中文摘要：

以3个不同熟性的菜心品种为试验材料,研究了菜心的糖分代谢规律。结果表明,不同熟性的菜心品种可溶性糖、蔗糖、果糖和还原糖含量在花芽分化期至花芽分化中期的变化幅度不大,但在花芽分化中期至现蕾期快速升高,在现蕾期至采收期缓慢上升或下降。花芽分化后,叶片各种糖含量均低于薹茎。叶片和薹茎的糖含量均以晚熟品种最高,而早、中熟品种叶片糖含量差异不显著,但中熟品种薹茎糖分含量比早熟品种高。叶片的NI、AI活性以及薹茎的SS、SPS活性与可溶性糖、蔗糖、果糖和还原糖含量均呈显著的正相关,但叶片的SS、SPS活性以及薹茎的NI和AI活性与可溶性糖、蔗糖、果糖和还原糖含量的相关性不显著。这说明在花芽分化中期至现蕾期的糖分积累最快,花芽分化后叶片的糖分逐渐向薹茎转移,为菜薹的膨大提供了充足的能量基础,从而促进菜薹的膨大生长。菜心在生长发育过程中叶片糖分不断降解,而薹茎的糖分则不断合成与积累,叶片糖分与NI、AI活性以及薹茎糖分与SS、SPS活性的关系密切,提高薹茎的SS和SPS活性可促进薹茎糖分的形成,提高糖分的积累,改善菜薹的品质与风味。

英文摘要：

The sugar metabolism regular were studied in flowering Chinese cabbage with different maturitycultivars（Early maturity cultivar,Mid maturity cultivar,Late maturity cultivar）. The results indicated that the contents of soluble sugar,sucrose,fructose and reducing sugar had little change in three type of cultivars from early to middle stage of flower bud differentiation,butincreased rapidly from middle stage of flower bud differentiation to budding stage,and gone steadily up or down from budding to harvest stage. After flower bud differentiation,all kinds of sugar contents in the leaves were lower than those in the stems. The contents of sugars both in leaves and stems in the latematuritycultivar were the highest among three type of cultivars,and had no significant difference in the leaves between early and mid maturity cultivar,but the sugar contents in the stems of the mid maturity cultivar were higher than those in early maturity cultivar. There were significant positively correlations between neutral invertase（NI）and acid invertase（AI）activities in the leaves as well as sucrose synthase（SS）andsucrose phosphate synthase（SPS）activities in the stems andthe contents of soluble sugar,sucrose,fructose and reducing sugar;while there were not significant correlations between SS and SPS activities in leavesas well as NI and AI activities in the stems and the contents of soluble sugar,sucrose,fructose and reducing sugar. This illustrated that sugar accumulation was the fastest from middle stage of flower bud differentiation to budding stage. After flower bud differentiation,the sugars gradually transported from leaves to stems for providing enough energy for flower stalk growing. During the whole growing stage,sugars in the leaves continuously degraded,but those in the stems continuously synthesized and accumulated. The sugar contents and activities of NI and AIin leaves as well as sugar contents and activities of SS and SPS in stem had close relationships. Therefore,higher activities of SS and SPS in