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1993~1994年冬小麦管栽水分试验结果表明,初生根与次生根生长量、数量及分枝能力基本与土体水量呈正相关,胁迫程度愈深,受抑程度愈大.初生根特别是一、二次根及其分枝数具有很强抗逆能力,水量愈大,三、四次根数愈多.次生根尤其是其数量对土水环境极为敏感,当土壤含水量低于田间持水量(以下简称“田持”)60％时,受到严重抑制.胁迫后复水,使初生根三次根数量增加,根系活性延长,对次生根的激励作用更大.前期胁迫愈严重,促进效果愈明显.初生根细长,一直发挥着重要功能,冬前根系功能主要由它完成.次生根粗短,数量大,需消耗较多物质和能量,通过促根实现增产应慎重.起身到抽穗阶段,特别是孕穗期水分对根系调控效果最佳期,田持60％可视为调控下限.“,”Study result indicated that the growth,number and branching of the primary and secondary roots were positively correlated with the moisture content in the earth body .The greater the stress is,the greater the inhibition will be.The primary roots ,especially the first and second lateral roots were found strong in stress resistance.The greater the moisture content is,the more the number of the third and fourth lateral roots will be.The secondary root was found extremely senstitive to soil and water conditions...