六、分蘖的成穂在适宜的环境条件下,一株麦苗能在较短时间里发生大量分蘖。随着植株生长,体内营养状况和各种生理活动不断变化,环境条件也不断地发生变化,使分蘖向有致和无效两极分化。所以,分蘖能否成穗,一株小麦的分蘖成穗多少,决定于内在原因和外在条件的影响。 1.分蘖成穂与出现时间的关系分蘖的两极分化首先从最早和最晚出现的一些分蘖之间开始,逐渐向中间蘖序扩展。所以,在出现时间上存在着一个分蘖有效和无效的分界期或分蘖成穗的临界期。从春播小麦南大2419的试验结果看(图1),4月18日以前出现的分蘖全部为有效分蘖,4月23日以后出现的分蘖全部为无效分蘖。4月18日到23日五 Six, tiller Cheng Cheng Under suitable environmental conditions, a wheat seedling can occur in a relatively short period of time a large number of tillers. With plant growth, nutritional status and various physiological activities in the body constantly changing, environmental conditions are constantly changing, tillering induced and ineffective polarization. Therefore, tillering can become a spike, a wheat tiller number of ears, depending on the internal causes and external conditions. The relationship between tillering and emergence time tillering Polarization first tilted between the earliest and some of the beginning of tillers, and gradually extended to the middle of the tiller. Therefore, in the appearance of time there is an effective and ineffective demarcation of tillering or panicle tillering critical period. According to the experimental results of spring wheat Nanda 2419 (Fig. 1), all the tillers that appeared before April 18 were all effective tillers, and the tillers that appeared after April 23 were all ineffective tillers. April 18 to May 23