The physiology of growth in Subterranean clover. I. Seedling growth and the pattern of growth at the shoot apex

1970 ◽  
Vol 18 (2) ◽  
pp. 127 ◽  
Author(s):  
RF Williams ◽  
D Bouma
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Shoot Apex ◽  
Exponential Growth ◽  
Leaf Growth ◽  
General Pattern ◽  
Subterranean Clover ◽  
Growth Period ◽  
Vascular Differentiation ◽  
Relative Growth

The shoot apex of Trifolium subterraneum L. is spirodistichous, with a divergence angle of 160° and a phyllotaxis index of 2. The vegetative plant is defined quantitatively in terms of lengths of successive leaves, leaf areas, and dry weights of the leaves and all major plant parts for a 29-day growth period. The selected environment gave very high values of net assimilation rate (3 .0 mg cm-2 day-1for early growth). The properties of the shoot apical system are further defined in terms of volumes of meristematic and very young parts. The picture is extended by linking it with fresh weight data for the leaves. To a remarkable extent the data, transformed to logarithms, can be accounted for by arrays of linear regressions on time, the members of which show decreasing slopes with increasing leaf number. However, the most instructive description is obtained from an array of relative growth rate curves for successive leaves. While the existence of one general pattern of leaf growth seems unlikely, there is evidence for a marked increase in relative growth rate during leaf initiation. Exponential growth in length seems to be fairly common in young leaf primordia, but exponential growth in volume occurs in a variety of patterns in different plants. Attempts to link these occurrences with events in vascular differentiation and thus with the supply of substrate for growth have not been successful. It is suggested that properties of the system as a whole may be relevant.

scholarly journals Alternative graphical displays for the monitoring of epidemic outbreaks, with application to COVID-19 mortality

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Thomas Perneger ◽  
Antoine Kevorkian ◽  
Thierry Grenet ◽  
Hubert Gallée ◽  
Angèle Gayet-Ageron
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Exponential Growth ◽  
Relative Rate ◽  
Linear Increase ◽  
Relative Growth ◽  
Graphical Displays ◽  
Straight Line ◽  
Exponential Rates ◽  
Over Time

Abstract Background Classic epidemic curves – counts of daily events or cumulative events over time –emphasise temporal changes in the growth or size of epidemic outbreaks. Like any graph, these curves have limitations: they are impractical for comparisons of large and small outbreaks or of asynchronous outbreaks, and they do not display the relative growth rate of the epidemic. Our aim was to propose two additional graphical displays for the monitoring of epidemic outbreaks that overcome these limitations. Methods The first graph shows the growth of the epidemic as a function of its size; specifically, the logarithm of new cases on a given day, N(t), is plotted against the logarithm of cumulative cases C(t). Logarithm transformations facilitate comparisons of outbreaks of different sizes, and the lack of a time scale overcomes the need to establish a starting time for each outbreak. Notably, on this graph, exponential growth corresponds to a straight line with a slope equal to one. The second graph represents the logarithm of the relative rate of growth of the epidemic over time; specifically, log10(N(t)/C(t-1)) is plotted against time (t) since the 25th event. We applied these methods to daily death counts attributed to COVID-19 in selected countries, reported up to June 5, 2020. Results In most countries, the log(N) over log(C) plots showed initially a near-linear increase in COVID-19 deaths, followed by a sharp downturn. They enabled comparisons of small and large outbreaks (e.g., Switzerland vs UK), and identified outbreaks that were still growing at near-exponential rates (e.g., Brazil or India). The plots of log10(N(t)/C(t-1)) over time showed a near-linear decrease (on a log scale) of the relative growth rate of most COVID-19 epidemics, and identified countries in which this decrease failed to set in in the early weeks (e.g., USA) or abated late in the outbreak (e.g., Portugal or Russia). Conclusions The plot of log(N) over log(C) displays simultaneously the growth and size of an epidemic, and allows easy identification of exponential growth. The plot of the logarithm of the relative growth rate over time highlights an essential parameter of epidemic outbreaks.

Variability among Festuca arundinacea cultivars for tolerance to and recovery from waterlogging, salinity and their combination

2021 ◽  
Vol 72 (1) ◽  
pp. 75
Author(s):  
F. E. Menon-Martínez ◽  
A. A. Grimoldi ◽  
G. G. Striker ◽  
C. E. Di Bella
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Festuca Arundinacea ◽  
Growth Traits ◽  
Global Climate ◽  
Growth Period ◽  
Recovery Phase ◽  
Combined Treatments ◽  
Combined Stress ◽  
Relative Growth

Frequency and intensity of floods and the extent of salt-affected lands are expected to increase in pastures and grassland ecosystems as a result of global climate change. This study evaluated the effects of waterlogging, salinity (150 mm NaCl, ~15 dS m–1) and their combination over 14 days of treatment on morphological and growth traits of seven cultivars of Festuca arundinacea (tall fescue). Recovery was also assessed after a 14-day growth period under aerated, non-saline conditions (recovery phase). All cultivars survived the imposed stresses, showing greater tolerance to waterlogging than to salinity or the combined stress, evaluated as a response ratio of total dry mass relative to the control. The combined stress provoked growth lower than predicted by a multiplicative model in one cultivar, growth equal to the model in three cultivars and growth higher than the model in three cultivars. High variability among cultivars in response to each stress and phase was observed; this was more evident for relative growth rate of roots than of shoots. Plant morphological traits were affected by treatments in different ways; mature tiller weight was maintained, and tiller number decreased by 79–71% under waterlogging and combined stresses, whereas the opposite responses occurred under salinity. During the recovery phase, plants in all stress treatments had lower tiller numbers than controls and prioritised the growth of pre-existing tillers, which were heavier. Number of dead leaves per plant increased in saline and combined treatments. In general, F. arundinacea proved more tolerant to waterlogging than to salinity or combined treatments, and showed promising variability among cultivars with respect to root relative growth rate under the evaluated stresses, which can be used in future breeding programs. The findings also provide a basis for further research into the tolerance mechanisms involved.

Studies on the nutrition of pasture plants in the South-west of Western Australia. IV The Growth of Subterranueum Clover (Trifolium subterraneum L.) as affected by lime, molybdenum, and Potassium

1952 ◽  
Vol 3 (3) ◽  
pp. 244 ◽  
Author(s):  
RC Rossiter
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Net Assimilation Rate ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Minimum Requirements ◽  
Net Assimilation ◽  
Pasture Plants

The results of a pot-culture experiment in which subterranean clover was grown on a coarse siliceous sand slightly acid in reaction are presented. Maximum yields resulted from application of potassium, together with either molybdenum or lime. The lime X molybdenum interaction was almost always negative, but its magnitude varied with time and potassium: in the absence of potassium it diminished in magnitude, but increased markedly in its presence. The lime X potassium and molybdenum X potassium interactions were strongly positive during the later stages of growth, but only in the absence of molybdenum and lime respectively. The effects of treatment on leaf-weight and leaf-area ratio were not closely related to those on relative growth rate. The latter were determined primarily by treatment effects on net assimilation rate. Both relative growth rate and net assimilation rate were increased by potassium. The results provide further support for the findings of Anderson and Oertel (1946) that, in legumes, nitrogen is the primary nutrient concerned in the response to lime and molybdenum, and that the molybdenum concentration gives little indication of the minimum requirements for satisfactory growth. The possible effect of lime on the transport of molybdenum from roots to tops is discussed.

scholarly journals Empirical growth models for the renewable energy sector

2018 ◽  
Vol 45 ◽  
pp. 35-44
Author(s):  
Kristoffer Rypdal
Keyword(s):  
Growth Rate ◽  
Renewable Energy ◽  
Power Consumption ◽  
Relative Growth Rate ◽  
Growth Model ◽  
Power Law ◽  
Exponential Growth ◽  
Logistic Model ◽  
Energy Sector ◽  
Relative Growth

Abstract. Three simple, empirical models for growth of power consumption in the renewable energy sector are compared. These are the exponential, logistic, and power-law models. The exponential model describes growth at a fixed relative growth rate, the logistic model saturates at a fixed limit, while the power-law model describes slowing, but unlimited, growth. The model parameters are determined by regression to historical global data for solar and wind power consumption, and model projections are compared to scenarios based on macroeconomic modelling that meet the 2∘ target. It is demonstrated that rational rejection of an exponential growth model in favour of a logistic growth model cannot be made from existing data for the historical evolution of global renewable power consumption y(t). It is also shown that the logistic model yields saturation of growth at unrealistic low levels. The power-law growth model is found to give very good fits to the data through the last decade, and the projections align very well with the scenarios. Power-law growth is equivalent to the simple law that the relative growth rate y′/y decays inversely proportional to time. It is shown that this is a natural model for growth that slows down due to various constraints, yet not experiencing the effect of a strict upper limit defined by physical boundaries. If the actual consumption follows the power-law curve in the years to come the exponential-growth null hypothesis can be correctly rejected around 2020.

The Genesis of Form in Casuarinaceae

1985 ◽  
Vol 33 (5) ◽  
pp. 563 ◽  
Author(s):  
RF Williams ◽  
RA Metcalf
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Shoot Apex ◽  
Growth And Development ◽  
Three Dimensional ◽  
Axillary Buds ◽  
Relative Growth ◽  
Rates Of Growth

The growth and development of the shoot apex of Casuarina distyla, in which the leaves commonly occur in whorls of 6-8 members, is described. The mature apex of C. torulosa, a species with only four leaves per whorl, is also described. Stages in the development of the apex of C. distyla are illustrated with three-dimensional scale drawings. The fused stem-and-leaf nature of the vegetative axis is recognized and the growth of the blade, tube and buttress portions of the axes is presented in units of length and volume. Stages in the development of axillary buds are illustrated with three-dimensional scale drawings. Phyllotactic parameters for whorled systems of phyllotaxis in Nerium and Casuarina are presented along with those for decussate systems in Eucalyptus. The role of physical constraint in the genesis of form and the determination of rates of growth in shoot apices are discussed and it is suggested that rapid maturation of tissues may contribute to the continuous fall in the relative growth rate of the leaves.

scholarly journals The Contribution by Leaves of Different Age to New Growth of Subterranean Clover Plants Following the Removal of a Sulphur Stress I. Origin and Distribution of Dry Matter

1972 ◽  
Vol 25 (6) ◽  
pp. 1147 ◽  
Author(s):  
D Bouma ◽  
EAN Greenwood ◽  
EJ Dowling
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Relative Growth Rate ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Area Ratio ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Net Assimilation ◽  
Nutrient Solutions

During the first 3 days after transfer of moderately sulphur-deficient plants (S1) to full nutrient solutions, the relative growth rate (Rw) was considerably lower than that of plants raised at higher sulphur levels (S2 and Sa). This was reflected in a lower leaf area ratio of the S1 plants, and particularly in a reduction of nearly 50% in the net assimilation rate (EA). Net losses in dry matter from younger emerged leaves and petioles accounted for 25% of the dry matter in new leaves and petioles of S1 plants produced during this period.

THE RATE OF DRY WEIGHT ACCUMULATION IN MARQUIS WHEAT AS AFFECTED BY TEMPERATURE AND LIGHT INTENSITY

1962 ◽  
Vol 40 (7) ◽  
pp. 939-955 ◽  
Author(s):  
D. J. C. Friend ◽  
V. A. Helson ◽  
J. E. Fisher
Keyword(s):  
Growth Rate ◽  
Light Intensity ◽  
Relative Growth Rate ◽  
Growth Period ◽  
Dry Weight ◽  
Continuous Illumination ◽  
Relative Growth ◽  
Absolute Growth Rate ◽  
Absolute Growth ◽  
The Mean

Plants were grown to the stage of anthesis at constant temperatures from 10 to 30 °C and under continuous illumination at intensities ranging from 200 to 2500 ft-c. The absolute growth rate was maximal at the time of ear emergence. The relative growth rate declined continuously with time; the rate of decline was greatest at the higher temperatures and light intensities. The optimal temperature for the mean absolute growth rate over the whole growth period was 20–25 °C. The optimum for the mean relative growth rate was 15–20 °C. This difference is attributed to the faster rate of floral development at high temperatures. Both absolute and relative growth rates increased with increasing light intensity up to 2500 ft-c.

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