Substituting green or far-red radiation for blue radiation induces shade avoidance and promotes growth in lettuce and kale

Photosynthesis, Morphology, Yield, and Phytochemical Accumulation in Basil Plants Influenced by Substituting Green Light for Partial Red and/or Blue Light

“…On the other hand, some responses to green light persist in cry knockout mutant backgrounds, such as green light-regulated leaf architecture changes and plant adaptation, suggesting an unknown green light receptor through a novel mechanism (Sellaro et al, 2010;Zhang et al, 2011). In our study, shoot FW and DW in purple basil plants decreased under treatments with greater green light proportions (32% and 45%), which was different from the results reported by Meng et al (2019) and Kim et al (2004), in which inclusion of green light resulted in greater shoot FW in kale and lettuce. One hypothesis of the difference might be a result of the different plant canopy architecture or canopy density (e.g., leaf area index) among lettuce, kale, and basil plants.…”

“…5). Similarly, Meng et al (2019) reported that substituting blue light with green light increased petiole length in kale (Brassica oleracea). Shade avoidance responses induced by green light are likely mediated in two categories: cryptochrome-dependent and cryptochrome-independent pathways (Folta, 2004;Wang and Folta, 2013).…”

“…It is postulated that shade avoidance responses induced by green light could increase light interception by a larger plant canopy, subsequently increasing whole-plant photosynthesis and resulting in a greater plant yield. For example, leaf length and width of 'Rex' and 'Rouxai' lettuce and 'Siberian' kale plants, and shoot FW of 'Siberian' kale plants all increased under green light compared with combined R&B light (Meng et al, 2019). Stomatal opening stimulated by blue light was reversed by green light in a range of plant species such as arabidopsis (Arabidopsis thaliana), broadbean (Vicia faba), pea (Pisum sativum), dayflower (Commelina communis), and two tobacco species (Nicotiana tabacum and N. glauca) (Frechilla et al, 2000;Talbott et al, 2002).…”

“…Compared to red and blue lights, green light is less studied because of its low absorptivity coefficient in the absorption spectra of chlorophylls compared with red or blue light. However, green light penetrates deep into the mesophyll layers at a single-leaf level and the lower leaves at a canopy level, therefore driving photosynthesis, whereas red and blue wavelengths are absorbed mostly by the upper leaves (Meng et al, 2019;Terashima et al, 2009;Wang and Folta, 2013). It was reported that the absorption of brief flashes of 2000 mmol • m -2 • s -1 monochromatic blue, red, and green light from the adaxial to abaxial surface of spinach leaves was at depths of 50, 100, and 150 mm, respectively (Vogelmann and Han, 2000).…”

“…Green light also contributes to plant growth, which can induce shade avoidance responses (i.e., stem elongation, leaf expansion, and petiole elongation) and alter secondary metabolism in plants (Meng et al, 2019). It was reported that known photoreceptors such as phytochromes and cryptochromes can respond to green light as a result of their broad-band absorption spectrum that tails into the green light wavelength (Smith et al, 2017).…”