紫苏叶片光合效率的日变化  

Diurnal Variations of Photosynthetic Efficiency in Leaves of Purple Common Peril la

作　　者：樊继莲[1] 许长成[1] 赵世杰[1] 杨玉芳 

机构地区：[1]山东农业大学植物教研室,山东泰安271018

出　　处：《作物学报》1997年第5期567-572,共6页Acta Agronomica Sinica

基　　金：国家自然科学基金资助课题

摘　　要：紫苏光合作用的光补偿点与光饱和点大约为60ixmol·m^(-2)·s^1和1100~xmol·m^2·s^(-1)。光合作用最适叶温为28℃。CO_2补偿点为50Pl·L^(-1)。为典型的C_3植物光合特征。 在干热、高温与适温3种不同类型的晴天,伴随叶温、光强及叶水汽压亏缺的升高,紫苏叶片光合速率表现明显的日变化,中午前后降低。光合效率则从上午测定开始时起持续下降,下午逐渐回升。一天中,由于光呼吸速率的升高,在普通空气中测定的表观量子效率下降的幅度总是大于在低氧空气中测定的表观量子效率下降的幅度。光系统Ⅱ的光化学效率(Fv/Fm)也表现出明显的午间降低,并在光照变弱时能较快地恢复。文中讨论了光抑制与光呼吸在自然条件下紫苏叶片光合效率午间降低中的作用。The light compensation point and light saturation point of photosynthesis in purple common perilla(Perilla frutescens)leaves were 60 μmol·m-2·s-1 and 1100μmol·m-2·s-1 respectively. The optimum leaf temperature of photosynthesis was 28°C. The CO2 compensation point was 50μl·L-1. Those were typical for photosynthetic properties of C3 plants.On clear days under field conditions, the rates of photosynthesis and photorespiration in leaves of purple common perilla often displayed marked diurnal variations. A midday depression of photosynthesis was observed, being accompanied by an increase in leaf temperature, photon flux density and air vapour pressure deficit. Photosynthetic efficiency of purple common perilla leaves as represented by the apparent quantum efficiency (AQE) declined steadily from sunrise up to some time between morning and early afternoon, and then gradually rose until the end of the day. Due to enhancement in photorespiration, decrease in AQE measured at 21% O2 was bigger than in AQE measuredat 2% O2 over a day. Furthermore, a midday decrease in photochemical efficiency of phbtosystem I (Fv/Fm) was also observed and this effect was reversible and vanished almost completely after 4h in the low light. This probably revealed the onset of mechanisms for photoprotection rather than photoinhibitory damage to PS I . The roles of pho-toinhibition and photorespiration in midday depression of photosynthetic efficiency were discussed.

关 键 词：紫苏 表观量子效率 光化学效率 日变化 光抑制 

分 类 号：S565.801[农业科学—作物学]