| Path coefficient analysis of grain yield in wheat
(T. aestivum L.) D. S. VIRK and S. Bahadur SINGH Department of Plant Breeding, Punjab Agricultural University, Ludhiana, India Introduction In quantitative inheritance, a character is often influenced by variations in other traits. The covariation between traits as measured by the correlation coefficients have been studied by various workers viz., GANDHI et al. (1964), JAIN et al. (1969), VIRK and ANAND (1970). Such correlations, however, do not provide a clear picture of the relative contributions of direct and indirect influences of the component characters towards a complex character like yield. WRIGHT (1921) developed a technique to partition the correlation coefficients into direct and indirect effects on the basis of standardised partial regression analysis-path coefficient analysis. Material and methods The material consisted of eleven widely divergent wheat strains viz., NP825 and NP847 from Delhi, C306, C303 and C273 from Punjab, and S227, S210, S354, S355, S- 409 and Mayo-64 from Mexico. These populations were grown in a randomised block design with six replications, consisting of paired 3.5 meter long rows in each replication. The plant to plant and row to row spacings were 15 cm and 22.5 cm respectively. The data were collected on 10 randomly selected plants from the paired plots in each replication. For the present analysis the overall means were used for the simple correlation coefficients. The path coefiicient analysis was done according to DEWERY and Lu (1959). Results and discussion The simple correlation coefficients and path coefficients of the components of yield have been set out in Tables 1 and 2 respectively. The grain yield had strong positive correlations with plant height, 100-grain weight and ears per plant. The observed correlations between the characters associated with grain yield were also positively high except plant height x eras per plant. These correlations were similar to VIRK and ANAND (1970). Plant yield have also been found to have close association with plant height, ears per plant and 100-grain weight by SIKKA and JAIN(1958), NANDPUI(1959), and GANDHI et al.(1964) Grain yield being a complex character is influenced by many factors. Selection based on simple correlations without determing the interactions between the ancilliary traits can be misleading. It is amply revealed from the Table 2 where plant height showed negligible direct effect (-0.0273) though it had a high positive correlation with yield which was mainly through 100-grain weight and to some extent through ears per plant. The grains per ear had high direct effect (0.9848) on the yield, though it had negative and non-significant correlation with grain yield. Its associations with 100-grain weight and ears per plant were highly negative which was confirmed by the path coefiicient analysis. The ears per plant also had good direct effect but the indirect effect through 100-grain weight was considerably high (1.0291). The direct contribution of 100-grain weight and its indirect importance from plant height and ears per plant very clearly emphasised the value of this character in practical selection procedures. However, due weight age should also be given to ears per plant whereas practically no significance should be attached to grains per ear and plant height. VIRK and ANAND (1970) also observed similar weightage for these traits. |
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