Carbon isotope discrimination and productivity in field-grown barley genotypes

Five barley genotypes of different origins were used to examine the relatio nships between carbon isotope discrimination (Delta) and grain yield, yield components, dry aerial biomass and harvest index under rainfed and irrigat ed Mediterranean conditions. High positive correlations were found between Delta and grain yield and harvest index under both water conditions, sugges ting that Delta may represent efficiency of dry matter partitioning to the grain. This hypothesis was also supported by the positive correlation found between Delta and thousand-grain weight when all the data were considered. The two drought-tolerant genotypes LM2887 and Tadmor presented the smalles t difference between the two treatments for traits related to productivity as well as the highest Delta values. These results highlight the potential of Delta as a selection criterion in barley breeding in Mediterranean regio ns. They also encourage the study of the genetics of Delta and the identifi cation of molecular markers linked to its variation in available progenies derived from crosses between the genotypes used in the present paper.