Morphogenesis of sporotrophophyll leaves in Platycerium bifurcatum depends on the red/far-red ratio in the light spectrum

Abstract

Although the fern Platycerium bifurcatum is popular among the producers of ornamental plants, it is a species of relatively poorly known physiology. Studies concerning the impact of the red/far-red (R/FR) ratio on photomorphogenesis refer primarily to spermatophytes. However, quite different phytochrome response mechanism functions in ferns, involving the localization of physiologically active form of phytochrome in the cytoplasm, without translocation to the nucleus. This work determined the reaction of young fern sporotrophophylls to the change of the R/FR ratio and investigated sporophyte ontogeny in various spectral light composition using nondestructive testing methods. It has been shown that the development of morphogenic sporophyte depends on the R/FR ratio. At a high R/FR ratio, sporotrophophylls showed a slower growth compared to those growing at a low value. A high R/FR value resulted in lower photochemical performance of PSII and adverse changes in the functioning of the acceptor portion of the PSII reaction center, while the PSII vitality analysis indicated the positive effect of simulated shadow. The value of the R/FR ratio did not affect the intensity of blue-green leaf fluorescence. However, the fluorescence intensity of red and far-red was significantly higher in plants growing at higher R/FR values. The analysis of leaf optical properties indicated higher concentrations of carotenoids and anthocyanins in the leaves of plants grown under the lower R/FR ratio. Determining the effect of spectral light composition on the physiology of this species may be useful for plant breeders and for the protection of these epiphytes in natural habitats.

A Low Ratio of Red/Far-Red in the Light Spectrum Accelerates Senescence in Nest Leaves of Platycerium Bifurcatum

“…2f and g). The parenchyma cells located deeper were larger with intercellular spaces, however, compared to the sporotrophophyll leaves, the intercellular spaces were significantly smaller (Oliwa et al, 2016). Such a structure of the parenchyma is associated with the function of collecting and storing water by the young nest leaves.…”

“…The overall shape of the spectrum and the wavelengths of the main bands of fluorescence in the nest leaves of P. bifurcatum, both in the blue-green and red spectrum, were similar to the sporotrophophyll leaves (Oliwa et al, 2016).…”

“…The principle functions of the nest leaves, i.e., collection of water and minerals and anchoring the plant to the substrate, force different structure and physiology of these organs in comparison with sporotrophophylls (Oliwa et al, 2016). Relatively short, intense growth in the size of the lamina was observed in the development of the nest leaves combined with the formation of characteristic venation and rapid loss of chlorophyll and assimilation properties in browning leaves ( (Fig.…”

“…For this reason, efficiency parameters of PSII in H-R/FR in the aforementioned conditions were not analyzed. Earlier observations of sporotrophophyll leaf development in P. bifurcatum also suggested that the high red/far-red ratio slowed down the processes of morphogenesis of the leaf lamina, even though the nest leaves demonstrated a weaker response to changes in the R/FR ratio than sporotrophophylls (Oliwa et al, 2016). Behera and Biswal (1990) indicate that red light delays senescence process in ferns.…”

“…These conditions were achieved by limiting the far-red radiation (730 nm). A slight increase in the intensity of radiation in the blue range allowed compensating for the amount of energy that reached the plants in both groups (Oliwa et al, 2016). All plants were grown at 25°C/15°C with a photoperiod of 16/8 hours (day/ night, respectively).…”