ONTOGENIC APPROACH TO GRAIN PRODUCTION IN SPRING BARLEY BASED ON PATH-COEFFICIENT ANALYSIS

Grain yield of barley (Hordeum vulgare L.) is influenced by several yield components and also by the duration of the vegetative and grain-filling periods. Path-coefficient analyses, based on an onto-genetic diagram, were conducted to study the relationships among grain yield, yield components, and duration of the vegetative and grain-filling periods. Nine genotypes (including seven near-isogenic lines) of spring barley varying in heading dates and several morphological traits were grown during the 1987 and 1988 seasons in two environments in the province of Granada in southern Spain. Grain-yield variations between environments and from year to year depended mainly on two yield components, the number of spikes per square meter and the number of kernels per spike. The average kernel weight had a negligible effect on grain yield. The number of spikes per square meter had a considerable negative influence on kernels per spike but contributed positively to both the length of the grain-filling period and the average kernel weight. The duration of the vegetative period had a positive influence on the kernels per spike and a negative influence on the length of the grain-filling period. A lengthening of the grain-filling period induced an increase in kernels per spike but did not significantly modify the average kernel weight. The path diagram also indicated that variations in the kernels per spike do not significantly influence kernel weight.