An important quality characteristic of pot, bedding and container plants is compactness. To keep plants compact, chemical growth regulators are used. Their use is, however, increasingly under pressure and it is expected that their use will be further restricted in the future. In three successive greenhouse tests, the effect of spectral composition of the light on compactness was investigated. In the 1st trial, in winter 2015/2016, a higher percentage of blue light and the absence of a natural twilight (by lighting until after the natural twilight) resulted in more compact Fuchsia plants, but not in the 4 Hibiscus species tested. In the 2nd trial, in autumn 2016, compactness of Fuchsia, pelargonium, petunia and violin was hardly affected. In the 3rd trial, from March 2017, with the same crops, the result depended on the crop and the cultivar. These results show that so far, perspectives for practical applications of blue light to affect compactness are still insufficient. Compactness was favorably affected by removing the natural twilight, which offers perspectives since it can be applied easily without additional costs.
Dieleman, A., van Noort, F., & Kromwijk, A. (2018). Sturen van compactheid met blauw lichten wegnemen van de schemering : onderzoek naar sturen compactheid met gebruik maken van lichtkleuren om gewasontwikkeling, strekking en groei te sturen: een studie naar blauw licht. (Rapport / Wageningen University & Research, BU Glastuinbouw; No. WPR-734). Wageningen University & Research, BU Glastuinbouw. https://doi.org/10.18174/440322