Effects of S_(3307) on the ability of rice seedlings to resist chilling stress

For a better understanding of the effects of S-3307 on the ability of rice seedlings to resist chilling stress,the extent of cold injury to rice seedlings and some cold tolerant physiology items were studied on two varieties(Dyou527 and Ⅱyou162) after soaking in different concentrations of S-3307.Cold injury to rice seedlings,electrolyte leakage,soluble sugar content,free proline content and MDA increased after S-3307 treatment,but SPAD,root vigor and respiratory rate decreased.The bigger effect of chilling stress was after seed had bourgeoned for 15 days,it lasted 4 days,then rebourgeoned at 20 days,lasted 6 days and after seeding bourgeoned 7 days,lasted 2 days.Soaking with S-3307 increased the cold tolerance of rice seedlings and 40 mg/L was the best concentration.The mechanism of cold tolerance was that compared with the CK,MDA increased while electrolyte leakage,relative chlorophyll content(SPAD value),root vigor and respiratory rate decreased.Soluble sugar content and free proline content both increased under chilling stress and enhanced the cold tolerance of rice seedlings.Ⅱyou162 had more cold tolerance than Dyou527.