Acclimation responses of macaw palm seedlings to contrasting light environments

Adriel N Dias,Kacilda N Kuki,João P Souza,Advanio I Siqueira-Silva,Eduardo G Pereira

doi:10.1038/s41598-018-33553-1

Adriel N Dias, Kacilda N Kuki + Show 3 more

Open Access

https://doi.org/10.1038/s41598-018-33553-1

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Abstract

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.

Highlights

Light is an essential resource for the growth and development of plants, and the main determining factors are intensity, quality, duration, and distribution of the photoperiod
In addition to the morphoanatomical plasticity, some plant species can adjust their photosynthetic responses to changes in irradiance, and these physiological variables play a decisive role in the acclimation of the plant to a
The seedlings grown under high light conditions showed significantly (p < 0.05) lower chlorophyll content indexes than seedlings that were transferred after 2 and 4 days did

Summary

Introduction

Light is an essential resource for the growth and development of plants, and the main determining factors are intensity, quality, duration, and distribution of the photoperiod. A similar seasonal effect can be observed in semi-deciduous tropical forests when the leaves fall from the canopy, which increases the light intensity that reaches the lower stratum[13]. This increased light intensity is a disadvantage to shade-tolerant species, whereas it favors the pioneers or the light-demanding species[13]. (Arecaceae), known as macaw palm, is found in savanna-like vegetation, semi-deciduous seasonal forests, and deforested areas, among other physiognomies of Central and South America[14,15] It preferentially occurs in areas of higher natural soil fertility and can occur in sandy and low-fertile soils[16]. Despite being described as a heliophytic species, little is known about the acclimatory responses of young macaw palm plants to light

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