Nitrate accumulation in spinach: Uptake and reduction of nitrate during a dark or a ‘low light’ night period

1986 ◽  
Vol 91 (3) ◽  
pp. 429-432 ◽  
Author(s):  
Eveliene Steingröver
Keyword(s):  
Nitrate Accumulation ◽  
Low Light ◽  
Night Period

scholarly journals The Effect of Light-dependent Application of Nitrate on the Growth of Aeroponically Grown Lettuce (Lactuca sativa L.)

2004 ◽  
Vol 129 (4) ◽  
pp. 570-575 ◽  
Author(s):  
Jernej Demšar ◽  
Jože Osvald ◽  
Dominik Vodnik
Keyword(s):  
Lactuca Sativa ◽  
Early Spring ◽  
Nitrate Content ◽  
Light Conditions ◽  
Nitrate Accumulation ◽  
Low Light ◽  
Efficient Reduction ◽  
Nitrate Supply ◽  
Lettuce Yield ◽  
Leaf Nitrate

With a high nitrate supply, and most frequently under low-light conditions, lettuce accumulates relatively large amounts of NO3-as a result of an excess of uptake over reduction. Different approaches, which are used to reduce leaf nitrate, often result in a yield loss. A computerized aeroponic system, which supplies different nitrate concentrations in accordance with the changeable light conditions (dynamic light-dependent application of nitrate), was used to reduce nitrate accumulation in lettuce (Lactuca sativa L.) var. Capitata cv. Vanity. Under unfavorable light conditions nitrate was supplied at limited rates (slight, medium, and strong reduction) to the plants. In response to given light conditions the nitrate supply was reduced close to one-half or one-fourth of the full nutrient solution (8 mmol·L-1 NO3-). Controlled nutrition resulted in efficient reduction in leaf nitrate. In the early-spring experiment the average nitrate content in outer leaves was decreased by 9%, 63%, and 92% and in the late-spring experiment the decrease was 23%, 58%, and 76% compared to control. At the same time, the controlled, light-dependent nitrate deprivation did not result in a loss of a lettuce yield (except in the treatment with strong nitrate reduction) and had limited effects on photosynthesis (PN-Ci measurements) and photosynthetic pigments.

A review of factors affecting and prevention of pasture-induced nitrate toxicity in grazing animals

2003 ◽  
pp. 171-178 ◽  
Author(s):  
N.S. Bolan ◽  
P.D. Kemp
Keyword(s):  
Plant Roots ◽  
Soil Conditions ◽  
Nitrate Accumulation ◽  
Forage Crops ◽  
Low Light ◽  
Factors Affecting ◽  
Treatment And Prevention ◽  
Common Causes ◽  
Ruminant Animals ◽  
Annual Weeds

Although plant roots take up nitrogen (N) both as ammonium (NH4 +) and nitrate (NO3 -) ions, under most soil conditions uptake of NO3 - dominates. Once absorbed by the plant roots, the NO3 - is reduced to NH4 +, which is subsequently assimilated into organic compounds. However, when the rate of uptake exceeds the rate of NO3 - reduction, accumulation of NO3 - in plants occurs. Ruminant animals with high NO3 - levels in their diets accumulate nitrite (NO2 -). Nitrite is absorbed into the blood and combines with hemoglobin to form methemoglobin. This condition is known as nitrate poisoning (i.e., methemoglobinaemea). Nitrate poisoning occurs when animals eat forage material with high NO3 - content. The most common causes of high NO3 - content in forage tissue include: (i) high application of N fertilizers; (ii) drought conditions; (iii) damage to plant tissue (such as defoliation as a result of herbicide application); (iv) low light intensity, which reduce photosynthetic activity; and (v) presence of NO3 - accumulating plant species, such as annual weeds. In this review paper, the processes of uptake and assimilation of N by plants, factors affecting NO3 - accumulation in plants, and the treatment and prevention of nitrate poisoning in grazing animals are discussed. Keywords: forage crops, methemoglobinaemea, methylene blue, N fer tilizer, nitrate accumulation, nitrate poisoning, nitrate reductase

NITRATE ACCUMULATION IN GREENHOUSE VEGETABLE CROPS

1974 ◽  
Vol 54 (4) ◽  
pp. 783-788 ◽  
Author(s):  
D. J. CANTLIFFE ◽  
S. C. PHATAK
Keyword(s):  
Spinacia Oleracea ◽  
Vegetable Crops ◽  
Nitrate Accumulation ◽  
Low Light ◽  
Total N ◽  
Spinacia Oleracea L ◽  
Grand Rapids ◽  
Greenhouse Vegetable ◽  
High Concentrations ◽  
Standard Cultivar

Four cultivars each of lettuce (Lactuca sativa L.), radish (Raphanus sativa L.) and spinach (Spinacia oleracea L.) were grown at three NH4NO3 levels (0, 14.7 and 29.4 g N/m2) in a muck soil as a commercial greenhouse crop under winter conditions (low light intensity and short photoperiod). Analysis of the tissues for NO3-N showed that all three vegetable crops contained high concentrations of NO3-N when grown under these conditions: radish highest, followed by lettuce, then spinach. Total N and NO3-N were increased by N fertilizer only in radish roots, and yield was promoted by the additional N only in lettuce. Lettuce cultivars Domineer and Korrekt contained significantly less NO3 than Grand Rapids or Noran and were higher yielding than the standard cultivar Grand Rapids. The NO3 content of radishes was extremely high, especially in the root of the white cultivar Icicle (1.68% NO3-N). Yield of roots from Icicle was not significantly different from Champion, Early Scarlet Globe and Red Boy, cultivars which did not contain as much NO3-N. Smooth-leaf spinach cultivar Northland was higher yielding with significantly less NO3 than savoyed cultivars America, Winter Bloomsdale or Savoy. High NO3 tissue concentrations can be reduced in these crops by growing cultivars that accumulate less NO3.

Software pattern recognition applied to nanodiffraction patterns from a STEM instrument

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.

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

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.

Morphogenetic machines revealed: Microscopy of living cells in the embryo of the frog, Xenopus laevis

1993 ◽  
Vol 51 ◽  
pp. 172-173
Author(s):  
Ray Keller
Keyword(s):  
Image Processing ◽  
Fluorescent Dyes ◽  
Cell Movement ◽  
Living Cells ◽  
Ease Of Use ◽  
Low Light ◽  
Amphibian Embryo ◽  
Large Populations ◽  
Light Fluorescence ◽  
Video Image Processing

The amphibian embryo offers advantages of size, availability, and ease of use with both microsurgical and molecular methods in the analysis of fundamental developmental and cell biological problems. However, conventional wisdom holds that the opacity of this embryo limits the use of methods in optical microscopy to resolve the cell motility underlying the major shape-generating processes in early development.These difficulties have been circumvented by refining and adapting several methods. First, methods of explanting and culturing tissues were developed that expose the deep, nonepithelial cells, as well as the superficial epithelial cells, to the view of the microscope. Second, low angle epi-illumination with video image processing and recording was used to follow patterns of cell movement in large populations of cells. Lastly, cells were labeled with vital, fluorescent dyes, and their behavior recorded, using low-light, fluorescence microscopy and image processing. Using these methods, the details of the cellular protrusive activity that drives the powerful convergence (narrowing)

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