AbstractSeeds of Pacen˜ o and Cuarenten˜ o cultivars of cowpea (Vigna unguiculata L. Walp.) were tested for salt and droughttolerance at germination, seedling emergence and early seedling growth in NaCl and PEG-8000 solutions ofdifferent osmotic potentials (0, )0.2, )0.4, )0.6, and)0.8 MPa). Daily and final germination and emergencepercentage, as well as germination and seedling emergence rate, and seedling growth were recorded under controlledconditions. Results showed that germination and emergence rate were delayed by both solutions in both cultivars, withdifferences between cultivars among growth stages, given that cultivar Cuarenten˜ o, showed a higher germination rate than Pacen˜ o in NaCl, but Pacen˜ o was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on both cultivars in terms of germination rate, emergence rate and the final germination and emergence percentage than did PEG-8000. This conclusively proves that the adverse effect of PEG-8000 on germination,emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth wasreduced by both stresses, but NaCl usually caused less damage than PEG to cowpea seedlings, suggesting thatNaCl and PEG acted through different mechanisms.
AbstractSeeds of Pacen˜ o and Cuarenten˜ o cultivars of cowpea (Vigna unguiculata L. Walp.) were tested for salt and droughttolerance at germination, seedling emergence and early seedling growth in NaCl and PEG-8000 solutions ofdifferent osmotic potentials (0, )0.2, )0.4, )0.6, and)0.8 MPa). Daily and final germination and emergencepercentage, as well as germination and seedling emergence rate, and seedling growth were recorded under controlledconditions. Results showed that germination and emergence rate were delayed by both solutions in both cultivars, withdifferences between cultivars among growth stages, given that cultivar Cuarenten˜ o, showed a higher germination rate than Pacen˜ o in NaCl, but Pacen˜ o was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on both cultivars in terms of germination rate, emergence rate and the final germination and emergence percentage than did PEG-8000. This conclusively proves that the adverse effect of PEG-8000 on germination,emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth wasreduced by both stresses, but NaCl usually caused less damage than PEG to cowpea seedlings, suggesting thatNaCl and PEG acted through different mechanisms.