ADAPTIVE RESPONSES OF PLANTS UNDER STRESS CONDITIONS

The effects of NaCl salinity and osmotic stress (administered as polye thylene glycol treatment) were investigated on the protein kinase acti vity and on the accumulation of cations and polyamines in maize and so rghum grown hydroponically. The influence of excess UV-B irradiation a s oxidative stress, on the glutathione antioxidant system was followed in young wheat plants. Concerning the response to osmotic stress of t he protein kinase activity in sorghum and maize, results suggest that substantial differences may exist between the two species in their sig nal reception/transduction mechanisms leading to divergent drought str ess tolerance. Potassium preference under NaCl stress as well as polya mine accumulation under both salt and osmotic stresses were regarded a s adaptive responses in sorghum which traits were less expressed in ma ize. Changes in glutathione levels and the glutathione reductase activ ity correlated with the adaptation of wheat plants to excess UV-B irra diation.