发布时间 : 星期二 文章光合作用 - 图文更新完毕开始阅读
径和CAM途径作为CO2的富集机制是卡尔文循环的有效补充。rubisco酶同时具有羧化和加氧双重反应活性，C2氧化光合碳循环减少了因rubisco酶加氧反应形成2-磷酸乙醇酸造成的毒害和碳损失。卡尔文循环合成的碳水化合物以蔗糖和淀粉两种形式储存。蔗糖在大多数植物中是可移动形式，而淀粉在叶绿体中合成。
光合器官的许多特性可随获得光量的多少而变化，包括光补偿点。同一叶片在同一时间内，光合过程中吸收的CO2和光呼吸及呼吸过程中放出的CO2等量时的光照强度，称为光补偿点。光下生长的植物（或阳生植物、或喜光植物）的叶片的光补偿点就比阴暗处生长的植物（或阴生植物）的叶片要高一些。根据光合作用的光-反应曲线可以计算整个叶片光合作用的量子产额。一般情况下，C3植物的量子产额高于C4植物。CO2扩散进入叶片的过程受到一系列阻力的限制。最大的阻力来自于气孔，孔径的调控为植物控制水分散失和CO2吸收提供了一种最佳的方式。气孔和非气孔因素都能通过影响植物对CO2的吸收对光合作用产生影响。阳光在提供叶片光能的同时也产生了大量的热负荷，这些热量又以长波辐射、感热损耗、或通过蒸腾作用等方式释放到空气中。温度对光合作用也十分重要，光合作用中参与生化反应的酶的活性和叶绿体光合膜系统的稳定性等均受温度的影响。
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