不同光强下生长的几种亚热带森林树木的Rubisco羧化速率和碳酸酐酶的活性

9月和12月测定了生长于3种不同光强（100％、36％和16％的自然光）下生长的乔木荷树、黧蒴和灌木九节、罗伞盆栽幼苗叶片的Rubisco羧化速率（RCR）、碳酸酐酶（CA）活性和细胞间CO2浓度（Ci)。当生长光强降低时，4种供试植物的RCR和CA活性明显降低。9月时生长在16％自然光下荷树的RCR和CA比100％自然光者分别降低55％和50％，藜蒴则降低20％和35％，耐有的灌木树的降幅较小，仅为33％－38％（RCR）和22％－30％（CA）。12月的RCR和CA的水平较9月时低，翌年1月时自然林不同光强下生长的同类植物的RCA和CA随光强变化也有类似的趋势。RCR和CA活性呈正相关性，且两者与Ci呈弱负相关。推测高光强可能有利于激活Rubisco，促进CA内化的CO2→DlC（可溶性碳）→CO2活性和DlC的传输过程。

The Carboxylation Rate of Rubisco and Activity of Carbonic Anhydrase in Plants from a Subtropical Forest Grown at Different Light Intensity

Carboxylation rate of Rubisco (RCR), activity of carbonic anhydrase (CA) and intercellular CO 2 concentration (Ci) were analyzed in September and December, 1998, in leaves of forest plants Schima superba, Castanopsis fissa, Psychotria rubra and Ardsia quinquegona seedlings grown at three different light intensities, which were 100%, 36% and 16% of natural sun light. RCR and CA activity of all tested plants were decreased obviously by declining growth light intensity, In comparison with plant at 100% sunlight, in September, the RCR and CA activity in leaves of Schima superba grown at 16% sunlight declined by 55% and 50%, respectively, while that in leaves of Castanopsis fissa declined by 20% and 35%. The decreasing ranges of RCR and CA activity in shade adapted shrub species. Psychotria rubra and Ardisia quinquegona were less than that of tree species, which decreased by 33% ~ 38% in RCR and by 22% ~ 30% in CA activity. In the same case, the levels of RCR and CA activity measured in December were lower than that in September. Similar changing trend of RCR and CA activity was also found in plants grown in different sites of natural forest with different light conditions sampling in January, next year. There was a positive relationship between RCR and CA ac tivity , and a weak negative relationship between Ci and RCR or CA activity. It is proposed that higher irradiance might promote the activation of Rubisco and induce the increase in CA activity and transport rate of DIC (dissoluble inorganic carbon).