Resumo
In this study, nickel tolerance (NiSO4.7H2O) of some Turkish national barley (Hordeum vulgare L.) genotypes (Bülbül-89, Kalayci-97, Karatay-94, Larende, Tarm-92, Tokak-157/37, Yesevi-93 and Zeynel Aga) was investigated. Barley genotypes were exposed to different nickel concentrations [0 mM (control), 250, 500, 1000, 1500, and 2000 ppm]. Nickel toxicity significantly inhibited root and coleoptile growth in all barley genotypes in a concentration-dependent manner. However, root growth was much more inhibited by nickel applications in comparison with coleoptile growth, probably due to a higher level of sensitivity of root meristems against nickel toxicity or direct contact of roots with nickel ions in the growth medium. Root growth in the genotype Karatay-94 and coleoptile growth in the genotype Yesevi-93 was more remarkably reduced by nickel toxicity. Root and coleoptile growth in the genotypes Larende and Kalayci-97 were less affected under nickel toxicity, respectively. In addition, nickel toxicity disturbed water relations in barley genotypes dependent on the organ type, as demonstrated by more severe inhibition in root fresh weight as compared to coleoptile fresh weight. These results could show that nickel toxicity reduced water uptake from growth medium in barley genotypes used in this study. Changes in dry weight of roots and coleoptiles indicated that nickel toxicity more severely decreased biomass accumulation in roots of barley genotypes. The calculated tolerance indices demonstrated that the genotype Kalayci-97 is the most tolerant to nickel toxicity, while the genotype Karatay-94 is the most susceptible one.(AU)