摘要
利用LiCor-6400光合测定系统测定了不同天气条件下,金钗石斛叶片24h CO_2吸收的动态变化,以及CO_2吸收对有效光合辐射的响应。结果表明:晴天,白天和夜间金钗石斛都能吸收CO_2,中午有光下呼吸现象,CO_2的交换方式具景天酸代谢途径(CAM)的特点;阴雨天,中午没有光下呼吸现象,白天都在吸收CO_2,夜间21:00仍有CO_2吸收,23:00以后至次日凌晨处于暗呼吸状态。金钗石斛叶片CO_2吸收对光照强度的效应表现出强光抑制现象,饱和光照强度为1000μmol/m^2s。叶片受到强光照射后,光合饱和点降低,CO_2吸收速率下降。说明金钗石斛是兼性景天酸代谢植物,随着环境条件的变化,光合作用可在CAM途径与C_3途径间变化,这一光合特性可能是金钗石斛适应需荫环境和生长缓慢、稀少的主要原因之一。
With LiCor - 6400 Portable Photosynthesis System, carbon dioxide exchange pattern for leaves of Dendrobium nobile during 24 hours were studied in sunny day and rainy day, and the variation of CO2 exchange rate to light intensity was analysed. The results showed that in sunny day D. nobile absorbed CO2 in all day except at midday, at noon photorespiration took place. The CO2 exchange pattern was similar to Crassulacean Acid Metabolism (CAM). In rainy day CO2 uptake was in all day, at night CO2 uptake was monitored at 21:00,then CO2 released from 23:00 to dawn. Light saturation point was 1000umol/m2s. Over light saturation point photosynthesis ,photoinhibition of photosynthesis will be induced by high-light. Exposed to high-light, the light saturation point and the CO2 uptake velocity would be decreased. With variation of environmental factors, photosynthetic pathway in D. nobile could change from CAM to C3 photosynthetic metabolism. It may be one of main reasons for D. nobile to adapt to the shade-requiring environment, the slow growth and rareness in nature.
出处
《中药材》
CAS
CSCD
北大核心
2003年第3期157-159,共3页
Journal of Chinese Medicinal Materials
