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作 者 ：郭水良^1,2;方芳²;倪丽萍²;陈万林²;石来娣²

期 刊 ：应用生态学报 2006年 17卷 12期 页码：2316-2320

关键词：莴苣；

摘 要 ：毒莴苣是我国东南沿海地区的新入侵杂草，也是国家进境植物的检疫对象.调查发现，毒莴苣植株高大，易在入侵地形成群落优势种;常见的伴生杂草有小飞蓬、野塘蒿、鬼针草、裂叶月见草、裂叶牵牛、狗尾草、野胡萝卜、苍耳、一年蓬、山莴苣、葎草、龙葵和钻形紫菀等.应用LCA4光合蒸腾测定系统对毒莴苣进行净光合速率测定,结果表明：该种实测净光合速率高达21.22±0.45 μmol CO₂·m^-2·s^-1，比入侵性杂草一年蓬、野塘蒿稍低，比藜、北美车前、山莴苣等高，是一种高光效植物；根据毒莴苣的光合-响应曲线，该外来入侵种的理论光补偿点为37.58 μmol·m^-2·s^-1, 光饱和点为1 480 μmol·m^-2·s^-1，理论最大净光合速率20.81 μmol CO₂·m^-2·s^-1；毒莴苣的光合作用具有午休现象，是由于高光照和高温导致气孔阻力增加、气孔关闭，影响了植株对外的气体交换；影响净光合速率的主要因素是气孔导度、叶面光合有效辐射和叶片的蒸腾.

Abstract:

Lactuca serriola, a national class quarantine object, is a new invasive species in
the coastal area of Southeast China. The coenological survey showed that
because of its big individual, L. serriola could easily form dominant population in
its invaded area, and its main accompany species were Conyza canadensis,
C. bonarinisis, Bidentis bipinnata, Oenothera laciniata, Ipomoea hederacea,
Setaria viridis, Daucus carota, Xanthium sibiricum, Erigeron annuus, L. indica,
Humulus scandens, Solanum nigrum and Aster sublatus. The measurements
with LC-A4 portable photosynthesis and transpiration system (ADC, England)
revealed that the net photosynthetic rate of L. serriola was as high as 21.22±0.45 μmol CO₂·m^-2·s^-1, being slightly lower than that of E. annuus and
C. bonarinisis, similar to that of C. canadensis, and higher than that of
Chenopodium album, Plantago virginica and L. indica. Based on the photosynthesis
-light response equation, the theoretic light compensation point of L. serriola
was 37.58 μmol m^-2·s^-1, its theoretic light saturation point was 1 480 μmol·m^-2·s^-1, and theoretic maximal net photosynthetic rate was 20.81 μmol CO_2·m^-2·s^-1. A distinct “noon break” phenomenon was observed in L. serriola
photosynthesis, which might result from the high stomatal resistance against
high light intensity and temperature. The main factors affecting the net phot-
osynthetic rate of L. serriola were leaf photosynthetic active radiation, stomatal
conductance, and leaf transpiration rate.

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