Drought-induced Accumulation of Soluble Sugars and Proline in Two Maize Varieties

Abstract: Drought stress is a major factor in reduce growth, development and production of plants. Stress was applied with polyethylene glycol (PEG) 6000 and water potentials were: zero (control),-0.15 (PEG 10%),-0.49 (PEG 20%),-1.03 (PEG 30%) and-1.76 (PEG40%) MPa. The solutes accumulation of two maize (Zea mays L.) cultivars-704 and 301- were determined after drought stress. In our experiments, a higher amount of soluble sugars and a lower amount of starch were found under stress. Soluble sugars concentration increased (from 1.18 to 1.90 times) in roots and shoots of both varieties when the studied varieties were subjected to drought stress, but starch content were significantly (p<0.05) decreased (from 16 to 84%) in both varieties. This suggests that sugars play an important role in Osmotic Adjustment (OA) in maize. The free proline level also increased (from 1.56 to 3.13 times) in response to drought stress and the increase in 704 var. was higher than 301 var. It seems to proline may play a role in minimizing the damage caused by dehydration. Increase of proline content in shoots was higher than roots, but increase of soluble sugar content and decrease of starch content in roots was higher than shoots. Key words: Drought stress • maize • polyethylene glycol 6000 • proline • soluble sugars • starch