According to the space - tim e maturation during the development of the vessel elements in primary vascular system : the vessel elememts of the cotyledons and the lower portion of cnz formed firstly , then downward hypocotyl - root zone , at length , the vessel elememts of the upper and middle portion of cnz and epicotyl - shoot region connected with each other , the result uphold the seedling partition model that divides seedling into cnz , hypocotyl - root region and epicotyl - shoot region 根据金鱼草幼苗初生维管系统导管分子发育的时空性，即子叶和子叶节区下部导管分子先形成，然后向下形成下胚轴-根区的导管分子，最后子叶节区中、上部与上胚轴-苗区的导管分子再发生连接，据此支持将幼苗分为子叶节区、下胚轴-根区和上胚轴-苗区的幼苗分区模型。
Afield experiment was conducted in the oasis region of shiyang river basin , gansu province to research the effect of alternate partial root - zone drip irrigafion ( adi ) and conventional drip irrigafion ( cdi ) on soil water distribution , cotton growth , yield and water use efficiency ( wue ) 摘要为了探讨旱区农业节水新途径，在甘肃省石羊河流域下游荒漠绿洲区采用常规滴灌和分根区交替滴灌方式研究不同灌溉方式对大田棉花生长发育、产量、水分利用效率以及土壤水分分布的影响。
