Leaf Chlorophyll Fluorescence and Gas Exchange Response to Different Light Levels in <i>Platycerium bifurcatum<i/>

Abstract

Problem statement: Platycerium bifurcatum (Cav.) C. Chr. is epiphytes which lives in forest canopy and commonly used for its ornamental value. In these environments, they were always exposed to many types of stresses such as high light intensity. Light intensity plays an important role in affecting plant's physiological performance. Therefore, the purpose of this study was to investigate physiological responses of P. bifurcatum to light stress. Approach: In this study, P. bifurcatum were grown under four different Photosynthetic Active Radiation (PAR) levels which were 20 µmol mT3) and 1500 µmol m −2 s −1 (T4). Leaf gas exchange and chlorophyll fluorescence were used to evaluate the stress response of various levels of light intensity. All measurements were carried out on weekly basis for twelve weeks. Results: Results showed that A net value of T1, T2 and T3 in the range near to the average A net value for most epiphytes. Conversely, T4 showed lower value in A net with 1.797 µmol CO 2 m −2 s −1 . Fv/Fm ratio in T3 and T4 were below 0.8indicates that there was a sign of stress occurred in these treatments. However A net of T3 was not affected although there have been event of photoinhibition observed in the treatment. On the contrary, T4 was fully affected by high light intensity as there was a reduction of Fv/Fm ratio and also A net . T1 and T2 of A net and Fv/Fm ratio values ranged of unstressed plants after subjected to light treatment. Conclusion: Measurement of leaf chlorophyll fluorescence and gas exchange are useful to detection of light stress in P. bifurcatum. Different levels of light intensity were significantly affecting physiological attributes of P. bifurcatum.

Different response of photosynthetic apparatus to high-light stress in sporotrophophyll and nest leaves of Platycerium bifurcatum

“…The previous research on P. bifurcatum physiology was primarily associated with ensuring proper growing conditions and micropropagation methods of these ornamental plants (Aspiras et al 2010, Liao andWu 2011). In addition, drought stress response was investigated by Rut et al (2003), and the subject of intense light stress was studied by Sanusi et al (2011). However, there is still a lack of information on the response of the photosynthetic apparatus to the sudden increase in light intensity, e.g., after tree logging in a large forest area.…”

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

“…A significant decrease in the PSII photochemical efficiency was recorded in plant leaves exposed to H-R/FR after 3 months of growth compared with that observed after 1 month (Table 1). Sanusi et al (2011) demonstrated that longer exposure of P. bifurcatum to intense sunlight above 200 lmol (quantum) m -2 s -1 contributed to the reduction of F V /F M , although it was not yet a sign of photoinhibition, which is diagnosed only at the PAR intensity of 1500 lmol (quantum) m -2 s -1 . This allowed to conclude that the plants growing under H-R/ FR responded to the information about a higher light energy dose.…”

“…Physiological studies conducted so far have been mainly limited to determination of the response of this plant to drought stress and a description of micropropagation methods for commercial purposes (Rut et al 2003;Aspiras 2010, Liao andWu 2011). In recent years, research has been initiated on the effects of light intensity on the functioning of photosynthetic apparatus of P. bifurcatum (Sanusi et al 2011), which natural habitats are increasingly exposed to stress radiation. It is associated with increased anthropogenic pressure in the areas of its occurrence, particularly with rainforest deforestation.…”

“…Plant response to the R/FR ratio is a key element of the so-called strategy of shade avoidance. Considering the information on the sensitivity of plants of the genus Platycerium to the high light intensity (Sanusi et al 2011), it was investigated whether an increase in the R/FR ratio affected the process of photomorphogenesis of P. bifurcatum sporophytes. The applied experimental conditions allowed to trace the differences in sporophyte ontogeny in various light spectral compositions.…”

A State of PSI and PSII Photochemistry of Sunflower Yellow-Green Plastome Mutant

“…F is a value of light-adapted steady state fluorescence. Fv/Fm is a value of PSII maximum quantum yield after dark adaptation and is an informative criteria to study induced changes in PSII (Sanusi et al, 2011). Y(II) is a value of PSII effective quantum yield.…”