以蝴蝶兰和萼脊兰为材料,对其叶片的CO2吸收速率、可滴定酸含量和叶绿素荧光参数的昼夜变化进行研究.结果表明:蝴蝶兰和萼脊兰的CO2交换方式都具景天酸代谢途径(CAM)的特点,其叶片的净CO2吸收速率分别在22:00和凌晨0:00左右达到最大值.蝴蝶兰暗适应下的叶绿素荧光参数最小荧光Fo、最大荧光Fm、最大可变荧光Fv、可变荧光产量与最大荧光产量之比Fv/Fm、光系统Ⅱ潜在活性Fv/Fo均高于萼脊兰.蝴蝶兰和萼脊兰叶绿素荧光参数日动态变化结果表明,蝴蝶兰所需要的光照强度显著低于萼脊兰,太高的光强将引起植株的光抑制,从而引起光化学效率的下降.总的来说,蝴蝶兰为专性CAM兰花,萼脊兰属兼性CAM兰花,在蝴蝶兰与萼脊兰杂交后代的栽培中,在避免过高的光强引起其光抑制的同时,可提供特定的环境条件以诱导其叶片更多地进行C3途径光合,尽量减少CAM途径光合,从而有效地促进其干物质的积累,促进杂交后代的生长.%The net CO2 uptake,titratable acidity contents and chlorophyll fluorescence characteristics of Phalaenopsis and Sedirea japonica were comparatively studied.The results showed that both orchid of Phalaenopsis and S.japonica were CAM orchid with the net CO2 uptake rate reached the maximum at 22:00 and 0:00,respectively.The results of chlorophyll fluorescence from dark-adapted state showed that minimal fluorescence (F o),maximal fluorescence (Fm),maximum variable fluorescence (Fv),maximum quantum efficiency of PSⅡ photochemistry (Fv/Fm) and potential photochemical efficiency of PS Ⅱ (Fv/Fo) of Phalaenopsis was higher than those of S.japonica.The measurement of the daily chlorophyll fluorescence parameters with sunlight as the photochemical light indicated that the suitable light intensity in Phalaenopsis was lower than that in S.japonica,and strong light might cause the photo-inhibition of photosynthesis,which reduce the photochemistry efficiency.Generally speaking,Phalaenopsis was a CAM orchid and S.japonica a facultative CAM orchid.The cultivation of cross offspring from Phalaenopsis and S.japonica should provide suitable light intensity to prevent photo-inhibition of photosynthesis,and the special conditions could increase the C3-type photosynthesis by decreasing CAM-type photosynthesis,which might promote the growth through accelerating the dry material accumulation.
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