Laboratory of Ecophysiology and Forest Production, Federal Institute of Education, Science, and Technology of Amazonas (IFAM) - Campus Humaitá, Humaita, Amazonas, Brazil.
National Institute of Science and Technology on Plant Physiology Under Stress Conditions (INCT-CNPq-Brazil), Viçosa, Minas Gerais, Brazil.
Plant Biol (Stuttg). 2024 Jun;26(4):647-661. doi: 10.1111/plb.13632. Epub 2024 Mar 15.
To investigate how and to what extent there are differences in the photosynthetic plasticity of trees in response to different light environments, six species from three successional groups (late successional, mid-successional, and pioneers) were exposed to three different light environments [deep shade - DS (5% full sunlight - FS), moderate shade - MS (35% FS) and full sunlight - FS]. Maximum net photosynthesis (A), leaf N partitioning, stomatal, mesophile, and biochemical limitations (SL, ML, and BL, respectively), carboxylation velocity (V), and electron transport (J) rates, and the state of photosynthetic induction (IS) were evaluated. Higher values of A, V, and J in FS were observed for pioneer species, which invested the largest amount of leaf N in Rubisco. The lower IS for pioneer species reveals its reduced ability to take advantage of sunflecks. In general, the main photosynthetic limitations are diffusive, with SL and ML having equal importance under FS, and ML decreasing along with irradiance. The leaf traits, which are more determinant of the photosynthetic process, respond independently in relation to the successional group, especially with low light availability. An effective partitioning of leaf N between photosynthetic and structural components played a crucial role in the acclimation process and determined the increase or decrease of photosynthesis in response to the light conditions.
为了研究树木在不同光照环境下光合作用的可塑性有何不同以及不同程度，我们将来自三个演替组（晚生演替、中生演替和先锋种）的 6 个物种暴露在三种不同的光照环境中[深荫（5%全光照-FS）、中荫（35%FS）和全光照-FS]。评估了最大净光合作用（A）、叶片 N 分配、气孔、中温、生物化学限制（分别为 SL、ML 和 BL）、羧化速度（V）和电子传递（J）速率，以及光合作用诱导状态（IS）。在 FS 中，先锋种的 A、V 和 J 值较高，这表明它们在 Rubisco 中投入了最多的叶片 N。先锋种较低的 IS 表明其利用光斑的能力降低。总的来说，主要的光合限制是扩散限制，在 FS 下 SL 和 ML 同等重要，而 ML 随着光照强度的降低而降低。叶片特性与演替组有关，特别是在光照不足的情况下，与光合作用过程更相关的叶片特性独立响应，在适应过程中发挥着关键作用，并决定了光合作用对光照条件的增加或减少。
