scholarly journals THE GROWTH AND DURATION OF LIFE OF CELOSIA CRISTATA SEEDLINGS AT DIFFERENT TEMPERATURES

1934 ◽  
Vol 17 (6) ◽  
pp. 763-781 ◽  
Author(s):  
Thomas I. Edwards ◽  
Raymond Pearl ◽  
Sophia A. Gould
Keyword(s):  
Growth Rate ◽  
Maximum Yield ◽  
Total Duration ◽  
Growth Curves ◽  
Growth Period ◽  
Hypocotyl Length ◽  
Rate Of Growth ◽  
Life Duration ◽  
Celosia Cristata ◽  
The Mean

Daily measurements of hypocotyl length were made on Celosia cristata seedlings cultured in darkness under aseptic conditions at six constant temperatures between 14.5° and 40.5°C. At 40.5° roots did not penetrate the agar and only the hypocotyls that were supported by the wall of the test tube could be measured. The growth curves were of the generalized logistic type, but of different degrees of skewness. The degree of symmetry of the growth curves was influenced by temperature. At the lower temperatures the maximal growth rate came relatively late in the grand period of growth; at successively higher temperatures it came progressively earlier. The mean total time rate of growth (millimeter per diem) was found to be a parabolic function of the temperature. The maximum rate of growth was found from the curve to be at 30.48°C. The maximum observed rate of growth, and the maximum yield, were found to be at 30°C. At all temperatures above 14.5° the maximum growth activity fell in the second quarter of the whole growth period. At all temperatures tested other than 30°, and at all parts of the growth cycle, the growth yield as measured by height of hypocotyl at any given equivalent point was less than at 30°. The total duration of life of the seedlings, and the duration of life after the end of the growth period (intermediate period) were inversely proportional to the mean total growth rate. The observations on Celosia cristata seedlings are thus in accord with the "rate of living" theory of life duration. The optimal temperature for life duration is the minimum temperature, within the range of these observations.

Variation in rectal temperature of cattle in a tropical environment and its relation to growth rate

1984 ◽  
Vol 38 (3) ◽  
pp. 417-427 ◽  
Author(s):  
H. G. Turner
Keyword(s):  
Growth Rate ◽  
Genetic Correlation ◽  
Rectal Temperature ◽  
Bos Indicus ◽  
Heritability Estimate ◽  
Growth Period ◽  
The Other ◽  
Tropical Environment ◽  
The Mean ◽  
Selection Of

ABSTRACTRectal temperatures of cattle grazed near the tropic of Capricorn in central Queensland were studied. The cattle were of Bos indicus, B. taurus and crossbred lines, and were represented by over 200 growing heifers in each of 2 years and some supplementary groups.Rectal temperatures were loge normally distributed when they were expressed as deviations from a basal temperature of 38°C. They were significantly repeatable, but were more highly repeatable when herd mean temperature was above 39·5°C. The heritability estimate was 0·33 (P < 0·01).The mean phenotypic regression of growth rate on rectal temperature, within breed groups, was 0·04 (s.e. 0·006) kg/day per °C (r = 0·3, P < 0·01) over the entire growth period from birth to 18 months of age but greater during warmer seasons. The estimated genetic correlation was insignificant in one group of heifers but −0·86 (s.e. 0·17) in the other.The evidence of favourable and possible unfavourable responses to selection of cattle for low rectal temperature in warm environments is discussed.

scholarly journals A critical statistical study of experimental data on the effect of minute electric currents on the growth rate of the coleoptile of barley

1926 ◽  
Vol 99 (695) ◽  
pp. 122-130 ◽  
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Statistical Study ◽  
Pure Line ◽  
Similar Data ◽  
Electric Currents ◽  
Rate Of Growth ◽  
The Mean ◽  
Positive Results ◽  
Case Based

A study of the effect of very minute electric currents on the rate of growth of the coleoptile of barley was published recently by one of us (F. G. G.) in collaboration. In this paper the mean rate of a number of control coleoptiles was compared with the mean rate of a number exposed to a minute electric discharge. The growth rate of individual coleoptiles showed, naturally, considerable divergences, so the mean result was in each case based on the observation of a large number of coleoptiles, the increments of growth of individual coleoptiles being stated as percentages of the rate of growth during the first hour of observation. It was assumed that the distribution of growth rates in a comparatively large sample of a pure-line barley would conform with the normal distribution; the probable errors of the mean results were therefore calculated in the ordinary way. During the continuation of this work positive results have been obtained in further experimental sets, but a number of these, though significant in the mass, were individually without significance. This suggested that a careful statistical study of the data on which the results were based might show how the accuracy of the method could be increased. Such a study has accordingly been undertaken, and it seems probable that methods employed are likely to be of use in the treatment of similar data.

scholarly journals Growth Curves of Texel Male Lambs

2018 ◽  
Vol 44 (1) ◽  
pp. 6
Author(s):  
Michelli De Fátima Sieklicki ◽  
Victor Breno Pedrosa ◽  
Caroline Gomes Rocha ◽  
Raphael Patrick Moreira ◽  
Paula Roberta Falcão ◽  
...  
Keyword(s):  
Growth Rate ◽  
Mean Square Error ◽  
Nonlinear Models ◽  
Growth Curves ◽  
Coefficient Of Determination ◽  
Good Growth ◽  
Von Bertalanffy ◽  
Mean Square ◽  
The Mean ◽  
Best Fit

Background: The consumption of lamb meat is growing due to improved farming methods. However, to be economically feasible, the animal should stand out for its precocity, fast finishing and muscular force, such as seen in Texel breed. Besides, knowledge about weight gain and development can facilitate the selection of the best animals, and allow a better fitting to farming systems. Growth curves are an effective method that describes animal development, modeling the relationship between weight and age and help to predict the growth rate. Thus, this study aimed to analyze which nonlinear model, including Brody, Gompertz, Von Bertalanffy and Logistic best describe the growth curve of Texel sheep.Materials, Methods & Results: In this experiment, the lambs were kept in confined system while the ewes, in a semi-extensive system. This study followed 42 Texel male lambs, which were confined from birth to slaughter, and fed concentrated feed (3% of body weight) and corn silage (average 1.5 kg/animal/day), 4 times a day. The lambs were weighed fortnightly, in different classes considered as follows, weight at birth (BW), 15 days (P15), 30 days (P30), 45 days (P45), 60 days (P60), 75 days (P75), 90 days (P90), 105 days (P105), and 120 days (P120), which was defined as the slaughtering weight. The growth curves were determined using the nonlinear models of Brody, Von Bertalanffy, Gompertz and Logistic. The following parameters were used in the curves, Y, slaughtering weight; A, asymptotic weight; k, growth rate, t, animal age; B, constant related to the initial weight; and, m, constant of the curve shape. The criteria used for selecting the model that best described the curve were the mean square error (MSE), which was calculated by dividing the sum of squared error by the number of observations, and also the coefficient of determination (R²), calculated as the square of the correlation between the observed and estimated weights. The average weights observed were as follows, 4.02 kg at birth, 21.68 kg at weaning (P60) and 32.55 kg at slaughtering (P120). The solution of the nonlinear models allows, thru the parameters, establish specific feeding programs and define the optimal slaughtering age. Furthermore, the coefficients of determination, with values close to 97.3%, showed good fits for all models. Still, considering the mean square error, where the lower value indicates the best fit to the data evaluated, the results were 13.1564 (Brody), 13.3421 (Von Bertalanffy), 13.4876 (Gompertz) and 13.6717 (Logistic). The results showed that Brody could be considered the model that best describes the growth rate up to 120 days old of Texel lambs.Discussion: Compared to other studies, the average weights obtained in the experiment varied widely. This large variation can be explained by the used rearing system that might favor or not the performance of lambs. However, the average weaning weight obtained was similar to several studies in the literature, confirming the potential of Texel breed. This breed demonstrated to be capable to provide a precocious animal, with good growth results from the early developmental stage until the slaughtering age. Regarding the growth curves, the Brody model was the best fit for the estimated and observed weights. Moreover, the coefficient of determination indicated good fits for all models. However, an important aspect is the negative correlation between the A and k parameters, demonstrating that the higher the animal growth rate, the lower its asymptotic size.

A study of the growth rate of F2 and F3 Africander cross, Brahman cross and British cross cattle from birth to 18 months in a tropical environment

1971 ◽  
Vol 11 (53) ◽  
pp. 593 ◽  
Author(s):  
JF Kennedy ◽  
GIK Chirchir
Keyword(s):  
Growth Rate ◽  
Rank Order ◽  
Growth Period ◽  
Dry Season ◽  
Tropical Environment ◽  
Wet Season ◽  
Male And Female ◽  
The Mean

The mean birthweights and weaning weights of approximately 1200 male and female calves of the F2 and F3 generations of Africander cross (AX), Brahman cross (BX) and Shorthorn X Hereford cross (SH) cattle, together with the weights at four months, and nine months post weaning for approximately 500 of the females, for the years 1964-1968, are presented. BX calves (29.7 kg) were lighter at birth than AX (31.0 kg) or SH (31.8 kg), but at weaning (eight-nine months) they were 13.7 kg heavier than the AX, and 28.9 kg heavier than the SH. In the first four months postweaning, at the end of the dry-season, female AX gained 21.5 kg, BX gained 18.5 kg, and the SH 11.7 kg, and in the next five months, which included the wet-season, AX gained 78.6 kg, BX 83.1 kg, and SH 63.2 kg. At approximately eighteen months old the AX weighed 282.8 kg, BX 294.8 kg, and SH 244.2 kg. There were substantial differences between years but the rank order of the breeds at each growth period did not change.

Growth and Phosphate Absorption in Lettuce and Cabbage Plants in Dilute Solution Culture

1977 ◽  
Vol 4 (4) ◽  
pp. 505 ◽  
Author(s):  
MG Temple-Smith ◽  
RC Menary
Keyword(s):  
Dry Matter ◽  
Maximum Yield ◽  
Growth Period ◽  
Solution Culture ◽  
Lower Solution ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Phosphate Absorption ◽  
Rate Of Growth ◽  
Total Plant

Growth and phosphate absorption of lettuce and cabbage plants were compared at seven solution phosphate concentrations in the range 0.06-8.0 �M. Phosphate levels were maintained constant throughout the 35-day growth period by the use of large volume (450 litres per 24 plants) continuous- flow solution culture units. Both lettuce and cabbage achieved maximum relative growth rates of approximately 14 g dry matter per 100 g dry matter per day. For cabbage this rate of growth was achieved at a solution phosphate concentration of 0.5 �M. However, to attain the same rate of growth, lettuce required a solution phosphate level at least fourfold greater (between 2.0 and 4.0 �M) . These phosphate concentrations are many times lower than those previously reported for maximum yield of these species. The ability of cabbage to achieve maximum dry matter yield at lower solution phosphate concentrations than that required by lettuce appears to be due to a combination of its greater rate of phosphate absorption per unit of root at low phosphate concentrations, its higher proportion of total plant phosphorus and dry matter contained in the shoot, and its higher phosphate utilization quotient at maximum yield.

Growth of Juvenile Chum Salmon (Oncorhynchus keta) Under Different Feeding Regimes

1969 ◽  
Vol 26 (6) ◽  
pp. 1631-1645 ◽  
Author(s):  
R. J. LeBrasseur
Keyword(s):  
Growth Rate ◽  
Chum Salmon ◽  
Oncorhynchus Keta ◽  
Rate Of Growth ◽  
Total Length ◽  
Chum Salmon Oncorhynchus Keta ◽  
Feeding Regimes ◽  
Size Groups ◽  
Juvenile Chum Salmon ◽  
The Mean

Juvenile chum salmon were fed on six different concentrations of size-selected zooplankton for 8 weeks. Zooplankton were caught daily and sorted through sieves into size-groups roughly as follows: 6–20 mm total length, mainly euphausiids; 2.5–4.5 mm, mainly copepods; and ≤ 1.5 mm, mainly small copepods. The rate of growth in weight of the fish was found to be dependent upon the concentration of the ration. Fish which were offered no food lost weight, and fish which were offered excess food increased in weight by 5.4% per day. The mean growth rate of the fish held on fixed rations ranged from 2.2 to 5.7% per day and was found to be independent of the type of prey. Electivity experiments showed that all the fish selected copepods 1.6–4.5 mm long in proportion to their abundance and rejected copepods ≤ 1.5 mm. The euphausiids were selected only by fish which had previously fed on euphausiids. The effect of variations in the availability of prey is discussed.

The pattern of growth in the early lifecycle of individual Sepia pharaonis

2004 ◽  
Vol 55 (4) ◽  
pp. 415 ◽  
Author(s):  
Jonathan W. Minton
Keyword(s):  
Growth Rate ◽  
Growth Phase ◽  
Growth Curves ◽  
Maximum Size ◽  
Control Group ◽  
Sepia Pharaonis ◽  
Second Growth ◽  
The Mean ◽  
R Value ◽  
The Individual

The pattern of growth in the early lifecycle of the pharaoh cuttlefish, Sepia pharaonis, was investigated by rearing hatchlings at 26°C in two separate trials. In each trial, the mean weight and mantle length (ML) was recorded in 5-day intervals. In addition, in each trial the growth of 20 group-reared cuttlefish was measured as a control to compare against the individual data. After 60 days of growth, the mean size for individuals in trial 1 was 2.75 g (maximum size 3.32 g) and in trial 2 was 12.76 g (maximum size 14.99 g) at 90 days. Each individual went through distinct growth phases during the first 90 days after hatching. The first growth phase matched exponential curves with an R-value of 0.98 or better, and the second growth phase corresponded with linear and power growth curves at an R-value of 0.98 or better. In trial 1, the mean growth rate for individuals during the first phase was 5.91% BW day–1 and the control group growth rate was 6.36% BW day–1. In trial 2, the mean growth rate for individuals during the first phase was 6.06% BW day–1 and the control group growth rate was 6.70% BW day–1.

scholarly journals The growth rate of the Long Rough Dab Hippoglossoides platessoides (Fabr.)

1955 ◽  
Vol 34 (2) ◽  
pp. 297-311 ◽  
Author(s):  
T. B. Bagenal
Keyword(s):  
Growth Rate ◽  
Age Group ◽  
Population Means ◽  
Rate Of Growth ◽  
The Mean ◽  
Standard Deviations ◽  
Hippoglossoides Platessoides

SUMMARYThe ages of 1426 female, and 135 male Long Rough Dabs have been determined from otolith readings. The females were found to live into their seventh year and reach 30.5 cm, compared with males that live to their fifth year and reach 19.0 cm in length. However, the mean increase in length per year for a given length, has been found to be the same. The growth of the females has been shown to fit the equation lt=26.437 (I—0.574t) and of the males lt=17.754 (I —0.585t). In the case of the females the observed and calculated values agree quite closely, but with the males there is a greater difference, and it is believed that the discrepancy is due to net selection. The suggestion is made that the calculated mean lengths for each age group are better estimates of those of the population than are the observed sample means. The two standard deviations limits can be estimated about the population means and the sample values are found to be within these limits.Comparison with previous studies shows that the Clyde fish are smaller and shorter-lived than more northern specimens, though broadly speaking the rate of growth for comparable ages is not so dissimilar.

The relative significance of growth rate and interdivision time in the size control of cultured mammalian epithelial cells

1987 ◽  
Vol 88 (1) ◽  
pp. 73-80
Author(s):  
M. Hola ◽  
P.A. Riley
Keyword(s):  
Growth Rate ◽  
Epithelial Cells ◽  
Cell Size ◽  
Negative Correlation ◽  
Average Rate ◽  
Growth Period ◽  
Time Lapse ◽  
Relative Significance ◽  
Initial Volume ◽  
The Mean

Genealogies of a line of mammalian epithelial cells (GPK) have been constructed from time-lapse film of monolayer cultures and measurements made of initial (post-divisional) cell size, final (pre-divisional) cell size and interdivision time (IDT). The mean initial cell volume was 2696 +/− 404 (S.D.) micron3, the mean final volume was 5247 +/− 696 micron3 and the mean IDT was 985 +/− 84 min. Cell size regulation must be by modulation of either the growth rate or the length of the growth period. Increase in size was strongly correlated with the average rate of growth (increase in volume per unit time) (R = 0.94, P much less than 0.001), whilst no correlation was found between increase in size and IDT. Although a negative correlation was found between initial volume and IDT (P less than 0.02), this appeared to be due to differences in IDT between sister cells being correlated with differences in their initial volumes (P less than 0.02), as indicated by the lack of correlation between mean sister IDT and mean sister initial volume. The regulatory effect of growth rate was demonstrated by a negative correlation between growth rate and the initial volume of the cell (P less than 0.005), which is independent of differences between siblings. The mean growth rate of sibling cells was found to be negatively correlated with both the maternal growth rate (P less than 0.01) and the maternal volume increase (P less than 0.005). This implies that the growth rate of division products (which manifest similar growth rates) is influenced by the growth of the progenitor cell.

scholarly journals A consideration of some attempts to analyse growth curves

1928 ◽  
Vol 102 (717) ◽  
pp. 280-285 ◽  
Keyword(s):  
Growth Rate ◽  
Growth Curves ◽  
Rate Of Change ◽  
The Other ◽  
Internal Factor ◽  
Internal Factors ◽  
Rate Of Growth ◽  
Constant Environment

No matter what attribute of an organism is considered—height, weight, activity, etc.—the rate of change of this attribute, the growth, depends upon the age of the organism. In many cases the rate of change is small at first, becomes faster and faster for a certain time, and then slower and slower. This drift of the rate of growth with increasing age is found when organisms are kept in constant environments. Such a drift in a constant environment may be taken as an expression of a drift, in the organism itself, and the rate of growth can be taken as a measure of this “internal factor.” If two precisely similar organisms were placed at their beginnings in two different constant environments, it is highly probable that the form of the drift of growth rate with time would be different. One of the organisms would be older than the other when a certain growth rate was attained. Although we might say that at these points the intensity of the “internal factor,” or the effective amount of “growing material” as it has been called (6), of the two organisms was the same, we do not mean that the organisms are identical. The “internal factor” determining the rate of growth is a kind of integration of all the various factors inside the organism. For example, in the case of the growth in weight of a plant, number and size of growing points, accessibility of food supplies, etc., are factors determining the dimensions of the “internal factor.” The two organisms may differ in each of their subsidiary factors whilst possessing “internal factors” of like dimensions.

Sign in / Sign up

Export Citation Format

Share Document