华北地区常年到三月下旬或四月初,小麦叶片就由匍匐状态转向直立,麦苗进入起身期。此时植株体内进行小穗分化,就是农民所说的长“码子”,这个时期约经历半个月,当主茎第一节长出地面1—2厘米时,为小麦拔节期,拔节期的开始标志着在每个小穗上进行小花分化。因此,起身拔节期小麦的主要生育特性是在根茎叶营养体繁茂生长的同时,又进行着以小穗和小花分化为中心的生殖生长,并且从起身期以后,主茎和大分蘖逐渐长成穗,小分蘖慢慢死亡,即分蘖向“两极分化”。所以起身拔节期是争取壮秆、大穗,提高分蘖成穗率的重要时期,这一时期的气象条件和管理措施的好坏关系到每 Perennial North China until the end of March or early April, the wheat leaves turned from prostrate state upright, wheat seedlings into the period of onset. At this time plant spikelet differentiation is the farmer said long “code”, this period of about two weeks, when the first stem grow 1-2 cm above the ground, the wheat jointing stage, the beginning of jointing Marked floret differentiation on each spikelet. Therefore, the main growth characteristics of wheat that rose from jointing stage were reproductive growth centered on spikelet and floret at the same time that vegetative growth of rhizomes and leaves were flourishing, and main stem and tillering grew gradually Spike, small tillers slow death, tillering to “polarization.” So get up and jointing period is to fight for strong stalks, big spike, increase the rate of tillering into an important period, the meteorological conditions and management measures of this period is related to the quality of every