Correlation and Path Coefficient Analyses of Cowpea (<i>Vigna unguiculata</i> L.) Landraces in Ethiopia

Abstract

Understanding the nature and extent of association between yield and yield related traits is the prerequisite study for any underutilized crop improvements of sustainable genetic enhancement. However, there is a lack of sufficient information on seed yield and related trait correlation and path coefficient analysis of cowpea in Ethiopia. To fill the existing knowledge gap, the present study was conducted to determine the nature and extent of phenotypic and genotypic correlation and path coefficient analysis among 18 quantitative traits. A total of 324 cowpea landraces were tested in 18 × 18 simple lattice design at Melkassa Agricultural Research Center and Miesso sub center during 2016 cropping season. The magnitude of genotypic correlations was higher than phenotypic correlations in most traits at both locations; this implies that the traits under consideration were genetically controlled. Seed yield was positively and highly significantly correlated with most of the traits at phenotypic and genotypic levels, indicating the presence of strong inherited association between seed yield and the other 17 traits. Almost all traits genotypic direct and indirect effects were higher than the phenotypic direct and indirect effects; this indicated that the other traits had a strong genetically inherited relationship with seed yield. Genotypic path coefficient analysis revealed that days to flowering, biomass and harvest index at Miesso, and seed thickness, plant height, days to maturity and biomass at Melkassa had relatively high positive direct effect on seed yield. However, seed width and hundred seed weight had exerted negative direct effect on seed yield at each location. Phenotypic path coefficient analysis showed that biomass and harvest index had exerted high positive direct effect on seed yield at both locations.

Variability and interrelation analysis in cowpea [Vigna unguiculata (L.) Walp.] Genotypes

“…Significant and positive phenotypic correlation of seed yield was perceived with harvest index (0.838**), number of pods per plant (0.710**), number of seeds per pod (0.415**), plant height (0.302**) and protein content (0.218*) hinting that these attributes are the primary yield determinant in cowpea. These findings were in accordance with the results of Srinivas et al (2017) [20] ; Tsegaye et al (2018) [24] and Walle et al (2018) [26] . The phenotypic correlation coefficient of pod length (-0.212*), days to 50 per cent flowering (-0.328**) and days to maturity (-0.259*) was recorded significantly negative with seed yield per plant.…”

“…Significant and positive correlation was registered by harvest index with number of pods per plant (0.394**) and number of seeds per pod (0.310**). Similar findings were reported by Walle et al (2018) [26] . At phenotypic level, the positive direct effect on seed yield per plant was majorly by harvest index (0.9094), biological yield per plant (0.3906), number of pods per plant (0.2089), plant height (0.0604), 100-seed weight (0.0080), number of branches per plant (0.0058), number of seeds per pod (0.0047), protein content (0.0023) and pod length (0.0003) indicating the direct selection for these traits in order to improve seed yield of cowpea whereas, highest negative direct effect were reported for days to 50 per cent flowering (-0.0204) and days to maturity (-0.0094).…”

“…Cokkizgin et al (2013) [5] reported positive direct effect by 100-seed weight and number of branches per plant. Direct positive effect over seed yield per plant via plant height was earlier reported by Jogdhande et al (2017) [7] , Manisha et al (2018) [11] and Walle et al (2018) [26] . Residual effect resulted in path analysis was found to be very low 0.1697 at genotypic level and 0.1820 at phenotypic level representing that there was maximum and sufficient effect of the characters evaluated on seed yield in cowpea.…”

“…The magnitude of genotypic correlation coefficients were higher than phenotypic correlation coefficients for every attribute under the study that indicated inherent interrelation between different characters (Table 2). Thorat and Gadewar (2013) [25] , Chattopadhyay et al (2014) [4] , Adetiloye et al (2017) [1] , Tsegaye et al (2018) [24] and Walle et al (2018) [26] reported the similar results. Significant and positive phenotypic correlation of seed yield was perceived with harvest index (0.838**), number of pods per plant (0.710**), number of seeds per pod (0.415**), plant height (0.302**) and protein content (0.218*) hinting that these attributes are the primary yield determinant in cowpea.…”

Response of Cowpea [Vigna unguiculata (L.) Walp] Genotypes under Residual Moisture Condition in Rice-Fallow Area of Goa State, India

“…The results indicated that straw yield (1.068) had highest positive direct effect on seed yield followed by harvest index (0.741). Similar observations of high direct effect of harvest index and pods per plant on seed yield was observed by Walle et al (2018) in their study on assessing the correlation and path coefficient in cowpea landraces from Ethiopia. However positive direct effect of straw yield on grain yield in the current study was contrary to some reports (Peksen and Artik, 2004) which had a nonsignificant negative effect on grain yield.…”