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温州蜜柑叶片光合效率的日变化 预览 被引量:21

Diurnal Variation in Photosynthetic Efficiency of Leaves in Satsuma Mandarin
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摘要 在5~10月的晴天,以最大表观量子产量Φi表示的温州蜜柑光合效率上午从测定开始时起持续下降,下午逐渐回升,与光强和叶温的日变化大致是镜象反相关。这与净光合速率峰谷交替的日变化明显不同。自然条件下遮荫或控制测定时的叶温得到的Φi的日变化主要取决于测定时的对温,叶温高则Φi低。不同时间在相近叶温下测得的Φi;没有显著差异。测定前叶片的光照强度对Φi不起决定作用。低O2可以消除升温的不利影响。光呼吸相对于光合的增强是升温导致Φi下降的主要原因。光合效率日变化的生理原因也部分地提供了对净光合日变化的解释。 Photosynthetic efficiency of satsuma mandarin(Citrus unshiu Marc.)leaves as represented by the maximum apparent quantum yield(Φi) and mearsured with an portable IRGA LCA-2,ADC,U.K.) declined steadily from sunrise up to some time between moring and early afternoon,and then gradually rose until the end of the day,following a Pattern which roughly mirrored daily changes in irradiance and temperature.From photosynthesis measurements of plants under field conditions and under artificial shading with leaf temperature controlled or uncontrolled during the measurement,it was found that daily variation in quantum efficiency was dependent on ies f t6mperature at which the CO2 uptake was measured.Φi decreased with increase in leaf temperature and remained unchanged throughout the day if measured at similar leaf temperature.There is no evidence that the light intensity to which the leaves were exposed prior to measurement played a Significant role in this regard.The negative effect of temperature increase on photosynthetic efficiency was attenuated or even eliminated by lowering the O2 concentration in the air.Quantitative measurements of the enhancement of photosynthesis by 2%O2 at different temperatures or different times of the day seem to indicate that it is the increase in rate of Photorespiration relative to rate of photosynthesis rather than a light-induced damage to and inhibition of reactions in photosynthetic apparatus that leads to the decrease in efficiency in midday.It is reasonable to suggest that the increased CO2 release from photorespiration contributes to the maintenance of a nearly constant intercellular CO2level in spite of reduction in stomatal conductance,which,together with the hightened photorespiration itself,is a means of protecting the photosynthetic apparatus from photoinhibition.The pattern of daily changes in net photosynthesis of citrus leaves,though distinct from that in photosynthetic efficiency and characterized by alternation of one or more crests and troughs,is nevertheless understandabl
作者 陈志辉 张良诚 CHEN Zhi-Hui and ZHANG Liang-Cheng(Zhejiang Agricultural University,Hangzhou 310029)
机构地区 浙江农业大学
出处 《植物生理学报(ISSN0257-4829)》 CSCD 1994年第3期 263-271,共9页 Acta Phytophysiologica Sinica
基金 国家自然科学基金
关键词 光合效率 日变化 光呼吸 温州蜜柑 phytosynthetic effidency,apparent quantum yield,phototespiration,diurnal variation,citrus unshin Mare.
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