Stomatal responses to CO/sub 2/ in Paphiopedilum and Phragmipedium: role of the guard cell chloroplast
A role of the guard cell chloroplasts in the CO/sub 2/ response of stomata was investigated through a comparison of the leaf gas exchange characteristics of two closely related orchids: Paphiopedilum harrisianum, which lacks guard cell chloroplasts and Phragmipedium longifolium, which has chlorophyllous guard cells. Leaves of both species had an apparent quantum yield for assimilation of about 0.05, with photosynthesis saturating at 0.300 to 0.400 millimoles per square meter per second. The response of assimilation to changes in CO/sub 2/ was similar in the two species, but the response of conductance was consistently weaker in Paphiopedilum than in Phragmipedium. The data suggest involvement of guard cell chloroplasts in the stomatal response to CO/sub 2/ and in the coupling of assimilation and conductance in the intact leaf.
- Research Organization:
- Stanford Univ., CA
- OSTI ID:
- 5818143
- Journal Information:
- Plant Physiol.; (United States), Vol. 77:2
- Country of Publication:
- United States
- Language:
- English
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