在我国大白菜研究的论著中,对其发芽期临界特征的划分有着不同的看法。一种观点认为:种子播种后在适宜的条件下开始发芽,经过2—3天幼芽出土,展开一对子叶,之后出现一对初生叶,7—8天初生叶完全展开并达到和子叶相等的大小。这时,子叶和初生叶交叉排列成十字形,这种长相称为“拉十字”,是发芽期结束的特征。其根据是:这一时期是种子中的胚长成幼芽的过 In our research on Chinese cabbage, there are different opinions on the division of critical characteristics of germination period. One view is that seeds begin to germinate under suitable conditions after sowing, and after 2-3 days of sprouting, a pair of cotyledons are unfolded, followed by a pair of primary leaves, with primary leaves 7 to 8 days fully unfolded and equal to cotyledons the size of. At this time, cotyledons and primary leaves cross arranged in a cross, this looks called “pulling the cross” is the end of the germination characteristics. The basis is: this period is the seed embryo grow into buds too