The photosynthetic adjustments of macaw palm (Acrocomia aculeata) were evaluated in 30-day-old seedlings exposed to high and low light environments, and sudden transference from low to high light and comparisons were made with the hardening protocol used in nurseries. Furthermore, we evaluated the responses to long-term exposure (265 days) to high and low light environments. Macaw palm seedlings exhibited an efficient mechanism that maximized light capture under scarce conditions, and dissipated excess energy to avoid damaging to the photosystem II under high light. The seedlings showed low saturation irradiance but no photoinhibition when exposed to excess light. When grown under low light intensities, seedlings presented higher photochemical efficiency and minimized the respiratory costs with positive carbon balance at lower irradiance than hardened seedlings did. The hardening procedure did not appear to be an advantageous method during seedling production. Long-term exposure to either low or high light did not cause significant leaf anatomical adjustments. However, the low light seedlings showed higher leaf area and chlorophyll content than those exposed to higher light intensity did, which enabled shaded seedlings to maximize the captured light. Furthermore, the high non-photochemical dissipation allowed rapid acclimation to excessive light exposure. These responses allow macaw palm cultivation and establishment in very different light environments.

中文翻译：

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金刚鹦鹉棕榈幼苗对对比光环境的适应反应。

在暴露于高光和低光环境的 30 日龄幼苗中评估了金刚鹦鹉棕榈 (Acrocomia aculeata) 的光合调节，以及从低光到高光的突然转移，并与苗圃中使用的硬化方案进行了比较。此外，我们还评估了长期暴露（265 天）高光和低光环境的反应。金刚鹦鹉棕榈幼苗表现出一种有效的机制，可以在稀缺条件下最大限度地捕获光线，并消散多余的能量，以避免在高光下损坏光系统 II。当暴露在过量的光线下时，幼苗表现出低饱和辐照度，但没有光抑制。当在低光强度下生长时，与硬化幼苗相比，幼苗表现出更高的光化学效率，并在较低的辐照度下通过正碳平衡最小化呼吸成本。在幼苗生产过程中，硬化程序似乎不是一种有利的方法。长期暴露在弱光或强光下并不会引起明显的叶子解剖结构调整。然而，低光幼苗比暴露在较高光强度下的幼苗表现出更高的叶面积和叶绿素含量，这使得遮荫幼苗能够最大限度地捕获光线。此外，高非光化学耗散允许快速适应过度光照。这些反应使得金刚鹦鹉棕榈树能够在非常不同的光照环境中种植和建立。