【摘要】 用红外线CO₂气体分析法研究了枇杷和杨梅在冬季的一些光合特性。发现在杭州条件下枇杷和杨梅等10种常绿树种冬季的净光合速率一般处于1.50mgCO₂·dm^-2·h^-1以下的低水平。枇杷花朵的存在明显提高了其邻近叶片的光合速率,但对枝条基部叶无效。冬季20℃的高温处理对枇杷和杨梅光合作用的抑制效应强于0℃和-2℃的低温处理。与杨梅相比,枇杷的光合作用更易受高、低温的抑制,说明它对冬季的温度变化较敏感,其抗寒性弱于杨梅。枇杷与杨梅的光补偿点和光饱和点都较低,分别为750Ix和18000Ix,反映出这类果树耐荫的特点。更多还原

【Abstract】 Some photosynthetic characteristics of two Chinese native subtropi-cal fruit crops——Loquat （Eriobotrya japonica Lindl. ） and Bayberry（Myrica rubra Sieb.& Zucc. ） were studied in winter by method of gas exchange with an infrared gas analyzer at 13 ±1 ℃and light saturated condition. It was found that the net photosynthetic rate （ Pn ） of wintering loquat, bayberry and other evergreen trees was low, usually below l.5mg CO2 ·dm^-2 ·h^-1.Among those measured, loquat which was in blossom, had the highest rate. The existence of flowers of loquat increased the Pn of adjacent leaves （ apicillary ones ） significantly, but had no effects on the basal leaves.The optimum temperature for photosynthesis of wintering loquat and bayberry was below 20 ℃. Photosynthesis was much more depressed after exposure to 20 ℃ than that after exposure to 0 ℃ and - 2 ℃. In comparision with bayberry, the photosynthesis of loquat was more easily inhibited by both high ( 2（℃ ） and low （ 0 ℃, - 2 ℃ ） temperature （ Tab. ） , thus indicating that the wintering loquat was more sensitive to the changes of temperature and weaker in cold endurance than the bayberry.The light saturation point and light compensation point of loquat and bayberry were 18000 lx ( 360 μmol · m^-2·s^-1 ) and 750 Ix ( 15 μmol· m^-2·s^-1 ) respectively, which were similar to those of citrus unshiu and lower than those of the apple. Photosynthetic induction of 45 minutes of loquat leaves on cloudy days was observed. The Pn in early induc-tion stage of loquat rose dramatically, instead of increasing very slowly as previously reported on citrus unshiu. This result showed that the Process of activating related enzymes and raising the level of the intermediates in photosynthetic carbon cycle by light, which was predominant in the early stage of induction, were faster in loquat than those in citrus leaves.更多还原