Fig 1.
Spectral distribution of sole-source lighting treatments.
Six sole-source lighting treatments were delivered from mint white (MW), red (R), blue (B), and green (G) light-emitting diodes (LEDs) at total photosynthetic photon flux density (PPFD) = 160 μmol∙m−2∙s−1. The subscript values after each LED type indicate the percentages of the total PPFD delivered from each LED type.
Table 1.
Spectral characteristics of sole-source lighting treatments.
Six sole-source lighting treatments were delivered from mint white (MW), red (R), blue (B), and green (G) light-emitting diodes (LEDs) at total photosynthetic photon flux density (PPFD) = 160 μmol∙m−2∙s−1. The subscript values after each LED type indicate the percentages of the total PPFD delivered from each LED type.
Fig 2.
1931 CIE (x, y) chromaticity coordinates, correlated color temperature (CCT), and color rendering index (CRI) of sole-source lighting treatments.
Six sole-source lighting treatments were delivered from mint white (MW), red (R), blue (B), and green (G) light-emitting diodes (LEDs) at a total photosynthetic photon flux density (PPFD) = 160 μmol∙m−2∙s−1. The subscript values after each LED type indicate the percentages of the total PPFD delivered from each LED type. CIE coordinates (x, y) for each sole-source lighting treatment (symbols) with the black-body curve (black solid line) and CCT values are presented.
Table 2.
Photosynthetic photon efficacy (PPE) and dry weight gain per unit electric energy consumption (dry weight efficacy) for four species.
Begonia ‘Olympia Red’, geranium ‘Pinto Premium Deep Rose’, snapdragon ‘Liberty Classic Yellow’, and petunia ‘Wave Blue’ seedlings were grown for 34 d, 25 d, 24 d and 19 d, respectively, under six sole-source lighting treatments delivered from mint white (MW), red (R), blue (B), and green (G) light-emitting diodes at a total photosynthetic photon flux density (PPFD) = 160 μmol∙m−2∙s−1. The values after each LED type represent their percentages of the total PPFD.
Fig 3.
Plant height, total leaf area, fresh and dry weight for four species at the transplant stage (A-O).
Begonia ‘Olympia Red’, geranium ‘Pinto Premium Deep Rose’, snapdragon ‘Liberty Classic Yellow’, and petunia ‘Wave Blue’ seedlings were grown for 34 d, 25 d, 24 d and 19 d, respectively, under six sole-source lighting treatments delivered from mint white (MW), red (R), blue (B), and green (G) light-emitting diodes at a total photosynthetic photon flux density (PPFD) = 160 μmol∙m−2∙s−1. The values after each LED type represent their percentages of the total PPFD. Means with different letters are significantly different by Tukey’s honestly significant difference test (P < 0.05) and lack of mean separation indicates nonsignificance. Error bars indicate standard errors of 20 observational units [two replications with 10 subsamples (plants) per replication per species].
Fig 4.
Stem length and percentage of flowering plants for petunia after the transplant stage.
Stem length (A) and percentage of flowering plants (B) of petunia ‘Wave Blue’ grown for 39 d and 45 d, respectively, under six sole-source lighting treatments delivered from mint white (MW), red (R), blue (B), and green (G) light-emitting diodes at a total photosynthetic photon flux density (PPFD) = 160 μmol∙m−2∙s−1. The values after each LED type represent their percentages of the total PPFD. Stem length is presented relative to that of the plants grown under the B15R85 treatment. Percentage of flowering plants was calculated by dividing the number of plants that had visible buds by that of the total number of plants for each radiation treatment. Means with different letters are significantly different by Tukey’s honestly significant difference test (P < 0.05). Error bars for relative stem length and percentage of flowering plants indicate standard errors of 20 observational units [two replications with 10 subsamples (plants) per replication and species (n = 20)] and two replications (n = 2), respectively.