Genotypic variability for carbon isotope discrimination in the mutant and improved lines of barley

Drought tolerance is an important breeding objective in dry and semi-dry conditions. Carbon isotope discrimination (Delta) is a tool that may be used to improve water-use efficiency (WUE) as an indirect selection criterion. The study investigated the variability for Delta in improved F7 lines and their parents (three cultivars and two mutant lines), which were sampled randomly from an F6 nursery performing well under semi-dry conditions. In total, 40 entries were grown in sand culture, arranged in three-replicated randomized complete block designs in two sets of experiments in Antalya, Turkey. There were statistically significant differences (p<0.01) among genotypes in both sets of experiments for Delta, and Delta values range from 20.14 to 21.86. Low coefficient of variation (C.V.) values, i.e. 2 and 1.65 %, for both data sets revealed efficient control of experimental error for Delta and indicated little effect of environment. Consequently, broad-sense heritability estimates for Delta were 0.63 and 0.74. As Delta showed a considerably high heritability and consistency over the two sets of experiments and low C.V. values, it was concluded that this trait could be used in breeding programmes aimed at developing drought tolerance lines. The early heading mutant, M-K-88, and the cultivar selected from land race, Tokak 157-37, showed lowest Delta values, indicating that they had the best water-use efficiency. Low Delta values of these two genotypes were inheritable.