Frond Optical Properties of the Fern Phyllitis scolopendrium Depend on Light Conditions in the Habitat

Abstract

Ferns display an elevated degree of phenotypic plasticity to changes in irradiance levels; however, only a few reports deal with their response to different light conditions. To get an insight into the extent of phenotypic plasticity of the fern Phyllitis scolopendrium, thriving in a forested area along a radiation gradient at the entrance of a cave, we examined selected biochemical, morphological, and physiological frond traits of the ferns from three different habitats. Sampling was performed two times during the vegetation season, in April and June. We also measured frond optical properties to point out the differences in leaf/light interactions between different plant samples. According to frond size, the middle habitat, receiving 125 µmol m−2s−1 of photosynthetically active radiation at both sampling times, appeared to be the most favourable. The production of UV-absorbing substances was highest in the habitat with the lowest radiation level. At the beginning of the season, the level of photosynthetic pigments in this habitat was the same as in the other habitats, while it was significantly lower in June when the tree canopy was closed. Frond reflectance was similar when comparing habitats and different sampling times. The most significant differences were obtained in the UV-A and near-infrared regions. The reflectance spectra depended mainly on frond biochemical properties, which altogether explained 54% (p ≤ 0.05) of the spectra variability. Frond transmittance depended on both, morphological parameters, explaining 51% (p ≤ 0.05), and frond biochemistry, explaining 73% (p ≤ 0.05) of the spectra variability. P. scolopendrium was revealed to be highly plastic regarding light conditions. The shapes of the frond reflectance and transmittance optical curves were similar to those typical of leaves of seed plants. The fronds exhibited high morphological plasticity when comparing different habitats. However, their biochemical and optical traits differed more between the two sampling times than between the habitats.

Comparative Study of Temporal Changes in Pigments and Optical Properties in Sepals of Helleborus odorus and H. niger from Prebloom to Seed Production

“…The reflectance and transmittance spectra in the two studied species had similar shapes, which confirmed the important role of sepal chemistry in shaping their optical properties, as shown by many other studies [ 12 , 36 ]. As expected, we obtained mainly negative relationships between the reflectance and transmittance spectra in the different regions and different sepal chemical traits, especially for anthocyanins and chlorophylls, as was also the case in other studies [ 5 ]. The strongest correlations were obtained in the early developmental phase.…”

“…The development of flowers before leaf unfolding depends on carbohydrates accumulated in the underground organs [ 1 ]. In addition, some of the plant species have evergreen leaves [ 5 ], while others have green organs other than leaves, such as bracts and sepals [ 6 ]. These green structures contribute significantly to the plant energy budget [ 7 , 8 ], since they harvest solar energy in the early season, before canopy leaves unfold [ 6 ].…”

Bracts and basal leaves in Hacquetia epipactis differ in their spectral signatures

“…This increase was possibly related to other functions that these compounds have, including protection against pathogens and h e r b i v o r e s . F o r e x a m p l e , i n t h e f e r n P h y l l i t i s scolopendrium, the highest levels of UV-absorbing compounds were measured in plants from the most shady habitat (Grašič et al 2020). However, in the case of Hypericum Fig.…”