Abstract: In order to explore the production conditions of good quality cigars, and understand the physiological and biochemical changing rules of cigars harvested at different time, and determine the appropriate harvesting time and maturity degree of cigars, this paper studied the changing rules of key enzymes activity in carbon and nitrogen metabolism, and chemical composition of cigar leaves harvested at different times by field experiments. The results showed that the activity of nitrate reductase in the middle leaves decreased gradually along with the postpone of harvesting time, while the upper leaves increased first then decreased. The activity of amylase in the middle and upper leaves decreased first then increased with the postpone of harvesting time. The contents of total nitrogen, total sugar, reducing sugar and starch in the middle and upper leaves increased first then decreased with the postpone of harvesting time. The decrease in contents of total sugar, reducing sugar and starch in the upper leaves at 45～50 d after topping was not remarkable. The chemical contents in the middle leaves at 35～40 d after topping were significantly decreased. Therefore, it was suggested that the middle leaves of cigar should be harvested at 35 d after topping, and upper leaves should be harvested at 45～50 d after topping. These research findings provided theoretical basis for harvesting cigar timely in Wuzhishan, Hainan province.

Key words: cigar, harvesting time, carbon and nitrogen metabolism, chemical composition

摘要： 为探索优质雪茄的生产条件，了解不同采收时间雪茄烟的生理生化变化规律，进而确定雪茄烟适宜的采收时间和成熟度，采用大田试验的方法，研究雪茄烟叶片在不同采收时间的碳氮代谢关键酶活性及其化学成分的变化规律。结果发现，中部叶硝酸还原酶活性随采收时间推迟逐渐下降，上部叶先升高后降低；中部叶和上部叶淀粉酶活性随采收时间的推迟先降低后升高。中部叶和上部叶的总氮、总糖、还原糖和淀粉含量均随采收时间的推迟呈先升高后降低的趋势；上部叶的总糖、还原糖和淀粉含量虽然在打顶后45～50 d降低，但差异不显著；中部叶在打顶后35～40 d，这些化学成分均显著降低。因此，雪茄烟的中部叶宜在打顶后35 d采收，上部叶宜在打顶后45～50 d采收。这些结果为海南省五指山市雪茄适时采收提供理论依据。

关键词: 雪茄, 采收时间, 碳氮代谢, 化学成分