Li-6400 portable photosynthesis system was used to study the water physiological characteristics and drought resistance of Dianthus plumarius under water stress. Results showed that the diurnal variation of transpiration rate of leaves could be described by a unimodal curve, and the peak value occurred between 11:00 and 12:00, and the leaves had different peak values during various seasons. The diurnal variation of water use efficiency showed a bimodal curve in summer and fall, but a unimodal curve in spring. The water use efficiency in spring and fall was higher than that in summer. Correlation a-nalysis and path coefficient analysis indicated that the most important factors influencing the diurnal variation of water use efficiency were air temperature, photosynthetically active radiation and relative humidity in spring, while relative humidity, intercellular CO2 concentration and air temperature in summer, and intercellular CO2 concentration in fall. Compared with the control, unobvious differences in relative water content, water deficit and electrolyte leakage were observed under mild and moderate stresses, and an insignificant difference was also found in chlorophyll content under mild stress. Net photo-synthetic rate, transpiration rate and stomatal conductance decreased with increasing water stress, while water use efficiency under mild stress increased to some extent.%以盆栽地被石竹为试材,通过水分胁迫试验,采用Li-6400光合作用系统对地被石竹的水分生理特性和抗旱性进行了研究,结果表明:地被石竹叶片蒸腾速率日变化均表现为单峰曲线,以11:00-12:00蒸腾速率最高,不同季节峰值不同.夏季和秋季地被石竹水分利用率日变化为双峰曲线；春季叶片水分利用率日变化曲线近似单峰曲线.一年中,夏季水分利用率最小,春季和秋季相对较高；影响叶片水分利用率变化的生理生态因子中,春季以气温、光合有效辐射、相对湿度的直接作用最大,夏季为相对湿度、胞间CO2摩尔分数、气温,秋季为胞间CO2摩尔分数；轻度和中度胁迫条件下地被石竹叶片的含水量、水分亏缺和电解质外渗率与对照差异不显著,轻度胁迫与对照叶绿素质量分数差异不显著；地被石竹叶片净光合速率、蒸腾速率、气孔导度随水分胁迫程度的加强而降低,水分利用率在轻度水分胁迫下有所提高.
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