Minimum Daily Light Integral for Growing High-quality Coleus

Abstract

<jats:p>Coleus (<jats:italic>Solenostemon scutellarioides</jats:italic>) traditionally has been recommended as a shade plant, but many cultivars are also suitable for full sun. In regions of the country where light limits growth and photosynthesis, supplemental lights are used to increase daily light integral (DLI). Understanding the minimum DLI necessary to produce coleus would minimize supplemental lighting use, reducing costs and improving production sustainability. ‘Kong Red’ and ‘Wizard Coral Sunrise’ coleus were grown in a greenhouse under a 12-hour photoperiod and a mean DLI of 2.9, 3.8, 5.8, or 10.0 mol·m<jats:sup>−2</jats:sup>·d<jats:sup>−1</jats:sup> to determine the lowest light level needed to produce high-quality plants. After 8 weeks, both cultivars had a 4.2-fold increase in shoot dry weight as DLI increased from 2.9 to 10.0 mol·m<jats:sup>−2</jats:sup>·d<jats:sup>−1</jats:sup>. Plants grown under 10.0 mol·m<jats:sup>−2</jats:sup>·d<jats:sup>−1</jats:sup> were 22% to 25% taller and 18% to 21% wider compared with those grown under 2.9 mol·m<jats:sup>−2</jats:sup>·d<jats:sup>−1</jats:sup>. ‘Kong Red’ had 3.6 times as many branches and ‘Wizard Coral Sunrise’ had over twice as many branches when grown under 10.0 mol·m<jats:sup>−2</jats:sup>·d<jats:sup>−1</jats:sup> compared with those grown under the lowest DLI. Leaf counts for both cultivars were 64% greater when grown under the highest DLI compared with those produced under the lowest DLI; leaf area for both cultivars was also positively correlated with DLI. Leaves of both cultivars had significantly more green area (i.e., less variegation) when grown under lower DLIs. Overall, both cultivars exhibited a more dense growth habit and greater degree of variegation when grown under the highest DLI. Therefore, we recommend growing ‘Kong Red’ and ‘Wizard Coral Sunrise’ coleus under a minimum DLI of 10.0 mol·m<jats:sup>−2</jats:sup>·d<jats:sup>−1</jats:sup>.</jats:p>

Geranium and Purple Fountain Grass Leaf Pigmentation Is Influenced by End-of-Production Supplemental Lighting with Red and Blue Light-emitting Diodes

“…This provides initial evidence that EOP SL is most effective when plants are finished under a low greenhouse DLI of <10 mol · m -2 · d -1 . Furthermore, the parameters mentioned here to quantify and track foliage color support previous investigations regarding the influence of DLI on coloration and quality of floriculture crops (Garland et al, 2010;Kim et al, 2012). For instance, Garland et al (2010) reported coleus [Solenostemon scutellarioides (L.) Codd 'Kong Red' and 'Wizard Coral Sunrise'] grown at DLIs < 5.8 mol · m -2 · d -1 for 8 weeks exhibited more green coloration and less burgundy and coral variegations, and plants were considered to be of low quality.…”

“…The influence of light on anthocyanin synthesis and accumulation (Beckwith et al, 2004;Nguyen and Cin, 2009;Paradiso et al, 2011) and on the change of leaf color (Garland et al, 2010;Kim et al, 2012) has been previously investigated for several floriculture crop species. In general, induction of anthocyanin synthesis and accumulation requires high light intensities, as these pigments protect cells from high light damage by absorbing blue or ultraviolet light (Seigler, 1998).…”

“…In general, induction of anthocyanin synthesis and accumulation requires high light intensities, as these pigments protect cells from high light damage by absorbing blue or ultraviolet light (Seigler, 1998). However, the majority of commercial bedding plant production occurs in late winter and early spring (Garland et al, 2010) when the ambient outdoor DLI is 15 to 35 mol · m -2 · d -1 (Korczynski et al, 2002). Inside the greenhouse, DLI is reduced by up to 50% or more from the greenhouse glazing material, superstructure, shading, and hanging baskets (Faust et al, 2005;Hanan, 1998;Peet, 1999;Warren et al, 1992).…”

Differential expression of a novel gene EaF82a in green and yellow sectors of variegated Epipremnum aureum leaves is related to uneven distribution of auxin

“…They are also valuable materials for studying environmental factors on chloroplast biogenesis (Downton and Grant 1994, Beardsell and Norden 2004, Chen et al 2004). In general, variegated plants are cultivated under shade conditions (Chen et al 2004); low light or a certain range of light intensity is crucial for stimulating variegation formation (Vladimirova et al 1997, Garland et al 2010, Kim et al 2012, which implies that light may be one of the important factors for the appearance of variegated leaves. However, lack of genome sequence information in most non-model species remains an obstacle for using them to study variegation formation at the molecular level.…”

Types of Shelter and Covering Materials Influencing Growth, Pigment, and Nutrient Concentrations of Baby Rubber Plants (Peperomia obtusifolia)

“…High levels of irradiance can result in a decrease or in an increase in leaf area, depending on the species studied. For instance, Kubatsch et al (2007) and Garland et al (2010) reported an increase of leaf area under high levels of irradiance in Schefflera arboricola and Solenostemon scutellarioides, whereas other studies reported a decrease in leaf area in ornamental species such as Spiraea tomentosa (Stanton et al, 2010). The specific leaf area can also show different trends under high levels of radiation intercepted by the canopy.…”