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一般年份到2月中旬前后,大气温度回升到5℃以上,麦苗由暗变绿,新叶开始生长,即开始进入返青期。这个时期,是小麦出现第二个分蘖扎根盛期,主茎和年前分蘖迅速生长,新根和新生分蘖陆续形成。随着气温的升高,小麦开始向两极分化。这时主茎和年前生长的大分蘖,已经形成自己的根系,都有抽穗的可能;而新生的分蘖因时间短,又多是二级和三级分蘖,部位较高,不能很快地形成自己的根系,一般很少能发育成穗。这个时期既要适当发展群体,促进多成穗;又要控制分蘖过多,以免田间荫蔽、光照不足,造成倒伏。所以说,这个时期需要肥水较多,对外界条件
The general year before and after the middle of February, the atmospheric temperature rose to above 5 ℃, barley from dark to green, new leaves began to grow, that is, began to enter the greenback period. During this period, wheat emerged the second tillering root stage, the main stem and years ago, the rapid growth of tillers, new roots and newborn tillers gradually formed. As temperatures rise, the wheat begins to polarize. At this time the main stem and the growth of large tiller years ago, have formed their own roots, have the possibility of heading; and the newborn tiller due to a short time, but also mostly two and three tillers, the higher parts can not quickly The formation of their own roots, rarely grow into spikes. This period should not only appropriate development of groups, to promote more into a panicle; but also to control excessive tillering, so as not to shade the field, inadequate lighting, causing lodging. So, this period requires more fertilizer, the external conditions