Abstract The eophylls (first photosynthetic leaves) of palm trees play crucial roles in seedling establishment, although information concerning their development and ecophysiology remain scarce. This work sought to evaluate eophyll development and the effects of shading on young plants of the neotropical oil palm Attalea vitrivir. Eophyll ontogenesis was characterized, and the effects of shading levels (0, 58, 73 and 93%) on their anatomy, histochemistry, and seedling development where evaluated. Photosynthetic responses were compared between plants exposed to full sunlight or shade. After germination, the cotyledonary petiole elongates downward, which promotes the burial of the vegetative axis. Two eophylls are formed by the apical meristem, and they develop a short petiole and a much-folded blade that grows through the action of a basal meristem. The eophylls emerge below soil level and show a typical leaf structure and an intense and diverse vasculature. Shading levels do not affect blade tissue thicknesses, stomatal density, or the presence of primary and secondary metabolic compounds. A low photosynthetic performance under shade conditions is compensated by greater blade growth, so that plant development is not affected by shading. The ontogenesis of A. vitrivir eophylls below the soil surface and their response to shading contributes to seedling establishment and the adaptation of the species to seasonal and anthropized environments.

中文翻译：

---

Attalea vitrivir (Arecaceae) 叶叶的个体发生和对遮荫的反应

摘要 棕榈树的叶绿素（第一片光合叶）在幼苗建立中起着至关重要的作用，尽管关于它们的发育和生态生理学的信息仍然很少。这项工作旨在评估叶叶的发育和遮荫对新热带油棕 Attalea vitrivir 幼苗的影响。对叶叶个体发生进行了表征，并评估了阴影水平（0、58、73 和 93%）对其解剖结构、组织化学和幼苗发育的影响。比较暴露于充足阳光或阴凉处的植物之间的光合反应。萌发后子叶叶柄向下伸长，促进营养轴的埋藏。两个叶叶由顶端分生组织形成，它们发育出一个短的叶柄和一个通过基部分生组织生长的折叠多的叶片。叶叶出现在土壤平面以下，显示出典型的叶子结构和密集多样的脉管系统。阴影级别不影响叶片组织厚度、气孔密度或初级和次级代谢化合物的存在。遮荫条件下的低光合性能由较大的叶片生长补偿，因此植物发育不受遮荫影响。A. vitrivir eophylls 在土壤表面下的个体发育及其对遮荫的反应有助于幼苗的建立和物种对季节性和人类化环境的适应。遮荫条件下的低光合性能由较大的叶片生长补偿，因此植物发育不受遮荫影响。A. vitrivir eophylls 在土壤表面下的个体发育及其对遮荫的反应有助于幼苗的建立和物种对季节性和人类化环境的适应。遮荫条件下的低光合性能由较大的叶片生长补偿，因此植物发育不受遮荫影响。A. vitrivir eophylls 在土壤表面下的个体发育及其对遮荫的反应有助于幼苗的建立和物种对季节性和人类化环境的适应。