Untersuchungen der Reaktionen verschiedener Gerstegenotypen auf zukünftige CO2-Konzentrationen als Grundlage zur züchterischen Optimierung des "CO2-Düngeeffektes"

Atmospheric CO2 concentration has risen all over the globe from pre-industrial times until today and is predicted to increase even more rapidly in future. Higher CO2 concentration stimulates photosynthesis and can increase biomass and yield in C3 crops (CO2 fertilization effect). To get information about the genetic variability in winter barley (Hordeum vulgare L.) on CO2 responses, 100 of about 630 genotypes analysed with the Illumina 9k iSelect chip were grown in open-top chambers at different CO2 levels. Plants were phenotyped for growth parameters, yield (seed weight per plant) and yield components (seed number per ear, number of ears per plant, and the thousand-kernel weight) as well as for physiological (carbon isotope discrimination) and morphological (leaf structure) traits. The genotypes differed significantly for thousand-kernel weight and number of ears per plant within the groups. The two-rowed genotypes varied in their seed number per ear, but this was not found in the six-rowed genotypes. Elevated CO2 enhanced yield (+28%), number of seeds per ear (+12%), and number of ears per plant (+15%) in six-rowed genotypes. Elevated CO2 increased the thousand-kernel weight (+4 %) and number of seeds per ear (+11%) in two-rowed genotypes, but not the yield and the number of ears per plant. First association analyses were carried out by using the relative phenotypic data (elevated CO2 vs. ambient CO2) and markers have been identified that are most likely associated with particular yield traits.