Photosynthetic Characteristics of Cymbidium ‘Red Fire’ and ‘Yokihi’ at Different Developmental Stages

다국어 초록 (Multilingual Abstract)

Photosynthetic characteristics of two Cymbidium hybrids, ‘Red Fire’ and ‘Yokihi’, were investigated at different developmental stages. The net CO2 assimilation rate (An) as a function of incident photosynthetic photon flux (PPF), intercellular CO2 concentration (Ci), and relative humidity (RH) in a leaf chamber head was determined in a greenhouse with 1- and 2-year-old plant leaves. The maximum net CO2 assimilation rate (Anmax) in response to PPF of 1-year-old ‘Red Fire’ was 6.11 μmol·CO2·m-2·s-1 at 700 μmol·m-2·s-1 PPF, whereas it was 4.9 μmol·CO2·m-2·s-1at 500 μmol·m-2·s-1 PPF in ‘Yokihi’. Under low light intensity (below 250 μmol·m-2·s-1 PPF), An was more pronounced in ‘Yokihi’ than in ‘Red Fire’. In 2-year-old Cymbidium, however, the maximum An was less than 2 μmol·CO2·m-2·s-1in both cultivars at the same CO2 condition of 600 μmol·CO2·mol-1 air. The An increased in the leaves of 2-year-old plant under an elevated CO2 condition up to 1,500 μmol·CO2·mol-1 air with increasing PPF up to about 800 μmol·m-2·s-1.
The An increased with increasing Ci and showed the highest value when Ci was over 1,000 and 2,000 μmol·mol-1 air in ‘Red Fire’ and ‘Yokihi’, respectively. The carboxylation efficiency of ‘Red Fire’ and ‘Yokihi’ were 0.044 and 0.036 μmol·CO2·m-2·s-1, respectively, while An of ‘Yokihi’ was higher than that of ‘Red Fire’ at above 1,000 μmol·mol-1air Ci. The An tended to increase with RH, increasing from 15 to 70% in both hybrids. The Anmax of ‘Yokihi’ was observed at over 70% of RH, whereas 45% of RH was sufficient enough to show Anmax in ‘Red Fire’. The results shows that the photosynthetic characteristics of Cymbidium ‘Red Fire’ and ‘Yokihi’ can be increased by controlling the PPF, CO2, and RH conditions and the optimal conditions for maximum photosynthetic efficiency vary by cultivar,developmental stage, and greenhouse conditions.

참고문헌 (Reference)

• 1 신윤경, "팔레높시스 기내 배양 시 광도(PPF)가 묘의 생장, 광합성 및 순화에 미치는 영향" 한국원예학회 27 (27): 476-481, 2009
• 2 Hew, C.S., "The physiology of tropical orchids in relation to the industry" World Scientific 2004
• 3 Motomura, H., "The occurrence of crassulacean acid metabolism in Cymbidium (Orchidaceae) and its ecological and evolutionary implications" 121 : 163-177, 2008
• 4 Pridgeon, A., "The illustrated encyclopedia of orchids" Timber Press 2000
• 5 Pan, R. C., "Physiology of Cymbidium sinense: A review" 70 : 123-129, 1997
• 6 Wong, S.C., "Photosynthesis and photorespiration in some thin-leaved orchid species" 3 : 150-157, 1973
• 7 Yong, J. W. H., "Photoassimilate partitioning in the sympodial thin leaved orchid Oncidium Goldiana" The National Univ. 1995
• 8 Hew, C.S., "Pathway of carbon fixation in some thin leaved orchids" 4 : 154-157, 1989
• 9 Iqbal, R.M., "Mathematical models and response functions in photosynthesis: An exponential model, In Handbook of photosynthesis" Marcel Dekker Inc. 803-810, 1996
• 10 Lootens, P., "Irradiance, temperature, and carbon dioxide enrichment affect photosynthesis in Phalaenopsis hybrids" 33 : 1183-1185, 1998
• 11 Hew, C. S., "In vitro CO2 enrichment of CAM orchid plantlets" 70 : 721-736, 1995
• 12 Ota, K., "Effects of leaf age, inflorecence, temperature, light intentisy, and moisture conditions on CAM photosynthesis in Phalaenopsis" 60 : 125-132, 1991
• 13 Constable, G.A., "Effect of leaf position, expansion and age on photosynthesis, transpiration, and water use efficiency of cotton" 7 : 89-100, 1980
• 14 Fu, C.F., "Crassulacean acid metabolism in orchids under water stress" 143 : 294-297, 1982