Genetic variability in agronomic traits of a germplasm collection of hulless barley

Germplasm collections represent an important genetic source for crop improvements. In this study, 220 accessions of hulless barley were collected worldwide and their genetic diversity was investigated. Sixteen agronomic traits, including yield and yield components, grain morphology, leaf size, plant height, and lodging resistance, were assessed under field conditions. All studied traits exhibited large variation. Thousand seed weight determined yield, and was strongly affected by spike length and spike number. Four varieties, Gaoyuan Zao 1, Fu 8-4, Zang 0331, and Harry (WDM00618), showed high resistance to lodging. Significant correlations among the traits were observed, indicating trait interactions. Life cycle had the smallest coefficient of variation (CV) among native, foreign, and improved varieties, whereas the CV of cellulose content was more or less balanced. Among the accessions from domestic and foreign germplasm, the CV for life cycle remained the lowest, whereas those for carbon/nitrogen and spike number per plant were the highest. Interestingly, higher genetic diversity was observed in domestic than in foreign accessions. Together, our findings demonstrate that there is abundant diversity in worldwide hulless barley germplasm collections, which would be useful when introducing their desirable traits into cultivars of hulless barley to improve yield and other agronomic traits.