Effect of shading on leaf anatomy in konjak plant (Amorphophallus konjac K. koch).

Abstract

Konjak plants were grown under different light intensities; full sunlight, 30, 50 and 70% shading. Leaf anatomy was studied with a light microscopy and the following results were obtained. 1. The corm dry weight increased by shading and statistically higher values were obtained from plants in shading as compared with those in full sunlight (Table 1). 2. The length of whole leaf and each leaflet increased with decreasing light intensity, but the width of leaflets was not affected by shading. Accordingly, the leaf area increased about 3-30% by shading (Table 2). 3. The thickness of upper and lower epidermis, palisade and spongy tissues in leaflets decreased with decreasing light intensity. The number of cell layers in palisade and spongy tissues also decreased by the shading treatment (Table 3, 4). 4. The total palisade cell surface area per unit leaf area was decreased with decreasing light intensity, because of decrease in number of cells and cell volume, but the intercellular space of palisade tissue was larger in leaves developed in shade than those in full sunlight (Table 5). 5. The above-mentioned anatomical changes of the leaflet were more remarkable at the base of the leaflets than those at the top portion. 6. The number of chloroplasts per unit leaf area in palisade tissue was greatest at 1-2 weeks after shading treatment and decreased thereafter with aging. The number of chloroplasts of leaves grown under 50% and 70% shading decreased more gradually than those under full sunlight (Fig. 4). Based on these observations, the relationship between photosynthetic rate and anatomy of the leaflet was discussed.