Data from: C4 photosynthesis boosts growth by altering physiology, allocation and size

C4 photosynthesis is a complex set of leaf anatomical and biochemical adaptations that have evolved more than 60 times to boost carbon uptake compared with the ancestral C3 photosynthetic type1,​2,​3. Although C4 photosynthesis has the potential to drive faster growth rates4,5, experiments directly comparing C3 and C4 plants have not shown consistent effects1,6,7. This is problematic because differential growth is a crucial element of ecological theory8,9 explaining C4 savannah responses to global change10,11, and research to increase C3 crop productivity by introducing C4 photosynthesis12. Here, we resolve this long-standing issue by comparing growth across 382 grass species, accounting for ecological diversity and evolutionary history. C4 photosynthesis causes a 19–88% daily growth enhancement. Unexpectedly, during the critical seedling establishment stage, this enhancement is driven largely by a high ratio of leaf area to mass, rather than fast growth per unit leaf area. C4 leaves have less dense tissues, allowing more leaves to be produced for the same carbon cost. Consequently, C4 plants invest more in roots than C3 species. Our data demonstrate a general suite of functional trait divergences between C3 and C4 species, which simultaneously drive faster growth and greater investment in water and nutrient acquisition, with important ecological and agronomic implications.

C4光合途径（C4 photosynthesis）是一套复杂的叶片解剖学与生化适应机制，已独立演化超过60次，相较祖先型C3光合类型（C3 photosynthetic type）可提升碳吸收效率1,2,3。尽管C4光合途径具备实现更快生长速率的潜力4,5，但直接对比C3与C4植物的实验并未得到一致的结果1,6,7。这一现状存在显著问题：生长差异是阐释C4热带稀树草原对全球变化响应的生态学理论8,9的核心要素，同时也是通过引入C4光合途径提升C3作物生产力的相关研究12的关键环节。本研究通过涵盖生态多样性与演化历史的分析框架，对比382个禾本科物种的生长表现，解决了这一长期存在的争议。研究发现，C4光合途径可使日生长量提升19%至88%。出人意料的是，在至关重要的幼苗建成阶段，这一生长增益主要源自叶面积与干重的高比值，而非单位叶面积的快速生长。C4植物的叶片组织密度更低，使得在相同碳成本下可生成更多叶片。因此，相较C3物种，C4植物会将更多资源分配至根系生长。本研究数据揭示了C3与C4物种间一套通用的功能性状分化模式，该模式可同时推动更快的生长速率与更强的水分、养分获取能力的投入，具有重要的生态学与农艺学意义。