中文摘要：

以枳橙砧山下红温州蜜柑、纽荷尔脐橙和沙田柚盆栽苗为试材,设盆栽土壤水分含量分别为最大田间持水量的60%、40%、20%共3个处理（以下简称60%PC、40%PC、20%PC处理）,以正常浇水的盆栽苗为对照,研究水分胁迫处理对柑橘光合特性的影响.结果表明,（1）随水分胁迫的加重,蜜柑叶片叶绿素含量降低,叶绿素a与叶绿素b的含量比减小;（2）各水分胁迫处理柑橘的净光合速率、气孔导度、蒸腾速率均低于对照,且下降幅度从大到小依次为20%PC（重度胁迫）、40%PC（中度胁迫）、60%PC（轻度胁迫）;（3）不同品种柑橘对照的净光合速率日变化曲线相似,均为双峰曲线,但峰值大小和出现时间有差异;不同品种柑橘40%PC处理净光合速率的日变化曲线不同,沙田柚的为单峰曲线,纽荷尔脐橙和山下红温州蜜柑的为双峰曲线;（4）不同处理山下红温州蜜柑叶片净光合速率的日变化曲线不同,20%PC处理的为单峰曲线,其余处理的为双峰曲线.

英文摘要：

Effect of water stress on Citrus photosynthesis characteristic was studied by using Yamasitaka,Newhall orange,Shatian pomelo as materials.The results showed：chlorophyll content of Citrus is significantly decreased by water stress,there are positive relationship between relative water content of soil and the volume of chlorophyll-a/chlorophyll-b.There are positive relationship between relative water content of soil and net photosynthetic rate（Pn） and transpiration rate,when there is a negative relationship with stoma resistance.Under well water condition,the diurnal variation of net photosynthetic rate of Shatian pomelo,Yamasitaka,and Newhall orange present bimodal curve,but the value and appeared time of peak are different among three varieties.Under water stress,the diurnal variation of Pn of Shatian pomelo show one peak while Yamasitaka,Newhall orange present two peaks.The diurnal variation of Pn of Yamasitaka present bimodal curve,under well water,60%PC and 40%PC treatments.However under 20%PC treatment,Yamasitaka show single curve.