中文摘要：

以宜兴市盛道茶场3、9和20a3个不同植茶年龄的茶园为研究对象,基于静态箱/红外气体分析仪法,辅以植被生态监测和土壤湿度监测,研究茶园清明采茶前蒸散速率日变化特征。结果发现：（1）3个不同植茶年龄的茶园日蒸散速率变化趋势一致,呈以12∶00～15∶00蒸散速率为峰值的单峰曲线;（2）虽然3a茶园叶面积指数（LAI）最低,但最大平均日蒸散速率、一日内蒸散速率的极值、6∶00～18∶00最大总蒸散量、一日内不同时段的蒸散速率最大变化幅度均出现在3a茶园;（3）茶园日蒸散速率与气温的日变化趋势相似,且两者存在极显著相关性（R2=0.81＊＊）,在湿润条件下与土壤含水率日变化相关性不明显,但两者呈相反的变化趋势。

英文摘要：

Applying Static Chamber/IRGA,this paper measured water vapor concentration of tea plantations of different growing years in Yixin City,on the west of Taihu Lake watershed,aimed to evaluate the effects of growing years on the diurnal variation of evapotranspiration.The results showed that diurnal variation of tea plantations evapotranspiration rate appeared in a single peak curve with the peak（2.73 mmol·m-2·s-1,2.36 mmol·m-2·s-1,2.09 mmol·m-2·s-1in the growing years order）,increasing from 6∶00 and reaching a maximum value between 12∶00 and 15∶00,then decreasing rapidly.The three variations had the same trends,while their variation ranges during all time intervals were different from each other.The variation ranges decreased as the tea plantation growed,so the youngest one ＇s（3 years old） amplitudes were the highest.Though the youngest＇s LAI was the lowest（1.463.253.75 in the growing years order）,it＇s averge of diurnal evapotranspiration rates was the highest one（1.29 mmol·m-2·s-11.21 mmol·m-2·s-11.15 mmol·m-2·s-1 in the growing years order）.Total evapotranspiration from 6∶00 to 18∶00 were also the highest（50.52 g·m-247.78 g·m-245.02 g·m-2 in the growing years order）,and the evapotranspiration rate maximum value during a day was in the order similar to the average ones,that the youngest＇s was 0.49 mmol·m-2·s-1and 0.64 mmol·m-2·s-1 more than 9 years old one and 20 years old one respectively,as the 3 years old tea plantation＇s lowest LAI brought most sunshine and surface turbulent flows which enhanced soil evaporation,canceled transpiration＇s difference,and conclusively,improved evapotanspiration.The diural evapotranspiration rate had the same trend with tempetature daily variation,in the morning,temperature was lowest（T=3.83℃）,evapotranspiration rate was lowest（ET rate=0.07 mmol·m-2·s-1）,then the rate increased as the temperature rised.From 12∶00 to 15∶00,tempetature was highest（T=30.87℃）,evapotranspiration rate came to the highest on