scholarly journals A Sensor Designed to Record Underwater Irradiance with Concern for a Shark’s Spectral Sensitivity

Biosensors ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 105
Author(s):  
A. Peter Klimley
Keyword(s):  
Spectral Response ◽  
High Light ◽  
Sensory Receptors ◽  
Response Curves ◽  
Low Light ◽  
Scalloped Hammerhead ◽  
Light Levels ◽  
Irradiation Energy ◽  
Underwater Irradiance ◽  
Peak Sensitivity

To ascertain how scalloped hammerhead sharks make nightly migrations to their feeding grounds as many as 20 km from their daytime abode, a seamount, a sensor was developed that measured irradiance intensity within the spectral range and sensitivity of the vision of the species. Could the sharks guide their movements by sensing the polarity of irradiation energy radiated from the sun or moon that penetrated into the oceanic depths? Two sensory receptors, cones and rods, are present in the retina of sharks to enable them to see both during daytime and nighttime. The peak sensitivity of the cones is red-shifted due to the presence of these wavelengths during the former period, while their response is linear under the range of the high light levels also present at this time; the peak sensitivity of rods is blue-shifted due to the presence of these wavelengths during dawn, dusk, and nighttime and is linear over the complementary range of low light levels. Spectral response curves for these two receptors were determined for sharks, and an attempt was made to match those of the sensors to the shark’s wavelength perception. The first sensor was matched to the photopic range using a photocell covered with a red-shifted gel filter; the second was matched to the scotopic range using a blue-shifted gel filter.

Are resources allocated differently to symbiosis and reproduction in Geranium sylvaticum under different light conditions?

2004 ◽  
Vol 82 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Jarkko Korhonen ◽  
Minna-Maarit Kytöviita ◽  
Pirkko Siikamäki
Keyword(s):  
Resource Allocation ◽  
Forest Canopy ◽  
Light Availability ◽  
Growing Season ◽  
High Light ◽  
Mycorrhizal Colonization ◽  
Fungal Colonization ◽  
Low Light ◽  
Light Levels ◽  
Dark Septate Fungi

Light levels under the forest canopy are low and generally limit plant photosynthetic gains. We hypothesized that in low-light habitats, plant photosynthate acquisition is too low to allow the same magnitude of resource allocation to symbiosis and reproduction as in high-light habitats. We tested this hypothesis in a field study where Geranium sylvaticum L. plants were collected on three occasions during the growing season from shade and light habitats. In addition, we investigated the relationship between mycorrhizal colonization level and soil nutrient levels in shade and high-light habitats over a growing season. We found that light availability affects resource allocation in G. sylvaticum. Plants were intensively colonized with both arbuscular mycorrhizal and dark septate fungi, and the colonization intensities of these two different groups of fungi correlated positively with each other. In comparison with high-light meadows, mycorrhizal colonization levels were as high or higher in low-light forest habitats, but plants produced fewer flowers. This indicates that allocation to symbiosis was of higher priority than allocation to reproduction in low light. Seed size was not affected by light levels and did not correlate with fungal colonization levels. We found no relationship between fungal colonization levels and soil characteristics.Key words: arbuscular mycorrhiza, dark septate fungi, Geranium sylvaticum, reproduction, shade.

scholarly journals Photochemical Acclimation of Three Contrasting Species to Different Light Levels: Implications for Optimizing Supplemental Lighting

2017 ◽  
Vol 142 (5) ◽  
pp. 346-354 ◽  
Author(s):  
Shuyang Zhen ◽  
Marc W. van Iersel
Keyword(s):  
Electron Transport ◽  
Light Intensity ◽  
Photochemical Efficiency ◽  
Light Response ◽  
High Light ◽  
Photon Flux ◽  
Ambient Light ◽  
Response Curves ◽  
Low Light ◽  
Supplemental Lighting

Photosynthetic responses to light are dependent on light intensity, vary among species, and can be affected by acclimation to different light environments (e.g., light intensity, spectrum, and photoperiod). Understanding how these factors affect photochemistry is important for improving supplemental lighting efficiency in controlled-environment agriculture. We used chlorophyll fluorescence to determine photochemical light response curves of three horticultural crops with contrasting light requirements [sweetpotato (Ipomea batatas), lettuce (Lactuca sativa), and pothos (Epipremnum aureum)]. We also quantified how these responses were affected by acclimation to three shading treatments-full sun, 44% shade, and 75% shade. The quantum yield of photosystem II (ΦPSII), a measure of photochemical efficiency, decreased exponentially with increasing photosynthetic photon flux (PPF) in all three species. By contrast, linear electron transport rate (ETR) increased asymptotically with increasing PPF. Within each shading level, the high-light-adapted species sweetpotato used high light more efficiently for electron transport than light-intermediate lettuce and shade-tolerant pothos. Within a species, plants acclimated to high light (full sun) tended to have higher ΦPSII and ETR than those acclimated to low light (44% or 75% shade). Nonphotochemical quenching (NPQ) (an indicator of the amount of absorbed light energy that is dissipated as heat) was upregulated with increasing PPF; faster upregulation was observed in pothos as well as in plants grown under 75% shade. Our results have implications for supplemental lighting: supplemental light is used more efficiently and results in a greater increase in ETR when provided at low ambient PPF. In addition, high-light-adapted crops and crops grown under relatively high ambient light can use supplemental light more efficiently than low-light-adapted crops or those grown under low ambient light.

Matched filtering in the visual system of the fly : large monopolar cells of the lamina are optimized to detect moving edges and blobs

1990 ◽  
Vol 240 (1298) ◽  
pp. 279-293 ◽  
Keyword(s):  
Receptive Field ◽  
Receptive Fields ◽  
High Light ◽  
Vertical Stripe ◽  
Ambient Light ◽  
Low Light ◽  
Temporal Properties ◽  
Light Levels ◽  
Spatio Temporal ◽  
Temporal Inhibition

At high levels of ambient light, large monopolar cells (LMCS) display spatially antagonistic receptive fields and a biphasic response to a brief flash of light from an axially positioned point source. In low ambient light the response becomes monophasic everywhere within the receptive field. Using the theory of matched filters, we infer that the LMCS are optimal for the detection of moving edges at high light levels, and for ‘blobs’ in low ambient light. The spatio-temporal properties predicted by the theory are in agreement with experimental observation. At high light levels, the strong temporal inhibition, the weak, diffuse lateral inhibition, and the non-separability of the receptive field in space and time are all properties that promote the sensitivity to a moving edge. At low light levels, the lack of spatial or temporal antagonism enhances the sensitivity to a blob. Our hypothesis is reinforced by the observation that flies tend to walk toward the edges of a broad, dark vertical stripe at high light levels, but uniformly toward all regions within the stripe in low ambient light.

Species variability in growth response to light across climatic regions in northwestern British Columbia

1998 ◽  
Vol 28 (6) ◽  
pp. 871-886 ◽  
Author(s):  
Elaine F Wright ◽  
K Dave Coates ◽  
Charles D Canham ◽  
Paula Bartemucci
Keyword(s):  
British Columbia ◽  
Shade Tolerance ◽  
Growth Response ◽  
High Light ◽  
Low Light ◽  
Climatic Regions ◽  
Light Levels ◽  
Tolerant Species ◽  
Trade Offs ◽  
Shade Tolerant Species

We characterize variation in radial and height growth of saplings of 11 tree species across a range of light levels in boreal, sub-boreal, subalpine, and temperate forests of northwestern British Columbia. Shade-tolerant species had the greatest response to an increase in light at low-light levels but had low asymptotic growth at high light. Shade-intolerant species had weaker responses to increases at low light but had the highest growth rates at high light. The effects of climate on intraspecific variation in sapling response to light were also related to shade tolerance: across different climatic regions, the most shade-tolerant species varied in their response to low-light but not high light, while shade-intolerant species varied only in their high-light growth. Species with intermediate shade tolerance varied both their amplitude of growth at high light and the slope of the growth response at low light. Despite the interspecific trade-offs between high- and low-light growth, there was a striking degree of overlap in the light response curves for the component species in virtually all of the climatic regions. Successional dynamics in these forests appear to be more strongly governed by interspecific variation in sapling survival than growth.

scholarly journals EFFECTS OF CARBON DIOXIDE ENRICHMENT AND IRRADIANCE ON EX VITRO ROOTING, ACCLIMATIZATION AND SUBSEQUENT GROWTH OF MICROPROPAGATED APPLE AND BLUEBERRY.

HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 254A-254
Author(s):  
Marvin Pritts ◽  
Dorcas Isuta
Keyword(s):  
Survival Rate ◽  
Dry Weight ◽  
Great Sensitivity ◽  
High Light ◽  
Low Light ◽  
Light Levels ◽  
Significant Difference ◽  
Vigorous Growth ◽  
Set Up

Previous findings reveal that rooting and acclimatization of apple and blueberry plants is often difficult, inconsistent and inefficient. This experiment was set up in a fog chamber lo investigate the effects of CO2 enrichment (CDE) and irradiance on unrooted stage II microshoots. Two CO2 and 3 light levels tested were: 1350 +/- 150 (+ CDE), and 450 +/- 50 (- CDE) ppm; 30 +/- 5 (low), 55 + 10 (medium), and 100 + 20 (high) umolm-2s-1 respectively. Cultivars assessed were Berkeley and Northsky for blueberry. G65 and NY30 for apple. Blueberry microshoots acclimatized successfully and gave between 90 to 100% rooting and survival rate. Apple microshoots acclimatized and rooted slowly, exhibited great sensitivity to in vivo conditions and gave between 40 to 100% rooting and survival rate. High light induced photo-inhibition which disappeared after complete acclimatization. There was a significant difference between low light and the other two light levels. The effect of CDE was dependent on cultivar. In most cases, high light (-) CDE gave the most vigorous growth (highest plant dry weight and leaf area). There was a significant difference between (+) CDE and (-) CDE at low and medium light, but none at high light. Low light (-) CDE and medium light (+) CDE were superior over low light (+) CDE and medium light (-) CDE. respectively. Stalling out in apple microshoots was corrected by GA sprays.

scholarly journals Postharvest Handling of Cut Campanula medium Flowers

HortScience ◽  
2002 ◽  
Vol 37 (6) ◽  
pp. 954-958 ◽  
Author(s):  
Theresa Bosma ◽  
John M. Dole
Keyword(s):  
Sucrose Concentration ◽  
High Light ◽  
Deionized Water ◽  
Vase Life ◽  
Light Conditions ◽  
Low Light ◽  
Storage Duration ◽  
Light Levels ◽  
Postharvest Handling

Various postharvest treatments were evaluated for effect on longevity and quality of cut Campanula medium L. `Champion Blue' and `Champion Pink' stems. Stems stored at 2 °C either wet or dry had no difference in vase life or percent flowers opened; however, flowers stored dry had a slightly greater percentage of senesced flowers at termination. Increasing storage duration from 1 to 3 weeks decreased vase life. Stems pretreated for 4 hours with 38 °C floral solution (deionized water amended to pH 3.5 with citric acid and 200 mg·L-1 8-HQC) or a 1-MCP pulse followed by a 5% sucrose pulse solution produced the longest vase life (10.3 or 10.4 days, respectively). Flowers opening after treatments commenced were paler than those flowers already opened and a 24-hour pretreatment with 5% or 10% sucrose did not prevent this color reduction. Stems had an average vase life of only 3.3 days when placed in floral vase foam but lasted 10.0 days without foam. Optimum sucrose concentration was 1.0% to 2.0% for stems placed in 22 °C floral vase solution without foam and 4% for stems placed in foam. High (110 μmol·m-2·s-1) or low (10 μmol·m-2·s-1) light levels did not affect postharvest parameters, but the most recently opened flowers were paler under low light conditions than under high light conditions. Chemical names used: 8-hydroxyquinoline citrate (8-HQC); 1-methylcyclopropene (1-MCP).

scholarly journals Black and Chestnut Oak Seedling Response to Glaciated Soil: Implications for Northward Expansion in Response to Climate Warming

2019 ◽  
Vol 65 (5) ◽  
pp. 637-643
Author(s):  
Lauren S Pile ◽  
Joanne Rebbeck ◽  
Patrick H Brose ◽  
Robert P Long
Keyword(s):  
Climate Warming ◽  
Carbon Sink ◽  
Net Photosynthesis ◽  
High Light ◽  
Soil Conditions ◽  
Low Light ◽  
Species Response ◽  
Light Levels ◽  
Mycorrhizal Association ◽  
Oak Seedlings

Abstract Species ranges are expected to move northward with climate warming. However, species will likely encounter soil conditions that differ from their historic ranges. Black (Quercus velutina) and chestnut (Q. montana) oaks are expected to do well in climates that are hotter and drier, but it is unknown as to how they respond to soils of different geological histories. At a glaciated and nonglaciated site in northwestern Pennsylvania, we compared the growth, biomass allocation, and mycorrhizal association for black and chestnut oak seedlings at two different levels of light. On nutrient-poor, nonglaciated soils at high light levels, both species had greater growth and biomass accumulation than on nutrient-rich, glaciated soils. However, at low light levels, these responses were greatest on glaciated soils, especially for chestnut oak. Although mycorrhizal association was beneficial on nonglaciated soil at high light levels, low light levels were associated with reduced growth when compared to glaciated soils. In low light and nutrient-poor soils, mycorrhizal association may result in a carbon sink with lower net photosynthesis, as carbon for plant growth is, instead, allocated to the mycorrhizae symbiont. Variable species response to soil types indicates reduced performance for black and chestnut oak seedlings on high-quality glaciated soils especially in high light environments.

Trade-offs between growth and survival of non-pioneer light-demanding tree seedlings in tropical forest of Hainan Island, China

2011 ◽  
Vol 27 (6) ◽  
pp. 611-620 ◽  
Author(s):  
Wenjie Yang ◽  
Fude Liu ◽  
Lingyan Zhou ◽  
Shiting Zhang ◽  
Shuqing An
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Tree Species ◽  
Seed Mass ◽  
High Light ◽  
Tree Seedlings ◽  
Low Light ◽  
Relative Growth ◽  
Growth And Survival ◽  
Light Levels

Abstract:We performed a pot experiment in which 540 seedlings of nine non-pioneer light-demanding tree species were grown for 12 months in shade houses at three light levels, 46% daylight, 13% daylight and 2% daylight, to examine the mechanisms contributing to the coexistence of seedlings of non-pioneer light-demanding tree species in secondary successional tropical rain forest in Hainan, China. Growth and survival of tree seedlings were compared at different light levels, and the morphological and physiological correlates of high-light seedling growth and low-light survival across species were determined. For all species, mortality was very low in the 46% daylight and 13% daylight treatment but increased significantly in the 2% daylight treatment. Seedling survival in 2% daylight treatment was positively related to seed mass. Trade-off between high-light growth and low-light survival was more evident in the relationship with 2% daylight treatment as compared with 13% daylight treatment. Relative growth rate in the 2% daylight treatment was not significantly related to relative growth rate in the 13% daylight or 46% daylight treatment; although a slight negative correlation was apparent. Interspecific variation in RGRm was only closely correlated with net assimilation rate (NAR). The results provide some support for the niche-partitioning hypothesis.

scholarly journals Effects of mycorrhizal fungi on tree seedling growth: quantifying the parasitism–mutualism transition along a light gradient

2016 ◽  
Vol 46 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Inés Ibáñez ◽  
Sarah McCarthy-Neumann
Keyword(s):  
Plant Growth ◽  
Mycorrhizal Fungi ◽  
High Light ◽  
Competitive Interactions ◽  
Tree Seedlings ◽  
Tree Seedling ◽  
Low Light ◽  
Light Levels ◽  
Light Gradient ◽  
Tree Seedling Growth

Mycorrhizal fungi colonize tree seedlings shortly after germination, and the nature of this relationship (mutualistic to parasitic) has been reported to vary as a function of resources; however, this transition has rarely been quantified. Using a light gradient, we grew seedlings of eight tree species in soils that were cultivated by several co-existing species of trees. We used data on root mycorrhizal fungi to quantify colonization along the gradient of light. We then analyzed plant growth as a function of both the light gradient and the extent of mycorrhizal colonization. Mycorrhizal fungi colonization varied among species but was not correlated with the species’ seed sizes or shade tolerances. Within a species, colonization varied among soil sources, but those differences followed neither the conspecific–heterospecific dichotomy, nor the soil host’s arbuscular–ectomycorrhizal associations commonly reported. At high light levels, seedlings growth increased with increasing levels of colonization for seven species, and at low light levels, the effect of colonization was negative for five species. We also quantified the light threshold at which the plant – mycorrhizal fungi relationship shifted from neutral to positive (four species), from negative to neutral (one species), and from neutral to negative (one species), documenting differences among species that could exacerbate competitive interactions during recruitment.

The Influence of pH and Light on Hydrilla (Hydrilla verticillata) Photosynthesis and Chlorophyll after Exposure to Flumioxazin

Weed Science ◽  
2012 ◽  
Vol 60 (1) ◽  
pp. 4-9 ◽  
Author(s):  
Christopher R. Mudge ◽  
Brett W. Bultemeier ◽  
William T. Haller
Keyword(s):  
Laboratory Experiments ◽  
Aquatic Plant ◽  
Hydrilla Verticillata ◽  
High Light ◽  
Low Light ◽  
Light Levels ◽  
Invasive Aquatic Plant ◽  
Water Ph ◽  
Herbicide Concentration ◽  
Influence Of Ph

Flumioxazin has recently (2010) been registered for aquatic use for control of hydrilla and other noxious invasive aquatic plant species. Due to the rapid degradation of flumioxazin, especially in high pH water, some hydrilla research trials have produced less than desirable results with rapid plant regrowth. Therefore, laboratory experiments were conducted to evaluate the influence of pH on flumioxazin's effect on photosynthesis. Flumioxazin applied at concentrations ≥ 200 µg ai L−1in high (9.0) pH water and ≥ 100 µg L−1in low (6.0) pH water required 68 to 123 h to reduce photosynthesis by 50% (ET50). The effect of 400 µg L−1flumioxazin on photosynthesis of apical hydrilla tips was also compared at low (20 µmol m−2s−1), medium (170 µmol m−2s−1), and high (400 µmol m−2s−1) light levels at pH 9.0. Low light–treated tips were still photosynthetic at approximately 73% of the nontreated control plants 168 h after treatment. Low light–treated hydrilla required an estimated 303 h to achieve a 50% reduction in photosynthesis, while high light plants only required 99 h. Chlorophyll content of hydrilla was reduced as flumioxazin concentration was increased from 100 to 1,600 µg L−1. These data indicate that flumioxazin activity on hydrilla photosynthesis is influenced by herbicide concentration, water pH, and light intensity.

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