scholarly journals The Light Growth Response of Phycomyces

1973 ◽  
Vol 62 (5) ◽  
pp. 590-617 ◽  
Author(s):  
K. W. Foster ◽  
E. D. Lipson
Keyword(s):  
Growth Response ◽  
Tracking System ◽  
Action Spectrum ◽  
Response Patterns ◽  
Growth Responses ◽  
Wide Range ◽  
Variable Damping ◽  
State Growth ◽  
Gradual Variation ◽  
Constant Period

With the help of an automated tracking system we have studied the characteristics of the transient light growth response of Phycomyces. The response shows a sharply defined latency. The Q10 of the reciprocal latency is 2.4. Response patterns at different peaks of the action spectrum are the same. The gradual variation of response magnitude over a wide range of adapted intensifies parallels that of phototropism. The responses to saturating stimuli exhibit a strong oscillation with a constant period of 1.6 min and variable damping. The growth responses to sinusoidally varying light intensities show a system bandwidth of 2.5 x 10-3 Hz. The linear dependence of phase shift on frequency is largely attributable to the latency observed with pulse stimuli. In the high intensity range a previously suspected increase of the steady-state growth rate with intensity has been confirmed. The light growth responses of mutants selected for diminished phototropism have been investigated. Many of these mutants have sizable but grossly distorted growth responses.

Growth responses in red deer hinds from 16-24 months of age when fed two energy levels during their second winter

1998 ◽  
Vol 1998 ◽  
pp. 141-141
Author(s):  
M H Davies ◽  
D W Deakin
Keyword(s):  
Growth Response ◽  
Red Deer ◽  
Energy Levels ◽  
Growth Restriction ◽  
Growth Responses ◽  
Wide Range ◽  
Feeding Regimes ◽  
Cost Of Production ◽  
Red Meats

It is important that venison competes with other red meats in efficiency and cost of production. The growth responses of farmed red deer during the first 15-18 months of life have been well defined under a wide range of feeding and daylength regimes (Davies, 1995). However there is a need to examine less intensive systems of production which aim to maximise growth from grazed grass, following various growth-restriction feeding regimes during winter. The objective of this experiment was to quantify the growth response in 16-24 month old hinds fed two contrasting feeding regimes during their second winter, followed by a period at pasture.

Growth responses in red deer hinds from 16-24 months of age when fed two energy levels during their second winter

1998 ◽  
Vol 1998 ◽  
pp. 141-141
Author(s):  
M H Davies ◽  
D W Deakin
Keyword(s):  
Growth Response ◽  
Red Deer ◽  
Energy Levels ◽  
Growth Restriction ◽  
Growth Responses ◽  
Wide Range ◽  
Feeding Regimes ◽  
Cost Of Production ◽  
Red Meats

It is important that venison competes with other red meats in efficiency and cost of production. The growth responses of farmed red deer during the first 15-18 months of life have been well defined under a wide range of feeding and daylength regimes (Davies, 1995). However there is a need to examine less intensive systems of production which aim to maximise growth from grazed grass, following various growth-restriction feeding regimes during winter. The objective of this experiment was to quantify the growth response in 16-24 month old hinds fed two contrasting feeding regimes during their second winter, followed by a period at pasture.

Studies of the growth and mineral nutrition of barley varieties. II. Potassium uptake and its regulation

1983 ◽  
Vol 61 (6) ◽  
pp. 1551-1558 ◽  
Author(s):  
M. Yaeesh Siddiqi ◽  
Anthony D. M. Glass
Keyword(s):  
Steady State ◽  
Kinetic Constants ◽  
Growth Responses ◽  
Short Term ◽  
Potential Growth ◽  
Wide Range ◽  
Rapid Loading ◽  
State Growth ◽  
Complete Nutrient Solution ◽  
Growth Experiments

Short-term K+ (86Rb) influx and its regulation by root K+ concentration was studied in barley varieties, using plants grown in complete nutrient solution at constant concentrations. The varieties employed in this study exhibited substantial differences not only in K+ influx but also in the intensity and the pattern of regulation of K+ influx. In the high-potential growth-rate varieties these K+ uptake characteristics were found to correlate well with their growth responses to K+ supply reported earlier by Siddiqi and Glass. Predictions of K+ influx, based upon kinetic constants and internal K+ concentrations derived from steady-state growth experiments, were found to correspond well with the observed fluxes for plants grown under these conditions over a wide range of root K+ concentrations. These predictions also provided good estimates of influx in CaSO4-grown plants for intermediate levels of root K+ concentration. However, at low root K+ concentration, predictions greatly overestimated observed fluxes, while at high root K+, influx was underestimated. Similarly, when kinetic constants derived from CaSO4-grown plants (whose root K+ concentrations were increased by rapid loading) were applied to steady-state plants, predicted influx values were close to observed in the intermediate range of root K+ concentration. However, at high root K+, influx was overestimated. These adjustments serve, in the steady state, to maintain tissue K+ concentration within rather narrow limits.

scholarly journals A Simulation Model of Rosa hybrida Growth Response to Constant Irradiance and Day and Night Temperatures

1994 ◽  
Vol 119 (5) ◽  
pp. 903-914 ◽  
Author(s):  
Douglas A. Hopper ◽  
P. Allen Hammer ◽  
James R. Wilson
Keyword(s):  
Plant Growth ◽  
Simulation Model ◽  
Growth Response ◽  
Growth Characteristics ◽  
Rosa Hybrida ◽  
Stem Length ◽  
Photon Flux ◽  
Growth Responses ◽  
Wide Range ◽  
Plant Growth Characteristics

This paper details the development and verification of ROSESIM, a computer simulation model of the growth of `Royalty' roses (Rosa hybrida L.) based on experimentally observed growth responses from pinch until flowering under 15 combinations of constant photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT). Selected according to a rotatable central composite design, these treatment combinations represent commercial greenhouse conditions during the winter and spring in the midwestern United States; each selected condition was maintained in an environmental growth chamber having 12-hour photoperiods. ROSESIM incorporates regression models of four flower development characteristics (days from pinch to visible bud, first color, sepal reflex, and flowering) that are full quadratic polynomials in PPF, DT, and NT. ROSESIM also incorporates mathematical models of nine plant growth characteristics (stem length and the following fresh and dry weights: stem, leaf, flower, and total) based on data recorded every 10 days and at flowering. At each design point, a cubic regression in time (days from pinch) estimated the plant growth characteristics on intermediate days; then difference equations were developed to predict the resulting daily growth increments as third-degree polynomial functions of days from pinch, PPF, DT, and NT. ROSESIM was verified by plotting against time each simulated plant growth characteristic and the associated experimental observations for the eight factorial design points defining the region of interest. Moreover, one-way analysis of variance procedures were applied to the differences between ROSESIM predictions and the corresponding observed means for all 15 treatment combinations. At 20 days from pinch, significant differences (P < 0.05) were observed for all nine plant growth characteristics. At 30 and 40 days from pinch, only flower fresh and dry weights yielded significant differences; at flowering, none of the 13 selected responses yielded significant differences. These graphical and statistical comparisons provide good evidence of ROSESIM's ability to predict the growth response of `Royalty' roses over a wide range of constant environmental conditions.

scholarly journals A Quantitative-Analysis of Dark Respiration and Carbon Content as Factors in the Growth-Response of Plants to Elevated CO2

1992 ◽  
Vol 40 (5) ◽  
pp. 501 ◽  
Author(s):  
H Poorter ◽  
RM Gifford ◽  
PE Kriedemann ◽  
SC Wong
Keyword(s):  
Carbon Content ◽  
Elevated Co2 ◽  
Respiration Rate ◽  
Growth Response ◽  
Dark Respiration ◽  
Growth Responses ◽  
High Co2 ◽  
Unit Leaf ◽  
Wide Range ◽  
Few Data

An analysis of elevated CO2 effects (2-4 times ambient) on dark respiration rate and carbon content was undertaken for a wide range of plant species, using both published reports and new data. On average, leaf respiration per unit leaf area was slightly higher for plants grown at high CO2 (16%), whereas a small decrease was found when respiration was expressed on a leaf weight basis (14%). For the few data on root respiration, no significant change due to high CO2 could be detected. Carbon content of leaves and stem showed a small increase (1.2 and 1.7% respectively), whereas C-content of roots was not significantly affected. In both data sets direction of responses was variable. A sensitivity analysis of carbon budgets under elevated CO2 identified changes in respiration rate, and to a lesser extent carbon content, as important factors affecting the growth response to elevated CO2 in quite a number of cases. Any comprehensive analysis of growth responses to increased CO2 should therefore include measurements of these two variables.

scholarly journals The Survival of Haloferax mediterranei under Stressful Conditions

2021 ◽  
Vol 9 (2) ◽  
pp. 336
Author(s):  
Laura Matarredona ◽  
Mónica Camacho ◽  
Basilio Zafrilla ◽  
Gloria Bravo-Barrales ◽  
Julia Esclapez ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Sea Water ◽  
Industrial Applications ◽  
Growth Responses ◽  
Haloferax Mediterranei ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Wide Range ◽  
High Metal ◽  
Plasma Mass Spectrometry

Haloarchaea can survive and thrive under exposure to a wide range of extreme environmental factors, which represents a potential interest to biotechnology. Growth responses to different stressful conditions were examined in the haloarchaeon Haloferax mediterranei R4. It has been demonstrated that this halophilic archaeon is able to grow between 10 and 32.5% (w/v) of sea water, at 32–52 °C, although it is expected to grow in temperatures lower than 32 °C, and between 5.75 and 8.75 of pH. Moreover, it can also grow under high metal concentrations (nickel, lithium, cobalt, arsenic), which are toxic to most living beings, making it a promising candidate for future biotechnological purposes and industrial applications. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis quantified the intracellular ion concentrations of these four metals in Hfx. mediterranei, concluding that this haloarchaeon can accumulate Li+, Co2+, As5+, and Ni2+ within the cell. This paper is the first report on Hfx. mediterranei in which multiple stress conditions have been studied to explore the mechanism of stress resistance. It constitutes the most detailed study in Haloarchaea, and, as a consequence, new biotechnological and industrial applications have emerged.

scholarly journals Faculty Teaching Practices and Perceptions: Comparative Analysis Based on Time Spent Lecturing

2017 ◽  
Vol 10 ◽  
pp. 27-44
Author(s):  
Gulnur Birol ◽  
Adriana Briseño-Garzón ◽  
Andrea Han
Keyword(s):  
Teaching Practices ◽  
Response Patterns ◽  
University Of British Columbia ◽  
Faculty Teaching ◽  
Wide Range ◽  
Baseline Information ◽  
Survey Responses ◽  
The University ◽  
Classroom Time ◽  
Large Research

The University of British Columbia-Vancouver (UBC-V) implemented a campus-wide survey of faculty teaching practices and perceptions. All 11 Faculties participated, resulting in a total of 1177 responses for an overall response rate of 24%. We compared response patterns of faculty who reported spending less than 25%, between 26-50%, between 51-75%, and more than 75% of classroom time lecturing. Using this breakdown, we analysed survey responses related to in and out-of-class practices and expectations for students, use of teaching assistant time, participation in professional development opportunities, and perceptions of whether the institution valued teaching. Participants across quadrants reported employing a wide range of teaching methods irrespective of years of experience and class size. Our findings outline the range of teaching practices employed by faculty at a large research-intensive Canadian institution and may provide baseline information for institutions of similar scale and focus.

Dose-Dependent Effects of the Action of Sulfur Nanoparticles on the Growth Response and Seed Production of Typical Steppe Phytocenoses

2017 ◽  
Vol 13 ◽  
pp. 156-161 ◽  
Author(s):  
Zinaida N. Ryabinina ◽  
Marija V. Ryabukhina ◽  
Maya V. Kolodina
Keyword(s):  
Seed Production ◽  
Biochemical Parameters ◽  
Growth Response ◽  
Growth Responses ◽  
Seed Productivity ◽  
Typical Steppe ◽  
Forms Of Life ◽  
Dose Dependent ◽  
Biological Group ◽  
Sulfur Nanoparticles

The article presents the results of a study of typical steppe phytocenoses presented one ecological and biological group - xeromesophyte but different systematic affiliation and forms of life, to the action of sulfur nanoparticles. Results of the study showed a relationship between the concentrations of sulfur nanoparticles and growth responses, biochemical parameters and seed productivity of investigated species

The Dose Determines the Stimulation (and Poison): Development of A Chemical Hormesis Database

1997 ◽  
Vol 16 (6) ◽  
pp. 545-559 ◽  
Author(s):  
Edward J. Calabrese ◽  
Linda A. Baldwin
Keyword(s):  
A Priori ◽  
Dose Range ◽  
Evaluation Criteria ◽  
Metabolic Effects ◽  
Growth Responses ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Real Phenomenon ◽  
Effect Level ◽  
Taxonomic Groups

A comprehensive effort was undertaken to identify articles demonstrating chemical hormesis. Nearly 4000 potentially relevant articles were retrieved from preliminary computer searches utilizing various keyword descriptors and extensive cross-referencing. A priori evaluation criteria were established including study design features (e.g., number of doses, dose range), statistical analysis, and reproducibility of results. Evidence of chemical hormesis was judged to have occurred in approximately 350 of the 4000 studies evaluated. Chemical hormesis was observed in a wide range of taxonomic groups and involved agents representing highly diverse chemical classes, many of potential environmental relevance. Numerous biologic endpoints were assessed, with growth responses the most prevalent, followed by metabolic effects, longevity, reproductive responses, and survival. Hormetic responses were generally observed to be of limited magnitude with the average low-dose maximum stimulation approximately 50% greater than controls. The hormetic dose-response range was generally limited to about one order of magnitude with the upper end of the hormetic curve approaching the estimated no-observed-effect level (NOEL) for the particular endpoint. Based on the evaluation criteria, high to moderate evidence of hormesis was observed in studies comprised of ≥ doses with <3 doses in the hormetic zone. The present analysis suggests that chem ical hormesis is a reproducible and generalizable biologic phenomenon. Over the last decade advances have been made providing mechanistic insight helpful in explaining the phenomenon of chemical hormesis in multiple biologic systems with various endpoints. The reason for the uncertainty surrounding the existence of hormesis as a “real phenomenon” is believed to be the result of its relatively infrequent observation in the literature due to experimental design considerations, especially with respect to the number of doses, range of doses, and endpoint selection.

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