Resco de Dios Víctor, Mereed Tessema E, Ferrio Juan Pedro, Tissue David T, Voltas Jordi
Department of Crop and Forest Sciences-AGROTECNIO Center, Universitat de Lleida, Rovira Roure 191, E 25198 Lleida, Spain
Department of Crop and Forest Sciences-AGROTECNIO Center, Universitat de Lleida, Rovira Roure 191, E 25198 Lleida, Spain.
Tree Physiol. 2016 Jun;36(6):682-93. doi: 10.1093/treephys/tpw026. Epub 2016 Apr 15.
Atmospheric carbon dioxide (CO2) concentrations are expected to increase throughout this century, potentially fostering tree growth. A wealth of studies have examined the variation in CO2 responses across tree species, but the extent of intraspecific variation in response to elevated CO2 (eCO2) has, so far, been examined in individual studies and syntheses of published work are currently lacking. We conducted a meta-analysis on the effects of eCO2 on tree growth (height, stem biomass and stem volume) and photosynthesis across genotypes to examine whether there is genetic variation in growth responses to eCO2 and to understand their dependence on photosynthesis. We additionally examined the interaction between the responses to eCO2 and ozone (O3), another global change agent. Most of the published studies so far have been conducted in juveniles and in Populus spp., although the patterns observed were not species dependent. All but one study reported significant genetic variation in stem biomass, and the magnitude of intraspecific variation in response to eCO2 was similar in magnitude to previous analyses on interspecific variation. Growth at eCO2 was predictable from growth at ambient CO2 (R(2) = 0.60), and relative rankings of genotype performance were preserved across CO2 levels, indicating no significant interaction between genotypic and environmental effects. The growth response to eCO2 was not correlated with the response of photosynthesis (P > 0.1), and while we observed 57.7% average increases in leaf photosynthesis, stem biomass and volume increased by 36 and 38.5%, respectively, and height only increased by 9.5%, suggesting a predominant role for carbon allocation in ultimately driving the response to eCO2 Finally, best-performing genotypes under eCO2 also responded better under eCO2 and elevated O3 Further research needs include widening the study of intraspecific variation beyond the genus Populus and examining the interaction between eCO2 and other environmental stressors. We conclude that significant potential to foster CO2-induced productivity gains through tree breeding exists, that these programs could be based upon best-performing genotypes under ambient conditions and that they would benefit from an increased understanding on the controls of allocation.
预计在整个本世纪，大气中二氧化碳（CO₂）浓度都会上升，这可能会促进树木生长。大量研究探讨了不同树种对二氧化碳响应的差异，但迄今为止，对于高浓度二氧化碳（eCO₂）响应的种内变异程度，仅在个别研究中有所涉及，目前还缺乏已发表研究的综合分析。我们对eCO₂对不同基因型树木生长（高度、茎生物量和茎体积）及光合作用的影响进行了荟萃分析，以检验对eCO₂的生长响应是否存在遗传变异，并了解其对光合作用的依赖性。我们还研究了对eCO₂和另一种全球变化因素臭氧（O₃）的响应之间的相互作用。尽管观察到的模式并不依赖于特定物种，但迄今为止，大多数已发表的研究都是在杨树属的幼树中进行的。除一项研究外，所有研究均报告了茎生物量存在显著的遗传变异，对eCO₂响应的种内变异幅度与先前对种间变异的分析幅度相似。根据环境二氧化碳浓度下的生长情况可以预测eCO₂浓度下的生长情况（R² = 0.60），并且基因型表现的相对排名在不同二氧化碳水平下保持不变，这表明基因型和环境效应之间没有显著的相互作用。对eCO₂的生长响应与光合作用的响应不相关（P > 0.1），虽然我们观察到叶片光合作用平均增加了57.7%，但茎生物量和体积分别增加了36%和38.5%，而高度仅增加了9.5%，这表明碳分配在最终驱动对eCO₂的响应中起主要作用。最后，在eCO₂条件下表现最佳的基因型在eCO₂和高浓度O₃条件下也有更好的响应。未来的研究需求包括扩大对杨树属以外种内变异的研究，并研究eCO₂与其他环境压力源之间的相互作用。我们得出结论，通过树木育种提高二氧化碳诱导的生产力具有巨大潜力，这些计划可以基于环境条件下表现最佳的基因型，并且增加对分配控制的理解将有助于这些计划的实施。
