Effectiveness of Five Vision-Lighting Sources on Photo-Regulation of 22 Species of Ornamental Plants1

Self Cite

The relative efficiencies of high-pressure (HPS) and low-pressure sodium (LPS) lamps for plant growth were determined for 32 species of foliage and flowering plants in greenhouse under winter conditions at 37°N latitude. HPS with a relatively wide spectral emission peaking at 589 nm, and low-pressure sodium (LPS) with a monochromatic line at 589 nm were compared at 42 W/m2 irradiance in the 400–700 nm region for various lengths of time at various times of day. Although radiation in the far-red region (700–800 nm) differed, HPS and LPS equally accelerated rates of increase in fresh weights, and heights, and flowering of most herbaceous and tropical foliage plants evaluated. High-pressure sodium and LPS were ineffective, however, in promoting growth of deciduous trees and some woody plants and had no more effect than exposure of the plants to natural winter days with 0.9 W/m2 from incandescent lamps for 8 hrs (2000-0400) night interruption (long day controls). After 16 hours, about half the species showed photomorphogical differences between plants grown at intensities of 21 and plants grown at 42 W/m2 from LPS. All showed significantly better growth characteristics (fresh weight, height, early flowering) than the long day controls. Lighting during the day or night (42 W/m2 from 0800–1600 or from 2000–0400) was equally effective in promoting growth responses with 15 of the 32 species evaluated. Night lighting was more effective than day lighting with 10 of the 32 species tested. The majority of the species grew equally well when lighted 16 hours daily (0800-2400) with 21 W/m2 or 8 hours daily (2000–0400) with 42 W/m2. Effectiveness of the lighting was generally unrelated to the photoperiodic requirements of the plants. Many of the plants, which were previously classified as day-neutral (DN), flowered as if they were long day plants. Such day-neutral plants apparently required adequate light (intensity and duration) for photosynthesis. Increased daylength alone, without regard to intensity, was not sufficient to accelerate growth and early flowering of day-neutral plants. Since HPS and LPS were equally effective on most species tested, we concluded that light quality was less important than total irradiation (energy) for the growth and early flowering of many herbaceous plants.

Section: Discussionsupporting

confidence: 57%

mentioning

confidence: 99%

Relative Efficiency of High- and Low-pressure Sodium and Incandescent Filament Lamps Used to Supplement Natural Winter Light in Greenhouses1

Cathey¹,

Campbell²

1979

Self Cite

“…In some species such as Cercis canadensis L., high latitude plants cease growth in late summer in response to photoperiod while low latitude populations are insensitive to daylength and cease growth in response to the dry winter season (3). A. rubrum is a wide ranging species in North America, but our plants, representing the southernmost population of this species, responded similarly to those from higher latitudes (2,4,5) in that growth was con tinuous under LD, but completely stopped under ND in early November.…”

Section: Discussionmentioning

confidence: 87%

Growth of Ten Species of Ornamental Tree Seedlings Exposed to Different Photoperiods

Broschat

Donselman

1983

Ten species of tropical to temperate ornamental tree seedlings. [Bauhinia variegata L., Tabebuia heterophylla (DC.) Britton, T. caraiba (Mart.) Bur., Delonix regia (Bojer) Raf., Bursera simaruba (L.) Sarg., Pongamia pinnata (L.) Pierre, Jacaranda mimosifolia D. Don, Tamarindus indica L., Acer rubrum L., and Quercus virginiana Mill.] were grown outdoors under natural photoperiods or long day (LD) photoperiods during the autumn, winter, and early spring months. Growth response to photoperiod and temperature varied widely among both tropical and temperate species. Jacaranda mimosifolia, B. variegata, and T. indica were classified as quantitative LD plants since growth was enhanced by LD, but not prevented by short days. However, temperature appeared to be an overriding factor in the growth of T. indica. Delonix regia and A. rubrum grew continuously under LD, but ceased all growth when natural daylength (ND) became shorter than 10.8 h. Quercus virginiana, P. pinnata, B. simaruba, and T. heterophylla showed virtually no response to photoperiod, but temperatures below 15°C prevented growth in Q. virginiana. LD increased growth rate in T. caraiba during the autumn months, but low temperature prevented growth in either LD or ND in the winter. ND plants of this species grew more rapidly in the spring than those maintained under LD. This negative influence of LD on growth during the spring months also was noted in other species in this study.

“…However, plants such as dumbcane may undergo membrane or enzyme degradation at high light intensities and long light durations which may lead to poor plant quality and leaf chlorosis regardless of carbohydrate level. Current apple orchard establishment recommendations include pruning the shoot back to 70-75 cm at planting (3,4). This practice stimulates new lateral shoot growth for the primary purpose of selecting scaffold limbs to develop the tree's fruiting structure.…”

Section: Resultsmentioning

confidence: 99%

Influence of Intensity and Duration of Cool White Fluorescent Lighting and Fertilizer on Growth and Quality of Foliage Plants1

Conover

Poole

Nell

1982

Brassaia actinophylla Endl., Chamaedorea elegans Mart., Dieffenbachia maculata (Lodd.) G. Don ‘Exotica’, Dracaena marginata Lam., and Ficus benjamina L. were grown for 1 year under 13 or 26 μE m−2sec−1 from Cool White fluorescent lamps for 12, 18, or 24 hours daily durations. Increasing light duration to 24 hours daily decreased quality of all plants tested, with Brassaia, Chamaedorea, and Dieffenbachia being most affected. The primary symptoms resulting from constant light were foliar chlorosis and decrease in plant quality, although necrotic spotting appeared at times. By experiment termination, best plants overall were associated with 26 μE m−2sec−1 light for 12 or 18 hours duration and poorest with 26 μE m−2sec−1 light and 24 hours duration. A second factorial experiment with Dieffenbachia and Dracaena tested effects of 3 fertilizer levels (0, 0.67, or 1.30 g Osmocote/3 months per 15-cm pot) under 2 light intensities (13 or 26 μE m−2sec−1) and 2 light durations (12 or 24 hours) on plant quality. Higher fertilizer levels had a limited effect on plant quality, while influence of light intensity and duration was similar to the initial experiment.