Abstract: Study of sunflowers (Helianthus annuus L.) exposed to salt stress of seawater was infrequently reported. In this study, effects of 20% and 40% seawater on the growth, ratio of root to shoot, contents of proline and MDA, activities of SOD and POD in the seedlings of two sunflower cultivars, a oil sunflower(G101B) and a edible one, were investigated. The results showed that the root growth rate and r/s ratio of two sunflower cultivars were significantly increased in 20% seawater. While membrane lipid peroxidation was not obvious in contrast to control seedlings. Proline content increased remarkably in two sunffower cultivars after a 4-day treatment with 40% seawater, and its change was significantly consistent with that of MDA. These results indicated the occurrence of oxidative stress under the treatwout. Based on the higher level of MDA, there was a more serious oxidative stress in the edible sunflower than in the oil sunflower after a 4-day treatment with 40% seawater, but the former had a greater ability of membrane reconstruction.

Key words: Sunflower, Seawater treatment, Growth, Proline, MDA, SOD, POD