Determination of ontogenetic selection criteria for grain yield in spring barley (Hordeum vulgare) by path-coefficient analysis

Path-coefficient analysis was performed to determine the interrelationships among grain yield, yield components (spike number per m super(-2), kernel number per spike, average kernel weight) and some phenological characteristics (duration and growing degree-days of vegetative and grain-filling periods) in spring barley genotypes in 2004-2005. Grain yield depended mainly on spike number per m super(-2) and kernel number per spike; average kernel weight had a negligible effect on grain yield in spring barley genotypes. Grain yield was significantly and positively associated with the spike number per m super(-2) and negatively correlated with other characteristics studied. Spike number per m super(-2) had considerable negative effect on the average kernel weight. A lengthening of the grain-filling period induced an increase in the average kernel weight and a positive and significant correlation was found between the two characteristics. Spike number per m super(-2) and kernel number had positive direct effects on grain yield in spring barley genotypes. The growing degree-days (GDD) for vegetative period had significant positive direct effect on kernel number, and the GDD for grain-filling period had significant positive direct effect on kernel weight. The results indicated that spike number per m super(-2), kernel number per spike and the GDD for vegetative and grain filling period were the most reliable selection criteria for improving grain yield in spring barley in cool and short-season environments.