中文摘要：

为了探索当归连作后产量和品质降低的影响因素,研究比较了轮连作当归光合特性及挥发油收率以及化学成分,为深入探讨连作对当归生长发育障碍提供理论依据。用CI-310系统光合测定仪,田间活体测定当归净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）、胞间CO2浓度（Ci）等光合生理生态因子;用水蒸气蒸馏法提取当归药材挥发油,并用GC-MS法鉴定化学成分,归一化法测定相对含量。结果表明,连作当归叶绿素a和b含量比轮作下显著降低,分别为轮作下的26.5%和57.0%;连作当归的日平均光合速率为1.73μmol/（m2.s）,比轮作当归降低50.9%（2.61μmol/m2.s）（P〈0.05）;一天中连作和轮作当归的蒸腾速率下午显著低于上午,连作低于轮作;气孔导度（Gs）12：00前的平均值连作当归（10.6mmol/m2.s）与轮作（11.4mmol/m2.s）差异不显著,而14：00后连作（1.3mmol/m2.s）极显著的低于轮作（4.4mmol/m2.s）;胞间CO2浓度（Ci）的变化和气孔导度一致;轮作和连作当归挥发油收率分别为0.95%和0.70%,挥发油中藁本内酯的相对含量分别为71.62%和29.49%,但挥发油组分基本一致。当归连作显著降低叶片的光合色素含量、光合特性和药材挥发油含量,进而导致产量和品质下降,因此在栽培中应注重合理的轮作倒茬。

英文摘要：

Comparison of photosynthetic characteristic and essential oils in crop rotation and continuous cropping of Angelica sinensis was studied to explore the influence factor of dropping the yield and quality after continuous cropping,this conclusions will provide theoretical basis for investigation of continuous cropping obstacle of A.sinensis.Chlorophyll,photosynthetic rate,transpiration rate,stomatal conductance and intercellular CO2 concentration of A.sinensis were measured with CI-310 photosynthesis system.The yield and constituent of the essential oils extracted from the A.sinensis.Water steam and GC-MS were used.Chl a and Chl b of continuous cropping dropped apparently,at 26.5% and 57.0% less than rotation one,and the differences were significant（P0.01）;Daily mean photosynthesis of continuous cropping was 1.73 μmol/（m2·s）,less than rotation（2.61 μmol/m2·s） by 50.9%,the differences were significant（P0.05）;In a day,transpiration rate in the morning was significant lower than that in the afternoon,the continuous cropping was significant lower than the rotation one.The difference of stomatal conductance average between rotation（11.4 mmol/m2·s） and continuous（10.6 mmol/m2·s） was not significant before 12：00,but had extremely significant difference between continuous（1.3 mmol/m2·s） and rotation（4.4 mmol/m2·s）;Intercellular CO2 concentration had the same variation.The yields of the essential oil of A.sinensis in crop rotation and continuous cropping are 0.95% and 0.70%,The relative amounts of ligustilide of essential oil are 71.62% and 29.49%.but the constiuents of the essential oil of A.sinensis from crop rotation and continuous cropping are identical.Continuous cropping decreased significantly the Chl,photosynthetic characteristica and essential oil of A.sinensis,which resulted in yield decreasing.Therefore Angelica contivation should think rotation low-toxin chemical.