Effect of Photon Flux Density and Temperature on the Production of Halogenated Monoterpenes by Plocamium cartilagineum (Plocamiaceae, Rhodophyta)

2004 ◽  
Vol 59 (9-10) ◽  
pp. 679-683 ◽  
Author(s):  
Rodrigo Palma ◽  
Mario Edding ◽  
Juana Rovirosa ◽  
Aurelio San-Martín ◽  
Victor H. Argandoña
Keyword(s):  
Growth Rate ◽  
Marine Alga ◽  
Effect Of Temperature ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Relative Growth ◽  
Halogenated Monoterpenes ◽  
Different Temperatures ◽  
The Relationship ◽  
Plocamium Cartilagineum

Abstract The effect of different photon flux densities (PFD) and temperatures on the relative growth rate (RGR) and the concentration of three halogenated monoterpenes in samples of Plocamium cartilagineum L.( Dixon), a marine alga (Rhodophyceae), were studied. The highest RGR (22.8 ± 0.04 d-1) was obtained at 15 °C and 41 μmol m-2 s-1 of PFD and the lowest (18.0 ± 0.2 d-1) was obtained at 18 °C and 120 μmol m-2 s-1. The different temperatures and light used in assays did not affect significantly the production of organic compounds. The production of mertensene and violacene was not affected significantly. However, compound 1 reached the highest concentration at 15 °C and 65 μmol m-2 s-1. The relationship between growth and production of monoterpenes of P. cartilagineum and the effect of temperature and the PFD were analyzed.

Effects of Photon Flux Density on Nutrient Productivity in Eucalyptus grandis Seedlings

1991 ◽  
Vol 18 (3) ◽  
pp. 307 ◽  
Author(s):  
MUF Kirschbaum
Keyword(s):  
Growth Rate ◽  
Flux Density ◽  
Relative Growth Rate ◽  
Eucalyptus Grandis ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Phosphorus Concentration ◽  
Phosphorus Addition ◽  
Relative Growth ◽  
Nutrient Productivity

In plants in which growth is limited by the availability of phosphorus, phosphorus productivity is defined as the plants' relative growth rate divided by their internal phosphorus concentration. An experiment was conducted to assess whether phosphorus productivity was dependent on photon flux density, or whether photon flux density only set an upper maximum relative growth rate below which phosphorus productivity remained constant with changing photon flux density. Eucalyptus grandis seedlings were grown in growth units in which plants were suspended in air while continuously being sprayed with nutrient solution (aeroponic system). Plants were grown at five different relative phosphorus addition rates, and under natural lighting over the period from late summer to mid-winter when daily photon flux density decreased from about 30 to 10 mol quanta m-2 d-1. Relative growth rate was then plotted as a function of internal phosphorus concentration for a series of harvests. For the three highest relative phosphorus addition rates, there was a negative relationship between relative growth rate and internal phosphorus concentration. For the two lowest phosphorus addition rates, the internal phosphorus concentration increased throughout the experiment, while relative growth rate remained almost constant. This meant that phosphorus productivity changed throughout the experiment. When phosphorus productivity was expressed as a function of daily photon flux density, a linear relationship between phosphorus productivity and photon flux density was obtained. That relationship had a positive intercept on the axis of photon flux density which was interpreted as the plants' light compensation point. This finding has important implications for applications of the concept of nutrient productivity to the modelling of ecosystems in which growth is limited by nutrient availability.

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

scholarly journals LED Illumination Spectrum Manipulation for Increasing the Yield of Sweet Basil (Ocimum basilicum L.)

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 344
Author(s):  
Md Momtazur Rahman ◽  
Mikhail Vasiliev ◽  
Kamal Alameh
Keyword(s):  
Growth Rate ◽  
Fold Increase ◽  
Photosynthetic Photon Flux Density ◽  
Ocimum Basilicum ◽  
Photon Flux ◽  
Photon Flux Density ◽  
White Led ◽  
Experimental Conditions ◽  
Sweet Basil ◽  
Optimal Illumination

Manipulation of the LED illumination spectrum can enhance plant growth rate and development in grow tents. We report on the identification of the illumination spectrum required to significantly enhance the growth rate of sweet basil (Ocimum basilicum L.) plants in grow tent environments by controlling the LED wavebands illuminating the plants. Since the optimal illumination spectrum depends on the plant type, this work focuses on identifying the illumination spectrum that achieves significant basil biomass improvement compared to improvements reported in prior studies. To be able to optimize the illumination spectrum, several steps must be achieved, namely, understanding plant biology, conducting several trial-and-error experiments, iteratively refining experimental conditions, and undertaking accurate statistical analyses. In this study, basil plants are grown in three grow tents with three LED illumination treatments, namely, only white LED illumination (denoted W*), the combination of red (R) and blue (B) LED illumination (denoted BR*) (relative red (R) and blue (B) intensities are 84% and 16%, respectively) and a combination of red (R), blue (B) and far-red (F) LED illumination (denoted BRF*) (relative red (R), blue (B) and far-red (F) intensities are 79%, 11%, and 10%, respectively). The photosynthetic photon flux density (PPFD) was set at 155 µmol m−2 s−1 for all illumination treatments, and the photoperiod was 20 h per day. Experimental results show that a combination of blue (B), red (R), and far-red (F) LED illumination leads to a one-fold increase in the yield of a sweet basil plant in comparison with only white LED illumination (W*). On the other hand, the use of blue (B) and red (R) LED illumination results in a half-fold increase in plant yield. Understanding the effects of LED illumination spectrum on the growth of plant sweet basil plants through basic horticulture research enables farmers to significantly improve their production yield, thus food security and profitability.

Low temperature effects on the growth of evening primrose (Oenothera spp.) rosettes

2004 ◽  
Vol 52 (1) ◽  
pp. 19-28
Author(s):  
A. F. Fieldsend
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Relative Growth Rate ◽  
Relative Rate ◽  
Field Trials ◽  
Effect Of Temperature ◽  
Relative Growth ◽  
Evening Primrose ◽  
Intermittent Exposure ◽  
Environment Experiment

In field crops of evening primrose (Oenothera spp.) the post-winter growth of rosettes is slow to re-start. The effect of temperature on the growth of rosettes was assessed in a controlled environment experiment. Relative growth rate was positively correlated with temperature, but in apparent contrast to the results from field trials, the rosettes grew at constant temperatures as low as 6.5ºC. However, following transfer to warmer temperatures an increase in relative growth rate did not occur until 7-10 days later, whilst a change to a cooler environment caused an immediate reduction in relative growth rate. Thus, it seems likely that growth is inhibited by intermittent exposure to temperatures of 0°C or below. Partitioning of biomass between root and shoot was independent of temperature, but at 6.5ºC the relative rate of leaf area increase was very low. Consequently, the specific leaf area was lower in rosettes growing at lower temperatures.

scholarly journals The Effect of Temperature and Humidity May Reduce the Growth Rate of the Coronavirus Disease 2019 Epidemic

2020 ◽  
Author(s):  
Lei Qin ◽  
Qiang Sun ◽  
Jiani Shao ◽  
Yang Chen ◽  
Xiaomei Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Relative Humidity ◽  
Effect Of Temperature ◽  
Average Temperature ◽  
Temperature And Humidity ◽  
Scatter Plots ◽  
Low Humidity ◽  
Average Relative Humidity ◽  
Effects Of Temperature ◽  
The Relationship

Abstract Background: The effects of temperature and humidity on the epidemic growth of coronavirus disease 2019 (COVID-19)remains unclear.Methods: Daily scatter plots between the epidemic growth rate (GR) and average temperature (AT) or average relative humidity (ARH) were presented with curve fitting through the “loess” method. The heterogeneity across days and provinces were calculated to assess the necessity of using a longitudinal model. Fixed effect models with polynomial terms were developed to quantify the relationship between variations in the GR and AT or ARH.Results: An increased AT dramatically reduced the GR when the AT was lower than −5°C, the GR was moderately reduced when the AT ranged from −5°C to 15°C, and the GR increased when the AT exceeded 15°C. An increasedARH increased theGR when the ARH was lower than 72% and reduced theGR when the ARH exceeded 72%.Conclusions: High temperatures and low humidity may reduce the GR of the COVID-19 epidemic. The temperature and humidity curves were not linearly associated with the COVID-19 GR.

The relationship between relative growth rate and susceptibility to aphids in wild barley under different nutrient levels

Oecologia ◽  
2003 ◽  
Vol 137 (4) ◽  
pp. 564-571 ◽  
Author(s):  
I. A. M. Elberse ◽  
J. H. B. Turin ◽  
F. L. W�ckers ◽  
J. M. M. Van Damme ◽  
P. H. Van Tienderen
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Wild Barley ◽  
Relative Growth ◽  
Nutrient Levels ◽  
The Relationship

scholarly journals Incorporation of Temperature and Solar Radiation Thresholds to Modify a Lettuce Downy Mildew Warning System

2002 ◽  
Vol 92 (6) ◽  
pp. 631-636 ◽  
Author(s):  
B. M. Wu ◽  
A. H. C. van Bruggen ◽  
K. V. Subbarao ◽  
H. Scherm
Keyword(s):  
Solar Radiation ◽  
Downy Mildew ◽  
Disease Incidence ◽  
Characteristic Curve ◽  
Warning System ◽  
Effect Of Temperature ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Leaf Wetness ◽  
High Solar Radiation

The effect of temperature on infection of lettuce by Bremia lactucae was investigated in controlled environment studies and in the field. In controlled conditions, lettuce seedlings inoculated with B. lactucae were incubated at 15, 20, 25, or 30°C during a 4-h wet period immediately after inoculation or at the same temperatures during an 8-h dry period after the 4-h postinoculation wet period at 15°C. High temperatures during wet and dry periods reduced subsequent disease incidence. Historical data from field studies in 1991 and 1992, in which days with or without infection had been identified, were analyzed by comparing average air temperatures during 0600 to 1000 and 1000 to 1400 Pacific standard time (PST) between the two groups of days. Days without infection had significantly higher temperatures (mean 21.4°C) than days with infection (20.3°C) during 1000 to 1400 PST (P < 0.01) but not during 0600 to 1000 PST. Therefore, temperature thresholds of 20 and 22°C for the 3-h wet period after sunrise and the subsequent 4-h postpenetration period, respectively, were added to a previously developed disease warning system that predicts infection when morning leaf wetness lasts ≥4 h from 0600 PST. No infection was assumed to occur if average temperature during these periods exceeded the thresholds. Based on nonlinear regression and receiver operating characteristic curve analysis, the leaf wetness threshold of the previous warning system was also modified to ≥3-h leaf wetness (≥0900 PST). Furthermore, by comparing solar radiation on days with infection and without infection, we determined that high solar radiation during 0500 to 0600 PST in conjunction with leaf wetness ending between 0900 and 1000 PST was associated with downy mildew infection. Therefore, instead of starting at 0600 PST, the calculation of the 3-h morning leaf wetness period was modified to start after sunrise, defined as the hour when measured solar radiation exceeded 8 W m-2 (or 41 μmol m-2 s-1 for photon flux density). The modified warning system was compared with the previously developed system using historical weather and downy mildew data collected in coastal California. The modified system was more conservative when disease potential was high and recommended fewer fungicide applications when conditions were not conducive to downy mildew development.

Experimental Research on the Thermal Damage of Concrete

2013 ◽  
Vol 351-352 ◽  
pp. 460-466
Author(s):  
Chao Chen ◽  
Ying She Luo ◽  
Song Hua Tang ◽  
Xuan Zhang
Keyword(s):  
Damage Evolution ◽  
Thermal Damage ◽  
Damage Model ◽  
Effect Of Temperature ◽  
Compression Tests ◽  
Thermal Compression ◽  
Relevant Reference ◽  
Different Temperatures ◽  
The Relationship ◽  
Fire Design

In order to investigate the effect of temperature (from normal temperature to 850°C) coursed by fire on the strength damage of concrete, thermal compression tests for concrete specimens named C35 have been performed under different temperature conditions. Emphasis is laid on the relationship between temperature and thermal damage strength; and the relevant formula is proposed in this paper. The regularity and mechanism of thermal damage evolution in concrete on strength under high temperature are analyzed. Combined the result of tests with the residual strength thermal damage model, we obtain the specific damage variable value D under different temperatures. Finally, we compare the fitting formula curve to relevant reference; there are some important conclusions which can be partly applied to fire design of concrete structure.

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