A preliminary account of aerial plant biomass in fynbos communities of the Mediterranean-type climate zone of the Cape Province

Bothalia ◽  
1977 ◽  
Vol 12 (2) ◽  
pp. 301-307 ◽  
Author(s):  
F. J. Kruger
Keyword(s):  
Growth Rates ◽  
Plant Biomass ◽  
Growth Curves ◽  
Annual Growth Rate ◽  
Biomass Growth ◽  
Significant Component ◽  
Preliminary Account ◽  
Structural Differences ◽  
Heath Communities ◽  
Mature Stands

Aerial plant biomass has been sampled by harvesting on several sites in fynbos communities of the south­western Cape Province. Biomass in stands of about two years old ranged from about 2 200 kg per ha to about 7 500 kg per ha. Mature stands comprised about 11 000 to 15 000 kg per ha in heaths and 15 000 to 26 000 kg per ha in sclerophyllous scrub. The data indicate a maximum annual growth rate of 1 000 to 4 000 kg per ha early in the development of a stand, but growth rates appear to decline rapidly as communities age. Young stands are dominated by hemicryptophytes, which comprise about 2 000 to  6  000 kg per ha, or about 60 to 75 per cent of the biomass in stands of about four years old. Shrubs become prominent later, but the hemicryptophytes persist. The data indicate that the biomass, growth rates and the shape of the growth curves of fynbos communities are on the whole similar to those of analogous vegetation in other zones of mediterranean type climate. However, there are important structural differences in that analogues of the northern hemisphere (garrigue, chaparral) do not have a significant component of persistent hemicrytophytes. Although Australian heath communities do have this feature, the hemicryptophytes are not as prominent as in fynbos.

A STUDY OF RATES OF GROWTH OF YORKSHIRE, LACOMBE, LANDRACE, AND CROSSBRED PIGS FROM BIRTH TO 200 LB

1964 ◽  
Vol 44 (3) ◽  
pp. 315-319
Author(s):  
J. M. Bell
Keyword(s):  
Growth Rates ◽  
Early Life ◽  
Growth Curves ◽  
Rates Of Growth ◽  
Similar Growth ◽  
Crossbred Pigs

Growth records were obtained from 12 research establishments across Canada for pigs fed according to current (1960–63) recommendations of nutrition and management. Growth curves showing age in days and weight in pounds are presented for the various breeds and crossbreds, for between-station comparisons, for comparison of upper and lower quartiles in purebred pigs, and for comparison of growth rates of purebreds with that of Yorkshires of 20 to 25 years ago.Age at 200 lb averaged from 152 to 187 days, among 10 stations for the Yorkshire breed. Pigs of each of the pure breeds reached 200 lb about 3 weeks earlier than that indicated in previous studies. Crossbred pigs of each of four different crosses grew more rapidly than average Yorkshires, some reaching 200 lb in 140 days and having gains in excess of 2.3 lb/day during the finishing period. Yorkshire, Lacombe, and Landrace pigs had similar growth curves. The upper quartile averaged 1.8 and the lower 1.4 lb/day gain between 100 and 200 lb weights. Slow-maturing pigs tended to be below average throughout life but differences in maturity between stations seemed to reflect differing rates of gain in early life, since finishing period gains were similar in 8 of 10 stations.

scholarly journals Affordable Phenotyping of Winter Wheat under Field and Controlled Conditions for Drought Tolerance

Agronomy ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 882
Author(s):  
Dhananjay Kumar ◽  
Sandeep Kushwaha ◽  
Chiara Delvento ◽  
Žilvinas Liatukas ◽  
Vivekanand Vivekanand ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Winter Wheat ◽  
Growth Rates ◽  
Plant Biomass ◽  
Growth Conditions ◽  
Seedling Stage ◽  
Growth Stages ◽  
Digital Cameras ◽  
Relative Growth ◽  
Relative Growth Rates

Drought stress is one of the key plant stresses reducing grain yield in cereal crops worldwide. Although it is not a breeding target in Northern Europe, the changing climate and the drought of 2018 have increased its significance in the region. A key challenge, therefore, is to identify novel germplasm with higher drought tolerance, a task that will require continuous characterization of a large number of genotypes. The aim of this work was to assess if phenotyping systems with low-cost consumer-grade digital cameras can be used to characterize germplasm for drought tolerance. To achieve this goal, we built a proximal phenotyping cart mounted with digital cameras and evaluated it by characterizing 142 winter wheat genotypes for drought tolerance under field conditions. The same genotypes were additionally characterized for seedling stage traits by imaging under controlled growth conditions. The analysis revealed that under field conditions, plant biomass, relative growth rates, and Normalized Difference Vegetation Index (NDVI) from different growth stages estimated by imaging were significantly correlated to drought tolerance. Under controlled growth conditions, root count at the seedling stage evaluated by imaging was significantly correlated to adult plant drought tolerance observed in the field. Random forest models were trained by integrating measurements from field and controlled conditions and revealed that plant biomass and relative growth rates at key plant growth stages are important predictors of drought tolerance. Thus, based on the results, it can be concluded that the consumer-grade cameras can be key components of affordable automated phenotyping systems to accelerate pre-breeding for drought tolerance.

EFFECTS OF ACUTE SIMULATED AND ACUTE GRASSHOPPER (ORTHOPTERA: ACRIDIDAE) DAMAGE ON GROWTH RATES AND YIELD OF SPRING WHEAT (TRITICUM AESTIVUM)

1983 ◽  
Vol 115 (6) ◽  
pp. 629-636 ◽  
Author(s):  
O. O. Olfert ◽  
M. K. Mukerji
Keyword(s):  
Soil Moisture ◽  
Spring Wheat ◽  
Growth Rates ◽  
Plant Biomass ◽  
Ground Level ◽  
Kernel Weight ◽  
Relative Growth Rates ◽  
Available Soil Moisture ◽  
Study Sites ◽  
And Control

AbstractStudies showed that the type of damage, the timing of damage with the phenological stage of the crop, and the amount of available soil moisture influenced the growth response of spring wheat to acute levels of grasshopper damage and acute levels of artificial damage. Ground-level cutting of plants resulted in the greatest reduction in plant biomass and crop yield, while grasshopper damage and artificial stripping of leaf material did not result in as severe a reduction in either biomass or yield.Damaged plants were not able to recover lost biomass when damage occurred any later than the early stages of tillering despite observed relative growth rates which were higher than control plants. The greatest degree of recovery occurred in study sites with the greatest amount of available soil moisture.The most detrimental effect of damage on yield was the reduction of heads per plant and kernel weight. In most cases differences in the number of seeds per head between damaged and control plants were not evident.

Age, growth and sex determination in a population of smooth snakes, Coronella austriaca in southern England

2004 ◽  
Vol 25 (2) ◽  
pp. 137-150 ◽  
Author(s):  
Keyword(s):  
Sex Determination ◽  
Age Structure ◽  
Growth Rates ◽  
Growth Curves ◽  
Tail Length ◽  
Daily Growth ◽  
Southern England ◽  
The Difference ◽  
The Relationship ◽  
Coronella Austriaca

AbstractBetween 1992-2001 a study of individually marked smooth snakes Coronella austriaca was done in Wareham Forest, southern England. The sex of individual snakes was determined using the relationship between tail length and snout-vent length, and the presence/absence of a hemi-penes swelling at the base of the tail. Males had longer tails than females at all ages/sizes and the difference between the sexes increased with increasing snout-vent length. Using multiple captures of known individuals over many years, size related daily growth rates were determined for each sex that enabled growth curves to be produced. The age structure of the population was determined for each complete year of the study. Very few young small snakes were captured each year. Of all the females who were potentially able to breed, only the oldest, and therefore largest, did so.

scholarly journals The demographics and morphometries of biogenic reefs: important considerations in conservation management

2017 ◽  
Vol 98 (6) ◽  
pp. 1231-1240 ◽  
Author(s):  
Jenna M. Brash ◽  
Robert L. Cook ◽  
Clara L. Mackenzie ◽  
William G. Sanderson
Keyword(s):  
Population Structure ◽  
Growth Rates ◽  
Conservation Management ◽  
Tidal Flow ◽  
Growth Curves ◽  
Shell Morphology ◽  
Published Data ◽  
Marine Habitat ◽  
Juvenile Abundance ◽  
Horse Mussel

Modiolus modiolus L. (horse mussel) reefs are a priority marine habitat of high conservation value that is currently listed as endangered and/or threatened across its European distribution. Population structure, density or shell morphology may influence the biodiversity of a reef, either directly or indirectly. Thus, such metrics are important considerations for successful conservation management of these biodiversity hotspots. Population structure, shell morphology and growth rates were examined in M. modiolus reefs across the UK range of the habitat to examine differences between key populations, including those near the Lleyn Peninsula in Wales (southern range), off Port Appin in Western Scotland (mid-range) and in Scapa Flow in the Orkney Isles, Scotland (northern range). Additionally, the influence of physical conditions (temperature and tidal flow) to growth rate and predicted maximum shell length for each population was examined. Growth rates were determined using acetate peels of sectioned shells. Lower juvenile abundance was observed in Scapa Flow. Small, narrow-shaped shells were found to be characteristic of North Lleyn mussels, and larger, globular-shaped shells were characteristic of mussels in Scapa Flow and off Port Appin. Mussels in Scapa Flow were slower growing, yet reached a longer asymptotic length (L∞) than mussels of Port Appin and North Lleyn. Growth curves from sites within this study were analysed with other published data. A trend of higher L∞ at higher latitudes and at lower flow rates was observed. Variations in growth and age are discussed in relation to flow regimes, connectivity to other reefs, density and latitude.

Interrelations in the growth and development of Lolium. I. Some effects of vernalization on growth and development

1965 ◽  
Vol 16 (6) ◽  
pp. 903 ◽  
Author(s):  
JH Silsbury
Keyword(s):  
Low Temperature ◽  
Growth Rates ◽  
Growth And Development ◽  
Growth Curves ◽  
High Growth ◽  
Reproductive Development ◽  
Controlled Environment ◽  
Lolium Rigidum ◽  
Vegetative Phase ◽  
Reproductive Phase

The responses of Lolium rigidum Gaud. and L. perenne L. to low temperature seed vernalization were determined by comparing the growth and development of vernalized and unvernalized plants raised in the field and in a controlled environment cabinet. Vernalization did not appear to influence growth in the vegetative phase, but usually induced earlier heading and a greater proportion of reproductive tillers. Comparisons of vernalized (reproductive) and unvernalized (vegetative) plants show increased reproductive development to be associated with higher growth rates, lower tillering, and greater weight per tiller. High growth rates during the reproductive phase are considered to be due to the ability of reproductive tillers to grow more rapidly than vegetative tillers through the growth of true stem functioning as a "sink" for assimilate. Generalized growth curves for vernalized and unvernalized ryegrass grown under long days are presented and discussed.

Experimental study of the stability of boundary-layer flow along a heated, inclined plate

1998 ◽  
Vol 367 ◽  
pp. 1-25 ◽  
Author(s):  
E. J. ZUERCHER ◽  
J. W. JACOBS ◽  
C. F. CHEN
Keyword(s):  
Boundary Layer ◽  
Growth Rates ◽  
Growth Curves ◽  
Leading Edge ◽  
Heated Plate ◽  
Inclined Plate ◽  
Double Pass ◽  
Longitudinal Vortices ◽  
Spatial Growth ◽  
Layer Flow

Experiments are conducted to study the longitudinal vortices that develop in the boundary layer on the upper surface of an inclined, heated plate. An isothermal plate in water is inclined at angles ranging from 20 to 60 degrees (from the vertical) while the temperature difference is varied from 2 to 23°C. A double-pass Schlieren system is used to visualize the vortices and particle image velocimetry (PIV) is used to measure velocities. In addition, a unique method is developed such that both the Schlieren visualization and PIV can be performed simultaneously. The wavelengths of the vortices and the critical modified Reynolds numbers (R˜) for the onset, merging, and breakup of the vortices are determined from Schlieren images for Pr=5.8. The critical values for R˜ and the critical wavelengths are compared to results of previous experiments and stability analyses. The spatial growth rates of vortices are determined by using the PIV measurements to determine how the circulation in the vortices grows with distance from the leading edge. This is the first time that the growth rate of the vortices have been found using velocity measurements. These spatial growth rates are compared to the results of Iyer & Kelly (1974) and found to be in general agreement. By defining a suitable circulation threshold, the critical R˜ for the onset of the vortices can be found from the growth curves.

Age structure and growth in a population of Pelobates varaldii (Anura, Pelobatidae) from northwestern Morocco

2011 ◽  
Vol 32 (4) ◽  
pp. 550-556 ◽  
Author(s):  
Marcello Mezzasalma ◽  
Fabio Maria Guarino ◽  
Angelica Crottini ◽  
Franco Andreone ◽  
Philip de Pous
Keyword(s):  
Body Mass ◽  
Age Structure ◽  
Growth Rates ◽  
Growth Curves ◽  
Von Bertalanffy ◽  
Growth Coefficient ◽  
Similar Profile ◽  
Spadefoot Toad ◽  
The Difference ◽  
First Time

AbstractAge structure and growth in the Moroccan spadefoot toad, Pelobates varaldii were estimated by skeletochronology and reported for the first time for a population living in NW Morocco. Snout vent length and body mass did not significantly differ between the sexes, although females appeared larger and heavier than males. Age ranged 2-7 years in males (mean age±SD: 4.5±1.2, n = 66) and 2-10 years in females (4.7±2.4, n = 20). The difference in age was not significant between the sexes. The modal age was 5 years for males and 3 years for females. The age distributions significantly differed between the sexes. Von Bertalanffy growth curves showed a similar profile between the sexes although growth coefficient was higher in males than in females. Longevity and growth rates of P. varaldii were compared with those of other species of the genus Pelobates.

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