Fig. 7.

CO₂ assimilation and ¹⁴C feeding in cucumber fruits. (A) The response curve of assimilation rate to photon flux density (PFD). (B) CO₂ evolution rate of exocarp (peels) in the dark and illuminated (1000 µmol quanta m^–2 s^–1 irradiance) conditions during ‘ZN16’ fruit development. The net photosynthetic rate per unit fruit surface area (black squares) was the difference between the CO₂ evolution rates in the light and dark. All data above were determined at ambient CO₂ between 390 mbar and 410 mbar and at air temperature of 28°C. (C) CO₂ evolution rate of intact fruit, peels, and internal tissue under dark and light (1000 µmol quanta m^–2 s^–1 irradiance) conditions, respectively (Variety ‘ZN16’, 9 DAA). Error bars represent the SD, n=3. (D, E) Allocation of ¹⁴C in cucumber fruits. Lower non-bagged (D) or bagged (E) fruits were fed with 3.7 × 10⁶ Bq ¹⁴CO₂ (blue arrows). After 24 h, specific activities (Bq g^–1 DW) of lower and upper fruits (red arrows) were determined. The means (n=3) followed by different letters indicate statistically significant differences according to Tukey’s test (P<0.05). Values in parentheses are percentages of the total measurements. (F) ¹⁴C autoradiograph of non-darkened fruit (upper photo) and darkened fruit (lower photo) at 1 h after the ending of ¹⁴CO₂ feeding.