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# Characteristics of the Photosynthetic Apparatus and CO2-Fixation in the Flower Bud of Lilium. I. Corolla

Christophe Clément, Pierre Mischler, Monique Burrus and Jean-Claude Audran
International Journal of Plant Sciences
Vol. 158, No. 6 (Nov., 1997), pp. 794-800
Stable URL: http://www.jstor.org/stable/2475358
Page Count: 7
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## Abstract

In order to test the positive net ${\rm CO}_{2}\text{-fixation}$ ability of tepals in the flower bud of Lilium hyb. enchantment, photoautotrophic characters were studied during pollen development in tepals and then compared with those in the leaf. Although mesophyll structure, plastid ultrastructure, stomata density, and chlorophyll content were significantly different in both organs, tepals performed positive net ${\rm CO}_{2}\text{-fixation}$ from the microspore mother cell stage up to pollen mitosis but not during pollen maturation. The measurements of ${\rm CO}_{2}\text{-fixation}$ were performed in the linear part of the saturation curve of the L5 leaf at $100\ \mu {\rm mol}\ \text{photon}\ {\rm m}^{-2}\ {\rm s}^{-1}$. In the tepals, ${\rm CO}_{2}\text{-fixation}$ reached its maximal intensity at the tetrad stage with $1.83\pm 0.12\ \mu {\rm mol}\ {\rm CO}_{2}\ {\rm m}^{-2}\ {\rm s}^{-1}$, against $3.17\pm 0.27\ \mu {\rm mol}\ {\rm CO}_{2}\ {\rm m}^{-2}\ {\rm s}^{-1}$ in the L5 leaf. Under these conditions, tepal ${\rm CO}_{2}\text{-fixation}$ corresponded to 57.7% of the leaf assimilation, whereas the maximum chlorophyll concentration in the tepal represented 21.9% of the chlorophyll concentration in the leaf. The flower bud of Lilium may be considered not solely as a sink structure for the whole plant but also as a partly autonomous organ in terms of photosynthates.

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