Journal
ENVIRONMENTAL AND EXPERIMENTAL BOTANY
Volume 155, Issue -, Pages 345-359Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.envexpbot.2018.07.021
Keywords
Light-emitting diode; Phytochrome photostationary state; Light quality; Light intensity; Plant species
Categories
Funding
- Natural Sciences and Engineering Research Council of Canada
- Ontario Ministry of Agricultural, Food and Rural Affairs
Ask authors/readers for more resources
To explore the action mode of blue light on elongation growth of bedding plants, the plant growth and morphology traits of petunia (Petunia x hybrida, 'Duvet Red'), calibrachoa (Calibrachoa x hybrida, 'Kabloom Deep Blue'), geranium (Pelargonium x hortorum, 'Pinto Premium Salmon'), and marigold (Tagetes erecta, 'Antigua Orange') were compared under four light quality treatments: (1) R, pure red light (660 nm); (2) B, pure blue light (450 nm); (3) BR, unpure blue light created by mixing B with a low level of R to provide B/R approximate to 9; (4) BRF, unpure blue light created by adding a low level of far red light to BR with red/far red approximate to 1. Continuous (24-h) light-emitting diode lighting with either 100 or 50 mu mol m(-2) s(-1) photosynthetic photon flux density at approximate to 23 degrees C was used with the above treatments. After 14-20 day of lighting treatment, B promoted elongation growth compared to R, as demonstrated by a greater canopy height, main stem length, intemode length, and daily main stem extension rate. However, BR showed similar or inhibitory effects on these traits relative to R, while BRF exhibited similar promotion effects as B. The calculated phytochrome photoequilibrium, an indication of phytochrome activity, was higher for R (0.89) and BR (0.74) than for B (0.49) and BRF (0.63). Adding red (or far red) light reversed the effects of B (or BR) on elongation growth and the phytochrome photoequilibrium, suggesting that blue light promotion of elongation growth is related to the lower phytochrome activity. Also, B and BRF, when compared to R or BR, promoted elongation growth to a greater degree at 50 than 100 mu mol m(-2) s(-1) for petunia and calibrachoa. In addition to the promoted elongation growth, B and BRF reduced side branch number, biomass allocation to side branches, leaf epinasty, leaf angle, and/or leaf chlorophyll content relative to R or BR, but increased individual leaf area, petiole length, and/or biomass allocation to main stem, which varied with different species. It suggests that the promoted elongation growth by blue light associated with lower phytochrome activity is one of shade-avoidance responses with varying sensitivity among species.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available