Abstract
This study was conducted to evaluate the physiological and growth responses of Sedirea japonica cultured in chambers under RCP 6.0 and different light conditions. S. japonica was grown in a soil–plant daylight system chamber under two treatments, a control (CO2 = 400 ppm) and a climate change treatment (CCT) (CO2 = 650 ppm, temperature = control + 3 °C), and three different shading treatments (60%, 90%, and no-shading). S. japonica showed the characteristics of typical Crassulacean acid metabolism (CAM) plants. As the shading rate increased, it increased chlorophyll content, leaf area, and leaf dry weight to efficiently absorb and use light. The CCT had a lower CO2 absorption rate, stomatal conductance, and growth rate and slightly higher water utilization efficiency than the control. This was because stomatal closure occurred in the CCT to reduce water loss due to a relatively higher temperature. As CO2 fixation decreased and consumption increased due to respiration, the overall growth was inhibited. The CCT without shading revealed a dynamic photoinhibition phenomenon showing a significant increase in ABS/RC, TRo/RC, ETo/RC, and DIo/RC and a decrease in PI ABS and DF ABS. In this group, leaf, root, and total dry weight, chlorophyll content, and carotenoid content were the worst growth indices.
Highlights
Sedirea japonica is a small epiphytic orchid that grows on a rock or tree and is characterized by 4–10 light greenish-white flowers in a racemose inflorescence between June and August [1]
The 5th Assessment Report presented by the Intergovernmental Panel on Climate Change (IPCC) indicated that when the global mean temperature increases by 1.5–2.5 ◦C or more, it will have a negative and irreversible effect on biodiversity and ecosystems, e.g., approximately 20–30% of the animal and plant species included in the assessment would become extinct and their geographical distribution range would be greatly altered [4]
The difference in daily mean relative humidity between the control and climate change treatment (CCT) samples was not large from August to mid-September; it became larger after mid-September (Figure 1)
Summary
Sedirea japonica is a small epiphytic orchid that grows on a rock or tree and is characterized by 4–10 light greenish-white flowers in a racemose inflorescence between June and August [1]. S. japonica is found in Korea, China, Japan, and Taiwan, it has almost disappeared in the wild due to indiscriminate harvesting [2,3]. It is registered as an endangered species in Japan and designated as a level 1 endangered species by the Ministry of Environment in South Korea [2,3]. The 5th Assessment Report presented by the Intergovernmental Panel on Climate Change (IPCC) indicated that when the global mean temperature increases by 1.5–2.5 ◦C or more, it will have a negative and irreversible effect on biodiversity and ecosystems, e.g., approximately 20–30% of the animal and plant species included in the assessment would become extinct and their geographical distribution range would be greatly altered [4]
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