Studies on Growth and Photosynthetic Capacity of Leaves in Eggplant (Solanum melongena L.)

In comparison of 9 leaves embryologically below the first flower of eggplant (Solanum melongena L., cv. Senryo No. 2), external and internal anatomy and photosynthetic capacity varying with the time after transplanting at the 2-leaf stage were investigated.1. The increase in laminar dry weight per unit laminar length during leaf expansion was highest in leaf 5 (abbreviated as L5. L1 is the basal) and lower in leaves below and above it. While, the increase in laminar area per unit laminar length was higher in upper leaves.2. Specific laminar dry weight (SLW) was higher in upper leaves at unfolding. Then, it decreased in upper leaves and slightly increased in lower leaves until it became almost constant and differed little with leaf position 35 days after transplanting. This trend was especially true for the values of SLW/laminar thickness, which, however, was slightly higher in upper leaves after becoming constant.3. The numbers of palisade parenchyma and mesophyll cells per unit laminar area were higher at unfolding regardless of leaf position, and then decreased until becoming almost constant. Within a leaf, they were always higher at the basal, middle and distal parts in this order, but differed little after taking constant values. Palisade cells enlarged with leaf growth, but were always greater in upper leaves.4. The number of chloroplasts per palisade cell was slightly greater at the distal, middle and basal parts in this order. It increased with leaf growth and the increase stopped in L3, L5 and L8 at the 7-, 8- and 11-leaf stages, respectively.5. The chlorophyll content per unit laminar area increased with leaf growth. It reached the maxima at the 8- and 10-leaf stages in L3 and L5, and in L8, respectively, and then decreased. The maximal values were higher in upper leaves. The total nitrogen content per unit laminar area decreased with leaf growth, and the decrease was greater in upper leaves.6. The photosynthetic rate increased from unfolding and reached the maxima of 21.2 (mgCO2 dm-2 h-1) for L3, 23.3 for L5 and 23.7 for L8 at the 8-, 10- and 11-leaf stages, respectively. The chlorophyll content was only parameter that showed a high correlation with the photosynthetic rate throughout the period up to the 14-leaf stage.7. The stomatal density on the adaxial side of laminar was about a half of that of the abaxial side. Stomatal density was higher at the basal, middle and distal parts in this order on both sides and decreased with leaf growth. In upper leaves, it was higher at unfolding and the decreasing rate thereafter was also higher than in lower leaves.