TY - JOUR
T1 - Far-red radiation promotes growth of seedlings by increasing leaf expansion and whole-plant net assimilation
AU - Park, Yujin
AU - Runkle, Erik S.
N1 - Funding Information:
This research is supported by Osram Opto Semiconductors; the USDA-ARS Floriculture and Nursery Research Initiative; the USDA National Institute of Food and Agriculture, Hatch project 192266; Michigan State University's (MSU) AgBioResearch and Project GREEEN; and horticulture companies supportive of MSU floriculture research. We thank C. Raker & Sons for donation of plant material and Nate DuRussel for technical assistance. We also thank Dr. Bert Cregg (Department of Horticulture, MSU) and Dr. Thomas Sharkey (Department of Biochemistry and Molecular Biology, MSU) for valuable input on this manuscript.
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/4/1
Y1 - 2017/4/1
N2 - By definition, photosynthetically active radiation (PAR) includes wavelengths between 400 and 700 nm and thus, far-red radiation (FR, 700–800 nm) is excluded when the photosynthetic photon flux density (PPFD) is measured and reported. However, FR radiation [and the ratio of red (R; 600–700 nm) to FR] regulates phytochrome-mediated morphological and developmental plant responses to promote radiation capture and survival under shade. We postulated that the inclusion of FR in a radiation spectrum would have little effect on photosynthesis but would increase radiation capture and plant growth, while accelerating the subsequent flowering of shade-avoiding species. Geranium (Pelargonium × hortorum), petunia (Petunia × hybrida), snapdragon (Antirrhinum majus), and impatiens (Impatiens walleriana) were grown at 20 °C under an 18-h photoperiod provided by sole-source lighting from light-emitting diodes that included 32 μmol m−2 s−1 of blue and the following intensities of R and FR radiation: R128 (128 μmol m−2 s−1 of R), R128 + FR16, R128 + FR32, R128 + FR64, R96 + FR32, and R64 + FR64. Plant height in all species studied and total leaf area of geranium and snapdragon linearly decreased as the R:FR (or the estimated phytochrome photoequilibrium) of each treatment increased. In geranium and snapdragon, the increase in total leaf area (by 7%) with the addition of FR to the same PPFD subsequently increased shoot dry weight (DW) (by 28–50%) while the increase in total leaf area (by 30–40%) with the partial substitution of R with FR partly compensated for the reduction in PPFD (by 40%), producing a similar shoot DW. Whole-plant net assimilation of geranium, snapdragon, and impatiens increased with additional FR radiation, showing a linear relationship with the calculated yield photon flux density of each radiation treatment. In addition, inclusion of FR during seedling growth promoted flowering in the long-day plant snapdragon. We conclude that FR radiation increases plant growth indirectly through leaf expansion and directly through whole-plant net assimilation and in at least some species, promotes subsequent flowering.
AB - By definition, photosynthetically active radiation (PAR) includes wavelengths between 400 and 700 nm and thus, far-red radiation (FR, 700–800 nm) is excluded when the photosynthetic photon flux density (PPFD) is measured and reported. However, FR radiation [and the ratio of red (R; 600–700 nm) to FR] regulates phytochrome-mediated morphological and developmental plant responses to promote radiation capture and survival under shade. We postulated that the inclusion of FR in a radiation spectrum would have little effect on photosynthesis but would increase radiation capture and plant growth, while accelerating the subsequent flowering of shade-avoiding species. Geranium (Pelargonium × hortorum), petunia (Petunia × hybrida), snapdragon (Antirrhinum majus), and impatiens (Impatiens walleriana) were grown at 20 °C under an 18-h photoperiod provided by sole-source lighting from light-emitting diodes that included 32 μmol m−2 s−1 of blue and the following intensities of R and FR radiation: R128 (128 μmol m−2 s−1 of R), R128 + FR16, R128 + FR32, R128 + FR64, R96 + FR32, and R64 + FR64. Plant height in all species studied and total leaf area of geranium and snapdragon linearly decreased as the R:FR (or the estimated phytochrome photoequilibrium) of each treatment increased. In geranium and snapdragon, the increase in total leaf area (by 7%) with the addition of FR to the same PPFD subsequently increased shoot dry weight (DW) (by 28–50%) while the increase in total leaf area (by 30–40%) with the partial substitution of R with FR partly compensated for the reduction in PPFD (by 40%), producing a similar shoot DW. Whole-plant net assimilation of geranium, snapdragon, and impatiens increased with additional FR radiation, showing a linear relationship with the calculated yield photon flux density of each radiation treatment. In addition, inclusion of FR during seedling growth promoted flowering in the long-day plant snapdragon. We conclude that FR radiation increases plant growth indirectly through leaf expansion and directly through whole-plant net assimilation and in at least some species, promotes subsequent flowering.
KW - Controlled environments
KW - Dry mass accumulation
KW - Flowering
KW - Phenotypic plasticity
KW - Photosynthesis
KW - Shade-avoidance response
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U2 - 10.1016/j.envexpbot.2016.12.013
DO - 10.1016/j.envexpbot.2016.12.013
M3 - Article
AN - SCOPUS:85009958002
SN - 0098-8472
VL - 136
SP - 41
EP - 49
JO - Environmental and Experimental Botany
JF - Environmental and Experimental Botany
ER -