isolated cluster's V, VI, VII and VIII. The inter-cluster and intra-cluster distances are shown in Table 5. The maximum inter-cluster distance (D = 286.16) was found between clusters VIII and VI, followed by that between VI and III (D = 284.34) and VII and VI (D = 198.28). The minimum inter-cluster distance was observed between clusters VI and I (D = 63.13). The highest intracluster distance (D = 47.72) was found for (cluster-I) followed by cluster II showed an intra-cluster distance (D = 43.09). Cluster III had an intra-cluster distance of (D = 35.53), indicating moderate diversity within the cluster. The lowest intra-cluster distance was recorded in cluster IV (D = 33.76), suggesting that the two genotypes in this cluster were relatively more similar genetically. The four clusters viz., V, VI, VII and VIII contained a single genotype and therefore, their intra-cluster distance was zero. Selection of parents based on large inter-cluster and intra-cluster distances for hybridization gives a range of useful combinations for the development of high yielding mungbean varieties. The cluster mean values for the 12 characters are presented in Table 6, which revealed considerable variation among the clusters for all the traits studied. Cluster V recorded the highest mean value for days to 50% flowering (38.34), whereas the lowest mean was observed in Cluster III (35.23). For days to maturity, Cluster II exhibited the highest mean (78.75), while Cluster VI recorded the lowest (72.67). The maximum plant height (45.60 cm) was observed in Cluster VIII, whereas Cluster VI recorded the minimum mean plant height (31.17 cm). Cluster VII exhibited the highest mean for branches per plant (3.80), while the lowest value was recorded in Cluster IV (2.65). The highest mean number of clusters per plant (4.80) was observed in Cluster I, whereas Cluster VI recorded the lowest value (2.17). Similarly, Cluster IV registered the highest mean for pods per cluster (5.13), while the lowest mean was observed in Cluster VI (2.63). With respect to pods per plant, Cluster VIII recorded the highest mean (28.73), whereas Cluster VI exhibited the lowest value (12.80). The maximum mean number of seeds per pod was recorded in Cluster VII (11.87), while Cluster II showed the minimum value (10.46). For pod length, Cluster II exhibited the highest mean (9.54 cm), whereas Cluster VI recorded the lowest mean (6.95 cm). Seed yield per plant was highest in Cluster VII (8.74 g) and lowest in Cluster V (6.53 g). The highest mean value for 100-seed weight was observed in Cluster VII (5.28 g), while Cluster IV recorded the lowest value (3.54 g). For crude protein content, Cluster V exhibited the highest mean (25.69%), whereas the lowest mean was recorded in Cluster VIII (23.70%). The analysis of character contribution to genetic divergence revealed that pods per plant (22.5%) contributed the highest proportion to the total genetic divergence, followed by clusters per plant (16.4%), pods per cluster (14.6%), branches per plant (9.2%), 100-seed weight (8.8%), days to 50% flowering (5.7%), crude protein content (4.8%), seeds per pod and plant height (4.1% each), pod length (4.0%), seed yield per plant (3.3%), and days to maturity (2.7%) (Table 7). Collectively, these characters accounted for 100% of the total genetic divergence observed among the experimental genotypes (Figure 8). Seed yield per plant (g) 3.

Conclusion

The experimental material exhibited sufficient genetic variability, indicating considerable potential for the development of early maturing and high-yielding mungbean genotypes. Based on mean performance, the genotypes ANDGG 2011, ANDGG 2029, and ANDGG 1808 were identified as promising elite genotypes for yield improvement while maintaining desirable quality attributes. High heritability coupled with high genetic advance as a percentage of the mean was recorded for branches per plant, clusters per plant, pods per cluster, pods per plant, and 100seed weight, suggesting the predominance of additive gene action and indicating that these traits can be effectively improved through direct selection. Considering the maximum inter-cluster distance, hybridization between the genotypes of Cluster VIII (ANDGG 2029) and Cluster VI (AM-K18-23), as well as between Cluster VI (AM-K18-23) and Cluster III (AM-15-3-2, AM-15-26-1, and AM-K18-11), is recommended to generate broad genetic variability and obtain superior recombinants for yield enhancement in mungbean. Among the traits studied, pods per plant, clusters per plant, pods per cluster, branches per plant, and 100-seed weight contributed the greatest proportion of genetic divergence, highlighting their importance in the selection of diverse parental lines for future breeding programmes.

Acknowledgement

AcknowledgementThe authors gratefully acknowledge the financial support provided by the College of Agriculture, Navsari Agricultural University, Bharuch, and thank the institution for providing the necessary infrastructural facilities to conduct this research.

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