Effects of Seed-coating Tebuconazole and Difenoconazole on Emergence ofMaize Seeds and Response of Seedlings at Chilling Stress

In order to study the effects of seed treatment on the emergence of maize seeds and the growth of maize seedlings at chilling stress,active ingredient coated maize seeds at different dosage were chilling stressed,using optimum temperature (25℃/20℃,day/night) as control.At 25℃/20℃,the seed treatment of tebuconazole and difenoconazole could improve the emergence of maize seeds,increase the contents of chlorophyll in the seedlings.and have no negative effect on seedling height and fresh weight.But at chilling temperature 17℃/6℃,15℃/0℃,10℃/0℃,the seed treatment of tebuconazole and difenoconazole could inhibit the emergence of maize seeds and the development of seedlings.Deterioration of peroxidation to membrain lipids and degradation of chloroplasts induced by chilling stress were observed in seedlings that seed-coated by tebuconazole and difenoconazole.The results showed that treatment of difenoconazole was relatively safer than tebuconazole to maize seeds because difenoconazole could inhibit the leakage of electrolytes from leaves,but tebuconazole worsened the leakage of electrolytes.Moreover,difenoconazole could enhance the respiration of roots which benefit the recovery of chilling stressed seedlings,but tebuconazole inhibited the respiration instead.