Drought hardening was conducted on cassava before water stress. The contents of endogenous phytohormones(ABA, IAA, GA, ZR)and soluble sugars (glucose, fructose, sucrose)were measured during the period of water stress. Cassava hormone regulation and osmoregulation were clarified by the content changes. The results showed when drought hardening cassava was under drought stress again, the endogenous ABA was accumulated in a short time and the accumulation and its rate in drought hardening cassava root were higher than the control (no drought hardening) ; the trends of endogenous IAA, GA and ZR in cassava root were changed opposite to the control in six days, and the volatility was increased; these indicated that cassava drought hardening exchanged the response speed and enhanced the response of endogenous phytohormone under drought stress. The trend of phytohormone in SC8(weak drought resistance)was different from other cassava varieties, which further showed the importance of the phytohormone regulation to the drought adaption. The content of glucose, fructose and sucrose in drought hardening cassava root was higher than the control at different period of water stress (expect a few time points). The results indicated that drought hardening increased the accumulation of soluble sugar and improved the resistance of cassava to drought. The study provided a theoretical basis for the further research and artificially increasing cassava drought resistance.%干旱胁迫前,对木薯进行前期干旱锻炼,胁迫期间测定干旱锻炼和未干旱锻炼木薯根系中内源激素(ABA、IAA、GA、ZR)及可溶性糖(葡萄糖、果糖、蔗糖)含量,根据其含量变化阐明前期干旱锻炼对木薯激素调节和渗透调节的影响.实验结果表明,经前期干旱锻炼的木薯再次受水分胁迫时,抗旱品种SC 124和KU50根系中内源ABA在短时期内大量积累,其积累速率与积累量均高于对照(未干旱锻炼)；而体内与植物生长发育相关激素IAA、GA和ZR的变化与对照相比在短时间内含量急剧下降,下降幅度增大.内源激素的变化结果说明前期的干旱锻炼改变了木薯再次受胁迫时内源激素的响应速度,提升了其响应程度,使植物在生理、生化等各方面发生相应变化,以提高自身的抗旱力,从而减轻干旱造成的伤害.不抗旱品种SC8的根系激素变化趋势不同于其他品种,变化幅度也明显小于抗旱品种,进一步说明了激素调节对木薯适应干旱的重要性.干旱锻炼的木薯根系中葡萄糖、果糖、蔗糖含量在不同的干旱胁迫时期(除少数几个时间点外)均高于未干旱锻炼情况,前期干旱锻炼增加了可溶性糖的积累,提高了植株的抗旱性能.本研究为深入研究木薯的抗逆性和人为提高木薯抗旱性能提供理论基础.
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