Light Exposure and Shade Effects on Growth, Flowering, and Leaf Morphology of Spiraea alba Du Roi and Spiraea tomentosa L

Abstract

<jats:p>Two native shrubs, <jats:italic>Spiraea alba</jats:italic> (meadowsweet) and <jats:italic>Spiraea tomentosa</jats:italic> (hardhack or steeplebush), have potential as landscape plants, but little is known about light requirements for these species. The performance of plants from four geographical seed sources of each species was evaluated in the field under six different light treatments: full sun; morning full sun; afternoon full sun; and 40%, 60%, and 80% shade. Provenance differences did exist for height, flowering, and leaf greenness. Growth, flowering, and canopy density were greater in full sun and 40% shade and least in 80% shade. Both species responded to shade with increased individual leaf area and higher specific leaf area. Relative leaf greenness decreased with shade in <jats:italic>S. tomentosa</jats:italic> but did not change in <jats:italic>S. alba</jats:italic>. Plants grown in morning or afternoon shade were shorter and smaller and had fewer inflorescences than did the full-sun plants. These species can survive in deep shade, but based on growth and appearance, they are best suited to full sun or light shade in the landscape.</jats:p>

Uptake Efficiency of Phosphorus in Different Light Environments by Zinnia (Zinnia elegans) and Vinca (Catharanthus roseus)

“…These approaches typically reduce temperatures by 1 to 4°C, depending on the conditions, but photosynthetic light is also reduced by 30% to 75% (Aberkani et al, 2010;Al-Arifi, 2006). The reduced radiation results in lower photosynthesis (Taiz and Zeiger, 1991), water use (Nobel, 1991), nutrient demand (Adams, 1980;Chapin et al, 1995), fewer or smaller flowers (Oh et al, 2009), and increases in height along with thinner leaves (Pramuk and Runkle, 2005;Stanton et al, 2010).…”

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.…”

“…Plants in general have the ability to adjust to changes in environmental conditions such as low-light conditions by undergoing morphological and physiological changes (Scuderi et al, 2012). For instance, a frequent variation that results from low light availability is thinner leaves with a greater leaf area (Stanton et al, 2010) and changes in the photosynthetic response (Miralles et al, 2011). In this sense, low-light conditions may involve changes in levels of chlorophyll per chloroplast, pigments concentration and their respective ratios (Lambers et al, 1998) as occurs in Dieffenbachia maculata (Chen et al, 2005a).…”

Nitrogen deposition does not alleviate the adverse effects of shade on Camellia japonica (Naidong) seedlings

“…Higher specific leaf area may allow plants to better integrate light patches of different intensity in a heterogeneous light environment and therefore increase their total biomass [ 15 , 42 ]. Changes in specific leaf area with light availability might be interpreted as a homeostatic mechanism to prioritize the optimization of light capture [ 14 , 35 , 40 , 43 ].…”