The principal component analysis for eight traits revealed eight principal components out of which maximum variability was concentrated in the first three principal components PC1, PC2 and PC3 which contributed to 68.61% variance (Table 2). The remaining five principal components were considered irrelevant as their eigen values were less than unity. The eigen values for the significant principal components were 2.3955 (PC1), 1.7101 (PC2) and 1.3830 (PC3).
The first principal component (PC1) contributed a maximum of 29.94% towards variance which was contributed mainly by pod length (cm) and number of pods per cluster. The second principal component explained 21.38% of variance which was contributed mainly by number of pods per plant, number of seeds per pod and 10 pod weight (g). The third principal component contributed 17.29% of total variance which was contributed mainly by yield per plant (g) and number of branches per plant. The results are in accordance with the findings of
Shama et al., (2019), Alice et al., (2018), Sofi et al., (2014) and
Verma et al., (2014) for number of pods per plant, 10 pod weight (g), pod length (cm), number of seeds per pod and yield per plant.
The clustering of genotypes into different clusters based on principal component scores and their intercluster distances. At an RMS distance of 79.76 all the 24 genotypes of french bean were grouped into three clusters (Table 3) based on the principal component scores from the standardized data. Cluster I comprised of 17 genotypes, Cluster II had 6 genotypes and Cluster III had only one genotype. Greater intercluster distance was observed between clusters III and II followed by clusters III and I while the least inter cluster distance was observed between clusters I and II. The genotypes from clusters with greater intercluster distance can be utilized as donor parents to obtain better transgressive segregants. The results are in accordance with the findings of
Shama et al., (2019) and
Alice et al., (2018).
Broad sense heritability for various traits is presented in Table 4. High heritability (> 60%) was observed for 10 pod weight (97.09), number of pods per cluster (94.25), number of seeds per pod (60.87). Moderate heritability (31-60%) was observed for pod length (50.61), number of pods per plant (46.10) and yield per plant (42.45) and low heritability (0-30%) was observed for plant height (22.27) and number of branches per plant (0.05). The traits with high heritability
viz., 10 pod weight (g), number of pods per cluster, number of seeds per pod can be improved by simple selection.
Jhanavi et al., (2018), Singh and Singh (2013),
Ahmed and Kamaluddin (2013) reported high heritability for 10 pod weight (g), number of pods per cluster, pod length (cm), yield per plant, plant height (cm), number of primary branches per plant and number of pods per plant.
The correlation between various traits under study was presented in Table 4. Pod yield per plant had a significant positive correlation with number of pods per plant (0.7154), 10 pod weight (0.6482) and number of branches per plant (0.4785) while pod yield per plant had significant negative correlation with number of seeds per pod (-0.4182). Number of branches per plant and number of pods per plant (0.4167) had significant positive correlation whereas, significant negative correlation exists between plant height and number of seeds per pod (-0.4817). Similar findings of positive correlation of yield with number of pods per plant, average pod weight and number of branches per plant were reported by
Shama et al., (2019), Verma et al., (2014) and
Karasu and Oz (2010).
All the twenty four bush type french bean genotypes were significantly different for the characters studied
viz., number of branches per plant, pod length (cm), number of pods per plant, 10 pod weight (g), number of seeds per pod, number of pods per cluster and yield per plant (g) whereas, no significant difference was observed for plant height in these bush type genotypes of french bean. Significant genotype × environment interactions were observed for the traits number of branches per plant, pod length, number of pods per plant and yield per plant (Table 5) while there was no significant G × E interactions observed for 10 pod weight (g), number of seeds per pod, plant height (cm) and number of pods per cluster.
Finlay-Wilkinson stability analysis was done to identify stable genotypes for various characters. A genotype is considered stable if its response to environment is parallel to the mean response of all genotypes in the trial
(Lin et al., 1986). Genotype with bi = 1.0 is considered dynamically stable, if bi value greater than 1.0 it is suitable for more favorable environments and if bi value less than 1.0 the genotype is expected to be suitable for less favorable environments.
The mean values and linear regression coefficient (bi) of the different genotypes and various characters presented in Table 6. For the trait number of branches per plant the genotypes that could be considered stable were Contender (1.08), FORC6V 1136 (0.97), FMGCV 1007 (1.30), FORC6V 1137 (1.35) and Rivergaro (0.92). The genotype Cartagenta (1.81) could be considered stable for pod length (cm) when compared to all other genotypes. The genotypes Paulista (0.99), Slender Pack (0.98), Arka Suvidha (0.89), Valentino (0.88), FMGCV 0958 (1.12), Banoa (0.86), FORC 6V 1136 (1.14), VRFBB-14-1 (1.32) and VRFBB-14-2 (1.45) were considered stable for number of pods per plant. The genotypes FMGCV 1378 (1.28), FMGCV 0958 (1.37), Arka Suvidha (1.47), Valentino (1.02), Banoa (1.14) and VRFBB-14-2 (1.08) were found stable for yield per plant.
For yield per plant the genotypes FMGCV 1007 (2.34), VRFBB 6 (2.21), VRFBB 7 (2.19), FMGC6V 1379 (2.30) were suitable for cultivation under more favourable environments. FMGCV 1006 (0.12), Cartagenta (0.19), Swarn Priya (0.23), Kashi Rajhans (0.23) and Slender Pack (0.45) were suitable for less favourable environments. The results are in accordance with the findings of
Singh et al., (2020), Jain et al., (2018) in rice,
Chavan et al., (2009) in groundnut,
Singh et al., (2018) and
Haydar et al., (2018) in Wheat.