Effect of end-of-day far-red light from a movable LED fixture on squash rootstock hypocotyl elongation

Zhen Chao Yang, Chieri Kubota, Po Lung Chia, Murat Kacira

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Effects of end-of-day far-red (EOD-FR) light on hypocotyl elongation of a commercial cucurbit rootstock were investigated using movable and stationary light fixtures, since adequate hypocotyl length is required in vegetable grafting. Seedlings of an interspecific squash 'Tetsukabuto' (Cucurbita maxima x Cucurbita moschata) were grown in greenhouse and subject to daily EOD-FR light treatments with various application methods. The response of seedling hypocotyl length was well described using a Michaelis-Menten-type saturation curve over the range of 0-8.8mmolm -2d -1 FR light doses, as we previously reported for tomato rootstocks. Using a near saturating dose of 4.0mmolm -2d -1 FR light, efficacy of a movable FR light fixture for EOD-FR light treatment was compared with that of a stationary FR light fixture. The movable light fixture was a 120-cm metal bar equipped with FR light emitting diodes (LEDs) and the application was tested at two different traveling speeds (0.78 and 3.13mms -1) with one and four repeated applications per day, respectively, to reach the same target FR light dose (4.0mmolm -2d -1). Regardless of traveling speed, the extent of hypocotyl elongation under the moving FR LED fixture was statistically the same as that under stationary LED fixture and was 55-69% greater than non-treated control, suggesting that EOD-FR light applications can be designed flexibly. As far as we are aware, this is the first paper demonstrating the effect of EOD light quality treatment using moving light fixtures.

Original languageEnglish (US)
Pages (from-to)81-86
Number of pages6
JournalScientia Horticulturae
StatePublished - Mar 1 2012


  • Controlled environment
  • Dose response
  • Grafting
  • Interspecific squash
  • Phytochrome

ASJC Scopus subject areas

  • Horticulture


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