为揭示不同种类灌木对干旱的根系适应策略，以中国北方常见的3种典型绿化灌木金叶女贞（Ligustrum × vicaryi Rehd.）、紫叶小檗（Berberis thunbergii ‘Atropurpurea’）和冬青卫矛（Euonymus japonicus Thunb.）的3年生大田苗为研究对象，对充分灌溉组（对照组，土壤平均含水量为最大田间持水量的85%）、自然雨养组（土壤平均含水量为最大田间持水量的70%）和重度干旱组（实验结束时土壤含水量为最大田间持水量的40%）金叶女贞、紫叶小檗和冬青卫矛各器官的干质量分配和根系分布进行比较。结果显示：除重度干旱组金叶女贞叶占比显著（P＜0.05）高于充分灌溉组、重度干旱组冬青卫矛叶占比显著高于自然雨养组外，不同处理组间的3种灌木各器官占比差异均不显著（P＞0.05）。不同处理组间的3种灌木深层根占比差异多不显著，仅重度干旱组紫叶小檗的深层根占比显著高于充分灌溉组和自然雨养组；并且，随干旱程度增加，金叶女贞深层根占比逐渐升高，冬青卫矛深层根占比逐渐下降。从总根系看，3种灌木不同功能根占比在不同处理组间的差异多不显著，仅重度干旱组金叶女贞运输根占比显著低于充分灌溉组，冬青卫矛运输根占比显著高于充分灌溉组；并且，与充分灌溉组相比，重度干旱组金叶女贞的支持根占比升高，而运输根和吸收根占比降低；紫叶小檗和冬青卫矛的功能根占比变化与金叶女贞恰好相反。值得注意的是，冬青卫矛深层根中运输根和吸收根占比均随干旱程度增加而逐渐升高。回归分析结果显示：随土壤含水量升高，金叶女贞支持根占比极显著（P＜0.01）降低，运输根和吸收根占比显著升高；冬青卫矛支持根占比显著升高，运输根和吸收根占比不显著降低；而紫叶小檗支持根、运输根和吸收根占比无显著变化。综合分析认为，3种灌木应对干旱的根系适应策略存在明显差异，其中，金叶女贞通过降低整个根系中运输根和吸收根占比并提高深层根占比的方式应对干旱，紫叶小檗通过提高深层根占比的方式应对干旱，而冬青卫矛则通过提高深层根中运输根和吸收根占比的方式应对干旱。比较而言，金叶女贞对干旱相对敏感，在移植初期需进行更多的灌溉管理；紫叶小檗和冬青卫矛对干旱的耐受性强，在城市绿化中可将二者组合种植，以高效利用水资源。

To reveal the root system adaptative strategy of different shrub species to drought, three-year-old field seedlings of three typical afforestation shrub species commonly seen in the north of China, namely Ligustrum × vicaryi Rehd., Berberis thunbergii ‘Atropurpurea’, and Euonymus japonicus Thunb.， were taken as research objects, the dry mass allocation of each organ and root system distribution of L. × vicaryi, B. thunbergii, and E. japonicus in fully irrigated group (the control group, the average soil water content is 85% of the maximum field capacity), naturally irrigated group (the average soil water content is 70% of the maximum field capacity), and severe drought group (the soil water content is 40% of the maximum field capacity at the end of the experiment) were compared. The results show that except proportion of leaf of L. × vicaryi in severe drought group is significantly (P＜0.05) higher than that in fully irrigated group and proportion of leaf of E. japonicus in severe drought group is significantly higher than that in naturally irrigated group, there is no significant (P＞0.05) difference in proportions of organs of the three shrub species between different treatment groups. Most of differences in proportion of deep root of the three shrub species are not significant between different treatment groups, only the proportion of deep root of B. thunbergii in severe drought group is significantly higher than that in fully irrigated group and naturally irrigated group; in addition, with the increase of drought degree, the proportion of deep root of L. × vicaryi gradually increases, while that of E. japonicus gradually decreases. In terms of the whole root system, most of differences in proportions of different functional roots of the three shrub species are not significant between different treatment groups, only the proportion of transport root of L. × vicaryi in severe drought group is significantly lower than that in fully irrigated group and the proportion of transport root of E. japonicus is significantly higher than that in fully irrigated group; in addition, compared with fully irrigated group, the proportion of supporting root of L. × vicaryi in severe drought group increases, while the proportions of transport root and absorptive root decrease; the variations of proportions of functional roots of B. thunbergii and E. japonicus are opposite to L. × vicaryi. Notably, the proportions of transport root and absorptive root in deep root of E. japonicus both gradually increase with the increase of drought degree. The regression analysis result shows that with the increase of soil water content, the proportion of supporting root of L. × vicaryi extremely significantly (P＜0.01) decreases, and the proportions of transport root and absorptive root significantly increase; the proportion of supporting root of E. japonicus significantly increases, but the proportions of transport root and absorptive root decrease insignificantly; while the proportion of supporting root, transport root, and absorptive root of B. thunbergii has no significant variation. The comprehensive analysis suggested that there are evident differences in root system adaptive strategy of the three shrub species responding to drought, in which, L. × vicaryi responds to drought via decreasing the proportions of transport root and absorptive root in the whole root system and increasing the proportion of deep root, B. thunbergii responds to drought via increasing the proportion of deep root, while E. japonicus responds to drought via increasing the proportions of transport root and absorptive root in deep root. In comparison, L. × vicaryi is relatively sensitive to drought, and more irrigation management is needed in early transplantation stage; B. thunbergii and E. japonicus have strong tolerance to drought, and they can be planted together in urban afforestation to increase water resource use efficiency.