Yield is a complex character that is dependent on a number of distinct yield contributing characters, which are referred to as yield components. All changes in the yield components, on the other hand, do not have to be reflected in changes in yield. This is due to the varied degrees of positive and negative associations that exist between yield and its constituents, as well as between components themselves. As a result, after examining their association with fruit output per plant, selection should be based on these component traits.
Correlation coefficient analysis
Tables 1 and 2 show that estimations of genotypic correlation coefficients were in most cases higher than their phenotypic correlation coefficients during both seasons. These present findings are in close harmony with
Saryam et al., (2017), Singh et al., (2016), Balai et al., (2014), Senapati et al., (2011). More significant genotypic correlation between distinct pairs of traits than phenotypic correlation stated that there is a strong genetic relationship between those characters genetically, but the phenotypic value is diminished by significant environmental interaction.
In the present study during summer season fruit yield per plant was positively and significantly correlated with leaf area (0.362 and 0.332), number of primary branches per plant (0.443 and 0.339) and number of fruits per plant (0.927 and 0.828) whereas, significantly negatively correlated with days to 50% germination (-1.029 and -0.679), days to opening first flower (-0.989 and -0.927), days to 50% flowering (-0.969 and -0.908) and days to first harvesting (-0.979 and -0.900) and during rainy season it was positively and significantly correlated with plant height at (0.672 and 0.468), number of nodes (0.608 and 0.376) and number of fruits per plant (0.600 and 0.297) at genotypic and phenotypic level respectively whereas, significantly negatively correlated with days to opening first flower (-0.918 and -0.574), days to 50% flowering (-0.922 and -0.651), days to first harvesting (-0.943 and -0.703) and pedicle length (-0.538 and -0.435). The present findings are in consonance with the earlier findings of
Khalid et al., (2018) who also reported positive association of number of fruits per plant and plant height with fruit yield per plant. Positive association of number of branches per plant with yield per plant is also reported by
Patero et al., (2004), Pachiyappan and Saravannam (2016) reported positive association of number of fruiting nodes with fruit yield per plant and significantly negative association of days to first flowering. Days to 50% flowering is negatively associated with fruit yield per plant is also reported by
Reddy et al., (2013). Similar result was correlated with
Singh et al., (2016) that plant height is significantly positively correlated with fruit yield per plant.
Days to 50% germination was positively and significantly correlated with days to opening first flower (0.960 and 0.718), days to 50% flowering (0.870 and 0.636) and days to first harvesting (0.905 and 0.652) during summer season and with pedicle length (0.484 and 0.415) during rainy season at genotypic and phenotypic level respectively.
Plant height was positively and significantly correlated with number of nodes (0.573 and 0.474), number of leaves (0.485 and 0.420), number of primary branches per plant (0.403 and 0.312) and fruit length (0.909 and 0.323) during summer season and with number of nodes (0.945 and 0.640) during rainy season.
Days to opening first flower showed positive and significant association with days to 50% flowering (0.985 and 0.940) and days to first harvesting (0.977 and 0.914) during summer season and with days to 50% flowering (0.937 and 0.919), days to first harvesting (0.941 and 0.890) and node to first flower appear (0.749 and 0.461) during rainy season.
Days to 50% flowering showed positive and significant association with days to first harvesting (0.963 and 0.949) and node to first flower appear (0.597 and 0.408) during summer season. These results are similar with the findings of
Sharma et al., (2010) that days to 50% flower was recorded highly significant and positive association with days to first harvest.
Days to first harvest during rainy season was significantly and positively associated with node to first flower appear (0.547 and 0.378).
Number of nodes during summer season was significantly and positive associated with number of leaves (0.810 and 0.613), number of primary branches per plant (0.807 and 0.496) and during rainy season with leaf area (0.445 and 0.323).
During summer season number of leaves with number of primary branches per plant (0.410 and 0.297) and fruit length (0.625 and 0.284) and during rainy season with number of primary branches per plant (1.043 and 0.576).
Path coefficient analysis
The estimates of direct and indirect effects of the fifteen fruit yield related characters on fruit yield per plant are presented in Table 3 and 4 for summer and rainy season respectively.
In the present study during summer season leaf area (0.760) had maximum direct contribution towards fruit yield per plant followed by number of fruits per plant (0.447), days to first harvesting (0.415) and days to 50% germination (0.349). However, days to opening first flower exhibited highest negative direct effect (-1.109) and during rainy season leaf area (3.274) had maximum direct contribution towards fruit yield followed by days to opening first flower (2.828) and pedicle length (0.854). However, days to first harvesting (-4.630) exhibited highest negative direct effect followed by plant height (-1.467), number of leaves (-1.036), node to first flower appear (-0.871) and fruit length (-0.232). These are the important traits which may be viewed in selection programme for the further improvement of okra.
During summer season the genotypic direct effect of leaf area, days to 50% germination and number of primary branches whereas, during rainy season leaf area, number of primary branches per plant contributed directly and positively to fruit yield per plant possess significant correlations suggesting that the association between these traits is perfect and direct selection through these traits will be effective.
During rainy season genotypic path coefficient analysis revealed that days to opening first flower had high positive direct effect on fruit yield per plant, though their association was significantly negative. Under these circumstances, a restricted simultaneous selection model is to be followed
i.e. restrictions are to be imposed to nullify the undesirable indirect effects
via days to 50% flowering to make use of the direct effect. Similar findings were reported by
Dhall et al., (2000), that number of fruits per plant and plant height had direct effect on fruit yield per plant.
Ramanjinappa et al., (2011) for number of fruits per plant and number of nodes.
Senapati et al., (2011) for number of fruits per plant and fruit length.
Singh et al., (2016) for number of fruits per plant and number of nodes.
Patro et al., (2004) for days to 50% germination. Number of branches per plant, number of nodes and plant height.
Saryam et al., (2017) for number of branches per plant.
Mehta et al., (2006) for fruit length.
Khalid et al., (2018) for days to 50 % flowering.
Highly positive indirect effect on fruit yield per plant during summer season exerted by number of leaves (0.404) via days to 50% germination. Whereas, during rainy season highly positive indirect effect on fruit yield per plant exerted by fruit length (3.7051), number of fruits per plant (2.753) and fruit diameter (2.6732),
via days to first harvesting.
The residual factor determines how best the casual factors account for the variability of the dependent factor, the fruit yield per plant in this case. In spite of the large number of characters used in the path coefficient analysis, the value of the residual factor was found to be negative during summer season which may be due to rounding off errors.
