Organization of Photosynthetic System of Dorsiventral Leaves as Adapted to the Irradiation from the Adaxial Side

Abstract

Terashima, I., & Takenaka, A. (1986, January). Organization of photosynthetic system of dorsiventral leaves as adapted to the irradiation from the adaxial side. In Biological Control of Photosynthesis: Proceedings of a Conference Held at the ‘Limburgs Universitair Centrum’, Diepenbeek, Belgium, 26–30 August 1985 (pp. 219-230). Dordrecht: Springer Netherlands. FIGURE 1. Calculated ratio of the light absorption within a leaf of Camellia japonica L. when irradiated at 680 nm (A) and at 550 nm (B).! 2e leaf (5 mg chlorophyll dm) is segmented parallel to the leaf surfaces into 10 imaginary layers so that ea~~ layer has 0.5 mg chlorophyll dm• The absorption rate by each layer was calculated theoretically (7-9) based upon the measurements of transmittance and reflectance (6). 2.2. Intra-leaf light environment of dorsiventral leaves As dorsiventral leaves have tissues of low absorbance (palisade tissue) and high absorbance (spongy tissue) in sunny and shady parts, respectively, the intra-leaf gradient in light environments is much more moderate than otherwise occurs. However, in spite of this moderating effect, there still exists steep gradient in light environments. Based on the data of transmittance and reflectance of paradermal sections of leaves of camellia japonica L.(6), intra-leaf distribution of light absorption was calculated for the cases of irradiation of monochromatic light at 680 nm (Fig. 1-A) and at 550 nm (Fig. 1-B) from the adaxial side. Although the effect of the differentiation of mesophyll into two optically different tissues is well understood by the results shown in Fig. 1-B, light absorption in abaxial mesophyll layers is much lower than those in adaxial mesophyll layers.