Clouds and cloud immersion alter photosynthetic light quality in a temperate mountain cloud forest

Botany ◽  
2010 ◽  
Vol 88 (5) ◽  
pp. 462-470 ◽  
Author(s):  
Keith Reinhardt ◽  
William K. Smith ◽  
Gregory A. Carter
Keyword(s):  
Light Quality ◽  
Cloud Forest ◽  
Spectral Band ◽  
Red Light ◽  
High Elevation ◽  
Cloud Forests ◽  
Specific Effects ◽  
Open Canopy ◽  
Low Cloud

Light quantity and quality strongly influence plant ecophysiology, especially in cloud forests. Only a few studies have investigated the quantitative effects of clouds on incident sunlight, and almost no studies have explored the specific effects of cloud immersion on light quality. In the present study, the spectral quantity and quality of sunlight during sunny (S), low cloud (LC), and cloud immersed (CI) days in open canopy and understory microsites are compared in high elevation cloud forests in the southern Appalachian Mountains, USA. Cumulative daily radiation measured on CI days was 85% less than on S days at open sites, but about the same as S days in understory sites. LC and CI conditions enhanced blue light by 5%–15% in open sites, but decreased it by 25%–60% in understory sites. In cloudy conditions, red light decreased by 6%–11% in open areas and increased by 25%–30% in understory sites. Cloudiness also resulted in important changes in spectral band ratios, and was associated with light diffusivity. Thus, cloud regimes had a strong influence on the photosynthetic light quality of incident sunlight.

scholarly journals The role of far-red light (FR) in photomorphogenesis and its use in greenhouse plant production

2020 ◽  
Vol 116 (1) ◽  
pp. 93
Author(s):  
Bojka KUMP
Keyword(s):  
Growth And Development ◽  
Light Quality ◽  
Red Light ◽  
Spectral Composition ◽  
Plant Production ◽  
Recent Developments ◽  
Long Time ◽  
Supplementary Lighting ◽  
Quality Of Products

<p>Light energy is one of the most important factors regulating the growth and development of plants. In greenhouses and other controlled- environments in which the natural radiation intensities are often low, plant production relies on supplementary lighting to optimize the photosynthesis, increase production levels, and enable year-round production. For a long time, the research related to artificial lighting sources focused on the optimization of the efficiency of use for photosynthesis. The quality of light in plant production has been widely addressed only recently with the development of advanced LED technology that is energy efficient and enables the control of the spectral composition of light. Red and far-red light are sensed by the phytochromes that trigger several morphological and developmental processes that impact productivity and yield quality. Thus, to efficiently exploit all the advantages of LEDs and to develop LED arrays for specific plant applications, it is essential to understand thoroughly how light quality influences plant growth and development. This paper presents an overview of the recent developments in light quality manipulation, focusing on far-red light and the R: FR ratio, to improve yield and quality of products and to manage plant architecture and flowering in vegetable and ornamental horticulture.</p>

scholarly journals Growth and Energy Use Efficiency of Grafted Tomato Transplants as Affected by LED Light Quality and Photon Flux Density

Agriculture ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 816
Author(s):  
Jianfeng Zheng ◽  
Peidian Gan ◽  
Fang Ji ◽  
Dongxian He ◽  
Po Yang
Keyword(s):  
Energy Use ◽  
Light Quality ◽  
Red Light ◽  
Electrical Energy ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Red Led ◽  
Use Efficiency ◽  
Led Lights

This study was conducted to compare the effects of broad spectrum during the whole seedling period and photon flux density (PFD) in the healing stage on the growth and energy use efficiency of grafted tomato (Lycopersicon esculentum Mill.) transplants in a plant factory. Fluorescent lights, white LED lights, and white plus red LED lights were applied at the growth processes of grafted tomato transplants from germination of rootstock and scion to post-grafting. Three levels of PFD (50, 100, 150 μmol m−2 s−1) were set in the healing stage under each kind of light quality. The results indicated that the growth and quality of grafted tomato transplants under different broad spectrums were influenced by the ratio of red to blue light (R/B ratio) and the ratio of red to far-red light (R/FR ratio). A higher R/B ratio was beneficial to total dry matter accumulation, but excessive red light had a negative effect on the root to shoot ratio and the seedling quality index. The higher blue light and R/FR ratio suppressed stem extension synergistically. The LED lights had good abilities to promote plant compactness and leaf thickness in comparison with fluorescent lights. The plant compactness and leaf thickness increased with the increase in daily light integral in the healing stage within a range from 2.5 to 7.5 mol m−2 d−1 (PFD, 50 to 150 μmol m−2 s−1). Compared to fluorescent lights, the LED lights showed more than 110% electrical energy saving for lighting during the whole seedling period. Higher PFD in the healing stage did not significantly increase the consumption of electric power for lighting. White plus red LED lights with an R/B ratio of 1.2 and R/FR ratio of 16 were suggested to replace fluorescent lights for grafted tomato transplants production considering the high quality of transplants and electrical energy saving, and PFD in the healing stage was recommended to be set to 150 μmol m−2 s−1.

Control by Light Quality of Chlorophyll Synthesis in the Brown Alga Desmarestia aculeata

1991 ◽  
Vol 46 (7-8) ◽  
pp. 542-548 ◽  
Author(s):  
F. López-Figueroa
Keyword(s):  
Blue Light ◽  
Light Quality ◽  
Red Light ◽  
Green Light ◽  
Chlorophyll Synthesis ◽  
Natural Conditions ◽  
Light Pulses ◽  
Light Effects ◽  
Starvation Conditions

Abstract The chlorophyll synthesis in the brown algae Desmarestia aculeata is affected by light quality and by the nutrient state in the medium before the illumination. Pulses of 5 min of red, green and blue light together with 200 μM nitrate in plants growing under natural conditions deter­ mined similar induction of chlorophyll synthesis. However, when the plants were incubated previously under starvation conditions the light effect was different. The induction of chlorophyll synthesis was greater after blue and green light than after red light pulses. Red-light photoreceptor was only involved in the chlorophyll synthesis under no nutrient limitations and under starvation conditions after previous illumination with blue light followed by far-red light. The induction of chlorophyll synthesis by green and blue light pulses applied together with nitrate was greater when the algae were incubated in starvation conditions than in natural conditions (normal nutrient state). Because all light effects were partially reversed by far-red light the involvement of a phyto-chrome-like photoreceptor is proposed. In addition, a coaction between blue-and a green-light photoreceptors and phytochrome is suggested.

scholarly journals Effects of Light on Growth and Flowering of Rosa hybrids `Mercedes'

1995 ◽  
Vol 120 (4) ◽  
pp. 571-576 ◽  
Author(s):  
Frank M. Maas ◽  
Edwin J. Bakx
Keyword(s):  
Light Quality ◽  
Day Treatment ◽  
Red Light ◽  
Spectral Composition ◽  
Dry Weight ◽  
Photon Flux ◽  
Short Treatment ◽  
Lateral Shoots ◽  
Single Shoot

Growth and flowering of shoots of `Mercedes' rose was investigated as a function of the level and spectral quality of photosynthetic photon flux (PPF). Experiments were performed with single-shoot plants decapitated above the two most basal leaves with five leaflets. The development of the two lateral shoots emerging from the axillary buds of these leaves was studied for 4 to 6 weeks. To discriminate between the effects of irradiance and light quality, plants were grown in growth chambers in which PPF and its spectral composition could be controlled. At a photoperiod of 12 hours, the length, weight, and flowering of the shoots strongly increased with irradiance. The growth and number of flowering shoots were always higher for the uppermost than for the second shoot. At the highest PPF (270 μmol·m-2·s-1), flowering occurred in 89% and 33% of the uppermost and second shoots, respectively. At an irradiance level of 90 μmol·m-2·s-1, these percentages were 6% and 0%. Although length and dry weight of both types of shoots were significantly increased by reducing the amount of blue light at constant PPF, flower development was not affected. In a second experiment, plants grown in white light (12 h/day) received a short treatment with low-intensity red or far-red `light at the end of each photoperiod. An end-of-day treatment with red light resulted in significantly more flowering shoots than far-red. The red far-red reversibility of this flowering response indicates the involvement of the photoreceptor phytochrome.

Antagonistic actions of Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction

Development ◽  
1999 ◽  
Vol 126 (10) ◽  
pp. 2073-2082 ◽  
Author(s):  
T.C. Mockler ◽  
H. Guo ◽  
H. Yang ◽  
H. Duong ◽  
C. Lin
Keyword(s):  
Flowering Time ◽  
Blue Light ◽  
Molecular Mechanisms ◽  
Light Quality ◽  
Floral Induction ◽  
Red Light ◽  
Floral Initiation ◽  
Sensitive Phase ◽  
Light Inhibition

The Arabidopsis photoreceptors cry1, cry2 and phyB are known to play roles in the regulation of flowering time, for which the molecular mechanisms remain unclear. We have previously hypothesized that phyB mediates a red-light inhibition of floral initiation and cry2 mediates a blue-light inhibition of the phyB function. Studies of the cry2/phyB double mutant provide direct evidence in support of this hypothesis. The function of cryptochromes in floral induction was further investigated using the cry2/cry1 double mutants. The cry2/cry1 double mutants showed delayed flowering in monochromatic blue light, whereas neither monogenic cry1 nor cry2 mutant exhibited late flowering in blue light. This result suggests that, in addition to the phyB-dependent function, cry2 also acts redundantly with cry1 to promote floral initiation in a phyB-independent manner. To understand how photoreceptors regulate the transition from vegetative growth to reproductive development, we examined the effect of sequential illumination by blue light and red light on the flowering time of plants. We found that there was a light-quality-sensitive phase of plant development, during which the quality of light exerts a profound influence on flowering time. After this developmental stage, which is between approximately day-1 to day-7 post germination, plants are committed to floral initiation and the quality of light has little effect on the flowering time. Mutations in either the PHYB gene or both the CRY1 and CRY2 genes resulted in the loss of the light-quality-sensitive phase manifested during floral development. The commitment time of floral transition, defined by a plant's sensitivity to light quality, coincides with the commitment time of inflorescence development revealed previously by a plant's sensitivity to light quantity - the photoperiod. Therefore, the developmental mechanism resulting in the commitment to flowering appears to be the direct target of the antagonistic actions of the photoreceptors.

THE EFFECT OF LIGHT QUALITY ON THE PRODUCTS OF PHOTOSYNTHESIS IN CHLORELLA VULGARIS

1962 ◽  
Vol 40 (1) ◽  
pp. 179-189 ◽  
Author(s):  
A. H. W. Hauschild ◽  
C. D. Nelson ◽  
G. Krotkov
Keyword(s):  
Blue Light ◽  
Chlorella Vulgaris ◽  
Glycolic Acid ◽  
Light Quality ◽  
Soluble Fraction ◽  
Red Light ◽  
Total Radioactivity ◽  
Rate Of Photosynthesis ◽  
Effect Of Light

Suspensions of Chlorella vulgaris, grown in synchronous culture, were pretreated in darkness for 45 to 225 minutes and illuminated in the presence of C14-bicarbonate with red, with red plus 4% of blue, and with blue light alone. The light intensities were so adjusted that the rate of photosynthesis (fixation of C14) was the same under the different conditions of illumination. The distribution of C14 among the various compounds of the ethanol-soluble fraction was obtained using paper chromatography and autoradiography.After 5 minutes of photosynthesis, the incorporation of C14 into aspartic acid was higher in the presence of red with supplementary blue light than in red light alone. At the same time the total radioactivity in glycine plus serine and in glycolic acid decreased. After 30 minutes of photosynthesis, blue light supplementary to red and blue light alone increased the total incorporation of C14 into the amino acid plus organic acid fraction as compared with incorporation in red light. This was due mainly to an increase in the radioactivity of aspartic and glutamic acids, while at the same time the radioactivity in glycine and glycolic acid was reduced.The duration of dark pretreatment was an important factor in the 30-minute experiments. The effect of increased dark pretreatment was to lower the incorporation of C14 into aspartic and glutamic acids when photosynthesis was carried out in red light, but the incorporation of C14 into these acids was increased in the presence of supplementary blue light.It is concluded that the distribution of carbon among the products of photosynthesis is affected by the quality of light.

scholarly journals Spatiotemporal Fusion of Formosat-2 and Landsat-8 Satellite Images: A Comparison of “Super Resolution-Then-Blend” and “Blend-Then-Super Resolution” Approaches

2021 ◽  
Vol 13 (4) ◽  
pp. 606
Author(s):  
Tee-Ann Teo ◽  
Yu-Ju Fu
Keyword(s):  
Satellite Images ◽  
Traditional Approach ◽  
Spectral Band ◽  
Super Resolution ◽  
High Temporal Resolution ◽  
Landsat 8 ◽  
Fusion Model ◽  
Image Blending ◽  
Fine Resolution

The spatiotemporal fusion technique has the advantages of generating time-series images with high-spatial and high-temporal resolution from coarse-resolution to fine-resolution images. A hybrid fusion method that integrates image blending (i.e., spatial and temporal adaptive reflectance fusion model, STARFM) and super-resolution (i.e., very deep super resolution, VDSR) techniques for the spatiotemporal fusion of 8 m Formosat-2 and 30 m Landsat-8 satellite images is proposed. Two different fusion approaches, namely Blend-then-Super-Resolution and Super-Resolution (SR)-then-Blend, were developed to improve the results of spatiotemporal fusion. The SR-then-Blend approach performs SR before image blending. The SR refines the image resampling stage on generating the same pixel-size of coarse- and fine-resolution images. The Blend-then-SR approach is aimed at refining the spatial details after image blending. Several quality indices were used to analyze the quality of the different fusion approaches. Experimental results showed that the performance of the hybrid method is slightly better than the traditional approach. Images obtained using SR-then-Blend are more similar to the real observed images compared with images acquired using Blend-then-SR. The overall mean bias of SR-then-Blend was 4% lower than Blend-then-SR, and nearly 3% improvement for overall standard deviation in SR-B. The VDSR technique reduces the systematic deviation in spectral band between Formosat-2 and Landsat-8 satellite images. The integration of STARFM and the VDSR model is useful for improving the quality of spatiotemporal fusion.

scholarly journals Biogeography of Tropical Montane Cloud Forests. Part II: Mapping of Orographic Cloud Immersion

2008 ◽  
Vol 47 (8) ◽  
pp. 2183-2197 ◽  
Author(s):  
Udaysankar S. Nair ◽  
Salvi Asefi ◽  
Ronald M. Welch ◽  
D. K. Ray ◽  
Robert O. Lawton ◽  
...  
Keyword(s):  
Costa Rica ◽  
Cloud Forest ◽  
United Nations Environment Programme ◽  
Cloud Base ◽  
Trade Wind ◽  
Cloud Forests ◽  
Study Region ◽  
Modis Data ◽  
Monitoring Centre ◽  
Tropical Montane Cloud Forests

Abstract This study details two unique methods to quantify cloud-immersion statistics for tropical montane cloud forests (TMCFs). The first technique uses a new algorithm for determining cloud-base height using Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products, and the second method uses numerical atmospheric simulation along with geostationary satellite data. Cloud-immersion statistics are determined using MODIS data for March 2003 over the study region consisting of Costa Rica, southern Nicaragua, and northern Panama. Comparison with known locations of cloud forests in northern Costa Rica shows that the MODIS-derived cloud-immersion maps successfully identify known cloud-forest locations in the United Nations Environment Programme (UNEP) World Conservation Monitoring Centre (WCMC) database. Large connected regions of cloud immersion are observed in regions in which the trade wind flow is directly impinging upon the mountain slopes; in areas in which the flow is parallel to the slopes, a fractured spatial distribution of TMCFs is observed. Comparisons of the MODIS-derived cloud-immersion map with the model output show that the MODIS product successfully captures the important cloud-immersion patterns in the Monteverde region of Costa Rica. The areal extent of cloud immersion is at a maximum during morning hours and at a minimum during the afternoon, before increasing again in the evening. Cloud-immersion frequencies generally increase with increasing elevation and tend to be higher on the Caribbean Sea side of the mountains. This study shows that the MODIS data may be used successfully to map the biogeography of cloud forests and to quantify cloud immersion over cloud-forest locations.

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