Impacts of Carbon Dioxide Enrichment on Landrace and Released Ethiopian Barley ( L.) Cultivars.

Barley ( L.) is an important food security crop due to its high-stress tolerance. This study explored the effects of CO enrichment (eCO) on the growth, yield, and water-use efficiency of Ethiopian barley cultivars (15 landraces, 15 released). Cultivars were grown under two levels of CO concentration (400 and 550 ppm) in climate chambers, and each level was replicated three times. A significant positive effect of eCO enrichment was observed on plant height by 9.5 and 6.7%, vegetative biomass by 7.6 and 9.4%, and grain yield by 34.1 and 40.6% in landraces and released cultivars, respectively. The observed increment of grain yield mainly resulted from the significant positive effect of eCO on grain number per plant. The water-use efficiency of vegetative biomass and grain yield significantly increased by 7.9 and 33.3% in landraces, with 9.5 and 42.9% improvement in released cultivars, respectively. Pearson's correlation analysis revealed positive relationships between grain yield and grain number ( = 0.95), harvest index ( = 0.86), and ear biomass ( = 0.85). The response of barley to eCO was cultivar dependent, i.e., the highest grain yield response to eCO was observed for (122.3%) and (140.2%). However, , , and showed reduced grain yield by 16, 25, and 42%, respectively, in response to eCO enrichment. While the released cultivars benefited more from higher levels of CO in relative terms, some landraces displayed better actual values. Under future climate conditions, i.e., future CO concentrations, grain yield production could benefit from the promotion of landrace and released cultivars with higher grain numbers and higher levels of water-use efficiency of the grain. The superior cultivars that were identified in the present study represent valuable genetic resources for future barley breeding.