Lighting Requirements for Gerbera in Controlled Environments

The vibrant colors and distinctive form of gerbera daisies have secured their position as one of the world’s most commercially important cut flowers. Their cheerful flowers have a unique ability to brighten any environments.

As climate change and market competition continue to challenge the floriculture industry, CEA (Controlled Environment Agriculture) becoming the popular choice for higher yields and better quality gerbera plants. Whether propagated through in vitro methods in laboratory setting or produced as cut flowers in commercial greenhouses, gerberas demonstrate remarkable sensitivity to light parameters.

In this blog, we will talk about the intricate relationship between light and gerbera development in controlled environments, with particular focus on the distinct requirements in vitro propagation and in cut flower production.

Gerbera’s natural requirements

To create the ideal environment for thriving gerberas, it’s important to first understand their natural growth conditions.

Gerberas (Gerbera jamesonii) are tender perennials native to South Africa, commonly grown as annuals in cooler climates. They thrive in full sunlight, well-drained, slightly acidic soil, and require regular watering while allowing the soil to dry slightly between watering. Moderate temperatures and good air circulation are also essential for healthy growth.

In CEA, artificial lighting is crucial, especially in regions with low natural light, such as during the darker months at higher latitudes. Proper lighting ensures consistent growth and flowering, compensating for seasonal light deficiencies.

LED Lights in Gerbera Regeneration

In vitro propagation, or micropropagation, is a powerful technique used to grow large quantities of plants from a small amount of tissue in a controlled environment. For commercial gerbera growers, this method allows for the rapid production of healthy and uniform plants.

LED lights have become the optimal solution, offering energy efficiency and environmental benefits, while also promoting the growth of high-quality microplants. Several studies have explored how various light qualities impact plant performance.

Red and blue LED light may be suitable for in vitro regeneration of gerbera

Several studies have looked at how different LED light colors affect the growth of gerbera in vitro and they suggest that the combination of red and blue LEDs may be suitable for gerbera regeneration.

A study evaluated the acclimatization efficiency of Gerbera jamesonii 'Big Apple' shoots rooted in vitro under different LED lights (blue, red, and a blue and red mix at 7:3) compared to a fluorescent light control [1]. Shoots rooted under red light exhibited the longest shoots, while those rooted under blue light had the highest number of leaves and the largest leaf surface. The control group showed the lowest number of roots. Additionally, the shortest roots were observed in plants rooted under the blue and red mixture, whereas the highest dry mass was recorded in plants rooted under monochromatic light.

Another study explore how different LED light qualities impact the phytohormone balance in Gerbera jamesonii during in vitro cultivation [2]. The study tested red, blue, and a red and blue light mix at 7:3 ratio, and control fluorescent lamps over 40 days, analyzing hormone levels every 10 days. This research found the red and blue LED (in 7:3 proportion) can obtain the best quality parameters of the propagated gerbera shoots, as it will make in vitro production more environmentally friendly and cost effective but at the same time will enable maintenance of the proper physiological and metabolic performances of the multiplied plants.

Further research examined the effects of various LED light spectra on the in vitro regeneration and acclimatization of Gerbera jamesonii cv. 'Shy Pink' [3]. The researchers evaluated the impact of red, blue, white, and combinations of red plus blue (1:1) and red, blue, plus green (1:1:1) LEDs on shoot regeneration, growth, and rooting.

The combination of red and blue (1:1) LEDs had the most substantial effect on these process, with the greatest regeneration of shoots and root growth. Red LEDs influenced shoot length, plantlet height, and petiole length, while blue LEDs affected leaf length, width, and area. Acclimatized plants regenerated under blue LEDs had higher photosynthetic pigment content, plants grown under the red and blue combination (1:1) exhibited higher internal CO2 concentrations, photosynthetic rates, stomatal conductance, and transpiration rates, whereas those grown under white LEDs had higher chlorophyll fluorescense. Overall, the findings suggest that the red and blue LED commbination is most suitable for the in vitro regeneration of gerbera compared to red, blue, and white LEDs.

Light intensity for in vitro regeneration of gerbera

While there isn’t a universally agreed-upon intensity for gerbera, research provides some valuable guidelines. A study examined the effects of varying light intensities and concentrations of 6-Benzyladenine (BA) on shoot development, leaf architecture, and photosynthetic pigment content in Gerbera jamesonii [4]. The study tested three light intensities: 40, 80, and 160 µmol m⁻² s⁻¹, in combination with three BA concentrations (0.0, 0.5, and 1.0 mg L⁻¹). The results indicated that an LED light intensity of 80 µmol m⁻² s-⁻¹, combined with 0.5 mg L⁻¹ BA, significantly enhanced shoot proliferation, improved leaf structure, and increased chlorophyll content. This suggests that an intensity of 80 µmol m⁻² s⁻¹ is optimal for promoting the growth and development of gerbera in vitro.

Optimizing Cut Gerbera Production with LED Lighting

Commercial cut gerberas are primarily grown in greenhouses, enabling year-round production of vibrant, high-quality flowers while maximizing profitability. Greenhouses provide a controlled environment that supports optimal growth, and advancements in lighting technology further enhance these benefits.

LED grow lights are effective in greenhouse cut gebera production

LED grow lights have proven to be an effective option for supplemental lighting in greenhouse gerbera production. In addition to being energy-efficient and promoting plant growth, LED lighting helps reduce the risk of Botrytis, a common fungal disease that can affect flower quality.

A research trials was carried out in 2013 and 2014 by researchers at Wageningen UR in Bleiswijk, The Netherlands. They performed several trials using different light strategies to grow gerbera crops. These included trials with: HPS lighting alone, a hybrid system with HPS and LED lighting, and a full LED system. The trials found that LED lighting can produce the same quality and yield of gerberas without increasing the risk of Botrytis.

Light Strategies for Higher Yields

To achieve high-quality gerbera production during periods of low natural light, growers should aim for a daily light integral (DLI) between 6 and 12 mol m⁻²d⁻¹. This can be accomplished through a combination of supplemental light intensity (PPFD) and photoperiod adjustments. Studies showing benefits from supplemental PPFD levels ranging from around 40 to 180 µmol m⁻² s⁻¹, often with a 12 hour photoperiod.

Economical lighting strategies for cut gerbera production

A study focused on the impact of varying LED light intensities on cut gerbera production during the low natural light season (November to March) [5]. It found that higher light intensities led to more numerous and faster-maturing flowers, though it had minor effects on vegetative growth and the size and quality of the harvested flowers. Specifically, the highest light intensity treatment resulted in flowers maturing 10% faster and produced more total and marketable flowers per plant compared to the lowest light intensity treatment.

These findings allow growers to implement more economical lighting strategies. By strategically increasing light intensity, particularly during the flowering stage, growers can accelerate maturation and achieve earlier harvests, capitalizing on market demands. This approach allows for optimized production cycles and increased profitability. In short, more light, faster flowers, and more profit.

Source:

[1]https://www.actahort.org/books/1201/1201_78.htm

[2]https://pmc.ncbi.nlm.nih.gov/articles/PMC8950344/

[3]https://www.mdpi.com/2073-4395/13/9/2216

[4] https://www.mdpi.com/2073-4395/9/7/358

[5]https://www.mdpi.com/2073-4395/10/9/1332