Genetic variability of spike and kernel traits in a collection of bread wheat landraces

Objective: Wheat landraces are a valuable source of allelic diversity for various traits that could be used to broaden the genetic basis of elite germplasms. Assessment of genetic variation of grain yield (GY) and correlated traits is essential for implications in wheat yield improvement. Methods: In the present study, 140 spring wheat landrace accessions, collected from various geographical regions of Iran, were evaluated for GY and spike-related characters at two successive cropping seasons. Results: Higher genetic variation was observed among the landraces for the studied traits as revealed by phenotypic (PCV) and genotypic (GCV) coefficient of variation. For all traits, PCV was higher than GCV indicating the influence of the growing season on the variation of the traits. Although the heritability estimate (h²) for GY was low (0.35), the yield-related traits showed higher h² ranging from 0.63 to 0.93. The distribution patterns of landraces, as revealed by cluster analysis and principal component analysis, did not align closely with their geographical distribution. However, accessions with similar phenotypic characteristics were grouped together. Conclusion: The population structure and genetic relationships of the Iranian bread wheat landraces presented here highlight their diverse genetic architecture. The results of this study provide valuable information for the utilization of landraces in the genetic improvement of bread wheat.