High R/FR HPS-pulses enhance earliness of flowering of exacum (Exacum affine Balf. F.) and geranium (Pelargonium × hortorum L. H. Bailey)
Year: 1993
Type: article
Abstract: Four consecutive crops (Fall 1988, Winter 1989, Summer 1989 and Fall 1989) of exacum (Exacum affine Balf. f. ’Elfin’) and geranium (Pelargonium × hortorum L. H. Bailey ’Hollywood Star’ and ’Hollywood Red’) were grown in a greenhouse under three lighting treatments: ambient: 16-h high pressure sodium (HPS) lighting of 100 μmol m−2 s−1 between 0600 and 2200 h; and 16 h HPS-pulse lighting (45 s shut off, 90 s recharge) once every hour between 0600 and 2200 h. The growth index [(height × width)/2] of exacum plants was similar, regardless of the light treatment used. However the growth index of both geranium cultivars receiving HPS-pulse lighting was significantly less than those receiving the two other treatments. Exacum top dry weight was 225% greater under pulse lighting than under ambient light. During fall 1988, HPS-pulse lighting increased flower dry weight of Hollywood Red by 400% and 87% compared to ambient and HPS lighting, respectively. Key words: Exacum affine, HPS-pulse, Pelargonium × hortorum, photomorphogenesis, photosynthesis, photosynthetic photon flux
DOI: 10.4141/cjps93-155
Authors: Michel Tardif, Blanche Dansereau
Language: English
Topic: Light effects on plants
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: bronze
OpenAlex ID: W1980345164