Photosynthetic characteristics of Cymbidium ‘Red Fire’ and ‘Yokihi’ at different developmental stages

• Published in: Horticulture, environment and biotechnology 2013, Environment, and Biotechnology, 54(1), , pp.9-13
• Main Authors: Kim, Yoon Jin, Lee, Seung Youn, Kim, Ki Sun
• Format: Article
• Language: English
• Subjects: Agriculture; Biomedical and Life Sciences; Life Sciences; Plant Breeding/Biotechnology; Plant Ecology; Plant Physiology; Research Report; 농학
• ISSN: 2211-3452; 2211-3460
• DOI: 10.1007/s13580-013-0135-6

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