Effect of Seawater on the Growth and Leaf Oxidative Metabolism of Sunflower Seedlings

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.