EFFECT OF SOAKING RICE (Oryza sativa, L.) SEED IN SOME ANITIOXIDANTS SOLUTIONS ON GERMINATION AND SEEDLING VIGOR UNDER DIFFERENT SALINITY LEVELS

Laboratory experiment was conducted at the laboratory of Seed Technology Research Section, Mansoura during 2009 and 2010 years to study the effect of soaking rice seed cv. Sakha 103 in five antioxidant solutions i.e. ascorbic acid, α-tochopherol, salicylic acid, citric acid and humic acid in addition to (control) distilled water on germination percentage, seed and seedling vigor as well as seedlings chemical traits under four salinity levels i. e. tap water (250ppm.), 2000ppm. 4000ppm and 6000ppm. The results revealed that: Increasing salinity levels not only reduced seed germination but also decreased seed vigor traits which measured by (speed germination index, germination energy, germination rate, mean germination time and time to get 50% germination).  Emerged seedlings at the highest salinity levels especially at 6000ppm were most weakness comparing with 250ppm (tap water), seedlings proline content increased up to salinity level 4000ppm and decreased at 6000ppm, meanwhile ascorbate content, peroxidase enzyme and chlorophyll A and B markedly decreased at high salinity levels. Soaking seed in ascorbic or salicylic acid solution improved seed germination, seed vigor and seedlings vigor comparing with soaking in distilled water and promote proline production and increased both of ascorbate content and peroxidase enzyme. Soaking seed in ascorbic or salicylic acid improved seed germination, seed and seedlings vigor under salinity levels comparing with the other antioxidants and distilled water. Also increased proline content within  each salinity level under study, except in salinity level (6000 ppm) with all antioxidant solution. In general under salinity conditions, soaking rice seed cv. Sakha 103 in ascorbic acid (100 ppm) or salicylic acid (100 ppm) improved seed germination and seedlings vigor and mitigation the harmful effect of salinity.