数種の疏菜の光合成と光質との関係
1973 年 29 巻 1 号 p. 17-23
詳細
1973 年 29 巻 1 号 p. 17-23
The experiments were carried out to clarify the relation between the photosynthetic rate of higher plants and light quality. Five species were employed. They hat been grown with gravel culture in greenhouse from February to April. Photosynthetic rate of single leaf was measured with an assimilation chamber under light of red, orange, yellow, green and blue of colored fluorescent lamps. The results were as follows.
(1) Photosynthetic rates of cabbage and swisschard showed maximum under the red light and minimum under the blue light. Photosynthetic rate decreased with the shorter wave length of light.
(2) In a case of lettuce, the red light showed the principal maximum and the blue light showed the second maximum. The green light had the least efficiency.
(3) Kidney bean and cucumber showed the principal maximum in the red light, but a difference of photosynthetic rate between the green light and blue light was not recognized.
The results of the first are in close agreement to Gabrielsen's experiment. The secend pattern is similar to Hoover's one. The third are an intermediate type between Gabrielsen's and Hoover's.
The discrepancy of photosynthetic activity in blue and green regions may be explained by means of the absorbing coefficient spectrum within the leaf.
The transmittive spectra of surface layers below the cuticle of cabbage and lettuce leaves (about 30μ thickness) were measured. Most of blue light is absorbed by the first 60μ-90μ surface layer. Green light is absorbed all over within the leaf. If we consider from a viewpoint of the light distribution, the former is not efficient to photosynthesis. The latter has the more efficiency. This means that a change in the absorbing coefficient Kλ gives variety to photosynthetic activity and that the greater absorbing coefficient Kλ has the less photosynthetic activity in thick leaf and much photosynthetic rate in thin leaf.
It is inferred that photosynthetic activity is decided by how the light is converged within leaf. Such results can be explained well by the application of Monsi-Saeki theory in plant canopy.
