入侵种喜旱莲子草和莲子草的营养生长和光合作用对温度的响应

Responses of Vegetative Growth and Photosynthesis to Temperature in the Invasive Species Alternanthera philoxeroides and Its Indigenous Congener A. sessilis

摘要:

比较温度对入侵种喜早莲子草（Alternanthera philoxeroides（Mart）Griseb.）和其本土近缘种莲子草（A.sessilis（L.）DC.）的营养生长、叶片光合作用及叶绿素荧光的影响。实验将生长均衡的这两种植物放在不同温度（10 ℃、15 ℃、20 ℃、25 ℃、30 ℃）的光照培养箱中处理28d。结果表明，喜旱莲子草营养生长的速率和对温度的响应明显不同于莲子草：前者主茎生长的有效积温明显低于后者，分别是l1.6 d ℃和27.0 d ℃；而新叶萌发的有效积温高于后者，分别是12.1 d ℃和6.7 d ℃。入侵种主茎和叶的发育起点温度都比本土种低，分别是10.4 ℃、11.O ℃和12.8 ℃、14.9 ℃，表明喜早莲子草的发育对低温反应不及莲子草敏感。对两种植物叶片的光合作用和叶绿素荧光的测定结果还表明：入侵种比本土种有较高的最大净光合速率和光饱和点，尤其在25 ℃时；10-30 ℃的温度范围内喜早莲子草的最大光化学效率F_v/F_m。没有显著变化，而莲子草在1O ℃低温条件下F_v/F_m值显著降低。较快的主茎生长速率、较宽的温度适应范围以及较高的光合能力可能使喜早莲子草比本地种具有更强的竞争力，从而在其入侵过程中起了重要作用。

Abstract:

An invasive species A lterrumthera philoxeroides and its indigenous congener A. sessilis were compared in the vegetative growth, photosynthesis and chlorophyll fluorescence. Stem tip cuttings of the herbs were cultivated for 28 d in 5 light growth chambers at 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, respectively. Results showed that the main stems ofA. philoxeroides developed with lower accumulated effective temperature （AET）（11.6 d ℃） than that ofA. sessilis （27.0 d ℃）, but the new leaves ofA. philoxeroides emerged with more AET （12.1 d ℃） than that ofA. sessilis （6.7 d ℃）. Main stems and leaves ofA. philoxeroides started to grow at lower temperatures, 10.4 ℃ and 11.0 ℃, respectively, than A. sessilis which needed 12.8 ℃ and 14.9 ℃, respectively, indicating that A. philoxeroides was less sensitive to low temperature than A. sessilis. Data of photosynthesis and chlorophyll fluorescence revealed that the maximum net photosynthetic rate （NPR） in A. philoxeroides was higher than that inA. sessilis, so was light saturation point （LSP）, esp. at 25 ℃. The maximal photochemical efficiency （F_v/F_m） varied slightly for A. philoxeroides in the range of 10-30℃, which, however, rapidly declined for A. sessilis at 10 ℃. It might be concluded that high growth rate in main stems, wide range of temperature adaptation and strong capacity for photosynthesis would be important factors for the invasion of A. philoxeroides.