The present investigation has been performed to evaluate Durum wheat (Triticum durum Desf.) tolerance to osmotic stress at the water potentials of -0.2, -0.4, -0.6 and -0.8 MPa induced by polyethylene glycol PEG-8000 (polyethylene glycol 8000) or NaCl solutions at an early stage of plant growth. Each, on germination, emergence and early seedling growth, were investigated for two Durum wheat (Triticum durum Desf.) varieties differing in drought tolerance (BD290273 and Omrabia). Daily and final germination and emergence percentage, as well as germination and seedling emergence rate, and seedling fresh and dry weight were measured in the study under controlled conditions. Results showed those germination and emergence rates were delayed by both solutions in both varieties, with differences between genotypes among growth stages, given that Omrabia variety showed a higher germination and emergence rate than BD290273 genotype in NaCl but BD290273 was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on varieties in terms of germination and emergence rates, the final germination and the emergence percentage than did PEG-8000. This conclusively proves that the adverse effect of PEG on germination, emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth was reduced by both stresses. But NaCl usually caused less damage than PEG to Durum wheat seedlings, suggesting that NaCl and PEG acted through different mechanisms. This difference in cultivar’s behaviour according to the growth conditions is discussed. It was concluded that inhibition in germination at equivalent water potentials of NaCl and PEG-8000 was mainly due to an osmotic effect rather than did salt toxicity.
Key words: Durum wheat, germination rate, emergence rate, seedling growth, salt and drought stresses.
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