Seed germination is a key part of plants' life cycle and is mostly affected by the genetic background, the environmental conditions experienced by the mother plant and the seedbed conditions. The germination response to light is essential to optimize germination and seedling establishment in space and time. In addition, the germination response to light is a trait often related to the response of the seeds to their position in the soil (uncovered/buried). Here, we studied the germination response to light of four key tree species of the Yungas forest (Anadenanthera colubrina, Enterolobium contortisiliquum, Jacaranda mimosifolia and Handroanthus impetiginosus) sampled along an elevational and environmental gradient with contrasting vegetation cover and disturbance. Relative light germination (RLG) and mean germination time (MGT) were determined. Final germination was tested under cycles of light (8 h) and darkness (16 h) versus complete darkness (24 h) and elevation, and MGT was tested as a function of elevation of the provenance. The RLG increased from smaller to larger-seeded species. The MGT of three of the studied species was affected by the elevation of the provenance. Complete darkness negatively affected final germination, while two species exhibited a significant interaction between the provenance and light. The variable germination responses to light along the elevational gradient highlights the influence of the environment on germination as a key factor that should be considered for forest management, conservation and restoration projects.

中文翻译：

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中安第斯山脉南部沿海拔梯度的四种新热带森林树种对光的萌发响应

种子萌发是植物生命周期的关键部分，主要受遗传背景、母株所经历的环境条件和苗床条件的影响。对光的发芽反应对于优化发芽和幼苗在空间和时间上的建立至关重要。此外，对光的萌发反应通常与种子对其在土壤中的位置（未覆盖/埋藏）的反应有关。在这里，我们研究了 Yungas 森林的四种主要树种（Anadenanthera colubrina、Enterolobium contortisiliquum、Jacaranda mimosifolia 和 Handroanthus impetiginosus）对光的发芽响应，沿海拔和环境梯度采样，植被覆盖和干扰形成对比。测定相对光发芽（RLG）和平均发芽时间（MGT）。在光照 (8 小时) 和黑暗 (16 小时) 与完全黑暗 (24 小时) 和海拔的循环下测试最终发芽，并测试 MGT 作为来源海拔的函数。RLG 从较小的种子物种增加到较大的种子物种。三个被研究物种的 MGT 受到来源海拔的影响。完全黑暗对最终萌发产生负面影响，而两个物种在来源和光之间表现出显着的相互作用。沿海拔梯度对光的可变发芽反应突出了环境对发芽的影响，这是森林管理、保护和恢复项目应考虑的关键因素。并且 MGT 被测试为出处海拔的函数。RLG 从较小的种子物种增加到较大的种子物种。三个被研究物种的 MGT 受到来源海拔的影响。完全黑暗对最终发芽产生负面影响，而两个物种在来源和光之间表现出显着的相互作用。沿海拔梯度对光的可变发芽反应突出了环境对发芽的影响，这是森林管理、保护和恢复项目应考虑的关键因素。并且 MGT 被测试为出处海拔的函数。RLG 从较小的种子物种增加到较大的种子物种。三个被研究物种的 MGT 受到来源海拔的影响。完全黑暗对最终发芽产生负面影响，而两个物种在来源和光之间表现出显着的相互作用。沿海拔梯度对光的可变发芽反应突出了环境对发芽的影响，这是森林管理、保护和恢复项目应考虑的关键因素。而两个物种在来源和光之间表现出显着的相互作用。沿海拔梯度对光的可变发芽反应突出了环境对发芽的影响，这是森林管理、保护和恢复项目应考虑的关键因素。而两个物种在来源和光之间表现出显着的相互作用。沿海拔梯度对光的可变发芽反应突出了环境对发芽的影响，这是森林管理、保护和恢复项目应考虑的关键因素。