Studies on the Photosynthetic Tissues in the Leaves of Cereal Crops : I. The mesophyll structure of wheat leaves inserted at different levels of the shoot.

Abstract

The mesophyll structure of leaves inserted at different levels of the main shoot of wheat plants were observed. In the leaves of wheat plant, most of the mesophyll cells, the arm-palisade cells, have several lateral protuberances developed at right angles to the leaf surface. The number of protuberances in a mesophyll cell increase from the lower to the upper leaves. The average cell length is longer in the upper leaves than that in the lower, and there are positive linear relationships between the number of protuberances and the cell length as far as the leaves in the same levels are concerned. The ratio of the protuberance length to the cell width is higher in the upper leaves. The diameter of protuberance is shorter in the upper leaves. In the leaves at lower levels, the protuberance diameter decreases from the base to the top of leaf portions, on the other hand, such a obvious relation is not seen in the upper leaves. The ratio of the cell surface to the cell volume is raised as the number of protuberances increase, and the number of cells per unit leaf area is increased from the lower to the upper leaves. Therefore, the total cell surface per unit leaf area is greater in the upper leaves, comparing with that in the lower leaves. Generalizing from the observations in this study, it may be concluded that the upper leaves have a relatively more strongly developed arm-palisade tissue than the lower leaves.