Variability studies
Estimation of phenotypic and genotypic coefficient of variation is important to find out the environmental interaction on various traits. Values of GCV and PCV for all the nine characters are furnished in Table1. High PCV and GCV were obtained for single plant yield (65.70% and 64.33% respectively) followed by number of clusters per plant (46.14% and 45.06% respectively), number of pods per plant (43.64% and 42.48% respectively), number of primary branches per plant (30.45% and 24.37% respectively). These results were found in agreement with
Sathees et al., (2019), where they studied 162 F
2 plants of a cross between IC 436656 x KKB 14045. Moderate PCV and GCV were obtained for plant height (17.73% and 16.74% respectively), 100 seed weight (19.64% and 19.36% respectively), pod length (12.50% and 12.30% respectively). These results are in agreement with
Panigrahi et al., (2014), where they studied 19 genotypes of black gram. High PCV coupled with moderate GCV obtained for number of seeds per pod (21.28% and14.24% respectively).
High heritability was recorded for the characters
viz., pod length (96.84%), hundred seed weight (97.21%), single plant yield (95.86%), number of clusters per plant (95.34%), number of pods per plant (94.72%), days to 50% flowering (89.86%), plant height (89.14%) and number of primary branches per plant (64.06%).
Reddy et al.,(2018) studied 30 black gram genotypes and reported high heritability for days to 50% flowering, plant height, number of clusters per plant, number of pods per plant and single plant yield.
Konda et al., (2009b) reported high heritability for days to 50% flowering, plant height and hundred seed weight. High GAM was recorded for single plant yield (129.74%) followed by number of clusters per plant (90.62%), number of pods per plant (85.16%), number of primary branches per plant (40.18%), hundred seed weight (39.33%), plant height (32.55%) and pod length (24.94%). Number of seeds per pod (19.63%) and days to 50% flowering (14.11%) were exhibiting moderate GAM. These results are in harmony with the finding of
Bandi et al.,(2018) for the traits
viz., number of clusters per plant, number of pods per plant, number of primary branches per plant, hundred seed weight, single plant yield, days to 50% flowering and number of seeds per pod and number of seeds per pod which in 36 black gram genotypes of diverse origin.
High heritability coupled with high GAM was obtained for plant height, number of primary branches per plant, number of clusters per plant, number of pods per plant, hundred seed weight, pod length and single plant yield.
Panigrahi et al.,(2014) studies revealed that plant height, number of clusters per plant, number of pods per plant, hundred seed weight and pod length had high heritability coupled with high GAM.
Bandi et al.,(2018) reported high heritability coupled with high GAM for single plant yield.
Konda et al., (2009b) studied 40 genotypes and obtained similar result for plant height. High GAM coupled with high heritability refer to the presence of additive gene action for these traits which indicated the scope of improvement of these traits
via selection.
Correlation
Correlation between different yield component traits are furnished in Table 2 and Fig 1. From the intra correlation studies, the characters plant height (0.39), number of primary branches per plant (0.68), number of clusters per plant (0.72), number of pods per plant (0.89), number of seeds per pod (0.67), hundred seed weight (0.41) and pod length (0.35) were significantly positive correlation with single plant yield and days to fifty per cent flowering was negatively correlated with single plant yield. This clearly exhibited that improvement of all the characters except days to fifty per cent flowering will ultimately increase the seed yield and particularly number of clusters per plant, number of pods per plant had greater association with yield. These results are in accordance with the earlier finding
Sathees et al.,(2019).
Konda et al.,(2009a) reported that positive significant association of single plant yield with number of primary branches per plant, number of clusters per plant, number of pods per plant, number of seeds per plant and pod length.
Senthamizhselvi et al., (2019) also observed positive significance of number of pods per plant, plant height, number of primary branches per plant, number of clusters per plant and hundred seed weight.
From the inter correlation studies, days to 50 % flowering was negative significant association with number of primary branches per plant, number of clusters per plant, number of pods per plant, number of seeds per pod and hundred seed weight. Plant height had positive significant with number of primary branches per plant (0.41), number of clusters per plant (0.38), number of pods per plant (0.46), number of seeds per pod (0.27) and pod length (0.23). Number of primary branches per plant had positive significance with number of clusters per plant (0.65), number of pods per plant (0.73), number of seeds per pod (0.36) and hundred seed weight (0.30). Number of clusters per plant had positive significance with number of pods per plant (0.86) and number of seeds per pod (0.32). Number of pods per plant had positive significance with number of seeds per pod (0.44) and pod length. Number of seeds per pod had positive significance with hundred seed weight (0.24) and pod length (0.23). Hundred seed weight had positive significance with pod length (0.37).
Suguna et al.,(2017) reported that positive significance of hundred seed weight with pod length in 4 genotypes and their 12 hybrids. The results of inter-correlation studies were closely harmony with the results of
Sathees et al., (2019).
Priya et al.,(2018) observed that number of primary branches per plant had positive significance with number of pods per plant, number of seeds per pod and hundred seed weight from 120 germplasm lines.
Hence, choice of these characters might improve the plant yield significantly. In correlation matrix chart (Fig 1), association of different traits with the yield is clearly displayed
i.e., the distribution of variables was displayed on the diagonal, bivariate scatter plots with fitted line were shown on the bottom of the diagonal.
Path analysis
Direct and indirect effects of various traits on the yield are furnished in Table 3. The trait number of pods per plant showed high direct effect (0.825) on single plant yield. Number of seeds per pod (0.291), hundred seed weight (0.194) and pod length (0.055) exhibited positive direct effects on single plant yield. These results had harmony with the findings of
Sathees et al.,(2019).
Sathya et al., (2018) reported that high direct effect on single plant yield by number of pods per plant and low positive effect by hundred seed weight in F
2 populations of five crosses
viz., VBN (Bg) 4 x Mash 114, VBN (Bg) 4 x Mash 1008, VBN 8 x Mash 114, VBN 8 x Mash 1008 and VBN 8 x VBG11-053.
Veeramani et al., (2005) revealed similar results for number of pods per plant, number of seeds per pod and pod length.
Days to 50% flowering had positive indirect effect on yield through number of primary branches per plant and number of clusters per plant. Plant height had a positive indirect effect on yield through number of pods per plant, number of seeds per pod, hundred seed weight and pod length. Number of primary branches per plant and number of clusters per plant had a positive indirect effect on yield through days to 50% flowering, number of pods per plant, number of seeds per pod, hundred seed weight and pod length. Number of pods per plant had a positive indirect effect on yield through days to 50% flowering, number of seeds per pod, hundred seed weight and pod length. Number of seeds per pod had a positive indirect effect on yield through days to 50% flowering, number of pods per plant, hundred seed weight and pod length. Hundred seed weight had a positive indirect effect on yield through days to 50% flowering, number of pods per plant, number of seeds per pod and pod length. Pod length had a positive indirect effect on yield through days to 50% flowering, number of pods per plant, number of seeds per pod and hundred seed weight. Among all the characters, number of pods per plant alone showed high positive indirect effect on yield. The residual effect (0.248) indicated that the characters which are included in the path analysis explained nearly 75% of the total variation on the dependent variable
i.e. seed yield.