scholarly journals Axillary Budbreak in a Cut Rose Crop as Influenced by Light Intensity and Red:far-red Ratio at Bud Level

2014 ◽  
Vol 139 (2) ◽  
pp. 131-138 ◽  
Author(s):  
A. Maaike Wubs ◽  
Ep Heuvelink ◽  
Leo F.M. Marcelis ◽  
Gerhard H. Buck-Sorlin ◽  
Jan Vos
Keyword(s):  
Light Intensity ◽  
Incident Light ◽  
Red Light ◽  
Axillary Buds ◽  
Light Spectrum ◽  
Correlative Inhibition ◽  
Whole Plants ◽  
Positive Effect ◽  
Cut Rose ◽  
Effect Of Light

When flower-bearing shoots in cut rose (Rosa ×hybrida) are harvested, a varying number of repressed axillary buds on the shoot remainder start to grow into new shoots (budbreak). Earlier experiments indicated that light reaching the bud affected the number of budbreaks. In all these studies, whole plants were illuminated with different light intensities or light spectra. The aim of this article is to disentangle the effects of light intensity and light spectrum, in this case red:far-red ratio, at the level of the buds on budbreak in a rose crop. Three experiments were conducted in which light intensity and red:far-red ratio at the level of the buds were independently varied, whereas intensity and red:far-red ratio of incident light on the crop were not changed. Light intensity and red:far-red ratio at the position of the buds were quantified and related to budbreak on the shoot remainders. Removal of vertical shoots increased light intensity and red:far-red ratio as well as budbreak (1.9 budbreaks per shoot remainder compared with 0.4 budbreaks when five vertical shoots were present). No vertical shoots and red light-absorbing shading paper over the plant base mimicked the effect of vertical shoots with respect to light intensity and red:far-red ratio, but budbreak (1.0 budbreaks) was intermediate compared with treatments with and without shoots. This suggested that the presence of shoots exerts an inhibiting effect on budbreak through both effects on light at the bud and correlative inhibition. When plants had no vertical shoots and light intensity and red:far-red ratio at bud level were changed by neutral and red light-absorbing shading paper, there was a positive effect of light intensity on budbreak (0.3 more budbreaks per shoot remainder) and no effect of red:far-red ratio. Combinations of high and low light intensity with high and low red:far-red ratio on axillary buds showed that there was a positive effect of light intensity on budbreak (0.5 more budbreaks per shoot remainder) and no effect of red:far-red ratio. Our study reveals that when light intensity and red:far-red ratio received by the plant are similar but differ at bud level, budbreak was affected by light intensity and not by red:far-red ratio.

scholarly journals Four Hypotheses to Explain Axillary Budbreak after Removal of Flower Shoots in a Cut-rose Crop

2013 ◽  
Vol 138 (4) ◽  
pp. 243-252 ◽  
Author(s):  
A. Maaike Wubs ◽  
Ep Heuvelink ◽  
Leo F.M. Marcelis ◽  
Robert C.O. Okello ◽  
Alisa Shlyuykova ◽  
...  
Keyword(s):  
Light Intensity ◽  
Supply And Demand ◽  
Axillary Buds ◽  
Leaf Removal ◽  
Crop Canopy ◽  
Light Spectrum ◽  
Direct Light ◽  
Correlative Inhibition ◽  
Cut Rose ◽  
Effect Of Light

When flower-bearing shoots in cut-rose (Rosa ×hybrida) are harvested (removed), a varying number of repressed axillary buds on the shoot remainder start to grow into new shoots (budbreak). Besides removing within-shoot correlative inhibition, it is hypothesized that shoot removal leads to 1) increased light intensity lower in the crop canopy; 2) changes in the light spectrum (particularly red:far-red ratio); and 3) changed source:sink ratio (i.e., the ratio between supply and demand of assimilates). As a fourth hypothesis it is proposed that the degree of budbreak on a shoot remainder is also influenced by the correlative inhibition exerted by other shoots on the plant. It is the goal of this work to determine which of these four hypotheses is most important for budbreak in a cut-rose crop. Four experiments were conducted, in which these factors were varied by leaf removal, removal of mature shoots, varying the number of young shoots, shading of the crop, and application of direct light on the buds. Increase in source:sink ratio was not consistently associated with higher budbreak. If source:sink ratio was decreased by removal of leaves or a mature shoot, budbreak showed even a tendency to increase. Budbreak was subject to correlative inhibition exerted by other shoots on the plant. Treatments where more light reached the bud (as a result of less shoots, no shading of the crop, application of local light) increased budbreak. Increased red:far-red ratio had the same result as more light reaching the bud but was often interrelated with light intensity. It was concluded that after removal of the flower-bearing shoot, among the factors tested, light intensity on the buds was an important and consistent factor explaining budbreak on the shoot remainder, whereas the effect of light spectrum should be further investigated.

LIGHT-STIMULATED LEAF GROWTH ON INTACT AND EXCISED BEAN PLANTS (PHASEOLUS VULGARIS L.) III. EFFECT OF LIGHT INTENSITY

1999 ◽  
Vol 47 (4) ◽  
pp. 231-236
Author(s):  
Shimon Lavee ◽  
Elizabeth Van Volkenburgh ◽  
Robert Cleland E.
Keyword(s):  
Light Intensity ◽  
Leaf Growth ◽  
Energy Requirement ◽  
Red Light ◽  
Continuous Light ◽  
Leaf Expansion ◽  
Minimal Amount ◽  
Light Intensities ◽  
Bean Plants ◽  
Effect Of Light

The effect of light intensity on primary bean leaf unfolding and elongation was studied with intact and excised 10-day-old plants grown under red light. Continuous light of 40 μmol; m−2S−1 was enough to induce maximal leaf expansion both on intact and excised bean plants. Lower light intensities had a partial effect. The growth rate during the first 24 h in light was linearly related to light intensity up to 130 μmol; m−2S−1, although this light intensity was already supra-optimal for final leaf size. The minimal amount of light energy needed for full leaf expansion was about 15 mol photons m−2. The mode of light application, level of intensity, and irradiance duration were not critical when the total energy requirement was fulfilled. Under insufficient light applications for full leaf expansion, interrupted irradiance and longer low light intensity application induced leaf elongation more efficiently. Generally, the effect of different white light intensities on primary bean leaf expansion was the same on both intact and excised red-light-grown plants.

scholarly journals Analysis of the light intensity dependence of the growth ofSynechocystisand of the light distribution in a photobioreactor energized by 635 nm light

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5256 ◽  
Author(s):  
Alessandro Cordara ◽  
Angela Re ◽  
Cristina Pagliano ◽  
Pascal Van Alphen ◽  
Raffaele Pirone ◽  
...  
Keyword(s):  
Light Intensity ◽  
Photosynthetic Activity ◽  
Genetic Manipulation ◽  
Incident Light ◽  
Red Light ◽  
Clear Correlation ◽  
Heterogeneous Distribution ◽  
Cultivation System ◽  
Modelling Studies ◽  
Set Up

Synechocystisgathered momentum in modelling studies and biotechnological applications owing to multiple factors like fast growth, ability to fix carbon dioxide into valuable products, and the relative ease of genetic manipulation.Synechocystisphysiology and metabolism, and consequently, the productivity ofSynechocystis-based photobioreactors (PBRs), are heavily light modulated. Here, we set up a turbidostat-controlled lab-scale cultivation system in order to study the influence of varying orange–red light intensities onSynechocystisgrowth characteristics and photosynthetic activity.Synechocystisgrowth and photosynthetic activity were found to raise as supplied light intensity increased up to 500 μmol photons m−2s−1and to enter the photoinhibition state only at 800 μmol photons m−2s−1. Interestingly, reverting the light to a non-photo-inhibiting intensity unveiledSynechocystisto be able to promptly recover. Furthermore, our characterization displayed a clear correlation between variations in growth rate and cell size, extending a phenomenon previously observed in other cyanobacteria. Further, we applied a modelling approach to simulate the effects produced by varying the incident light intensity on its local distribution within the PBR vessel. Our model simulations suggested that the photosynthetic activity ofSynechocystiscould be enhanced by finely regulating the intensity of the light incident on the PBR in order to prevent cells from experiencing light-induced stress and induce their exploitation of areas of different local light intensity formed in the vessel. In the latter case, the heterogeneous distribution of the local light intensity would allowSynechocystisfor an optimized usage of light.

Effect of light intensity during extended photoperiod on growth of amabilis fir, mountain hemlock, and white and Engelmann spruce seedlings

1979 ◽  
Vol 9 (1) ◽  
pp. 82-89 ◽  
Author(s):  
J. T. Arnott
Keyword(s):  
High Pressure ◽  
Light Intensity ◽  
Growth Response ◽  
Significant Positive Effect ◽  
Engelmann Spruce ◽  
Bud Set ◽  
Terminal Bud ◽  
Positive Effect ◽  
Minimum Intensity ◽  
Effect Of Light

Abiesamabilis (Dougl.) Forbes, Tsugamertensiana (Bong.) Carr., Piceaglauca (Moench) Voss, and Piceaengelmannii Parry seedlings were grown in an outdoor container nursery using one high-pressure sodium vapor lamp to provide a 24-h photoperiod. Eight intensities of lighting were arranged, viz., 220, 80, 40, 20, 12, 8, 5, and 0 lx.Extending the photoperiod and increasing the light intensity had a significant positive effect on the length and weight of seedling shoots and delayed terminal bud set. Root growth response to these treatments was negative, although the differences were rarely significant. Seedlings grown under a light intensity of 220 lx were the largest. The minimum intensity required to produce seedling shoot lengths which were significantly larger than the controls was in the range 20–80 lx.

Influence of light intensity and photoperiod on frost-hardiness development in Douglas-fir seedlings

1970 ◽  
Vol 48 (12) ◽  
pp. 2129-2134 ◽  
Author(s):  
R. van den Driessche
Keyword(s):  
Light Intensity ◽  
Rapid Development ◽  
Red Light ◽  
Continuous Light ◽  
Douglas Fir ◽  
Frost Hardiness ◽  
Conductivity Method ◽  
Rapid Hardening ◽  
Effect Of Light ◽  
Electrical Conductivity Method

Effect of light intensity and photoperiod on frost-hardiness development in 2-year-old Douglas-fir seedlings was studied using an electrical conductivity method to assess stem hardiness. Hardiness increased with light intensity to 1000 ft-c at 7.5 °C, under both 8-h and 16-h photoperiods, after about 8 weeks. This response suggested photosynthesis was necessary for rapid hardening, as also did the more rapid hardening obtained under continuous light at 40 ft-c, compared with 8-h photoperiods of the same intensity. By contrast, short photoperiods enhanced the rate of hardening at a light intensity of 3000 ft-c and 500 ft-c (after 7 weeks), compared with long photoperiods. After 7 weeks plants under short photoperiods with supplementary red light hardened like plants under long photoperiods, but after 10 weeks this effect of red light was no longer apparent. Far-red light did not produce any effect. Evidently a certain amount of photosynthesis must be carried out by Douglas-fir seedlings for rapid development of hardiness, but, with sufficient light for this to occur, short photoperiods hasten hardening.

scholarly journals Supplemental Far-Red Light Stimulates Lettuce Growth: Disentangling Morphological and Physiological Effects

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 166
Author(s):  
Reeve Legendre ◽  
Marc W. van Iersel
Keyword(s):  
Plant Biomass ◽  
Incident Light ◽  
Red Light ◽  
Leaf Length ◽  
Interactive Effects ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Dry Matter Accumulation ◽  
Light Spectrum ◽  
Canopy Size

Light-emitting diodes allow for the application of specific wavelengths of light to induce various morphological and physiological responses. In lettuce (Lactuca sativa), far-red light (700–800 nm) is integral to initiating shade responses which can increase plant growth. In the first of two studies, plants were grown with a similar photosynthetic photon flux density (PPFD) but different intensities of far-red light. The second study used perpendicular gradients of far-red light and PPFD, allowing for examination of interactive effects. The far-red gradient study revealed that increasing supplemental far-red light increased leaf length and width, which was associated with increased projected canopy size (PCS). The higher PCS was associated with increased cumulative incident light received by plants, which increased dry matter accumulation. In the perpendicular gradient study, far-red light was 57% and 183% more effective at increasing the amount of light received by the plant, as well as 92.5% and 162% more effective at increasing plant biomass at the early and late harvests, respectively, as compared to PPFD. Light use efficiency (LUE, biomass/mol incident light) was generally negatively correlated with specific leaf area (SLA). Far-red light provided by LEDs increases the canopy size to capture more light to drive photosynthesis and shows promise for inclusion in the growth light spectrum for lettuce under sole-source lighting.

PHOTOCATALYTIC CONVERSION OF METHANE INTO METHANOL OVER THE MoO3(010) SURFACE USING A SIMULATION METHOD

2004 ◽  
Vol 11 (01) ◽  
pp. 33-39 ◽  
Author(s):  
A. Z. MOSHFEGH ◽  
M. DASHTI
Keyword(s):  
Light Intensity ◽  
Atmospheric Pressure ◽  
Incident Light ◽  
Formation Rate ◽  
Simulation Method ◽  
Incident Light Intensity ◽  
Formation Reaction ◽  
Methanol Formation ◽  
Conversion Of Methane ◽  
Effect Of Light

In this investigation, we have studied the kinetics and mechanism of photocatalytic conversion of methane into methanol reaction over the MoO 3(010) surface using a computer simulation method. Methane and oxygen as the reactants are used at room temperature and atmospheric pressure under UV photoirradiation of the catalyst. According to our data analysis, the order of methanol formation reaction with respect to CH 4 and O 2 was determined to be l=0.30 and m=-1.03, respectively. The highest methanol formation rate (TOF) value was obtained at about 0.05 molecule/s.site in a range of 25–35 W/cm2 incident light intensity with energy hν≥Eg. The selectivity of CH 3 OH was increased with increasing partial pressure of CH 4, while the selectivity of CHOH was decreased. The effect of light intensity on the CH 3 OH selectivity was also studied under different P CH 4/P O 2 ratios, namely 0.9, 1.5 and 2.6. The highest CH 3 OH selectivity was obtained at 1.5 ratio.

scholarly journals Optimization of LED Lighting and Quality Evaluation of Romaine Lettuce Grown in An Innovative Indoor Cultivation System

2019 ◽  
Vol 11 (3) ◽  
pp. 841 ◽  
Author(s):  
Danilo Loconsole ◽  
Giacomo Cocetta ◽  
Piero Santoro ◽  
Antonio Ferrante
Keyword(s):  
Energy Consumption ◽  
Light Intensity ◽  
Cultural Practices ◽  
Red Light ◽  
Electrical Energy ◽  
Light Spectrum ◽  
Romaine Lettuce ◽  
Light Emitting ◽  
Physiological Indexes

Sustainability is the most critical point in micro-scale indoor crop systems. It can be improved through the optimization of all of the production factors, such as water, nutrients, and energy. The use of light-emitting diodes (LED) allows the fine regulation of the light intensity and light spectrum to be obtained, with a significant reduction in energy consumption. The objective of this study was the optimization of a LED-based protocol of light management for Romaine lettuce cultivation in a micro-growing environment specifically designed for home cultivation. Four different growing cycles were tested. In each one, the light spectrum was modified by increasing the percentage of red light and decreasing the blue light. This resulted in a change in the light intensity which ranged from 63.2 to 194.54 µmol m−2 s−1. Moreover, the photoperiod was shortened to reduce the energy consumption and, in the last cycle, the effect of the daily alternation of dark and light was tested. The fresh and dry biomass produced were measured and the energy consumed in each cycle was monitored. The quality of lettuce was evaluated by measuring several physiological indexes, including chlorophyll a fluorescence, chlorophyll, sugars, nitrate, lipid peroxidation, carotenoids, and phenolic index. The results obtained showed that the productivity and the quality of lettuce can be positively affected by modulating the light quality and intensity, as well as other cultural practices. At the same time, the estimation of the electrical energy consumption indicated that little changes in the lighting recipe can significantly affect the energetic, environmental, and economic impact of home productions.

scholarly journals The Effect of Light Spectrum on the Morphology and Cannabinoid Content of Cannabis sativa L.

2018 ◽  
Vol 1 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Gianmaria Magagnini ◽  
Gianpaolo Grassi ◽  
Stiina Kotiranta
Keyword(s):  
Light Intensity ◽  
Cannabis Sativa ◽  
Red Light ◽  
Total Yield ◽  
Plant Morphology ◽  
Dry Weight ◽  
Light Sources ◽  
Light Spectrum ◽  
Light Spectra ◽  
Generative Phase

Cannabis sativa L. flowers are the main source of Δ-9-tetrahydrocannabinol (THC) used in medicine. One of the most important growth factors in cannabis cultivation is light; light quality, light intensity, and photoperiod play a big role in a successful growth protocol. The aim of the present study was to examine the effect of 3 different light sources on morphology and cannabinoid production. Cannabis clones were grown under 3 different light spectra, namely high-pressure sodium (HPS), AP673L (LED), and NS1 (LED). Light intensity was set to ∼450 µmol/m2/s measured from the canopy top. The photoperiod was 18L: 6D/21 days during the vegetative phase and 12L: 12D/46 days during the generative phase, respectively. At the end of the experiment, plant dry weight partition, plant height, and cannabinoid content (THC, cannabidiol [CBD], tetrahydrocannabivarin [THCV], cannabigerol [CBG]) were measured under different light treatments. The experiment was repeated twice. The 3 light treatments (HPS, NS1, AP673L) resulted in differences in cannabis plant morphology and in cannabinoid content, but not in total yield of cannabinoids. Plants under HPS treatment were taller and had more flower dry weight than those under treatments AP673L and NS1. Treatment NS1 had the highest CBG content. Treatments NS1 and AP673L had higher CBD and THC concentrations than the HPS treatment. Results were similar between experiments 1 and 2. Our results show that the plant morphology can be manipulated with the light spectrum. Furthermore, it is possible to affect the accumulation of different cannabinoids to increase the potential of medicinal grade cannabis. In conclusion, an optimized light spectrum improves the value and quality of cannabis. Current LED technology showed significant differences in growth habit and cannabinoid profile compared to the traditional HPS light source. Finally, no difference of flowering time was observed under different R:FR (i.e., the ratio between red and far-red light).

Effect of light intensity on the ultrastructure of the filamentous cyanobacterium, Anabaena variabilis

1988 ◽  
Vol 46 ◽  
pp. 300-301
Author(s):  
C. S. Bricker ◽  
S. R. Barnum ◽  
B. Huang ◽  
J. G. Jaworskl
Keyword(s):  
Fatty Acid ◽  
Light Intensity ◽  
Acid Content ◽  
Fatty Acid Content ◽  
Anabaena Variabilis ◽  
Chloroplast Envelope ◽  
Major Constituent ◽  
Filamentous Cyanobacterium ◽  
Photosynthetic Membrane ◽  
Effect Of Light

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane in Anabaena variabilis grown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.

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