scholarly journals Impact of Flower Removal and Light and Temperature Stresses on Acidification of Nutrient Solution by Geranium

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 970C-970
Author(s):  
Matthew D. Taylor ◽  
Paul V. Nelson ◽  
Jonathan M. Frantz
Keyword(s):  
High Light ◽  
Temperature Stresses ◽  
Ph Values ◽  
Light Levels ◽  
Acceptable Range ◽  
Light Effects ◽  
Flowering Control ◽  
Temperature Levels ◽  
Substrate Ph ◽  
Low Temperature Treatments

The cause of sudden substrate pH decline by geranium (Pelargonium ×hortorum Bailey) is unknown. Published reports indicate that this response can be influenced in other plants by temperature and light extremes. The first of five experiments compared plants with all flowers removed to plants that were allowed to flower. Experiment 2 compared plants grown at four light levels (105, 210, 450 and 1020 μmol·m–2·s–1). Experiment 3 compared plants grown at four temperatures (14/10, 18/14, 22/18 and 26/22 °C day/night). Experiment 4 was a repeat of Experiment 1 and Experiment 5 was a factorial combining the three highest light levels and the three highest temperature levels. Plants allowed to form flowers had a final substrate pH of 5.7 compared to 6.3 for plants where flowers were removed. With increasing increments of temperature, substrate pH declined from 6.8 to 4.6 and with increasing light intensity from 6.1 to 4.8. There was no effect of flower removal in Experiment 4. Light and temperature had no consistent effects in Experiment 5 throughout 46 days after planting, with most pH values remaining in the acceptable range of 5.6–6.1. By 60 days, temperature treatments began to segregate, with pH being highest in the low-temperature treatments and lowest, down to 5.5, in the highest-temperature treatments. High temperature stimulated geranium acidification in both experiments, with the effect more severe in the first experiment. The flowering and high light effects were not duplicated in the second trial. This indicates that an additional factor is involved in expression of the light, temperature, and flowering control of acidification.

scholarly journals Substrate Acidification by Geranium: Light Effects and Phosphorus Uptake

2008 ◽  
Vol 133 (4) ◽  
pp. 515-520 ◽  
Author(s):  
Matthew D. Taylor ◽  
Paul V. Nelson ◽  
Jonathan M. Frantz
Keyword(s):  
Light Intensity ◽  
Phosphorus Uptake ◽  
Dry Weight ◽  
P Uptake ◽  
High Light Intensity ◽  
High Light ◽  
P Deficiency ◽  
Light Levels ◽  
Direct Light ◽  
Substrate Ph

Sudden pH decline (SPD) describes the situation where crops growing at an appropriate pH rapidly (within 1–2 weeks) cause the substrate pH to shift downward one to two units. ‘Designer Dark Red’ geraniums (Pelargonium ×hortorum Bailey) were grown in three experiments to assess possible effects of light on SPD and phosphorous (P) uptake. The first experiment tested the effect of four light intensities (105, 210, 575, and 1020 ± 25 μmol·m−2·s−1) on substrate acidification. At 63 days, substrate pH declined from 6.0 to 4.8 as light intensity increased. Tissue P of plants grown at the highest two light levels was extremely low (0.10%–0.14% of dry weight). P stress has been reported to cause acidification. Because plants in the two lowest light treatments had adequate P, it was not possible to determine if the drop in substrate pH was a direct light effect or a combination of light and P. The second experiment used a factorial combination of the three highest light levels from Expt. 1 and five preplant P rates (0, 0.065, 0.13, 0.26, or 0.52 g·L−1 substrate) to assess this question. When tissue P concentrations were deficient, pH decreased by 0.6 to 1.0 pH units within 2 weeks and deficiency occurred more often with high light intensity. These data indicated that P deficiency caused substrate acidification and indicated the possibility that P uptake was suppressed by high light intensity. The third experiment was conducted in hydroponics to determine the direct effect of high light intensity on P uptake. In this experiment, cumulative P uptake per gram root and the rate of P uptake per gram root per day both decreased 20% when light intensity increased from 500 to 1100 μmol·m−2·s−1. It is clear from this study that P deficiency causes geraniums to acidify the substrate and that high light suppresses P uptake.

Change of color appearance due to extremely high light level: corresponding colors under 100 and 3000 cd/m2

2019 ◽  
Vol 2019 (1) ◽  
pp. 320-325 ◽  
Author(s):  
Wenyu Bao ◽  
Minchen Wei
Keyword(s):  
Light Level ◽  
Limited Range ◽  
High Light ◽  
Color Preference ◽  
Color Appearance ◽  
Appearance Model ◽  
Color Matching ◽  
Light Levels ◽  
Appearance Models ◽  
Psychophysical Study

Great efforts have been made to develop color appearance models to predict color appearance of stimuli under various viewing conditions. CIECAM02, the most widely used color appearance model, and many other color appearance models were all developed based on corresponding color datasets, including LUTCHI data. Though the effect of adapting light level on color appearance, which is known as "Hunt Effect", is well known, most of the corresponding color datasets were collected within a limited range of light levels (i.e., below 700 cd/m2), which was much lower than that under daylight. A recent study investigating color preference of an artwork under various light levels from 20 to 15000 lx suggested that the existing color appearance models may not accurately characterize the color appearance of stimuli under extremely high light levels, based on the assumption that the same preference judgements were due to the same color appearance. This article reports a psychophysical study, which was designed to directly collect corresponding colors under two light levels— 100 and 3000 cd/m2 (i.e., ≈ 314 and 9420 lx). Human observers completed haploscopic color matching for four color stimuli (i.e., red, green, blue, and yellow) under the two light levels at 2700 or 6500 K. Though the Hunt Effect was supported by the results, CIECAM02 was found to have large errors under the extremely high light levels, especially when the CCT was low.

Characteristics of Photosynthesis in Different Wheat Cultivars under High Light Intensity and High Temperature Stresses

2009 ◽  
Vol 34 (12) ◽  
pp. 2196-2201 ◽  
Author(s):  
Xue-Li QI ◽  
Lin HU ◽  
Hai-Bin DONG ◽  
Lei ZHANG ◽  
Gen-Song WANG ◽  
...  
Keyword(s):  
High Temperature ◽  
Light Intensity ◽  
High Light Intensity ◽  
High Light ◽  
Wheat Cultivars ◽  
Temperature Stresses

scholarly journals Luminance and chromatic contrast sensitivity at high light levels

2019 ◽  
Vol 19 (10) ◽  
pp. 70b ◽  
Author(s):  
Sophie Wuerger ◽  
Rafal Mantiuk ◽  
Maria Perez-Ortiz ◽  
Jasna Martinovic
Keyword(s):  
Contrast Sensitivity ◽  
High Light ◽  
Chromatic Contrast ◽  
Light Levels ◽  
Chromatic Contrast Sensitivity

Caffeine and light effects on nighttime melatonin and temperature levels in sleep-deprived humans

1997 ◽  
Vol 747 (1) ◽  
pp. 78-84 ◽  
Author(s):  
Kenneth P Wright ◽  
Pietro Badia ◽  
Bryan L Myers ◽  
Steven C Plenzler ◽  
Milton Hakel
Keyword(s):  
Light Effects ◽  
Temperature Levels

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 Effect of Light Intensity and Leaf Temperature on Photosynthesis and Transpiration in Wheat and Sorghum

1970 ◽  
Vol 23 (4) ◽  
pp. 775 ◽  
Author(s):  
RW Downes
Keyword(s):  
Carbon Dioxide ◽  
Water Use ◽  
Carbon Dioxide Concentration ◽  
Leaf Temperature ◽  
High Light ◽  
Intercellular Spaces ◽  
Concentration Difference ◽  
Light Levels ◽  
Light Intensities ◽  
Water Vapour Concentration

Wheat stomata offered less resistance to water and carbon dioxide diffusion than sorghum stomata at light intensities of 0�06 and 0�26 cal cm-2 min-i (400-700 nm) but resistances were comparable at 0�46 cal cm-2 min-i. Consequently, transpiration rates were higher in wheat than in sorghum, except at the high light levels, in leaf chamber experiments described here. Rates of photosynthesis were higher in sorghum than in wheat, with the greatest difference at high light levels. This resulted in a greater efficiency of dry matter production relative to water use in sorghum. Transpiration rate increased with increased temperature in both species. Photosynthesis was independent of temperature in wheat, and in sorghum under low light conditions, but otherwise photosynthesis increased with temperature in sorghum. In both species, efficiency of water use decreased as temperature increased at all light intensities. Water vapour concentration difference between the intercellular spaces and the air was comparable in wheat and sorghum and increased with temperature. The carbon dioxide concentration difference between air and intercellular spaces was substantially greater in sorghum than in wheat and increased with leaf temperature. Maximum values were obtained at the intermediate light level in sorghum.

Crosstalk in Phototransistor Imaging Mosaics at Very High Light Levels

1969 ◽  
Vol 4 (6) ◽  
pp. 326-333 ◽  
Author(s):  
R.A. Anders ◽  
D.E. Callahan ◽  
W.F. List
Keyword(s):  
High Light ◽  
Light Levels ◽  
Very High

scholarly journals Urea Hydrolysis in Pine Tree Substrate Is Affected by Urea and Lime Rates

HortScience ◽  
2014 ◽  
Vol 49 (11) ◽  
pp. 1437-1443 ◽  
Author(s):  
Alexander X. Niemiera ◽  
Linda L. Taylor ◽  
Jacob H. Shreckhise
Keyword(s):  
Urea Hydrolysis ◽  
Substrate Solution ◽  
Ph Values ◽  
Pine Tree ◽  
Initial Substrate ◽  
Initial Ph ◽  
Ph Increase ◽  
N Rates ◽  
Substrate Ph ◽  
Urea Addition

To reduce the carbon-to-nitrogen (C:N) ratio, pine tree substrate (PTS) and other wood-based substrates can be precharged with urea so that growers do not have to add extra nitrogen (N) during crop production to compensate for immobilization. However, the impact of urea hydrolysis from this addition on the substrate solution has not been documented for wood-based substrates. The objectives of these experiments were to determine how urea hydrolysis in PTS impacts substrate solution and how hydrolysis is affected by urea and lime rates. In Expt. 1, 16-month-old pine chips (from loblolly pine trees, Pinus taeda L.) were milled to make PTS and PTS was amended with 0 or 1.0 kg·m−3 dolomitic limestone in factorial combination with urea-N rates of 0, 0.5, 1.0, 1.5, or 2.0 mg·g−1 dry weight. Urea hydrolysis was quantified by the detection of NH4-N in the substrate solution at 0, 48, 96, and 144 hours after urea addition. Substrate pH and electrical conductivity (EC) values were also measured. In Expt. 2, non-limed PTS was treated with the same urea rates as described; NH4-N and pH were measured at 24 and 48 hours after urea addition. Substrate solutions were incubated with jackbean urease to determine the remaining urea-N amount after 144 hours in Expt. 1 and after 24 and 48 hours in Expt. 2. In Expt. 1, NH4-N increased from 0 to 48 hours for the 0 and 1.0-kg·m−3 lime treatments and for all urea-N rates (except for the 0 rate); NH4-N did not increase thereafter. As urea-N rate increased, the amount of NH4-N increased and more N was detected for the limed PTS than in the non-limed PTS. Initial substrate pH values for the 0 and 1.0-kg·m−3 lime treatments were 4.5 and 5.6, respectively, and peaked 48 hours after urea application; pH values were higher in the limed PTS than for the non-limed PTS. At the highest urea-N rate and after 48 hours (Expt. 1), the PTS pH value increased 3.1 units to 7.6 for the non-limed PTS and the value increased 2.3 units to 7.9 for limed PTS. In Expt. 2 the increase in PTS pH values was approximately half of the Expt. 1 pH increases. Samples treated with urease derived from jackbean had less than 2% of the initial urea amount after 144 hours in Expt. 1 and after 48 hours in Expt. 2. However, less than 13% of the total amount of urea-N added to PTS was detected as NH4-N in the non-limed treatment after 144 hours in Expt. 1 (for all urea rates); detected amounts for the 1.0-kg·m−3 lime treatment ranged from 15.5% to 18.3%. Five percent or less of the total amount of urea-N added to PTS was detected as NH4-N in non-limed PTS after 48 hours in Expt. 2 (for all urea rates). The large amount of unrecovered NH4-N is likely explained by microbial N consumption. Using pH increase as an indication of urea hydrolysis, we found that an initial pH of 4.5 or higher (Expt. 1) resulted in twice the urea hydrolysis as an initial pH of 4.2 (Expt. 2). Initial substrate pH had a major impact on the amount of pH increase and substrate pH status and our findings suggest that the urea precharge rate should be based on the initial pH of the substrate.

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