Mean performance of parents and F1g hybrids
Mean performance of the F1 hybrids and parent genotypes for seed yield and its attributes are shown by boxplot distribution in Fig 1. Seed yield plant
-1 varied significantly between genotypes ranging from 5.70 g to 24.77 g. Out of 39 genotypes, 23 genotypes (22 crosses and 1 parent) exhibited above mean seed yield (13.97). The highest seed yield plant
-1 was found in Aman x GP02/1108 (24.77g) followed by IPF 14-16 x GP02/1108 (18.84 g), IPF 14-16 x HFP 1426 (18.39 g) and Aman x HFP 1545 (18.23 g) and lowest in genotype GP02/1108. It was also observed that these genotypes proportionately exhibited above average mean performance for almost all the traits. Likewise lowest yielding parents and crosses
viz., GP02/1108, HFP 715, RFP 2009-02 x HFP 1426 and HFP715 x HFP 1426, respectively showed low value for most of traits. These results indicated that there is a plenty of variation among these genotypes for almost all traits and selection would be effective among these genotypes. Significant variability was also observed in previous studies of
Singh et al. (2018) and
Yang et al., (2022) in fieldpea and
Manjunath et al., (2023) in garden pea for seed yield and its attributes.
Genetic variability analysis
The overall magnitude of PCV was observed higher than that of GCV almost all the traits implying a significant role of environment in expression of these traits as shown in Fig 2a,b. The phenotypic and genotypic coefficients of variation were grouped in three categories
i.
e., low (less than 10%), moderate (between 10 to 20) and high (greater than 20%) as suggested by
Deshmukh et al., (1986). Likewise, similar results were observed by
Pratap et al., (2021), Jagadeesh et al., (2023) and
Pratap et al., (2021) in fieldpea and
Sharma et al., (2023) in gardenpea.
Heritability (H2ns) represents the genetic strength of the traits and indicates the efficiency of selection, whereas genetic advance in percentage (expected) of mean (GAM) serve as indicator of efficacious and systematic progress of selection. Genetic advance as per cent mean was grouped in three categories as described by
Johnson et al., (1955) i.
e., low (0-10%), moderate (10-20%) and high (above 20%). According to
Johnson et al., (1955), the degree of additive gene effects has a direct correlation with the narrow sense heritability and expected genetic advance as percentage of mean. Therefore, simple selection would be effective for all traits with high heritability. The heritability and GAM in the present investigation varied from 0.16% to 82.92% and 0.05% to 16.88%, respectively as shown in Fig 2c,d. Low magnitude of H2nscoupled with low GAM indicating pre-dominance of non-additive gene action and hence heterosis breeding would be rewarding for their genetic improvement whereas, moderate H2ns along with low GAM were observed for days to maturity and height of first pod while plant height exhibited high heritability with moderate GAM indicating that these characters might be governed by non-additive gene action and high heritability might be exhibited due to favourable influence of environment. Similar studies on heritability and genetic advance in fieldpea made by
Singh et al., (2017) Pratap et al., (2021), Jagadeesh et al., (2023) and
Pratap et al., (2021) were in partial agreement with our findings.
Association among yield contributing traits
For initiating an effective breeding programme,
a priori knowledge of inter-trait correlation among the traits is must. The inter-relationship among quantitative traits was analyzed using Pearson’s product-moment correlation. Critical perusal of scatter plot (Fig 3) represents the correlations coefficient between the traits and it was observed that most of the examined traits had significant phenotypic correlations. There was concurrence between these correlations; although in some cases differences were prominent which indicated a crucial role of environment in expression of these parameters. In the present investigation number of secondary branches plant
-1, number of primary branches plant
-1, height of 1
st pod, plant height, number of pods plant
-1, biological yield plant 1 and harvest index showed positive significant association with seed yield plant
-1. Therefore, selection for these positively associated traits could increase yield by a significant proportion.
In the present study, path coefficient analysis (Table 1) revealed that highest positive direct effect on seed yield was exhibited by biological yield plant
-1 (0.739) followed by plant height (0.427), harvest index (0.353), number of secondary branches plant
-1 (0.174), number of seeds pod-1 (0.137), number of nodes plant
-1 (0.086), 100-seed weight (0.084), number of primary branches plant
-1 (0.079) and days to 50% flowering (0.058).
However, day maturity (0.03), height of 1
st pod (0.336) and number of pods plant
-1 (0.180) had negative direct effect on seed yield plant
-1. Days to 50% flowering, days to maturity, number of primary branches plant
-1, number of secondary branches plant
-1, number of nodes plant
-1, plant height of 1
st pod, plant height, pods plant
-1, 100-seed weight contributed direct effects towards seed yield plant
-1 through biological yield per plot. The correlation and path studies of
Singh et al., (2017), Panwar et al., (2023) and
Pratap et al., (2021) in fieldpea also corroborate our findings.