Stock and Snapdragon as Influenced by Greenhouse Covering Materials and Supplemental Light

We examined effects of single-layer glass and double-layer antifog polyethylene films on growth and flowering of stock (Matthiola incana L.) and snapdragon (Antirrhinum majalis L.) in a 3-year period. Stock produced more buds/spike with shorter but thicker stems under single-layer glass and under antifog 3-year polyethylene, and showed higher photosynthetic capacity (Pc) under single-layer glass than under other covers regardless of light regimes. Similarly, growth and flowering of snapdragon were significantly better under single-layer glass than in polyethylene houses. A supplemental light of 60 μmol·m-2·s-1 accelerated flowering by 20 to 25 days, improved flower quality, and eliminated differences in plant growth and quality of snapdragon between covering treatments. The Pc of stock was lower under all polyethylene covers than under single-layer glass. Among the three antifog polyethylene films, a slightly higher Pc was measured for plants under antifog 3-year polyethylene. However, there was no difference among covering treatments in the net photosynthetic rate (PN) at low light level (canopy level). Supplemental lighting reduced Pc of stock leaves, especially under single-layer glass, and diminished differences in Pc among covering treatments. Dry mass was more influenced by larger leaf area caused by higher leaf temperature than by PN. Overall, antifog 3-year polyethylene was a good covering material when both plant quality and energy saving were considered.

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Physiological responses of two tropical weeds to shade: I. Growth and biomass allocation

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x1999000600004 ◽

1999 ◽

Vol 34 (6) ◽

pp. 944-952 ◽

Cited By ~ 1

Author(s):

Moacyr Bernardino Dias-Filho

Keyword(s):

Leaf Area ◽

Weed Management ◽

Dry Mass ◽

High Light ◽

Low Light ◽

Light Regimes ◽

Leaf Dry Mass ◽

Lower Ability ◽

Total Plant ◽

Plant Dry Mass

Ipomoea asarifolia (Desr.) Roem. & Schultz (Convolvulaceae) and Stachytarpheta cayennensis (Rich) Vahl. (Verbenaceae), two weeds found in pastures and crop areas in Brazilian Amazonia, were grown in controlled environment cabinets under high (800-1000 µmol m-² s-¹) and low (200-350 µmol m-² s-¹) light regimes during a 40-day period. For both species leaf dry mass and leaf area per total plant dry mass, and leaf area per leaf dry mass were higher for low-light plants, whereas root mass per total plant dry mass was higher for high-light plants. High-light S. cayennensis allocated significantly more biomass to reproductive tissue than low-light plants, suggesting a probably lower ability of this species to maintain itself under shaded conditions. Relative growth rate (RGR) in I. asarifolia was initially higher for high-light grown plants and after 20 days started decreasing, becoming similar to low-light plants at the last two harvests (at 30 and 40 days). In S. cayennensis, RGR was also higher for high-light plants; however, this trend was not significant at the first and last harvest dates (10 and 40 days). These results are discussed in relation to their ecological and weed management implications.

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Interactive Effects of Light and CO2 on Photosynthesis and Growth of Brassica spp.

HortScience ◽

10.21273/hortsci.32.3.491d ◽

1997 ◽

Vol 32 (3) ◽

pp. 491D-491

Author(s):

Jan M. Kossowski ◽

David W. Wolfe

Keyword(s):

Light Response ◽

Light Level ◽

Dry Mass ◽

Compensation Point ◽

Interactive Effects ◽

Response Curves ◽

Low Light ◽

Light Response Curves ◽

Nutrient Film Technique ◽

Plant Dry Mass

Long- and short-term physiological responses of pak choi (Chinese cabbage, Brassica campestris cv. `Hypro') to elevated CO2 and light environments were evaluated in the series of growth chamber experiments. Plants were grown hydroponically (Nutrient Film Technique) at 25/18°C (day/night) temperature, a 16-h photoperiod, and at three CO2 levels (350, 700, 1400 ppm) and two light levels (200 and 400 μmol·m–2·s–1 PPFD). Relative to 350-ppm CO2 treatment, the final total plant dry mass in low light increased by 37% and 38% at 700 and 1400 ppm CO2, respectively. In high light the increase was 7% and 13% at 700 and 1400 ppm CO2, respectively. Light response curves showed a positive CO2 effect on light compensation point, a slight increase in quantum yield and increase in maximum Pn rates at elevated CO2. Carbon dioxide response curves (measured at saturating PPFD of 1600 μmol·m–2·s–1) showed no effect of growth light treatment on the CO2 compensation point, but a 20% to 30% higher maximum Pn rate at saturating CO2 in plants grown at the higher light level. Overall, the highest Pn rates and the highest plant dry mass at final harvest were found in plants grown at the 400 μmol·m–2·s–1 PPFD and 1400 ppm CO2. Relative beneficial CO2 effects, however, were the most pronounced in low light conditions.

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Leaf nitrogen distribution within canopies is (also) optimal

10.5194/egusphere-egu2020-12097 ◽

2020 ◽

Author(s):

Han Wang ◽

Colin Prentice ◽

Trevor Keenan ◽

Ülo Niinemets ◽

Nils Stenseth

Keyword(s):

Photosynthetic Capacity ◽

Temporal Distribution ◽

Light Level ◽

Leaf Nitrogen ◽

Saturation Curve ◽

Field Observations ◽

Light Regimes ◽

The Vertical Distribution ◽

Global Datasets ◽

Apparent Conflict

The distribution of leaf nitrogen (NL) within canopies has been discussed for decades in relation to the optimality hypothesis that predicts coordination of carboxylation capacity with absorbed light. Although an optimal (that is, proportional) response of both carboxylation capacity and NLto light is extensively supported by field observations of variation among sites, the observed saturation curve of NLwithin canopies seems to challenge the generality of that response. By considering dynamic light regimes, we propose an optimality-based theory that successfully reconciles the apparent conflict of observed NLdistribution within and between canopies. This theory proposes that due to the highly uneven temporal distribution of sun flecks, the light level to which understory leaves acclimate is much higher than the average light level. This proposition leads to a saturation curve for the vertical distribution of NL. Our within-canopy data analysis supports this theory. Understorey leaves require significantly less NLto achieve photosynthetic capacity as an acclimation to sun flecks. The contribution of structural and photosynthetic components to NLpredicted by the theory is quantitatively and consistently supported by global datasets of variation both within and between canopies.

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Daily Light Integral Affects Flowering and Quality of Greenhouse-grown Achillea, Gaura, and Lavandula

HortScience ◽

10.21273/hortsci.40.1.114 ◽

2005 ◽

Vol 40 (1) ◽

pp. 114-118 ◽

Cited By ~ 8

Author(s):

Beth A. Fausey ◽

Royal D. Heins ◽

Arthur C. Cameron

Keyword(s):

Growth And Development ◽

Visual Quality ◽

Light Level ◽

Dry Mass ◽

Ambient Light ◽

Herbaceous Perennials ◽

Daily Light Integral ◽

Light Integral ◽

Prostrate Growth

The growth and development of Achillea ×millefolium L. `Red Velvet', Gaura lindheimeri Engelm. & Gray `Siskiyou Pink' and Lavandula angustifolia Mill. `Hidcote Blue' were evaluated under average daily light integrals (DLIs) of 5 to 20 mol·m-2·d-1. Plants were grown in a 22 ± 2 °C glass greenhouse with a 16-h photoperiod under four light environments: 50% shading of ambient light plus PPF of 100 μmol·m-2·s-1 (L1); ambient light plus PPF of 20 μmol·m-2·s-1 (L2); ambient light plus PPF of 100 μmol·m-2·s-1 (L3); and ambient light plus PPF of 150 μmol·m-2·s-1 (L4). Between 5 to 20 mol·m-2·d-1, DLI did not limit flowering and had little effect on timing in these studies. Hence, the minimum DLI required for flowering of Achillea, Gaura and Lavandula must be <5 mol·m-2·d-1, the lowest light level tested. However, all species exhibited prostrate growth with weakened stems when grown at a DLI of about 10 mol·m-2·d-1. Visual quality and shoot dry mass of Achillea, Gaura and Lavandula linearly increased as DLI increased from 5 to 20 mol·m-2·d-1 and there was no evidence that these responses to light were beginning to decline. While 10 mol·m-2·d-1 has been suggested as an adequate DLI, these results suggest that 15 to 20 mol·m-2·d-1 should be considered a minimum for production of these herbaceous perennials when grown at about 22 °C.

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A SEC Vidicon System for Satellite Applications

Symposium - International Astronomical Union ◽

10.1017/s007418090010378x ◽

1971 ◽

Vol 41 ◽

pp. 360-360

Author(s):

G. E. Brückner

Keyword(s):

Signal To Noise Ratio ◽

Light Level ◽

Zero Order ◽

Signal To Noise ◽

Compression Scheme ◽

Low Light ◽

Low Contrast ◽

Satellite Applications ◽

Theoretical Considerations

This paper describes a small, low power SEC vidicon camera developed for recording images of the outer solar corona from an OSO satellite. The SEC vidicon has been selected for this application because of its capability to integrate and store low light level and low contrast images. The achieved signal to noise ratio will be discussed and compared with theoretical considerations. A new operational method to readout the tube very slowly will be described. The influence of a zero order data compression scheme on the quality of the coronal images will be discussed.

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Effect of soldering process on the tube body quality of low-light-level image intensifier

2015 International Conference on Optoelectronics and Microelectronics (ICOM) ◽

10.1109/icoom.2015.7398863 ◽

2015 ◽

Author(s):

Yang Xiaojun ◽

Shi Hongli ◽

Hou Zhipeng ◽

Liu Feng ◽

Li Dan ◽

...

Keyword(s):

Image Intensifier ◽

Light Level ◽

Low Light ◽

Soldering Process

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Software pattern recognition applied to nanodiffraction patterns from a STEM instrument

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014484x ◽

1986 ◽

Vol 44 ◽

pp. 694-695

Author(s):

G.Y. Fan ◽

J.M. Cowley

Keyword(s):

Image Processing ◽

Pattern Recognition ◽

Computer Software ◽

Processing System ◽

Light Level ◽

Host Computer ◽

Low Light ◽

Image Processing System ◽

Recent Developments ◽

On Line

In recent developments, the ASU HB5 has been modified so that the timing, positioning, and scanning of the finely focused electron probe can be entirely controlled by a host computer. This made the asynchronized handshake possible between the HB5 STEM and the image processing system which consists of host computer (PDP 11/34), DeAnza image processor (IP 5000) which is interfaced with a low-light level TV camera, array processor (AP 400) and various peripheral devices. This greatly facilitates the pattern recognition technique initiated by Monosmith and Cowley. Software called NANHB5 is under development which, instead of employing a set of photo-diodes to detect strong spots on a TV screen, uses various software techniques including on-line fast Fourier transform (FFT) to recognize patterns of greater complexity, taking advantage of the sophistication of our image processing system and the flexibility of computer software.

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Low-light-level three-dimensional video microscope with long working distance objective lenses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168864 ◽

1994 ◽

Vol 52 ◽

pp. 226-227

Author(s):

W. Lin ◽

J. Gregorio ◽

T.J. Holmes ◽

D. H. Szarowski ◽

J.N. Turner

Keyword(s):

Three Dimensional ◽

Light Level ◽

Stereo Pair ◽

Light Illumination ◽

Initial Image ◽

Low Light ◽

Image Recording ◽

Depth Discrimination ◽

Video Microscope ◽

Working Distance

A low-light level video microscope with long working distance objective lenses has been built as part of our integrated three-dimensional (3-D) light microscopy workstation (Fig. 1). It allows the observation of living specimens under sufficiently low light illumination that no significant photobleaching or alternation of specimen physiology is produced. The improved image quality, depth discrimination and 3-D reconstruction provides a versatile intermediate resolution system that replaces the commonly used dissection microscope for initial image recording and positioning of microelectrodes for neurobiology. A 3-D image is displayed on-line to guide the execution of complex experiments. An image composed of 40 optical sections requires 7 minutes to process and display a stereo pair.The low-light level video microscope utilizes long working distance objective lenses from Mitutoyo (10X, 0.28NA, 37 mm working distance; 20X, 0.42NA, 20 mm working distance; 50X, 0.42NA, 20 mm working distance). They provide enough working distance to allow the placement of microelectrodes in the specimen.

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