中文摘要：

为进一步清晰酸雨抑制植物生长的内在机制,采用水培法研究酸雨（pH 5.0—2.5）对水稻根系激素含量（生长素IAA、赤霉素GA、玉米素ZT、脱落酸ABA）、根系活力与质膜H＋-ATPase活性及根系生长的影响.结果表明,与对照（CK）相比,经酸雨胁迫5 d后,pH 5.0组水稻幼苗根长及鲜重下降,但激素含量IAA和ABA、根系活力、H＋-ATPase活性、根表面积和体积均显著上升,表明pH 5.0酸雨下水稻幼苗通过提高IAA、ABA含量,根系活力以及激活H＋-ATPase活性调控水稻对营养的吸收,使根长及鲜重较其他酸雨处理组受抑较弱.pH 4.5、pH 3.5和pH 2.5酸雨组水稻幼苗IAA/ABA、GA/ABA、ZT/ABA、根系活力以及根系生长指标显著下降,表明pH 4.5、pH 3.5和pH 2.5酸雨降低激素含量影响根系细胞分裂和伸长,抑制根系活力导致水稻根系各生长指标受抑.将胁迫后幼苗移至对照条件下恢复5 d后,pH 5.0酸雨组根系活力和生长指标均恢复至CK,IAA/ABA、GA/ABA和ZT/ABA和质膜H＋-ATPase活性有所上升;而pH 4.5—2.5酸雨组各指标变幅减小且优于胁迫期,表明水稻幼苗通过提高生长促进型激素（IAA、GA、ZT）含量、根系活力以及质膜H＋-ATPase活性减轻酸雨对根系生长的制约,根系生长指标均有一定程度的恢复,且恢复程度受酸雨强度制约.

英文摘要：

To clarify further the internal mechanism on damage caused by acid rain to plants,we studied effects of acid rain（ pH 5.0—pH 2.5） on hormone concentrations（ auxin IAA,gibberellin GA,zeatin ZT and abscisic acid ABA）,root activity,plasma membrane H＋-ATPase activity and growth in rice roots by hydroponic culture. Results show that root length and fresh weight in rice seedlings treated with acid rain at pH 5. 0 were lower than those of the control, whereas concentrations of IAA and ABA,root activity,H＋-ATPase activity,root surface area and volume were higher. They indicate that the decrease of root length and fresh weight treated with acid rain at pH 5.0 was less than those at pH 4.5,3.5 or 2.5 by increasing concentrations of IAA and ABA,and then promoting root activity and H＋-ATPase activity to regulate nutrients absorption. The IAA / ABA,GA / ABA,ZT / ABA,root activity,and root growth parameters treated with acid rain（ pH 4.5,3.5or 2.5） were all lower than those of the control. It shows that the root growth was inhibited because acid rain decreased the hormone concentrations to reduce the division and elongation of root cells and inhibited the root activity. After acid rain treated-seedlings being moved to the control condition for 5days,the root activity and root growth parameters of rice seedlings treated with acid rain at pH 5.0were close to the control. Moreover,the IAA / ABA,GA / ABA,ZT / ABA and H＋-ATPase activity were higher than those measured during the exposure period. For groups treated with acid rain at pH4.5,3.5 or 2.5,all parameters were better than those measured during the exposure period. Results indicate that the inhibition on root growth was alleviated during the recovery period by increasing the growth-promoting hormone（ IAA,GA,ZT） concentrations,root activity and H＋-ATPase activity.And the recovery degree of root growth depended on the intensity of acid rain.