RESUMO
Twenty-eight high yielding advanced lines of bread and durum wheat genotypes were screened for their callusing ability under NaCl stressed conditions in vitro. The screening was performed through culturing wheat root explants on callus-induction medium supplied with 2 mg/l 2,4-D and increasing levels of NaCl. The tolerant genotypes were then identified according to their ability to initiate and maintain callus growth on such medium. The wheat genotypes were also evaluated for their ability to initiate callus under unstressed conditions. Results showed that the bread wheat genotypes expressed better callusing ability than the durum ones, genotypes average% callusing was 58% and 22% for the bread and durum wheat, respectively. The callus of bread wheat genotypes also expressed better tolerance to salinity as reflected by their ability to induce callus on media supplied with increasing NaCl concentrations. Among the 14 bread wheat genotypes screened, genotypes ACSAD 921 and 949 were able to maintain 41 and 51% callus on such a high NaCl level, respectively and therefore, were considered highly tolerant. In particular ACSAD 921 showed good callusing ability under both stressed and unstressed conditions. On the other hand, the bread wheat genotypes Towpe and ACSAD 947 were identified as extremely sensitive to salt where no callus growth could be observed at high NaCl concentrations. The callus of the other bread wheat genotypes showed variation in their tolerance levels ranging from slightly sensitive to moderately tolerant. As for the durum wheat genotypes, genotype ACSAD 1031 had the highest relative salt tolerance being able to maintain 43% of its callus on medium supplied with 1.5% NaCl. Others showed moderate degree of tolerance such as genotypes ACSAD 1071, Cham1/brachua and Haurani, while Youssef-1 was slightly tolerant. All other examined durum genotypes were very sensitive and showed no callus growth at 1.5% NaCl