Analysis of variance and genetic variability
The mean sum of squares for different morphological traits of mungbean genotypes is given in Table 2. All the traits under study showed considerable genetic variability. The analysis of variance of indicated that the mean sums of squares due to genotype were highly significant for all the morphological traits, suggesting presence of sufficient variation among genotypes for these characters.
An insight into the nature and magnitude of genetic variability present in the gene pool is of immense value for starting any systematic breeding programme because of considerable genetic variability in the base material ensures better chances of evolving desirable plant type.
Patel et al., (2012), Vir and Singh (2016) and
Singh et al., (2016) also revealed significant differences for all the traits studied.
The estimates of genetic variability
viz, phenotypic coefficient of variation (PCV), genotypic coefficient variation (GCV), heritability, genetic advances are important in determining the method of selection to improve a particular plant population for a specific trait. The estimates in Table 3 indicated that high heritability is not necessary association with high genetic advance. It showed that the estimates phenotypic coefficient of variation (PCV) was higher than that genotypic coefficient variation (GCV) for all the morphological traits, indicating greater influence of environment on these traits as also reported earlier by
Muthuswamy et al., (2019).
High PCV with High GCV estimates were observed for clusters per plant, no. of branches per plant, days to maturity which are akin to the results of
Azam et al., (2018) for pods per plant, plant height and 100 seed weight and
Asari et al., (2019) observed for primary branches per plant, pods per plant, seed yield per plant and clusters per plant. Moderate PCV and GCV were found for days to 50% flowering, seed yield per plot, plant height and no. of pods per plant. Similar results were also reported by
Singh et al., (2015) for no. of seed per pods and plant height, while
Raturi et al., (2015) for seed yield, plant height and no of pods per plant. The lowest PCV and GCV estimates have been recorded for pods per cluster and such lowest estimates have been indicated by
Alemu et al., (2014) for days to flowering and seeds per plant. Heritability and genetic advance serve as predictive function of genotypic performance in a succeeding generation but eventually guide the breeder in effective selection. High value of heritability coupled with high genetic advance as percentage of mean observed for clusters per plant, no. of branches per plant, days to maturity, seed yield, days to 50% flowering, plant height and no. of pods per plant. This clearly brought out the role of additive gene effects with low environmental influence in the inheritance of these traits suggesting phenotypic selection may be effective for improving these traits. These findings are in agreement with
Malli et al., (2018) for the traits like biological yield per plant, branches per plant, no of pods per plant.
High heritability coupled with low genetic advance estimates for pods per clusters observed in the present study explains preponderance of the non additive gene action. The high heritability observed may due to be the favorable influence of environment. The presence of non additive gene action can be exploited better through recombination breeding. These findings are also in agreement with
Roy chowdhury et al., (2012) for the trait plant height and
Suresh et al., (2010) for days to maturity. Low heritability coupled with low genetic advance recorded for seeds per pods suggested that the trait is highly affected by environment and phenotypic selection would be ineffective. Similar estimates also reported by
Mehandi et al., (2013) for the trait pod length (cm).
Correlation and character association
Correlation is essential for making efficient selection strategies by the geneticists and breeders. Correlation coefficient estimates are extensively used to measure the degree and direction of associations between various attributes including grain yield, consequently correlation coefficient analysis was done to understand the relative importance of the component traits and start an effective selection or breeding programme. The results in Table 4 indicated that genotypic correlation coefficients were higher than the phenotypic correlation coefficients for most of the traits. At genotypic level, seed per pod (r=0.478), no. of branches per plant (r=0.396), plant height (r=0.387), no. of pods per plant (r=0.273) and clusters per plant (r=0.197) were significant and positively correlated with seed yield per plot. Similar results were observed by
Tah (2008).
Dhole and Reddy (2018) also reported positive correlation coefficients for clusters per plant, pods per cluster and seeds per pod. This result indicates improvement through direct selection of these traits can result directly in enhanced grain yield in mungbean. Days to 50% flowering (r=-0.219) showed significant and negative genotypic correlation with seed yield. This result was also in agreement with the studies of
Mahanta and Sao (2019). Days to 50% flowering showed significant and positive correlation with no. of branches per plant (r=0.928), days to maturity (r=0.510), plant height (r=0.394), no. of pods per plant (r=0.367) and clusters per plant (r=0.326) while negative and significant correlation with seeds per pod (r=-0.235). Similar result has also been revealed by
Varma et al., (2018) for days to maturity, primary branches, plant height but was negatively correlated with 100 seed weight, yield per plant, pod length, seed per pod, pods/ plant and cluster/ plant. Plant height (r=0.646) was significantly associated with days to maturity along with no. of pods per plant (r=0.452), clusters per plant (r=0.259) and no. of branches per plant (r=0.185). These results were also in agreement with
Lal and Singh (2014) for plant height. Plant height showed significant and high correlation coefficient with no. of pods per plant (r=0.530), clusters per plant (r=0.447), no. of branches per plant (r=0.419) and seeds per pod (r=0.285).No. of branches per plant showed significant high positive association with no. of pods per plant (r=0.622), clusters per plant (r=0.535), pods per plant (r=0.324). Similar result was also revealed by
Varma et al., (2018) for primary branches per plant was positively correlated with pods per plant.
Clusters per plant (r=0.547) was significantly and positively correlated with no. of pods per plant along with the pods per cluster (r=0.277) and seeds per pod (r=0.181) and showed significant and positive correlation coefficient with seeds per pod (r=0.258) and also pods per cluster was positively and significantly associated with seeds per pod (r=0.237).
