Journal
PHOTOSYNTHETICA
Volume 43, Issue 1, Pages 55-64Publisher
ACAD SCI CZECH REPUBLIC, INST EXPERIMENTAL BOTANY
DOI: 10.1007/s11099-005-5064-x
Keywords
carbon budget; chlorophyll fluorescence; CO2 re-fixation; floral photosynthesis; nectaries; sepals
Categories
Ask authors/readers for more resources
Photosynthetic irradiance response of vegetative and reproductive structures of the green-flowered deciduous perennial green hellebore was studied by the comparative use of chlorophyll (Chl) fluorescence techniques and gas exchange measurements. All the Chl-containing organs (leaves, sepals, stalks, and fruits) examined were photosynthetically active showing high intrinsic efficiencies of photosystem 2 (F-v/F-m: 0.75-0.79) after dark adaptation. Even in the smaller fertile and sterile parts of the flower (nectaries and anthers) a remarkable photosynthetic competence was detected. With increasing photon flux densities (PFD) electron transport rates, actual quantum yields, and photochemical quenching coefficients of the main photosynthetic organs decreased in the order: leaf > sepal > fruit > stalk. At moderate to high PFDs the sepals achieved maximum electron transport rates corresponding to about 80 % of concomitant mature leaves. In contrast, maximum net photosynthetic rate of the sepals [2.3 mu mol(CO2) m(-2) s(-1)] were less than one fourth of the leaves [10.6 mu mol (CO2) m(-1) s(-1)]. This difference is explained by a 70-80 % lower stomatal density of sepals in comparison to leaves. As the basal leaves emerge late during fruit development, the photosynthetically active sepals are a major source of assimilates, contributing more than 60 % of whole-plant CO2 gain in early spring. The ripening dehiscent fruits are characterized by an effective internal re-fixation of the respirational carbon loss and thus additionally improve the overall carbon budget.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available