Objective] A comparison of drought resistance was made between two fast-growing species in South China, Eucalyptus urophylla ×E.grandis (EE for abbr.) and bamboo willow (BW for abbr.).[Method]Effective quantum yield of PSⅡ photochemistry ( Yield ) , apparent electron transport rate ( ETR) , the photochemical quenching ( qP ) , the non-photochemical quenching ( qN) , minimal fluores-cence(F0), maximal fluorescence(Fm), potential photochemical efficiency of PSⅡ(Fv/Fm) in EE and BW were tested by OS5P pulse modulated chlorophyll fluorometer under drought stress .[Result and con-clusion] Yield, ETR, qP, Fm and Fv/Fm all declined during the drought .At day 24 after treatment, ETR declined by 48.02% and 25.12% EE and BW , respectively.qN and F0 in the 2 species in-creased.qN in BW rose by 217.59%, which was significantly higher than that in EE (146.40%, P<0.05).The relative increment in F0 in BW (49.11%) was smaller than that in EE (92.03%) at the end of the drought treatment .Correlation analyses were made concerning chlorophyll fluorescence charac-teristics and soil water content .In both species , ETR showed a significant positive correlation with soil water content ( P<0.01 ) .F0 in EE showed a significant negative correlation with soil water content (P<0.01).Fm and Fv/Fm of BB and soil water content showed a significant positive correlation (P<0.01).These results indicate that correlations existe among chlorophyll fluorescence characteristics in two species under drought.BW has greater drought resistance than EE as revealed by chlorophyll fluo-rescence characteristics.%目的对华南地区2个速生树种尾巨桉Eucalyptus urophylla × E．grandis和竹柳（ bamboo willow ）的抗旱性进行比较．方法采用干旱胁迫处理，利用脉冲调制式叶绿素荧光仪（ OS5 P-美国）对2树种叶绿素荧光参数进行测定．结果和结论在干旱胁迫条件下，实际光量子产量（ Yield）、表观光合电子传递速率（ ETR）、光化学淬灭系数（qP）、最大荧光（Fm）和PSⅡ最大光化学效率（Fv／Fm）均有不同程度的下降，在干旱处理第24天，尾巨桉ETR比对照下降48.02％，而竹柳仅下降25.12％；到重度干旱时期，尾巨桉和竹柳Fv／Fm 分别下降31.55％和21.84％；供试树种的非光化学淬灭系数（ qN）、初始荧光（ F0）均呈上升趋势，与对照相比，竹柳qN上升幅度为217.59％，显著大于尾巨桉（146.40％，P＜0.05），F0上升幅度（49.11％）小于尾巨桉（92.03％）；2种树种ETR与土壤含水量均呈极显著正相关（P＜0.01），尾巨桉F0与土壤含水量呈极显著负相关（P＜0.01），竹柳Fm 和Fv／Fm 与土壤含水量呈极显著正相关（P＜0.01）．研究结果表明：在干旱胁迫下，竹柳与尾巨桉叶绿素荧光参数间均表现一定相关性，相比尾巨桉，竹柳在叶绿素荧光参数上表现出更强的抗旱性．
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