【目的】为华南石灰岩地区植被恢复的树种选择及人工造林提供理论依据.【方法】应用温室盆栽生长法，通过不同浇水频度控制干旱条件，并用常规方法测定各项指标.【结果和结论】在干旱胁迫条件下，圆叶乌桕 Triadica rotundifolia 和毛果巴豆 Croton lachnocarpus 的苗高净生长量分别比对照减少2%~5%和8%~10%，基径净生长量增加17%~35%和10%~30%；随着干旱胁迫的加剧，2种植物幼苗的地上部和地下部生物量、根冠比均呈现下降趋势.生理检测结果表明，圆叶乌桕苗木的可溶性蛋白含量、过氧化物酶（POD）活性、超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量均低于毛果巴豆；2种植物苗木的可溶性蛋白含量和POD活性对干旱胁迫的响应比较敏感，但SOD活性和MDA含量对干旱胁迫的响应变化不明显.茎部解剖结构比较结果表明，2种植物在茎部皮层、韧皮部、木质部和髓部比例存在较大的差异，干旱胁迫会导致其木质部与髓部厚度比值增加，反映了2个树种可通过增加木质部与髓部结构来适应干旱胁迫.模糊隶属函数值分析结果表明，无论是轻度干旱，还是中度和重度干旱，圆叶乌桕的耐旱能力均强于毛果巴豆，其生理指标和茎部结构对干旱胁迫响应的不同反映了其耐干旱胁迫机制存在差异.
【Objective】Seedling growth， morphology and physiological characteristics of Triadica rotundifolia and Croton lachnocarpus were investigated under drought stress to provide scientific basis for species selection and artificial reforestation in the limestone region of South China. 【Method】Pot culture experiment was applied in this study to simulate drought stress by watering frequency.The physiological indicators were measured with comventional methods.【Result and conclusion】The results showed that height growth of T.rotundifolia and C. lachnocarpus declined by 2%-5% and 8%-10% respectivly， while basal diameter growth increased by 17%-35% and 10%-30% respectivly under drought stress. Seedling aboveground biomass， underground biomass， total biomass， and root shoot ratio could be enhanced by light drought stress， but they declined with the increase of drought stress. Results of physiological examination showed that the soluble protein content， peroxidase （POD） activity， activity of superoxide dismutase （SOD）， and malondialdehyde （MDA） content varied with species and drought stress. Soluble protein content and POD activity were more sensitive than the activity of SOD and MDA content. Comparison of the stem anatomical structure showed that there were differences in the structure of cortex， phloem， xylem and marrow. Drought would result in increasing ratio of xylem and marrow， which indicated that they could adapt to drought stress by adjusting xylem and marrow structure. Analyses of subordinate functions showed that the drought tolerance of T.rotundifolia were higher than that of C. lachnocarpus under various drought stresses. They may possess different resistance mechanisms to drought stress based on their difference in physiological responses and stem anatomical structures.