| The effects of seed film coating by cold-resistant (No.6 and No.7 ) and natural matter coating agent (No.8 and No.9) on germination, seedling quality and physiological and biochemical changes in supersweet corn, cv. Tetian No. 1 and Zengtian No.2 (with sh2 gene), were investigated under low temperature stress condition (at 5~6"C). The effects of the seed film coating on seedling emergence and establishment, plant development, yield and vigor of harvested seeds were also studied in field experiment with two sowing stages. Main results obtained are as follows:After germinating seeds met low temperature stress, the percentage germination, germination index, vigor index, vigorous seedling percentage, seedling radical number and volume, fresh and dry weight of total seedling and dry weight ratio of root to shoot in Tetian No.l treated by both cold-resistant coating agents were significantly higher than that in the uncoated controls. Between cold-resistant coating agents No.6 and No.7, coating agent No.7 was better than No.6 in percentage germination, vigor index, vigorous seedling percentage, radical number, coating agent No.6 was better than No.7 in fresh and dry weight of seedling. The decline of root volume and seedling dry weight in treatment of coating agent No.6 was observed, the increase of abnormal seedling, vigor index and seedling dry weight and the decling of germination index in treatment coating agent No.7 was also observed in Zengtian No.2. Two cold-resistant coating agents elevated shoot height and decreased seedling radical length in two varieties.After seedling met low temperature stress, two varieties treated by two cold-resistant coating agents maintained a lower level in the relative permeability of plasmmembrane before and after the stress and recovering growth for three days as compared with the control. The proline content increasing in Tetian No. 1 was less than that in Zengtian No.2 after treated in two cold-resistant coating agents in low temperature stress. Both cold-resistant coating agent keeped radical vigor in a higher level and protected chlorophyll in two varieties The activities ofcatalase (CAT) and peroxidase (POD) in seedling treated by two cold-resistant coating agents were higher than that in the control after low temperature stress, however, malondialdehyde (MDA) content was lower than that in control at all time.In the first sowing stage, both cold-resistant coating agent decreased seedling emergence percentage in Zengtian No.2. The seedling emergence index and stand establishment was declined in Zengtian No.2, the seedling emergence was increased in Tetian No.l after treated by coating agent No.7. In the second sowing stage, seedling emergence, seedling emergence index and stand establishment were improved by both cold-resistant coating agent in two varieties. In the two sowing stages, two cold-resistant coating agents accelerated seedling growing, improved seedling quality and controlled pest damage effectively. In the first sowing stage, the theoretical yields of Tetian No.l coated with coating agent No.6 was significantly enhanced. In the second sowing stage, real yields of Tetian No.l was increased by two cold-resistant coating agents, theoretical and real yields were significantly enhanced by coating agent No.7.After germinating seeds met low temperature stress, germination was declined and abnormal seedling percentage, fresh and dry weight of seedling and dry weight ratio of shoot to root were increased in Tetian No.l treated by coating agent No.8. After treated by coating agent No.9, germination, vigorous seedling, root number, root volume, fresh and dry seedling weight and dry weight ratio of shoot to root were increased in Tetian No. 1, the increase of root volume was observed in Zengtian No.2. After seedling met low temperature stress, two natural matter coating agents were similar to two cold-resistant coating agents in physiological and biochemical changes.In the first sowing stage, coating agent No.8 significantly decreased stand establishment pe...
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