Phytochrome Action in the Induction of Plowering in Short-day Plants: Effect of Photoperiod Quality

1974 ◽  
Vol 1 (3) ◽  
pp. 445 ◽  
Author(s):  
RW King
Keyword(s):  
Photosynthetic Pigments ◽  
Prolonged Exposure ◽  
Dark Period ◽  
Red Light ◽  
Spectral Composition ◽  
Chenopodium Rubrum ◽  
Fluorescent Light ◽  
Flowering Response ◽  
Short Day ◽  
Red Radiation

Seedlings of Phavbitis nil and Chenopodium rubrum flower in response to a single inductive dark period preceded and followed by continuous fluorescent light. However, when a far-red irradiation for 1 h or longer was substituted for fluorescent light, the flowering response to an ensuing dark period could be completely inhibited or enhanced up to threefold depending on when the far-red exposure commenced. Evidence of red/far-red photoreversibility established phytochrome as the photoreceptor controlling these responses. There was no indication of the involvement of photosynthetic pigments. For P. nil prolonged exposure (1.5-6 h) to far-red radiation during the photoperiod could shorten (2-3 h) or lengthen (2 h) the duration of darkness required for flowering. The degree of change depended on whether the far-red radiation was imposed just prior to darkness (shortening) or about 9 h prior to darkness (lengthening). In a similar manner the spectral composition of the photoperiod influenced the timing during darkness for earliest sensitivity to brief (5 min) red light interruptions. The shorter the critical dark period, the earlier in darkness the seedlings became sensitive to red light interruptions of darkness. It is clear that the form of phytochrome during the photoperiod influences the timing of phytochrome- linked processes in darkness. Two explanations discussed are a coupling via rhythmic changes in substrate on which phytochrome acts, and an effect on phytochrome reactions which alters the timing of Pf, disappearance during a subsequent dark period.

scholarly journals Influence of Light of Different Spectral Compositions on the Growth, Photosynthesis, and Expression of Light-Dependent Genes of Scots Pine Seedlings

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3284
Author(s):  
Pavel Pashkovskiy ◽  
Vladimir D. Kreslavski ◽  
Yury Ivanov ◽  
Alexandra Ivanova ◽  
Alexander Kartashov ◽  
...  
Keyword(s):  
Red Light ◽  
Spectral Composition ◽  
Fluorescent Light ◽  
Auxin Signaling ◽  
Gene Encoding ◽  
Chl A ◽  
Expression Of Genes ◽  
Dependent Change ◽  
The Difference ◽  
Photosynthesis And Respiration

Varying the spectral composition of light is one of the ways to accelerate the growth of conifers under artificial conditions for the development of technologies and to obtain sustainable seedlings required to preserve the existing areas of forests. We studied the influence of light of different quality on the growth, gas exchange, fluorescence indices of Chl a, and expression of key light-dependent genes of Pinus sylvestris L. seedlings. It was shown that in plants growing under red light (RL), the biomass of needles and root system increased by more than two and three times, respectively, compared with those of the white fluorescent light (WFL) control. At the same time, the rates of photosynthesis and respiration in RL and blue light (BL) plants were lower than those of blue red light (BRL) plants, and the difference between the rates of photosynthesis and respiration, which characterizes the carbon balance, was maximum under RL. RL influenced the number of xylem cells, activated the expression of genes involved in the transduction of cytokinin (Histidine-containing phosphotransfer 1, HPT1, Type-A Response Regulators, RR-A) and auxin (Auxin-induced protein 1, Aux/IAA) signals, and reduced the expression of the gene encoding the transcription factor phytochrome-interacting factor 3 (PIF3). It was suggested that RL-induced activation of key genes of cytokinin and auxin signaling might indicate a phytochrome-dependent change in cytokinins and auxins activity.

Semidian rhythmicity in the flowering response of Pharbitis nil to changes in temperature

1998 ◽  
Vol 25 (2) ◽  
pp. 183 ◽  
Author(s):  
O.M. Heide ◽  
R.W. King ◽  
L.T Evans
Keyword(s):  
Circadian Rhythm ◽  
Constant Temperature ◽  
Opposite Effect ◽  
Dark Period ◽  
Floral Induction ◽  
Continuous Light ◽  
The Other ◽  
Pharbitis Nil ◽  
Flowering Response ◽  
Short Day

Our earlier experiments on flowering in the short day plant Pharbitis nil involved far- red/dark (FR/D) interruptions of 90 min duration at various times during a continuous light, constant temperature period before a single inductive dark period. They revealed a rhythm with a period of 12 h, hence semidian. We concluded that the phasing of this semidian rhythm determined the length of darkness required for floral induction. This conclusion has since been challenged so we sought other pretreatments which reveal the semidian rhythm. Interruptions at 12°C–17°C for 45–90 min at various times prior to the inductive dark period were as effective as FR/D in eliciting the semidian rhythm, with significant effects on flowering persisting for at least three cycles in constant conditions in continuous light. The rhythmic response to 12°C pretreatments was 3 h out of phase with that to FR/D pretreatments. Flowering responses to the semidian rhythm exposed by 12°C pretreatments were additive to and independent of those to a circadian rhythm. Some evidence was obtained of reversal of the inhibition or promotion of flowering by FR/D or 12°C by exposure immediately afterwards to the other pretreatment at times of their opposite effect. Pretreatments at 12°C, like those with FR/D, either reduced (if promotive) or extended (if inhibitory) the length of the dark period required for floral induction in this short day plant.

RHYTHMIC FLOWERING RESPONSES AND PHYTOCHROME CHANGES IN A SELECTION OF CHENOPODIUM RUBRUM

1965 ◽  
Vol 43 (7) ◽  
pp. 825-853 ◽  
Author(s):  
Bruce G. Cumming ◽  
Sterling B. Hendricks ◽  
H. A. Borthwick
Keyword(s):  
Dark Period ◽  
Continuous Light ◽  
Endogenous Rhythm ◽  
Chenopodium Rubrum ◽  
Flowering Response ◽  
Initial Substrate ◽  
Endogenous Circadian Rhythm ◽  
Light Darkness ◽  
Rhythmic Change

Flowering of Chenopodium rubrum L., selection 374, was examined with respect to an endogenous circadian rhythm, the state of phytochrome, and the result of changing the form of phytochrome during a single dark period of 2 to 96 hours interrupting continuous light. Darkness was imposed either 4 or 5 days after seeds were placed on moist filter paper in Petri dishes.The following working hypothesis, which is partly retrospective, is projected to explain the main features of the experimental results. Flowering is controlled by a product of the enzymatic action of the far-red absorbing form of phytochrome (Pfr) on a single but unknown substrate. In acting, Pfr finally reverts to the inactive red-absorbing form of phytochrome (Pr) or is changed from the Pfr form in some other way. The available substrate, if not utilized by Pfr action, is soon depleted by other reactions. The substrate for Pfr action is low during the skotophile but high during the photophile phases. The significant time for phasing is the beginning of darkness. The initial substrate supply appears to be derived from the preceding light period but some time in the region of the 9th to 12th hour of darkness a significant rhythmic change of substrate starts up. The dependence of flowering on the time that darkness is interrupted by light is directly related to a rhythmic change in the optimum Pfr level required for the processes leading to flowering.The role of the endogenous rhythm in flowering under natural conditions is questioned. Similarities that are shown in the control of flowering, whether the display is governed by an endogenous rhythm or by a daily photoperiodic cycle, indicate that phytochrome acts as a "pacemaker". It is suggested that the distinct ecotypic populations of C. rubrum that differ in flowering response have dissimilar levels and rates of supply of substrate for phytochrome action. In C. rubrum-374, complete reversion or loss of Pfr does not occur during a long dark period of 72 hours at 20 °C, but Pfr does decrease to low levels.A hydrodynamic system is discussed as an analogy to rhythmic flowering response.

Effect of Far-red Radiation on the Growth and Productivity of the Cucumber Plant

2020 ◽  
Vol 67 (2) ◽  
pp. 32-36
Author(s):  
Aleksandr A. Smirnov
Keyword(s):  
Red Light ◽  
Spectral Composition ◽  
Growth Period ◽  
Research Purpose ◽  
Winter Period ◽  
Cucumber Plant ◽  
Initial Growth ◽  
Vegetable Crops ◽  
Large Area ◽  
Red Radiation

In the conditions of a short light day in the autumn-winter period, phyto-emitters of various spectral composition of radiation are used for additional illumination of plants in greenhouses. The effect of radiation in the photosynthetically active radiation zone (400-700 nanometers) on vegetable crops and the cucumber plant has been sufficiently studied. However, little attention is paid to the effect of far-red radiation on fruit-bearing vegetable crops during all growth periods. (Research purpose) The research purpose is in studying the effect of far-red light emitting diodes on the growth and productivity of a cucumber plant grown in full light culture. (Materials and methods) The morphological parameters and productivity of plants of parthenocarpic hybrids of cucumber for cultivation in closed fotocamera and irradiation led vetoablechange in two versions: with far-red radiation and without far-red radiation, has been studied. (Results and discussion) It was found that cucumber plants that grew without a far-red component of the spectrum have a smaller leaf size, while plants growing with a far-red has the leaf of a larger size and is oriented horizontally. A large area of leaves leads to shading of the lower tiers, which leads to a decrease in the concentration of chlorophyll in them and a decrease in the final productivity of the plant. (Conclusions) It has been revealed that the addition of far-red radiation in the range 700÷760 nm with an intensity of 20 percent of the total radiation flux leads to an increase in the length of internodes by 15% and leaf area up to 30 percent. It was recommended to irradiate with long-range red radiation only in the initial growth period to build up the green mass.

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

Agronomy ◽  
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.

BIOSYSTEMATIC STUDIES ON XANTHIUM: TAXONOMIC APPRAISAL AND ECOLOGICAL STATUS

1959 ◽  
Vol 37 (2) ◽  
pp. 173-208 ◽  
Author(s):  
Doris Löve ◽  
Pierre Dansereau
Keyword(s):  
North America ◽  
South America ◽  
Ecological Status ◽  
Distinct Species ◽  
Eastern North America ◽  
Flowering Response ◽  
Short Day ◽  
Stable Species ◽  
Enormous Variation

The following paper is an evaluation of the taxonomic and ecological status of the genus Xanthium L. A review of its systematics demonstrates that many so-called "species" described on material from Europe actually have their origin in America, except one, X. strumarium s. str., which seems to have a Mediterranean–European center of dispersal. Another conclusion drawn is that Xanthium consists of only two distinct species: X. spinosum L. and X. strumarium L. The former is a relatively stable species, the latter an enormously variable one readily subdivided into a number of minor taxonomic entities.Ecologically, in eastern North America at least, Xanthium is primarily a beach plant, which prefers open habitats and succumbs to crowding. The seeds are most often dispersed by water and wind. It enters easily into ruderal habitats, but only as long as these are open and unshaded.The generalized short-day flowering response in this genus supports our hypothesis that Xanthium has a tropical–subtropical origin, and we feel that it has its center in Central and/or South America, whence it has spread over the continents north and southward.There is no evidence for any sterility barriers separating the entities of X. strumarium, but we feel that an intense inbreeding with an occasional outbreeding is responsible for the enormous variation, often resulting in small, local, but unstable taxa.

The influence of red and blue light on the rate of photosynthesis and the CO2 compensation point at various oxygen concentrations

1970 ◽  
Vol 48 (6) ◽  
pp. 1251-1257 ◽  
Author(s):  
N. P. Voskresenskaya ◽  
G. S. Grishina ◽  
S. N. Chmora ◽  
N. M. Poyarkova
Keyword(s):  
Nicotiana Tabacum ◽  
Blue Light ◽  
Photosynthetic Rate ◽  
Prolonged Exposure ◽  
Red Light ◽  
Compensation Point ◽  
Gas Analyzer ◽  
Co2 Compensation Point ◽  
Rate Of Photosynthesis ◽  
Light Inhibition

Apparent photosynthesis of attached leaves of Phaseolus vulgaris, Vicia faba, Pisum sativum, and Nicotiana tabacum at various intensities of blue and red light was measured by infrared CO2 gas analyzer in a closed system. Simultaneously the CO2 compensation point was measured.It was found that light-limited photosynthetic rate in blue light was equal to or more than that in red light. Inhibition of photosynthesis, which sometimes occurred at light-saturated intensities of blue light, could be avoided by addition of red light, prolonged exposure of the plants to blue light, or by lowering the O2 concentration. Accordingly, the increase of photosynthetic rate due to change of O2 concentration from 21 to 3% O2 is higher in blue light only when photosynthesis is inhibited by blue light at 21% O2. The data on the action of blue and red light on the CO2 compensation point seems to exclude the activation of photorespiration by blue light.The possible effects of blue light on apparent photosynthesis are discussed on the basis of the results presented.

Effects of specific wavelength spectra on antioxidant stress and cell damage of the ornamental cleaner shrimp Lysmata amboinensis (De Man, 1888) (Decapoda, Caridea, Lysmatidae) exposed to changing saline environments

Crustaceana ◽  
2018 ◽  
Vol 91 (10) ◽  
pp. 1231-1245 ◽  
Author(s):  
Jong Ryeol Choe ◽  
Ji Yong Choi ◽  
Jin Ah Song ◽  
Cheol Young Choi
Keyword(s):  
Cell Damage ◽  
Red Light ◽  
Aquatic Organisms ◽  
Major Influence ◽  
Fluorescent Light ◽  
Saline Environments ◽  
Positive Effects ◽  
Negative Results ◽  
Antioxidant Stress ◽  
Cleaner Shrimp

Abstract A variety of environmental factors have a major influence on the survival of aquatic organisms, particularly light and salinity, changes in which lead to a range of physiological changes. In the present study, we investigated the levels of stress caused by changes in salinity in the ornamental cleaner shrimp, Lysmata amboinensis, as well as the effect of specific light wavelengths following stress to changes in salinity. We measured the activity of superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (LPO) in the tissues (gill, hepatopancreas, and muscle) for three days after irradiating shrimp with specific wavelengths of light [red (630 nm), green (520 nm), and blue (455 nm)] at two intensities (0.5 and 1.0 W/m2) following exposure to different saline environments [25 practical salinity units (psu), 30 psu, 35 psu (normal seawater), and 40 psu]. DNA damage was measured using comet assays. Although all of the experimental groups exhibited negative results to changes in salinity, the green and red light groups exhibited positive effects when compared to the other wavelengths and fluorescent light. The effect of wavelength was not influenced by the intensity. In conclusion, the light of green and red wavelengths effectively reduces antioxidant stress and cell damage in cleaner shrimp.

LIGHT AND TEMPERATURE EFFECTS ON GROWTH AND SPOROPHORE FORMATION OF LENZITES TRABEA

1967 ◽  
Vol 45 (4) ◽  
pp. 525-530
Author(s):  
C. Madhosingh
Keyword(s):  
Temperature Effects ◽  
Growth Form ◽  
Red Light ◽  
Vegetative Mycelium ◽  
Temperature Growth ◽  
Low Intensity ◽  
Morphological Studies ◽  
Brown Pigmentation ◽  
Yellow Pigments ◽  
Red Radiation

Growth, pigmentation, and sporophore formation in Lenzites trabea, a polypore fungus, are shown to be affected by differences in light and temperature. Growth occurred under all conditions provided, being greater on liquid substrate than on agar and with maximum mycelium production in continuous red light at 25 °C. Sporophores, however, were formed only under certain continuous fluorescent and red radiations on liquid substrate; and on agar at 15 °C, 20 °C, and 25 °C in darkness broken by occasional brief exposures to low intensity daylight. The growth form under the red radiation and in darkness at 25 °C was similar. The form of fructification varied from poroid resupinate at 15 °C, to somewhat raised structures with larger pores at 20 °C, to an assemblage of discrete upright bodies with lacerated surface at 25 °C. Yellow-brown pigmentation was consistently associated with the fruiting areas in contrast with the predominantly fawn-yellow pigments of the vegetative mycelium. The significance of these results in comparative morphological studies is discussed.

scholarly journals Photocontrol of Flowering and Extension Growth in the Long-day Plant Pansy

2003 ◽  
Vol 128 (4) ◽  
pp. 479-485 ◽  
Author(s):  
Erik S. Runkle ◽  
Royal D. Heins
Keyword(s):  
Flower Development ◽  
Red Light ◽  
Reproductive Development ◽  
Extension Growth ◽  
Separate Experiment ◽  
Flower Initiation ◽  
Minimal Extension ◽  
Short Day ◽  
Long Day ◽  
Light Duration

Plastics that selectively reduce the transmission of far-red light (FR, 700 to 800 nm) reduce extension growth of many floricultural crops. However, FR-deficient (FRd) environments delay flowering in some long-day plants (LDPs), including `Crystal Bowl Yellow' pansy (Viola ×wittrockiana Gams). Our objective was to determine if FR light could be added to an otherwise FRd environment to facilitate flowering with minimal extension growth. In one experiment, plants were grown under a 16-hour FRd photoperiod, and FR-rich light was added during portions of the day or night. For comparison, plants were also grown with a 9-hour photoperiod [short-day (SD) control] or under a neutral (N) filter with a 16-hour photoperiod (long day control). Flowering was promoted most (i.e., percent of plants that flowered increased and time to flower decreased) when FR-rich light was added during the entire 16-hour photoperiod, during the last 4 hours of the photoperiod, or during the first or second 4 hours after the end of the photoperiod. In a separate experiment, pansy was grown under an FRd or N filter with a 9-hour photoperiod plus 0, 0.5, 1, 2, or 4 hours of night interruption (NI) lighting that delivered a red (R, 600 to 700 nm) to FR ratio of 0.56 (low), 1.28 (moderate), or 7.29 (high). Under the N filter, the minimum NI duration that increased percent flowering was 2 hours with a moderate or low R:FR and 4 hours with a high R:FR. Under the FRd filter, 2 or 4 hours of NI lighting with a moderate or low R:FR, respectively, was required to increase percent flowering, but a 4-hour NI with a high R:FR failed to promote flowering. Pansy appears to be day-neutral with respect to flower initiation and a quantitative LDP with respect to flower development. The promotion of reproductive development was related linearly to the promotion of extension growth. Therefore, it appears that in LDPs such as pansy, light duration and quality concomitantly promote extension growth and flowering, and cannot readily be separated with lighting strategies.

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