CHYTRIDS AND ALGAE: II. FACTORS INFLUENCING PARASITISM OF RHIZOPHYDIUM SPHAEROCARPUM ON SPIROGYRA

1967 ◽  
Vol 45 (4) ◽  
pp. 431-440 ◽  
Author(s):  
D. J. S. Barr ◽  
C. J. Hickman
Keyword(s):  
Light Intensity ◽  
Pure Culture ◽  
Optimum Temperature ◽  
Light Saturation ◽  
Light Intensities ◽  
Alkaline Side ◽  
Culture Growth ◽  
Ph Range ◽  
Host Parasite ◽  
Effect Of Light

Host–parasite interrelationship studies showed that temperature was the most important environmental factor associated with epidemics of Rhizophydium sphaerocarpum (Zopf) Fischer on Spirogyra. Certain highly susceptible spring species of Spirogyra grew poorly or not at all at 30 C, the optimum temperature for R. sphaerocarpum, while resistant summer species grew well at 30 C, and even at 35 C. Both pure-culture growth of R. sphaerocarpum and infection of Spirogyra were optimal at approximately pH 7.0–7.5, falling off markedly below pH 6.0 and above pH 8.5. Spirogyra itself grew over a wider pH range, especially on the alkaline side. Infection of Spirogyra was negligible in darkness but a light intensity of 40 ft-c permitted some infection. No difference in infection occurred over a range of light intensities from 65 to 980 ft-c or in day lengths varying from 8 to 16 hours at a light intensity of 600 ft-c. Light saturation for Spirogyra was 400 ft-c. In contrast to the effect of light upon infection, pure culture growth of R. sphaerocarpum was considerably greater in total darkness than at light intensities of 20 ft-c or higher.

scholarly journals Effect of Light Intensity on the Rate of Apparent Photosynthesis in Coffee Leaves

1969 ◽  
Vol 46 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Marco A. Tió
Keyword(s):  
Light Intensity ◽  
Photosynthetic Activity ◽  
High Light ◽  
Light Saturation ◽  
Arabica Coffee ◽  
Light Intensities ◽  
Effect Of Light

The rate of apparent photosynthesis relative to light intensity was determined for Bourbon variety of Arabica coffee. A curve for the effect of light-saturation on apparent photosynthesis of coffee showed that saturation was reached at a maximum of 2,000 foot-candles and that maximum apparent photosynthesis was maintained up to 6,000 foot-candle intensity, after which it decreased. Evidence is also presented to demonstrate that high light intensities may cause an impairment of the photosynthetic activity.

The Tetrazolium Reaction as a Measure of the Action of Diquat in Elodea

Weed Science ◽  
1968 ◽  
Vol 16 (3) ◽  
pp. 329-331 ◽  
Author(s):  
P. J. Davies ◽  
D. E. Seaman
Keyword(s):  
Light Intensity ◽  
Living Cells ◽  
Elodea Canadensis ◽  
Triphenyl Tetrazolium Chloride ◽  
Light Saturation ◽  
Tetrazolium Chloride ◽  
Light Intensities ◽  
Triphenyl Formazan

The production of red triphenyl formazan (hereinafter referred to as TPF) from colorless 2,3,5-triphenyl tetrazolium chloride (hereinafter referred to as TTC) by living cells was used as a vitality indicator for examining the effects of 6,7-dihydrodipyrido[1,2-a:2′,1′-c] pyrazidiinium salt (diquat) in elodea (Elodea canadensisMichx) shoots at varying light intensities. Diquat at 10 ppmw completely killed the elodea in 6 hr at 183 ft-c and at almost the same rate at 13,000 ft-c due to light saturation near the lower level. Over 24 hr were required for this effect in the dark. Between 29 and 183 ft-c, TPF production varied inversely with the light intensity. A comparison is made with the destruction of chlorophyll by diquat.

Does light intensity affect embryonic development of squid (Heterololigo bleekeri)?

2004 ◽  
Vol 84 (6) ◽  
pp. 1215-1219 ◽  
Author(s):  
Yuzuru Ikeda ◽  
Kingo Ito ◽  
Gen Matsumoto
Keyword(s):  
Body Size ◽  
Light Intensity ◽  
Embryonic Development ◽  
Early Stage ◽  
Constant Darkness ◽  
Light Intensities ◽  
Development Duration ◽  
Experimental Group ◽  
Effect Of Light

The effect of light intensity on the course of embryonic development of squid (Heterololigo bleekeri) was examined. Heterololigo bleekeri embryos at an early stage were incubated in the egg cases under six to seven gradients of light intensities which varied from constant darkness to intensive light >1000 lx (12L:12D for all experimental groups except for the constant darkness group). Duration of hatching in every experimental group ranged from seven to 15 days with a peak for ≈30–50% of total number of hatchlings. However, there were no particular relationships between light intensities and duration of embryonic development, duration of hatching, number of hatchlings at hatching peak, and body size of hatchlings. In all groups, body size of hatchlings increased up to seven days post-hatching and thereafter did not change remarkably. Just after hatching, strongly positive photo taxis was observed for H. bleekeri

Laboratory study of the effect of light on the emergence behaviour of eight species of commercially important adult penaeid prawns

1994 ◽  
Vol 45 (1) ◽  
pp. 43 ◽  
Author(s):  
TJ Wassenberg ◽  
BJ Hill
Keyword(s):  
Light Intensity ◽  
Laboratory Study ◽  
Carapace Length ◽  
Rate Of Change ◽  
Metapenaeus Ensis ◽  
The Third ◽  
Light Intensities ◽  
Commercially Important ◽  
Penaeus Merguiensis ◽  
Effect Of Light

The emergence behaviour of eight species of commercial prawns (between 25.0 and 30.0 mm carapace length) was studied in the laboratory. All except Penaeus merguiensis were nocturnal: they emerged from the substratum in the evening when the light was dimmed and buried themselves in the morning, usually before dawn. P. merguiensis generally remained on the substratum during the day. The species can be grouped on the basis of their behaviour: the first group (P. plebejus and P. latisulcatus) was most sensitive to light, the second group (P. semisulcatus, Metapenaeus ensis, P. esculentus, M. endeavouri and M. bennettae) was less sensitive to light, and the third (P. merguiensis) was least sensitive to light. To find out what triggered emergence, two species (P. esculentus and P. plebejus) were exposed to different rates of light dimming at dusk. Both species responded to absolute light intensity, but the response of P. plebejus was affected by the rate of change of light intensity. The different responses of the species to different light intensities explains some of the differences in catchability in a multi-species prawn fishery.

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 Larval growth and survival in Indian Butter Catfish, Ompok bimaculatus (Bloch): effect of light intensity and photoperiod

2019 ◽  
Author(s):  
Kalpana Arambam ◽  
Pradyut Biswas ◽  
Soibam Khogen Singh ◽  
A. B. Patel ◽  
Alok Kumar Jena ◽  
...  
Keyword(s):  
Light Intensity ◽  
Larval Growth ◽  
Maximum Growth ◽  
Continuous Darkness ◽  
Growth And Survival ◽  
Light Intensities ◽  
Randomized Design ◽  
Significant Difference ◽  
Ompok Bimaculatus ◽  
Effect Of Light

AbstractTwo sequential indoor rearing trials each of 21 days duration were conducted to investigate the effect of light intensity and photoperiod respectively on the growth and survival of Ompok bimaculatus larvae. In first trial, five different light intensities viz. 0, 300, 500, 900, 1200 lx were applied randomly to 800 larvae (0.003 g; 0.51 cm) stocked in triplicate following a completely randomized design into aquarium (30.0 x 15.0 x 15.0 cm) tanks. Sequentially, in second trial, five photoperiod cycles (light: dark, L: D) namely, 24L: 0D, 16L: 8D, 12L: 12D, 8L: 16D and 0L: 24D in combination with the best performing light intensity (300 lx) as observed from the first trial were employed in triplicates in similar set up. From the first trial, significantly higher survival was observed in 0 and 300 lx, whereas growth was highest in 900 lx (P < 0.05). In the second trial, survival was higher in continuous darkness (0L: 24D), whereas, maximum growth was recorded in 24L: 0D and 16L: 8D groups (P < 0.05). Performance index (PI) showed no significant difference (P > 0.05) among 0 and 300 lx light intensities, but were reduced at higher light intensities. The lowest PI was found in 12L: 12D and 8L: 16D condition but did not have any effect in other photoperiod cycles. Overall, from the present study it can be concluded that growth of the larvae is found to be higher in higher light intensity (900lx) and longer photoperiodic cycles (24L: 0D and 16L: 8D), however, better survival was recorded in total dark conditions suggesting that continuous dark condition is recommended for better hatchery performance of the larvae.

Differential Regulation of Flavone Glycosylation during Ontogeny of Silene pratensis

1983 ◽  
Vol 38 (7-8) ◽  
pp. 544-548 ◽  
Author(s):  
J. M. Steyns ◽  
G. van Nigtevecht ◽  
G. J. Niemann ◽  
J. v. Brederode
Keyword(s):  
Light Intensity ◽  
Differential Regulation ◽  
Low Light ◽  
Leaf Pair ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Flower Stem ◽  
Pair Number ◽  
Silene Pratensis ◽  
Effect Of Light

Two isovitexin glycosides have been found in the cotyledons and foliage leaves of Sitene pratensis plants that are unable to glycosylate isovitexin in their petals (genotype gg glgl fgfg). The glycosides (isovitexin 7-O-galactoside and isovitexin 7-O-galactose 2″-O-arabinoside) were present only in the lower leaves: leaves produced later in the development of the flower stem accumulated only the aglycon isovitexin. The transition in the flavone composition during the ontogeny of the plants could be influenced by light intensity. In plants grown at low light intensity, glycoside production continued until a higher leaf pair number than in plants grown at higher light intensities. However, the effect of light intensity is indirect: the transition in the flavone composition is correlated with the transition from rosette leaves to stem leaves. The presence of the 7-O-galactosides in cotyledons and rosette leaves suggests that in addition to the g, gl and fg loci, there are further glycosylating loci which are not expressed in stem leaves and petals.

scholarly journals Effect of light on N<sub>2</sub> fixation and net nitrogen release of <i>Trichodesmium</i> in a field study

2018 ◽  
Vol 15 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Yangyang Lu ◽  
Zuozhu Wen ◽  
Dalin Shi ◽  
Mingming Chen ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Light Intensity ◽  
Carbon Fixation ◽  
Physiological State ◽  
Light Stress ◽  
Light Response ◽  
Light Change ◽  
Filamentous Cyanobacterium ◽  
Light Saturation ◽  
Net Release ◽  
Effect Of Light

Abstract. Dinitrogen fixation (NF) by marine cyanobacteria is an important pathway to replenish the oceanic bioavailable nitrogen inventory. Light is the key to modulating NF; however, field studies investigating the light response curve (NF-I curve) of NF rate and the effect of light on diazotroph-derived nitrogen (DDN) net release are relatively sparse in the literature, hampering prediction using models. A dissolution method was applied using uncontaminated 15N2 gas to examine how the light changes may influence the NF intensity and DDN net release in the oligotrophic ocean. Experiments were conducted at stations with diazotrophs dominated by filamentous cyanobacterium Trichodesmium spp. in the western Pacific and the South China Sea. The effect of light on carbon fixation (CF) was measured in parallel using the 13C tracer method specifically for a station characterized by Trichodesmium bloom. Both NF-I and CF-I curves showed a Ik (light saturation coefficient) range of 193 to 315 µE m−2 s−1, with light saturation at around 400 µE m−2 s−1. The proportion of DDN net release ranged from ∼ 6 to ∼ 50 %, suggesting an increasing trend as the light intensity decreased. At the Trichodesmium bloom station, we found that the CF ∕ NF ratio was light-dependent and the ratio started to increase as light was lower than the carbon compensation point of 200 µE m−2 s−1. Under low-light stress, Trichodesmium physiologically preferred to allocate more energy for CF to alleviate the intensive carbon consumption by respiration; thus, there is a metabolism tradeoff between CF and NF pathways. Results showed that short-term (< 24 h) light change modulates the physiological state, which subsequently determined the C ∕ N metabolism and DDN net release by Trichodesmium. Reallocation of energy associated with the variation in light intensity would be helpful for prediction of the global biogeochemical cycle of N by models involving Trichodesmium blooms.

Factors affecting growith and distribution of kauri (Agathis australis Salisb.) I. Effect of light on the establishment of Kaura and of Phyllocladus trichomanoides D.Don

1959 ◽  
Vol 7 (3) ◽  
pp. 252 ◽  
Author(s):  
RL Bieleski
Keyword(s):  
Light Intensity ◽  
Frequency Distribution ◽  
High Light Intensity ◽  
High Light ◽  
Low Light ◽  
Factors Affecting ◽  
Light Intensities ◽  
Seedling Distribution ◽  
Conifer Seedling ◽  
Effect Of Light

A method for determining the effect of light on seedling distribution in the field is described. It can be applied when seedling frequencies are as low as 1/m2. The frequency distribution of light intensities occupied by seedlings in a quadrat is compared with the frequency distribution of light intensities measured on a grid in the quadrat. This method was used to study the effect of light intensity on the establishment of two New Zealand gymnosperms, kauri (Agathis australis) and Phyllocladus trichomanoides, in the nursery community, a semimature Leptospermum scoparium – L. ericoides associes. Kauri and Phyllocladus did not occur at light intensities below 0.015 and 0.018 full daylight respectively. This limitation appeared to be due to the low light intensity presumably limiting photosynthesis. Kauri, but not Phyllocladus, also showed a high light intensity limit, at 0.30 full daylight, above which seedlings did not establish. Reasons are given for considering this as an indirect effect, probably through related solar heating affecting soil temperature or moisture. The optimal light intensity for kauri and Phyllocladus seedling establishment was close to the modal light intensity under the Leptospermum community: Leptospermum spp. were incapable of regenerating under their own cover. These two reasons appear to explain the suitability of the Leptospermum community as a nurse crop for the two conifer seedling species.

Effect of Light Intensity on Schottky Barrier Widths and I-V Characteristics of Polymer Heterojunction Photodiodes

2011 ◽  
Vol 1359 ◽  
Author(s):  
Ali Bilge Guvenc ◽  
Cengiz Ozkan ◽  
Mihrimah Ozkan
Keyword(s):  
Experimental Data ◽  
Light Intensity ◽  
Mathematical Models ◽  
Schottky Barrier ◽  
Butyric Acid ◽  
Organic Semiconductor ◽  
Schottky Barriers ◽  
Light Intensities ◽  
Effect Of Light

ABSTRACTThe Schottky barriers that forms on the interface between aluminum and organic semiconductor of polymer heterojunction photodiodes based on poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methylester blend, has been investigated according to Mott-Schottky curves. We focused on the effect of light intensity on the Schottky barrier widths and I-V characteristics of the devices. Comparison of the mathematical models and experimental data measured under different light intensities indicate a dependency of Schottky barrier to the light intensity.

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