Biophysical Response Of PEG Pretreatment On Rice Seeding Under Salt Stress Or Combined Stresses Of Salt And PEG

Liaoxing1and Yanjing48were used as experimental materials. Water content，chlorophyll (Chl) content, superoxide dismutase (SOD), peroxidase (POD),catalase(CAT), ascorbate peroxidase (APX), glutath reductase (GR), ascorbic acid (AsA),glutathione (GsH) were determined when rice seedling were grown for the7d,10%PEG was added to nutrient solution as pretreatment. After rewater3d or non-rewater3d,100mM NaCl stress was added to nutrient solution for3d, so did100mM NaCl+15%PEG. The test results are as the followings：1. The leaf and root water content of the two varieties are decreased under saltstress or combined stresses of salt and PEG. The leaf and root water content of the twovarieties under pretreatment is higher than that of non-pretreament.This indicates10%PEG pertreatment can decrease the water loss and then increase it salt tolearance.2. The Chlorophyll a, Chlorophyll b and Chlorophyll a+b content of leaf androot under pretreatment is higher than non-pretreament in Liaoxing1and Yanjing48exposed to salt stress or combined stresses of salt and PEG. This indicates PEGpretreatment can alleviate the reduction of photosynthetic rate.3. The activity of SOD,POD,CAT of leaf and root under pretreatment are higherthan that of non-pretreament in Liaoxing1and Yanjing48exposed to salt stress orcombined stresses of salt and PEG. Incresing activity on SOD,POD,CAT increasedresistance and partially protected the seedlings from salinity and other stresses duringthe following growth period.4. The content of GsH and AsA of leaf and root under pretreatment are higherthan that of non-pretreament in Liaoxing1and Yanjing48exposed to salt stress orcombined stresses of salt and PEG. Leaf APX activity of Liaoxing1under thepretreament is the same with that of non-pretreament, but the root APX activity ishigher than that of non-pretreament. The activity of GR of leaf and root underpretreatment in Liaoxing1and Yanjing48are higher than that of non-pretreament.The results indicated that10%pretreatment partially protectedof rice seedling duringthe following growth period.