Abstract: In order to study the effects of drought stress on root of Malus micromalus cv. ‘Ruby’, 1-year-old sapling of M. micromalus cv. ‘Ruby’ seedlings were selected as materials, 5 drought stress treatments including 85%±5% (CK), 70%±5% (T1), 55%±5% (T2), 40%±5% (T3), and 25%±5% (T4) were set up, the root morphology, activity and physiological characteristics of M. micromalus seedlings under different treatments were detected. The results showed that mild drought stress significantly increased root total length, surface area, total volume and root tips quantity of M. micromalus seedlings, and the continuous increase of drought stress intensity significantly reduced these morphological indexes. Root activity increased firstly and then decreased with the increase of stress degree, which of T4 decreased 15196% compared to CK. The contents of proline (Pro), soluble sugar (SS) and malondialdehyde (MDA) in roots increased with the increase of drought stress, those of T4 increased by 1.37, 1.68 and 2.82 times compared to CK, respectively. The content of soluble protein (SP) increased first and then decreased with the increase of drought stress degree. With the increase of drought stress, the activity of peroxidase (POD) in roots increased, however the activity of catalase (CAT) increased firstly and then decreased. Therefore, the appropriate water management measures should be formulated in the cultivation of M. micromalus. The relative soil water content should be maintained at the level of  more than 55%, otherwise, the development of root system and the growth of M. micromalus could be affected.

Key words: drought stress, root morphology, physiological characteristics, Malus micromalus cv. ‘Ruby’

摘要： 为探讨干旱胁迫对红宝石海棠根系的影响，以盆栽控水法，对1年生红宝石海棠幼树进行干旱胁迫，设置5个水分梯度，相对含水量分别为85%±5%（CK）、70%±5%（T1）、55%±5%（T2）、40%±5%（T3）和25%±5%（T4），分析干旱胁迫对根系的形态特征、活力和生理特性的影响。结果表明，轻度干旱胁迫显著提高红宝石海棠根系的总长度、表面积、总体积和根尖数，持续增加胁迫强度则显著降低这些形态指标值。根系活力随胁迫程度增加呈先上升后下降的趋势，重度胁迫处理（T4）较对照（CK）降低151.96%。根系中脯氨酸（prolin, Pro）、可溶性糖（soluble sugar, SS）和丙二醛（malondialdehyde, MDA）含量随干旱胁迫程度增强而升高，T4分别较CK提高1.37、1.68和2.82倍；可溶性蛋白（soluble protein, SP）含量随干旱胁迫强度增加呈先升高后降低趋势；随胁迫程度加剧根系中的过氧化物酶（peroxidase, POD）活性不断上升，过氧化氢酶（catalase, CAT）活性则呈先上升后下降的趋势。因此，在红宝石海棠栽培中应制定合理的水分管理措施，当土壤相对含水量低于55%时应及时浇水，否则将影响根系的发育，进而影响红宝石海棠生长。

关键词: 干旱胁迫, 根系形态, 生理特征, 红宝石海棠