Correlation, cluster, and path analysis of agronomic traits of the F₂ population from tetraploid hybrid crested wheatgrass

To lay a foundation for further gene mapping analysis of quantitative traits related to yield and the breeding of excellent new germplasm for tetraploid wheatgrass, 120 individual plants from the F₂ population of tetraploid crested wheatgrass and their parents (Agropyron mongolicum × A. cristatum ‘Fariway’) were used as materials. Eight agronomic traits, including plant height, leaf length, leaf width, panicle length, panicle width, stem diameter, stem-leaf ratio, and fresh weight per plant were analyzed. The results showed that all of these traits were quantitative traits controlled by multiple genes, with a normal distribution and transgressive segregation. Cluster analysis showed that the F₂ population was divided into three groups at a Euclidean distance of 17.5. The first and third groups showed superior quality and high yield, respectively. Correlation analysis and path analysis showed that plant height had a significant effect on fresh weigh per plant, with a correlation coefficient of 0.265 (P < 0.01) and a direct path coefficient of 0.174. This was followed by spike length (r = 0.214, P < 0.05), stem-leaf ratio (r = 0.197, P > 0.05), and stem diameter (r = 0.109, P > 0.05). The results provided the basis for breeding new varieties of tetraploid hybrid crested wheatgrass with high quality and high yield.