Correlation and Path Coefficients among Quantitative Traits in Wheat (Triticum aestivum L.)

Since many of the quantitative plant characters of economic values are highly influenced by environmental condition, the progress in breeding in such a population is primarily conditioned by the magnitude, nature and inter-relations of genotypic and non-genotypic variations in plant characters. Therefore we estimated phenotypic, genotypic and environmental correlation coefficients and path coefficients among eight quantitative traits of bread wheat to make selection efforts more efficient. These traits were measured in 30 wheat genotypes, which were laid out in a randomized block design with three replications in Khumaltar, Kathmandu during 2003. The highest genotypic correlation (0.81) was between heading and maturity days. Tiller number was negatively correlated with grain number per spike (-0.78) at genetic level. Phenotypically, number of grains and grain weight per spike showed the largest coefficient (0.92) and maturity days exhibited negative association with plant height (-0.37). Environmental correlation coefficient was the highest between tillers number and grain yield (0.5) and heading days showed negative relationship with grain yield (-0.28). It indicates that number of tiller and grains per spike are the most important traits for yield. In most of the cases, genotypic correlations were higher than phenotypic correlations. Maturity days exerted the greatest influence (2.41) directly upon yield. Negative direct effect of heading days and positive effect of tiller number on yield was also considerable on magnitude. Indirect effect of heading days via maturity days was the highest followed by spike grain weight via maturity on grain yield. Results showed that grain filling period is an important factor and number of tillers and grains per spike should also be considered during selection for getting high yielding genotypes.