中文摘要：

以盆栽4年生的苹果砧木湖北海棠（Malus hupehensis）为试材，叶面喷施100mmol·L^-1的甜菜碱，研究外源甜菜碱对干旱胁迫下湖北海棠叶片超微弱发光（UWL）、丙二醛（MDA）、超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢（H2O2）、脯氨酸（Pro）及甜菜碱（GB）含量的影响．结果表明，轻度干旱胁迫下，叶片UWL强度提高，但随着干旱胁迫程度的加重而下降，至严重干旱胁迫时UWL明显低于正常供水处理；H2O2、MDA含量随干旱胁迫加重而升高；SOD和POD活性随胁迫加重而升高，但至重度干旱时下降．与单独干旱处理相比，叶片喷施甜菜碱显著提高了轻度和中度干旱胁迫叶片的UWL（分别提高35．27％和43．95％）、SOD和POD活性，降低了H2O2和MDA含量；促进了Pro和GB的积累．表明甜菜碱及通过甜菜碱诱导的脯氨酸积累，能够提高干旱胁迫下叶片的抗氧化能力，减轻过氧化损伤，对叶片细胞起到保护作用．

英文摘要：

In a pot experiment with 4-year-old apple root stock （Malus hupehensis） , this paper studied the effects of foliarspraying exogenous glycinebetaine （GB） on the leaf ultraweak luminescence （UWL） , contents of malondialdehyde （ MDA）, hydrogen peroxide （ H2O2 ） , endogenous GB and proline （Pro） , and activities of superoxide dismutase （SOD） and peroxidase （POD） under drought stress. The results showed that UWL intensity increased under slight- and mid drought stress, but decreased with increasing drought stress till lower than the control. Under slight- and mid drought stress, foliar-spraying GB improved the UW＇L intensity by 35.27% and 43.95% , respectively, decreased H2O2 and MDA contents, increased SOD and POD activities, and promoted the accumulation of GB and Pro. The exogenous GB and its induced Pro accumulation could increase the anti-oxidative capability of M. hupehensis leaves, and protect the leaf cells from oxidative damage under drought stress.