Actavia 0 NOMURA, K. SAITO, M. ITO, M. YAMANE, S. IWAO, T. TADA, I. YAMAZAKI, T. ONO, S. YASUTAKE, D. KITANO, M. Diurnal decline in the photosynthetic capacity of uppermost leaves in an eggplant canopy grown in a horticultural greenhouse 2022 2022-9-8 457-464 Parameters representing leaf photosynthetic capacity, namely, the maximal carboxylation rate (V<sub>cmax</sub>), maximal electron transport rate (J<sub>max</sub>), and triose phosphate-utilization rate (T<sub>p</sub>), can vary depending on various factors. The present study investigated diurnal variations in V<sub>cmax</sub>, J<sub>max</sub>, and T<sub>p</sub> of uppermost leaves of soil-grown, well-watered eggplant in a greenhouse based on the simultaneous measurements of leaf gas exchange and chlorophyll fluorescence. The values of net photosynthetic rates and electron transport rates plotted against intercellular CO<sub>2</sub> concentrations were noticeably higher in the morning than in the afternoon. Significant differences were detected among the values of V<sub>cmax</sub>, J<sub>max</sub>, and T<sub>p</sub> obtained at different times of day (08:30, 11:00, 13:30, and 16:00 h). All three parameters tended to decline as the time of day advanced; compared to the values at 08:30 h, V<sub>cmax</sub>, J<sub>max</sub>, and T<sub>p</sub> declined by approximately 15% at 16:00 h. Among the three parameters, T<sub>p</sub> appeared to be the most sensitive to time. 3 60