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 （Fv/Fm） 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.
