Stem Elongation of Chrysanthemum in Response to End-of-Day Light Treatments and Photoperiod

Lund, Janni Bjerregaard; Körner, Oliver; Aaslyng, Jesper Mazanti; Blom, Theo J.

doi:10.17660/actahortic.2008.766.12

Cited by 1 publication

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, another possible explanation for the lack of significant EOD-FR-induced shade avoidance responses in our study may have been due to the photoperiod duration. However, Lund et al (2008) also found that EOD-FR applied after longer photoperiods resulted in increased leaf area relative to the shorter photoperiods followed by EOD-FR treatments. Different photoperiod durations were not implemented in the present study so the effect of photoperiod duration on EOD-FR treatments could not be examined.…”

Section: Resultsmentioning

confidence: 85%

“…Lund et al (2007) found that chrysanthemum (Chrysanthemum morifolium) 'Coral Charm' grown under a 9-hour photoperiod and 30-minute EOD-FR treatments with R:FRs of 0.4 or 0.7 displayed increased plant height compared with an EOD-R (R:FR 5 2.4) treatment; these authors cited earlier work by Mortensen and Moe (1992) showing that natural EOD radiation quality did not affect chrysanthemum grown under longer photoperiods (12-18.5 hours), as well as work by Downs et al (1957) showing that the effect of EOD-FR on elongation was reduced for bean (Phaseolus vulgaris) when grown under longer relative to shorter photoperiods. Lund et al (2008) conducted further work using the same EOD-FR treatments and study taxa as Lund et al (2007), but with photoperiod durations of 9, 14, and 19 hours; they found EOD-FR was more effective in promoting an increase in plant height when grown under the 9-hour treatment compared with the 14-and 19-hour treatments. Thus, another possible explanation for the lack of significant EOD-FR-induced shade avoidance responses in our study may have been due to the photoperiod duration.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

A Low Ratio of Red to Far-red Radiation (R:FR) Throughout the Photoperiod but Not at End-of-day Promotes Shade Avoidance for Petunia ×hybrida Seedlings

Percival,

Craver

2024

horts

View full text Add to dashboard Cite

Electric lighting is often necessary to achieve a target daily light integral (DLI) for the production of high-quality young annual bedding plants (plugs). Early in production, plugs have a low leaf area index that limits light interception and likely results in wasted radiation supplied by electric sources. Previous research has shown that the addition of far-red radiation (700–780 nm) to the radiation spectrum in sole-source lighting experiments or the use of end-of-day far-red (EOD-FR) radiation treatments can promote an increase in leaf expansion and leaf area for many species. However, leaf expansion in response to far-red radiation may depend on other factors such as the ratio of red (600–699 nm) to far-red radiation (R:FR) and air temperature. Thus, the objectives of this work were to examine the effects of far-red radiation applied throughout the photoperiod and as an end-of-day radiation treatment on the morphology of petunia ‘Dreams Midnight’ seedlings grown under different temperature conditions. Specifically, petunia seed was sown in 128-cell trays and moved to one of two growth chambers set at 16 or 21 °C when cotyledons unfolded. Seedlings received an equal total photon flux density (400–780 nm) of 164 µmol·m−2·s−1 for a 17.25-hour photoperiod, and either a high (∼10.7) or low R:FR (0.5). Low R:FR-treated seedlings were grown at a constant temperature of either 16 or 21 °C and placed under blackout conditions at the end of the photoperiod. High R:FR-grown seedlings received either a 1-hour end-of-day white (EOD-W) or EOD-FR treatment at the end of the photoperiod, and were grown at a constant 16 or 21 °C; one EOD-FR treatment was also shifted from the 21 °C chamber to the 16 °C at the end of the photoperiod for both the EOD-FR treatment and subsequent dark period. Seedlings were harvested at 21 and 28 days after treatment initiation. For petunia seedlings grown at 21 °C, EOD-FR treatments had minimal effect on morphology or dry mass as all measured parameters, including total and average leaf area and stem length, were similar to EOD-W treatments. In contrast, low R:FR-treated seedlings showed responses characteristic of plants grown under shade, including significant stem elongation, an increase in total and average leaf area, and a reduction in leaf mass per unit area. As expected, production at 16 °C slowed the growth of petunia seedlings resulting in much smaller plants compared with the 21 °C grown plants, but shade responses such as elongated leaves and stems under a low R:FR were apparent. The EOD-FR–treated seedlings that received the diurnal temperature shift also showed reduced leaf area and dry mass compared with their constant 21 °C counterparts. Shade responses were observable at both 16 and 21 °C for low R:FR-grown plants, but the quantifiable impact of temperature on far-red responses could not be fully determined in the present study. Further research is warranted investigating crop responses to far-red radiation as well as potential interacting environmental factors as the promotion of morphological responses, such as leaf expansion, early in production may prove a useful strategy.

show abstract

Section: Resultsmentioning

confidence: 85%