1Yangzhou PolytechnicCollege，Yangzhou 225009，Jiangsu，China；2Yangzhou University，Yangzhou 225009，Jiangsu，China；3Jiangdu District Agricultural Technology Comprehensive Service Center of Yangzhou City，Yangzhou 225009，Jiangsu，China
Abstract：In order to defi nite the eff ect of low light on enzymatic activity related to sweet corn quality and yield，this paper took sweet corn variety‘ Jingtian No.9’ as test material and studied the eff ects of diff erent shading rate and shading duration on sugar accumulation of sweet corn grain，sucrose synthesis-related enzymes and yield of sweet corn．The results showed that the activities of sucrose synthetase and sucrose phosphate synthase in leaf blades at ear position after fl owering，accumulation of sucrose and soluble sugar at each stage after fl owering，and yield of fresh plant ear were decreased gradually，manifested as：shading rate 30% ＞ shading rate 50% ＞ shading rate 80%．During the growth and development process of sweet corn，the activities of sucrose synthetase and sucrose phosphate synthase in ear leaves after anthesis，the accumulation amount of sucrose and soluble sugar in each stage after anthesis，and the fresh ear yield，their overall performance was：whole growth period shading ＜ big mouth to spinning period shading ＜ spinning till after spinning 25 d shading ＜ jointing to big mouth stage shading ＜ emergence to jointing stage shading．Under the combined action of diff erent shading rate and diff erent shading period，80% shading treatment during the whole growth period had the greatest effect on corn grain sugar accumulation and yield．In conclusion，different shading rate and diff erent shading period all could signifi cantly limit the yield and quality improvement of super sweet corn．Moreover，shading from big mouth to spinning period was a critical stage．
