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representation of three cucumber chilling experiments conducted under controlled conditions [5.5 h (0800 to 1330 hr ) at 4 °C (immediate and constant) where the light level was 270 μmol·m −2 ·s −1 photosynthetic photon flux ( PPF ) supplied by only cool white

days ( Fig. 1 ). This resulted in precise control, and all supplemental lighting treatments received a DLI of 12.0 ± 0.0 mol·m −2 ·d −1 every day. Fig. 1. Photosynthetic photon flux density ( PPFD ) over the course of a 24-h period on an overcast day

uptake during the day (○), during the night (•), and over a daily 24-h period (△), in Phalaenopsis amabilis ‘TS97’ leaves. The photosynthetic photon flux ( PPF; μmol·m −2 ·s −1 ) measured on the leaves were shown in the left corner ( A ). Levels of ( C

below a photosynthetic photon flux ( PPF ) of 200 μmol·m −2 ·s −1 , the leaf assimilation of chrysanthemum can be considered as responding close to linearly to irradiance levels. Supplemental light levels differ but are often lower than 200 μmol·m −2 ·s

.5 µmol·m −2 ·s −1 far-red light; BRFR H = 15% blue and 85% red with additional 155 µmol·m −2 ·s −1 far-red light; BG L R = 9% blue, 6% green, and 85% red; BG H R = 5% blue, 10% green, and 85% red. The photosynthetic photon flux density of each lighting

(top) and a simplified diagram of the duty cycle control board (bottom). A fluorometer is used to measure the quantum yield of photosystem II and the datalogger calculates the electron transport rate from this and the photosynthetic photon flux density

known as integrated photosynthetic photon flux (IPPF), Chun et al., 2001 ] is not yet a commonly-used metric in the scientific community, it can normalize quantifications of light “doses” from different production scenarios (e.g., SS vs. greenhouse) and

) . Fig. 1. The spectral distribution of seven light quality treatments delivered by blue (B; 400–500 nm) and red (R; 600–700 nm) LEDs or cool-white fluorescent lamps, each delivering a photosynthetic photon flux of 160 μmol·m −2 ·s −1 . The value after

sunlight plus direct (SL; 90 μmol·m −2 ·s −1 ) or diffuse lighting [photoperiodic lighting (PL); 3 μmol·m −2 ·s −1 ] from high-pressure sodium (HPS) lamps. Lamps were operated when the ambient greenhouse photosynthetic photon flux ( PPF ) was less than 400

collected from D. surculosa ‘Florida Beauty’ stock plants in late spring. The stock plants had grown in a shaded greenhouse for 3 years under a maximum photosynthetic photon flux ( PPF ) density of 300 μmol·m −2 ·s −1 at the University of Florida's Mid