The pooled analysis of variance (ANOVA) showed in (Table 2) as a measure of variability was carried out for 30 mungbean genotypes. Significant differences among all the genotypes and interaction between genotypes and environments were revealed for all the characters studied. This indicates that genotypes were taken under the research work had present the characters.
Salman et al., (2021) and
Dhoot et al., (2017) also reported significant differences for all the characters studied. Over two years of study, some genotypes consistently had good performance than the other genotypes (Table 3). Early flowering was observed in SIKHA, IPM2K-14-9, MH2-15, PRATIKSHA NEPAL and IPDI-539. These genotypes could be considered for the development of early maturity lines of mungbean. Among the genotypes, ML-1059, PUSA-9972, PDM04-123, SML-1808 and PDM-281 were recorded for more days to mature. The genotypes such as VIRAT, SIKHA, SAMRAT, AKM-96-2, SUKETI-1, IPM-2-17 were consistently showing the significantly good performance for most of the characters like plant height, number of primary branches per plant, number of branches per plant, number of clusters per plant, number of pods per plant, pod length, number of seeds per plant and 100 seed weight. Highest seed yield per plant was recorded in VIRAT and it was followed by SIKHA, SAMRAT, IPDI-539 and SUKETI-1. This indicates great scope for the effective selection.
Table 4 showed various genetic variability parameters of the characters like mean values, range having minimum and maximum values, phenotypic (PV) and genotypic variance (GV) and its coefficients, heritability in broad sense (%), genetic Advance (GA) and genetic advance as percent of mean. The mean and range of the characters revealed the large variation had recorded of the genotypes due to the interaction between genotypes and environment. A comparison of genotypic variance and phenotypic variance was performed to determine the magnitude of the genotypic contribution to the mungbean improvement. The highest genotypic variance and phenotypic variance was observed for plant height, number of pods per plant and days to 50% flowering. The phenotypic variance was higher than the genotypic variance due to the combination of genotypic variance and environmental factors. Similarly, the phenotypic coefficient of variation (PCV) was consistently higher than the genotypic coefficient of variation (GCV) for all the traits, suggesting a significant influence of environmental factors on the observed traits. The GCV and PCV value between above 20%, between 10% and 20% and below 10% as interpretated high, moderate and low respectively. High GCV and PCV (<20) was observed for seed yield per plant and it was followed by number of primary branches per plant and number of pods per plant. similar results were reported
Ramakrishnan et al., (2018), Parimala et al., (2020). The highest values of GCV and PCV indicates that presence of high variability in these characters suggested reasonable scope for the improvement through selection. Moderate GCV and PCV (10 -20) was recorded for number of branches per plant and it was followed by number of clusters per plant, 100 seed weight and plant height. The above results were corroborated with
Salman et al., (2021). Similar results were observed by
Pandey et al., (2007) and
Nand and Anuradha (2013) for number of branches per plant and
Rao et al., (2006); Makeen et al., (2007) and
Kumhar and Choudhary (2007) for 100 seed weight. Low GCV and moderate PCV was exhibited for days to 50% flowering and number of seeds per pod. Similar results were also recorded by
Harini et al., (2022). This indicates that traits have more influenced of environment. Low GCV and low PCV was showed for days to maturity and pod length. Similar findings were revealed by
Shiv et al., (2017). It indicates less variability present in these characters, provides the selection may not be effective.
Heritability is the ratio of genotypic variance to the total phenotypic variance of the character. It provides the information of the transmission of the characters from parents to the offsprings. It is crucial parameter in the plant breeding where plant breeders could rely on it. The heritability values show the possible and extent of improvement could occur through selection.
(Sawarkar, et al., 2023) On the basis of diverse genotypes, the variation in the heritability was recorded. It is usually classified as high (above 60%), medium (30-60%) and low (0 to 30%). The high heritability helps in the effective selection of the genotypes. The broad sense of heritability of the characters was observed from (60.83%) to (95.75%). All the characters were showed as high heritability. The highest broad sense of heritability was recorded for number of branches per plant (95.75%) which was followed by seed yield per plant (95.58%), number of pods per plant (94.54%) and number of primary branches per plant (94.06%). Similar results were obtained by
Salman et al., (2021) for number of branches per plant,
Garg et al., (2017) for seed yield per plant and number of pods per plant. It indicates that the environment had little influence on the expression of these traits and it would be reasonable to select easily.
Katiyar et al., (1974) noted that relying solely on heritability values does not provide any insight into the extent of genetic advancement that could be achieved through the selection of the most superior individuals. Nevertheless,
Johnson et al., (1955) proposed that incorporating heritability estimates together with genetic advance would yield greater utility in forecasting yield outcomes under phenotypic selection, compared to relying solely on heritability estimates. In the present study, high genetic advance was observed for plant height and number of pods per plant. The comparison of heritability in relation to genetic advancement, expressed as a percentage of the means across various traits revealed that seed yield per plant, 100 seed weight, number of pods per plant, number of clusters per plant, number of branches per plant, number of primary branches per plant and plant height had high heritability and high genetic advance as a percentage of mean indicated genetic variation. The prevalence of the additive gene action can be ascribed to the influence of activity and it would be advantageous to employ selection in order to enhance the seed yield in relation to these particular traits. Similar findings were obtained by
Reshmi et al., (2020) for these characters except number of clusters per plant, number of branches per plant,
Choudary et al., (2017) for number of primary branches per plant,
Talukdar et al., (2020) for number of pods per plant,
Rahim et al., (2010)) and Ghimire. (2017) for seed yield per plant. Moreover, high heritability along with moderate genetic advance as a percentage of mean was observed for days to 50% flowering and number of seeds per pod. Similar results were reported by
Hemavathy et al., (2015). It indicates that these traits were predominantly regulated by the additive genes and that direct targeting of these attributes could be effective. Nevertheless, pod length and days to maturity had high heritability and low genetic advance as a percentage of mean. Hence, these characters were regulated by nonadditive genes
i.
e. dominance and epistasis, thereby enabling environmental regulation over the manifestation of these traits and their improvement could be achieved through the utilization of heterosis breeding.
Correlation coefficient analysis is usually do to study the relationships between the seed yield and other attributes. Table 5 represent the phenotypic and genotypic correlation coefficient of the seed yield and its attributing traits. Overall basis, the genotypic correlation exhibited a higher magnitude compared to the corresponding phenotypic correlation across all pairs of characters. This suggests that the presence of environmental effects has a dampening effect on the association observed at the phenotypic level. This finding indicates that both the environmental and genotypic correlations in those specific cases operate in a similar direction, ultimately leading to the maximization of their expression at the phenotypic level. Seed yield per plant highly significant and positively correlated with plant height, number of primary branches per plant, number of clusters per plant, number of pods per plant, number of seeds per pod and 100 seed weight at phenotypic and genotypic level except pod length at genotypic level only. These results are in accordance with
Baisakh et al., (2016) for plant height,
Ghimire et al., (2017) for number of primary branches per plant,
Sandhiya and Saravanan (2018) for the number of clusters per plant,
Reshmi et al., (2020), Ramakrishnan et al., (2018) for number of pods per plant,
Das and Barua (2015) for the number of seeds per pod;
Kate et al., (2017) for 100 seed weight. These traits could be directly selected in the development of high yielding varieties of mungbean. Days to 50% flowering was observed non-significant and negative correlation between most of the characters but exhibited significant positive correlation with days to maturity and significant negative correlation with number of pods per plant and seed yield per plant at phenotypic and genotypic level. Similarly, days to maturity had negative and non-significant correlation all the characters except pod length, number of seeds per plant and 100 seed weight had negative correlation at genotypic level only and seed yield per plant at both levels. Plant height showed the significant and positive correlation with number of primary branches per plant, number of clusters per plant, number of pods per plant and 100 seed weight at both levels. However, it had negative significant correlation with number of seeds per plant at genotypic level only. Number of primary branches per plant exhibited significantly high and positive correlation with number of clusters per plant, number of pods per plant and 100 seed weight. In case of number of branches per plant significant and negative correlation with number of seeds per plant while number of clusters per plant significant and positively correlation with the number of pods per plant and 100 seed weight at both levels. Likewise, characters like number of pods per plant had positive correlation with the 100 seed weight and pod length had significant positive correlation with the number of seeds per pod at phenotypic and genotypic level and with seed yield per plant at genotypic level only.
The significance of the correlation coefficient is greatly enhanced when the correlation coefficients are divided into distinct parts that represent the direct and indirect effects through the utilization of path analysis. This is crucial as correlation coefficients merely illustrate the interrelationship between various variables without taking into consideration the cause and effect aspect. This approach, as suggested by
Dewey and Lu (1959), allows for a more comprehensive understanding of the underlying factors influencing the correlation coefficients. The path analysis ultimately results in the identification of crucial component traits that can be effectively utilized in the process of indirect selection for complex traits, such as yield. This is due to the fact that a character like seed yield is intricately dependent on numerous component characters that are mutually associated with one another. Therefore, if there is any alteration or modification in any one of these characters, it is highly likely to have a significant impact on the cause and effect relationships that exist within the system. Table 6 represent the direct and indirect effect of various characters of mungbean on seed yield. The values appearing in the diagonal are the direct effect of the traits
via positive or negative direction on seed yield. Out of 10 yield attributing characters, seven characters were recorded positive direct effects on seed yield while two were negative indirect effect on seed yield. Highest direct effect was observed by number of pods per plant and it was followed by 100 seed weight, pod length, days to 50% flowering, number of branches per plant, number of clusters per plant and lowest had number of seeds per plant. Similar findings were obtained by
Reshmi et al., (2020) for number of pods per plant,
Thippani et al., (2013) for pod length and 100 seed weight. While, highest negative indirect effect was noticed for number primary branches per plant and it was followed by days to maturity and plant height on seed yield. Characters like number of pods per plant, in addition to the 100 seed weight and the pod length, not only exhibit a higher magnitude of positive direct effect but also demonstrate a significant and positive correlation with the seed yield per plant. This implies that by directly selection of these traits, can effectively improve the seed yield of mungbean. On the other hand, the days to 50% flowering exhibited a positive direct effect, yet its correlation with the yield was negative. This indicates that the cause of this correlation lies in the indirect effects. Consequently, in order to fully utilize the high positive direct effect of the days to 50% flowering, it is recommended to adopt a restricted selection model that can eliminate the undesirable indirect effects. By doing so, it could ensure that the use of this particular trait positively contribute to the mungbean improvement program. The positive direct effect of the number of branches per plant on seed yield, though significant, was found to have a non-significant association with the seed yield. Consequently, it can be concluded that indirect selection, specifically through the consideration of the number of clusters per plant, the number of pods per plant and 100 seed weight, would prove to be more effective in increasing the yield in the mungbean. Similarly, number of primary branches per plant showed high and significant positive correlation with the seed yield but unfortunately it had negative direct effect on seed yield. Therefore, indirect effect were mainly responsible for the production of such correlation. Hence indirect selection through number of pods per plant, 100 seed weight, pod length could be helpful in enhancing the seed yield of mungbean. The residual effect observed in the current study, with a value of 0.092, serves as a significant indication of the amount of variability that occurred in seed yield. This variability can be attributed to the various traits that were studied in the path analysis, thereby highlighting their potential influence on the final outcome. It is important to note that the residual effects observed in this particular study can be attributed to a multitude of factors, including environmental conditions and cultural practices, which have been known to significantly impact the seed yield.