“冷冻贮苗”,是根据当归阶段发育的原理,为控制当归“早期抽苔”而进行的一项试验处理。反复实验证明,这一贮苗方式在控制当归早期抽苔方面,是一项行之有效的技术措施。一、“冷冻贮苗”为何不抽苔当归能抽苔,这是当归的遗传特性。这一特性,在一般情况下,是不以人们的意志为转移。但何时抽苔?这就不能由当归自己来作主,因为抽苔是有条件的。在“对当归‘早期抽苔’特性的分析和控制”一文中指出,当归为一“低温长日照”发育型,这就是说,在它的个体发育中,要由没抽苔到抽苔,至少经过两个发育阶段:一是春化阶段;一是光照阶段。前者要求0℃左右的低温,后者要求12小时以上的长日照,二者缺一不可。否则,它的抽苔便不可能。在自然条件下,当归要求的低温 “Frozen storage seedling”, is based on the principle of the development of Angelica stage, to control the Angelica “early bolting” and conducted a test treatment. Repeated experiments show that this seedling storage methods in the control of early bolting Angelica, is an effective technical measures. First, the “cold storage seedlings,” why not bolting Angelica can bolting, which is the genetic characteristics of Angelica. This feature, in general, is not based on the will of the people. But when to draw? This can not be made by angels themselves, because bolting is conditional. In his article “Analysis and Control of Early Bolting Characteristics of Angelica sinensis”, it is pointed out that Angelica sinensis is a “low temperature long sunlight” developmental type, which means that in its individual development, After at least two stages of development: one is the vernalization stage; one is the light stage. The former requires a low temperature of about 0 ℃, the latter requires more than 12 hours of long sunshine, both indispensable. Otherwise, it will not be suitable for bolting. Under natural conditions, Angelica claims a low temperature