FLORAL INITIATION IN STRAWBERRY AND SOME EFFECTS OF RED AND FAR-RED RADIATION AS COMPONENTS OF CONTINUOUS WHITE LIGHT

The effects of different ratios of red to far-red radiation in continuous light on flower initiation in strawberry are described. A correlation was found between flower promotion and the content of far-red light in the supplied radiation which may be related to the red/far-red ratio of light and therefore to the level of phytochrome-Pfr in the plants. However, since relatively high energy (white) light was the only radiation used, a clear distinction between photosynthetic and red/far-red photoreversible effects is not possible. Flowering did not occur on all runner plants. Where flowering was promoted it invariably occurred first on the second- or third-formed runner plants on the stolon. Flowering was delayed on the proximal runner plants and never occurred on the mother plants. The results support the premise that a flower-inhibiting system was present along a concentration gradient in the runner.

Download Full-text

Betacyanin accumulation, chlorophyll content, and flower initiation in Chenopodium rubrum as related to endogenous rhythmicity and phytochrome action

Canadian Journal of Botany ◽

10.1139/b70-001 ◽

1970 ◽

Vol 48 (1) ◽

pp. 1-18 ◽

Cited By ~ 51

Author(s):

Edgar Wagner ◽

Bruce G. Cumming

Keyword(s):

Gibberellic Acid ◽

Chlorophyll Content ◽

Dark Period ◽

Continuous Light ◽

High Energy ◽

Hypocotyl Elongation ◽

Chenopodium Rubrum ◽

Physiological Status ◽

Flower Initiation ◽

Endogenous Rhythmicity

In Chenopodium rubrum seedlings (ecotypes 50°10′ N and 49°58′ N) betacyanin synthesis is light dependent (completely dark-grown seedlings contain no betacyanin) and is under phytochrome control via both the low energy and the high-energy (HER) reactions of photomorphogenesis. In continuous light, accumulation of betacyanin is linear with time. However, when a single dark period interrupts continuous light, the amount of both betacyanin and chlorophyll synthesized during a given period of time after the dark interruption shows a rhythm reflecting differences in the rate of, and (or) the capacity for, pigment accumulation that are dependent on the duration of the dark period. The rhythm in chlorophyll content was higher in frequency than circadian, with a period of about 15 h, while rhythmicity in the rate of synthesis of betacyanin was circadian. These results suggest that there is endogenous rhythmicity in the metabolic state of the system in darkness. The imposition of light after darkness apparently stabilizes the specific physiological status attained at that respective time of darkness and thus determines the metabolic activity of the seedlings.When glucose was supplied throughout darkness interrupting continuous light, the phasing of the rhythm of betacyanin synthesis was positively correlated with the rhythm of flower initiation, but this was not so when phenylalanine was supplied during darkness. In contrast, when glucose was supplied for a varied length of time in continuous light, there was rhythmicity in the rate of betacyanin accumulation, with a periodicity of about 15 h, that was dependent on the duration of the glucose application.When seedlings were supplied with 10−6 M gibberellic acid during darkness there was a rhythm in the amount of hypocotyl elongation that depended on the length of a single dark period interrupting continuous light. Other evidence has suggested that there is a rhythm in the stability of the cellular membranes; this rhythm was assayed (non-physiologically) by the time of onset of betacyanin leakage from seedlings into an extraction medium and was apparent only after application of 10−10 M gibberellic acid. The rhythms in hypocotyl elongation and in membrane stability that were revealed after the application of gibberellic acid suggest that there may be a rhythm in the rate of differentiation and (or) development of the system.It is postulated that endogenous rhythmicity is due to the spatial separation of energy production and use in different cell particulates, with phytochrome acting as a membrane operator.

Download Full-text

Smallseed Dodder (Cuscuta planiflora) Phototropism toward Far-red When in White Light

Weed Science ◽

10.1017/s0043174500093838 ◽

1996 ◽

Vol 44 (2) ◽

pp. 233-240 ◽

Cited By ~ 20

Author(s):

Gregory L. Orr ◽

Mustapha A. Haidar ◽

Deborah A. Orr

Keyword(s):

Blue Light ◽

Potassium Iodide ◽

White Light ◽

Host Location ◽

Red Light ◽

Infra Red ◽

Red Radiation

White light-grown seedlings of smallseed dodder were (a) provided with unilateral far-red (700 to 800 nm) at photon irradiances ranging from 20 to 110 μmol m−2s−1against a background of cool white light (400 to 700 nm) from above at 77 μmol m−2s−1, or (b) transferred to darkness and provided with unilateral white light at 20 μmol m−2s−1, unilateral blue light (400 to 500 nm) at 10 μmol m−2s−1, unilateral red light (600 to 700 nm) at 10 μmol m−2s−1, unilateral far-red at 50 μmol m−2s−1, or (c) in experiments utilizing bilateral irradiations, provided with unilateral far-red perpendicular to unilateral white light. Positive phototropic curvature was induced by unilateral white light and by unilateral blue light in otherwise darkness and by unilateral far-red in a background of cool white light. Seedling vines were also phototropic toward unilateral far-red when provided with unilateral white light perpendicular to unilateral far-red. Phototropism to unilateral white light was inhibited in seedlings treated with 200 μM norflurazon and 50 mM potassium iodide. Norflurazon- and potassium iodide-treated seedlings remained phototropic toward unilateral far-red when provided with unilateral white light perpendicular to unilateral far-red. Seedling vines were not phototropic to unilateral red or to unilateral far-red in otherwise darkness, and seedlings in cool white light were neither skototropic (i.e., tropic toward unilateral darkness) nor tropic to or from infra-red (radiation with wavelengths greater than 900 nm). Phototropism toward regions of lowered red:far-red may aid smallseed dodder in chlorophyllous host location and attachment.

Download Full-text

CHLOROPHYLL SYNTHESIS IN SQUASH SEEDLINGS: ACTION AND INTERACTION OF RED AND FAR-RED IRRADIATION

Canadian Journal of Botany ◽

10.1139/b67-094 ◽

1967 ◽

Vol 45 (6) ◽

pp. 929-938 ◽

Cited By ~ 2

Author(s):

Kenneth Surrey

Keyword(s):

Energy Balance ◽

Exposure Time ◽

White Light ◽

Slow Rate ◽

Red Light ◽

Chlorophyll Synthesis ◽

The Other ◽

Pigment Formation ◽

Red Radiation

Two different rates of chlorophyll synthesis were observed in the cotyledons when squash (Cucurbita moscata) seedlings were exposed to continuous red radiation: a slow rate which lasted for about three hours and an accelerated rate that proceeded thereafter. Determination of red, far-red reversible reaction indicated that pigment formation in seedlings exposed initially to far-red was promoted by red radiation, and this promotion was repeatedly reversed by subsequent far-red treatments. On the other hand, seedlings exposed first to red radiation followed by far-red, red light cycles failed to respond according to the typical red-accelerated and far-red-inhibited photomorphogenic responses. Variations in these photoresponses were observed when the exposure time at each alternating waveband was changed, or the energy balance between red and far-red bands was changed or even when the seedlings were exposed to white light either before or after the red, far-red light treatments. The results of these experiments are reported.

Download Full-text

The influence of light color on the rooting of 'Horim Golden' Chrysanthemum cuttings

Acta Agrobotanica ◽

10.5586/aa.1986.005 ◽

2013 ◽

Vol 39 (1) ◽

pp. 47-57

Author(s):

Edward Borowski ◽

Lidia Kozłowska

Keyword(s):

White Light ◽

Red Light ◽

Green Light ◽

Morphological Differentiation ◽

Root Systems ◽

Carbohydrate Content ◽

Light Blue ◽

Mother Plants ◽

Light Color ◽

White Control

The influence of three different colors of light; blue, green and red, compared with white light as the control, on the rooting of <i>Chrysanthemum</i> cuttings, is presented in this paper. The mother plants and cuttings were irradiated during rooting with different colors of light. This was shown to have had visible influence on the morphological differentiation of cuttings. It also affected the carbohydrate content in them. The rooting of the cuttings reflected this influence. The cuttings obtained from plants grown under white (control) or red light were characterized by well-developed root systems in terms of the number, length and mass of the roots. The cuttings from the plants grown under green light were the worst. The influence of the color of the light on the speed with which the first roots were formed was the reverse. The cuttings from the plants irradiated with green light rooted the quickest, next in order were those from plants irradiated with blue, red and white light. Irradiating cuttings with differently colored light during rooting only had an effect on the number of roots formed. This number was high, close to that of control cuttings, in cuttings exposed to red light, decidedly lower in those exposed to blue and, in particular, green light.

Download Full-text

Photoperiod and Temperature Influence on Flower Initiation and Development for Euphorbia pulcherrima Grown Under Florida Conditions

HortScience ◽

10.21273/hortsci.33.3.509a ◽

1998 ◽

Vol 33 (3) ◽

pp. 509a-509

Author(s):

C.E. Wieland ◽

J.E. Barrett ◽

D.G. Clark ◽

G. J. Wilfret

Keyword(s):

Subsequent Development ◽

Flower Initiation ◽

Euphorbia Pulcherrima ◽

Floral Initiation ◽

Temperature Influence ◽

Average Temperature ◽

Long Day ◽

Time To Initiation ◽

Growth Room ◽

Maximum Temperatures

Four poinsettia cultivars were grown in glass greenhouses in Gainesville, Fla., in the Fall 1997 to evaluate differences in floral initiation and subsequent development. Three means of regulating photoperiod were 1) natural days 2) long-day lighting to 6 Oct. and then natural days (lights out) 3) long-day lighting to 6 Oct., and then short-day conditions by black cloth for 15 h (black cloth). At 2-day intervals, sample meristems were collected and examined for initiation of reproductive development. Average minimum and maximum temperatures during the first two weeks of October were 22 and 29 °C, respectively, with an average temperature of 25.3 °C. The overall average temperature was 23.2 °C from planting to anthesis. Differences in anthesis dates among cultivars were primarily due to time to initiation vs. rate of development. Under natural days, `Lilo' initiated first on 8 Oct. and `Freedom', `Peterstar', and `Success', followed by 6, 8, and 18 days, respectively. Lights out resulted in `Lilo' initiating 17 Oct., followed by `Freedom', `Peterstar', and `Success' initiating 7, 12, and 15 days later, respectively. Differences between cultivars in time of initiation was reduced under black cloth, where `Lilo' initiated 14 Oct., followed by `Freedom' 2 days later, and `Peterstar' and `Success' 7 days afterward. Initiation was positively correlated to visible bud and anthesis. First color was positively correlated to initiation and visible bud, with the exception of `Lilo'. Growth room studies conducted using various high temperatures and photoperiods indicated similar trends.

Download Full-text

The Preferences of Different Cultivars of Lettuce Seedlings (Lactuca sativa L.) for the Spectral Composition of Light

Agronomy ◽

10.3390/agronomy11061211 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1211

Author(s):

Barbara Frąszczak ◽

Monika Kula-Maximenko

Keyword(s):

Chlorophyll Content ◽

Blue Light ◽

White Light ◽

Leaf Shape ◽

Red Light ◽

Spectral Composition ◽

Fresh Weight ◽

Light Spectrum ◽

Dark Green ◽

Relative Chlorophyll Content

The spectrum of light significantly influences the growth of plants cultivated in closed systems. Five lettuce cultivars with different leaf colours were grown under white light (W, 170 μmol m−2 s−1) and under white light with the addition of red (W + R) or blue light (W + B) (230 μmol m−2 s−1). The plants were grown until they reached the seedling phase (30 days). Each cultivar reacted differently to the light spectrum applied. The red-leaved cultivar exhibited the strongest plasticity in response to the spectrum. The blue light stimulated the growth of the leaf surface in all the plants. The red light negatively influenced the length of leaves in the cultivars, but it positively affected their number in red and dark-green lettuce. It also increased the relative chlorophyll content and fresh weight gain in the cultivars containing anthocyanins. When the cultivars were grown under white light, they had longer leaves and higher value of the leaf shape index. The light-green cultivars had a greater fresh weight. Both the addition of blue and red light significantly increased the relative chlorophyll content in the dark-green cultivar. The spectrum enhanced with blue light had positive influence on most of the parameters under analysis in butter lettuce cultivars. These cultivars were also characterised by the highest absorbance of blue light.

Download Full-text

The role of high-energy protons and electrons in powering the solar white-light flare emission

Solar Physics ◽

10.1007/bf00146341 ◽

1996 ◽

Vol 167 (1-2) ◽

pp. 307-320 ◽

Cited By ~ 1

Author(s):

E. Rieger ◽

D. F. Neidig ◽

D. W. Engfer ◽

D. Strelow

Keyword(s):

White Light ◽

High Energy

Download Full-text

Effects of electron-withdrawing groups in imidazole-phenanthroline ligands and their influence on the photophysical properties of EuIII complexes for white light-emitting diodes

New Journal of Chemistry ◽

10.1039/c7nj02291c ◽

2017 ◽

Vol 41 (18) ◽

pp. 9826-9839 ◽

Cited By ~ 8

Author(s):

Boddula Rajamouli ◽

Rachna Devi ◽

Abhijeet Mohanty ◽

Venkata Krishnan ◽

Sivakumar Vaidyanathan

Keyword(s):

Thin Film ◽

Quantum Yield ◽

White Light ◽

Light Emitting Diode ◽

Photophysical Properties ◽

Red Light ◽

Europium Complexes ◽

Light Emitting ◽

White Light Emitting Diodes ◽

Phenanthroline Ligands

The red light emitting diode (LED) was fabricated by using europium complexes with InGaN LED (395 nm) and shown digital images, corresponding CIE color coordinates (red region) as well as obtained highest quantum yield of the thin film (78.7%).

Download Full-text

(K0.5Na0.5)NbO3:Eu3+/Bi3+: a novel, highly efficient, red light-emitting material with superior water resistance behavior

RSC Advances ◽

10.1039/c4ra10888d ◽

2015 ◽

Vol 5 (6) ◽

pp. 4707-4715 ◽

Cited By ~ 13

Author(s):

Qiwei Zhang ◽

Haiqin Sun ◽

Tao Kuang ◽

Ruiguang Xing ◽

Xihong Hao

Keyword(s):

Blue Light ◽

White Light ◽

High Performance ◽

Water Resistance ◽

Light Emitting Diodes ◽

Red Light ◽

Light Emitting ◽

Highly Efficient ◽

White Light Emitting Diodes

Materials emitting red light (∼611 nm) under excitation with blue light (440–470 nm) are highly desired for fabricating high-performance white light-emitting diodes (LEDs).

Download Full-text