The Dependence of the Relation Between Light Quality and Photosynthesis on Optical and Anatomical Characterisyics of Leaves (1)

The relation between light quality and photosynthesis of leaves irradiated from both sides

Abstract

It was proved in the proceding paper that the action spectrum of photosynthesis in the leaf of higher plants differs with absorbing rate of each light of different wave length, assuming that the structure within the leaf was uniform.
From the viewpoint of optical and anatomical characteristics, the present paper discusses the dependence of the difference in the mesophyll structure on the action spectrum of photosynthesis by investigating each photosynthetic rate of leaves irradiated by red, green and blue light from adaxial side and both sides. Five plants, cabbage, Swiss chard, cucumber, kidney bean, and lettuce, were provided as materials. The results obtained were as follows:
1) The photosynthetic rates of Swiss chard, cabbage and lettuce, when irradiated by red or blue light from both sides, were much more than those obtained under the irradiation from adaxial side.
2) The photosynthetic rate of cucumber, when irradiated by red light from either adaxial side or both sides, was the same as that under blue light. The photosynthetic rate in green light was less for both sides than adaxial side.
3) In all cases, the photosynthetic rate of kidney bean when irradiated from adaxial side was much more than that for irradiation from both sides.
4) The efficiency of absorbed light in red and blue light depended on the variety of plants in the same way as the photosythetic rate. In green light, however, the efficiency was equal in all leaves whether irradiated from adaxial side or both sides.
5) The leaves of cabbage, Swiss chard, and lettuce had the uniform mesophyll layers. The leaves of cucumber and kidney bean had the palisade and the spongy tissue layers.
6) The transmission spectra of thin layers were the same anywhere within the mesophyll layer in the leaf of Swiss chard. But the transmission of thin layers within the palisade and the spongy tissue was not exactly alike in the léaves of cucumber and kidney bean. It was higher in the spongy tissue layer than in the palisade layer. The difference between these two layers increased at the wave length which gives lower transmission.