Frequency distribution of shoot weight of plants in populations ofTrifolium repenspersisting by clonal growth in grazed pastures

1990 ◽  
Vol 115 (1) ◽  
pp. 41-47 ◽  
Author(s):  
M. J. M. Hay ◽  
V. J. Thomas ◽  
J. L. Brock
Keyword(s):  
Gini Coefficient ◽  
White Clover ◽  
Clonal Growth ◽  
Dry Weight ◽  
Plant Size ◽  
Size Hierarchy ◽  
Gini Coefficients ◽  
Shoot Dry Weight ◽  
The Gini Coefficient ◽  
Variable Nature

SUMMARYOver two years (1984/85 and 1986/87), monthly sampling of shoots of white clover plants compared the populations of white clover in mixed swards at Palmerston North, New Zealand, under set stocking, rotational grazing and a combination of both systems, at a common stocking rate of 22·5 ewe equivalents/ha.The frequency distributions of shoot (or stolon) dry weight per plant in each population over the study period was described by a log-normal model, which indicated that the populations consisted of many small individuals and few large individuals. Such inequality of shoot dry weight within populations is commonly termed size hierarchy; a statistic giving a measure of such size hierarchy is the Gini coefficient. The populations under different managements had similar Gini coefficients which differed little among seasons or between years. Lack of significant correlation between the Gini coefficient and mean shoot dry weight per plant of each population indicated that, in these white clover populations, size hierarchy was independent of mean plant size.These results were considered in relation to the clonal growth of white clover in grazed swards and it is suggested that the variable nature of death of older basal stolons makes an important contribution to the variability in size of individual plants and hence to size hierarchy. As size hierarchy, as assessed by Gini coefficients, was relatively stable in these populations over 3½ years, it appears that clonal growth of white clover incorporates sufficient variability within the growth and death processes at the individual plant level to maintain the size hierarchy, irrespective of variations in mean plant size of populations.

A quantitative genetics approach to nitrogen use efficiency in sugarcane

2010 ◽  
Vol 37 (5) ◽  
pp. 448 ◽  
Author(s):  
Alex Whan ◽  
Nicole Robinson ◽  
Prakash Lakshmanan ◽  
Susanne Schmidt ◽  
Karen Aitken
Keyword(s):  
Protein Content ◽  
Nitrogen Use Efficiency ◽  
Female Parent ◽  
Dry Weight ◽  
Plant Size ◽  
Saccharum Officinarum ◽  
Leaf Protein ◽  
Nitrogen Use ◽  
Shoot Dry Weight ◽  
Use Efficiency

The economic and environmental consequences of inefficient use of nitrogen (N) fertiliser in agricultural crops is of concern worldwide, so new crop varieties with improved nitrogen use efficiency (NUE) are sought. Here, we report the first study of mapping quantitative trait loci (QTL) for nitrogen physiology traits in sugarcane. QTL analysis was undertaken for each parent of a segregating bi-parental sugarcane mapping population. We grew 168 progeny under limiting (0.2 mM NH4NO3) and non-limiting (5.0 mM NH4NO3) N supplies in two glasshouse experiments. Significant marker-trait associations (MTA) were detected in each treatment for shoot dry weight, root dry weight, total shoot N, shoot internal NUE (iNUE; measured as units shoot dry weight per unit N), leaf protein content and glutamine synthetase (GS) activity. MTA for GS activity did not co-locate with other traits except leaf protein content, indicating that variation in GS activity is not linked to plant size or iNUE during early growth. Under high N, there were no significant MTA for iNUE among markers from the male parent, Q165, an Australian commercial cultivar, but six MTA were found for markers inherited from the female parent, IJ76–514, a Saccharum officinarum ancestral variety. The results indicate that variation for iNUE under high N may be lower in commercial varieties than unimproved genotypes. Further, four MTA were consistent with previous field-based research on sugar and biomass production. Our study provides initial evidence that QTL may be incorporated in sugarcane breeding programs targeting improved NUE.

Morphology of white clover (Trifolium repens L.) plants in pastures under intensive sheep grazing

1988 ◽  
Vol 111 (2) ◽  
pp. 273-283 ◽  
Author(s):  
J. L. Brock ◽  
M. J. M. Hay ◽  
V. J. Thomas ◽  
J. R. Sedcole
Keyword(s):  
White Clover ◽  
Plant Morphology ◽  
Dry Weight ◽  
Plant Size ◽  
Early Spring ◽  
Axillary Buds ◽  
Branching Order ◽  
Wide Range ◽  
Stolon Length ◽  
Total Plant

SummaryThere has been little study on the growth and morphology of individual plants constituting the population of white clover in mixed swards under grazing. Such information is required if the mechanisms governing plant productivity and persistence are to be understood.Intact white clover plants were sampled from intensively sheep-grazed pastures under set stocking, rotational grazing, and a combination of both systems, by taking turves (250 × 250 mm), and washing out the plants, every month for a year. Characters measured for every stolon of each plant were: presence of a growing point; numbers of leaves, roots and axillary buds; stolon length. Total plant leaf and stolon dry weight were also recorded. Plants were classified according to degree of branching, and the contribution of each branching order to the population determined.There were strong seasonal variations in plant size (leaf and stolon dry weight, stolon length, and numbers of stolons and leaves per plant) which showed a significant decrease in spring with recovery over the following summer. This was paralleled by a rapid increase in the proportion of less branched plants (1st and 2nd branching order) in the population from 60 to 80% in spring, as higher-order plants broke up into smaller- and lower-ordered plants at this time. Numbers of roots per plant increased over winter to peak in early spring then declined in the following summer-autumn. While system of grazing management had no significant effect on branching structure of plants, it had a large effect on plant dry weight; rotationally grazed plants were 2·5 times larger than set stocked plants (0·182 cf. 0·073 g respectively).Other general features of plant morphology were that each successive order of branch stolons was shorter and length before branching was less than that of their preceding parent stolon. The highest branching order observed was 6th order. There was no relationship between branching and numbers of roots; in branched plants only 55% of stolons were rooted regardless of plant order, but rooted stolons accounted for 85% of total stolon length and carried 62, 48 and 90% of the leaves, growing points and axillary buds per plant, respectively.Comparison with other studies suggests that the processes outlined in this report may be common to white clover growth under grazing over a wide range of favourable environments.

scholarly journals Novel approaches to improving growth of pasture legumes at low phosphorus levels

2014 ◽  
Vol 76 ◽  
pp. 197-202
Author(s):  
S.N. Nichols ◽  
J.R. Crush
Keyword(s):  
White Clover ◽  
Root Length ◽  
Specific Root Length ◽  
Root Traits ◽  
Dry Weight ◽  
Root Weight ◽  
Soil P ◽  
P Acquisition ◽  
Shoot Dry Weight ◽  
Use Efficiency

Abstract Strategies to reduce the economic and environmental costs of phosphate (P) fertiliser use in mixed pastures through plant breeding are focussed on inefficiencies in the legume component. One approach is breeding within white clover for root systems with improved P acquisition properties. Selection for root length per unit root weight (specific root length, SRL) showed that higher SRL plants could retain more biomass in the above ground fraction with decreasing soil P, whereas plants with lower SRL diverted more biomass to roots. Back cross 1 (BC1) generation interspecific hybrids between white clover and a wild relative, Trifolium uniflorum L., may possess additional root traits influencing P acquisition. In glasshouse experiments, some T. repens × T. uniflorum hybrids, back-crossed to white clover, also exhibited higher shoot dry weight than their white clover cultivar parents at low nutrient supply levels and low to intermediate soil Olsen P. This, combined with low internal P concentrations, suggests some BC1 hybrids may be more tolerant of low soil P than white clover. Differences in both P acquisition ability and internal P use efficiency may contribute to the observed yield differences. There are good prospects for delivery of new-generation clover cultivars with improved phosphate use efficiency to New Zealand farmers. Keywords: phosphorus, white clover, Trifolium uniflorum, interspecific

scholarly journals Adaptation of Trifolium repens × T. uniflorum hybrid clovers to drought stress

2014 ◽  
Vol 76 ◽  
pp. 183-188
Author(s):  
Keith Widdup ◽  
Shirley Nichols ◽  
Warren Williams ◽  
Isabelle Verry ◽  
Ben Harvey
Keyword(s):  
Water Stress ◽  
Drought Resistance ◽  
White Clover ◽  
Trifolium Repens ◽  
Performance Indicator ◽  
Field Evaluation ◽  
Dry Weight ◽  
Moisture Stress ◽  
Backcross Generation ◽  
Shoot Dry Weight

Abstract White clover (Trifolium repens L.) is valued for its contribution to pasture quality and utilisation by animals, compatibility with grass, and fixation of nitrogen. However, it is limited by poor adaptation to drought. Hybridisation with Trifolium uniflorum L. may have potential to improve the drought resistance of white clover. An experiment in a rain shelter facility with contrasting moisture treatments, and a field evaluation under dryland conditions, were used to compare the agronomic potential of these interspecific hybrids (ISH) with white clover in moisture limited conditions. In the rain shelter experiment, there were smaller effects of water stress on shoot dry weight (DW), leaf area, internode length and senescence of first backcross generation hybrids compared with white clover and second backcross generation hybrids. Differences in photosynthetic responses were possibly influenced by the effect of root DW allocation on water uptake. In the field evaluation, growth scores of a wider range of hybrid families during summer moisture stress concurred with the results under water stress in the rain shelter. Growth of some ISH families outperformed the best white clover cultivars, particularly in the third and most stressful summer and this result was a key performance indicator of the value of the hybrids for drought prone areas. These findings using early, unselected, hybrid populations indicate the potential for further selection of elite, adapted cultivars from ISH breeding strategies. Keywords: Interspecific clover hybrid, drought resistance, rain shelter, field evaluation

scholarly journals The Gini Coefficient as a useful measure of malaria inequality among populations

2020 ◽  
Author(s):  
Jonathan Abeles ◽  
David Conway
Keyword(s):  
Global Health ◽  
Confidence Intervals ◽  
Gini Coefficient ◽  
Malaria Incidence ◽  
Potential Range ◽  
Gini Coefficients ◽  
The Gini Coefficient ◽  
World Regions ◽  
Village Communities ◽  
High Level

BACKGROUND: Understanding inequality in infectious disease burden requires clear and unbiased indicators. The Gini coefficient, conventionally used as a macroeconomic descriptor of inequality, is potentially useful to quantify epidemiological heterogeneity. With a potential range from 0 (all populations equal) to 1 (populations having maximal differences), this coefficient is used here to show the extent and persistence of inequality of malaria infection burden at a wide variety of population levels. METHODS: We first applied the Gini coefficient to quantify variation among WHO world regions for malaria and other major global health problems. Malaria heterogeneity was then measured among countries within the geographical sub-region where burden is greatest, among the major administrative divisions in several of these countries, and among selected local communities. Data were analysed from previous research studies, national surveys, and global reports, and Gini coefficients were calculated together with confidence intervals using bootstrap resampling methods. RESULTS: Malaria showed a very high level of inequality among the world regions (Gini coefficient, G = 0.77, 95% CI 0.66-0.81), more extreme than for any of the other major global health challenges compared at this level. Within the most highly endemic geographical sub-region, there was substantial inequality in estimated malaria incidence among countries of West Africa, which did not decrease between 2010 (G = 0.28, 95% CI 0.19-0.36) and 2018 (G = 0.31, 0.22-0.39). There was a high level of sub-national variation in prevalence among states within Nigeria (G = 0.30, 95% CI 0.26-0.35), but more moderate variation within Ghana (G = 0.18, 95% CI 0.12-0.25) and Sierra Leone (G = 0.17, 95% CI 0.12-0.22). There was also significant inequality in prevalence among local village communities, generally more marked during dry seasons when there was lower mean prevalence. The Gini coefficient correlated strongly with the Coefficient of Variation which has no finite range. CONCLUSIONS: The Gini coefficient is a useful descriptor of epidemiological inequality at all population levels, with confidence intervals and interpretable bounds. Wider use of the coefficient would give broader understanding of malaria heterogeneity revealed by multiple types of studies, surveys and reports, providing more accessible insight from available data.

scholarly journals Growth of Transplants and in Vitro-cultured Clones of Asparagus in Response to CO2 Enrichment and Supplemental Lighting

1990 ◽  
Vol 115 (3) ◽  
pp. 364-368 ◽  
Author(s):  
Yves Desjardins ◽  
André Gosselin ◽  
Michel Lamarre
Keyword(s):  
Co2 Enrichment ◽  
Dry Weight ◽  
Plant Size ◽  
Asparagus Officinalis ◽  
Photon Flux ◽  
Long Term Effects ◽  
Shoot Dry Weight ◽  
Supplemental Lighting

Asparagus (Asparagus officinalis L.) transplants and in vitro-cultured clones were grown and acclimatized under two photosynthetic photon flux (PPF) conditions (ambient and ambient + 80 μmol·s-1·m-2) and three atmospheric CO2 concentrations (330, 900, and 1500 ppm). Short- and long-term effects were measured in the greenhouse and after two seasons of growth in the field, respectively. In the greenhouse, CO2 enrichment (CE) and supplemental lighting (SL) increased root and fern dry weight by 196% and 336%, respectively, for transplants and by 335% and 229%, respectively, for clones. For these characteristics, a significant interaction was observed between SL and CE with tissue-cultured plantlets. In the absence of SL, CE did not significantly increase root or shoot dry weight. No interaction was observed between CE and SL for transplants, although these factors significantly improved growth. It was possible to reduce the nursery period by as much as 3 weeks with CE and SL and still obtain a plant size comparable to that of the control at the end of the experiment. Long-term effects of SL were observed after two seasons of growth in the field. Supplemental lighting improved survival of transplants and was particularly beneficial to in vitro plants. Clones grown under SL were of similar size as transplants after 2 years in the field.

scholarly journals Effects of invertebrate pests on white and annual clovers in dryland soil

2010 ◽  
Vol 63 ◽  
pp. 235-240
Author(s):  
T.M. Eden ◽  
P.J. Gerard ◽  
D.J. Wilson ◽  
N.L. Bell
Keyword(s):  
Plant Growth ◽  
White Clover ◽  
Seedling Survival ◽  
Plant Root ◽  
Subterranean Clover ◽  
Dry Weight ◽  
Cyst Nematode ◽  
Shoot Dry Weight ◽  
Sitona Lepidus ◽  
Clover Root

Two experiments were carried out at Ruakura in soil taken from Whatawhata hill country pasture The relative susceptibility of several annual clovers (Trifolium spp) and perennial white clover (T repens) to slugs (Deroceras reticulatum) clover root weevil (Sitona lepidus) adults native crickets (Nemobius sp) or wheat bugs (Nysius huttoni) was tested by sowing seed of the clovers into separate rows in turf Susceptibility of clovers to clover cyst nematode (Heterodera trifolii) was tested by sowing each clover variety into Whatawhata soil inoculated with the nematode Plant growth was assessed in both experiments 4 weeks after sowing White clover was more susceptible to pests than the annual clovers with slugs and clover root weevil significantly reducing seedling survival and clover cyst nematode significantly reducing plant growth Subterranean clover (T subterraneum) cv Denmark was the least affected by pests showing no significant reduction in survival in the presence of slugs the most damaging pest and no significant decrease in plant root and shoot dry weight when exposed to nematodes

scholarly journals Gini coefficients for measuring the distribution of sexually transmitted infections among individuals with different levels of sexual activity

2018 ◽  
Author(s):  
Sandro Gsteiger ◽  
Nicola Low ◽  
Pam Sonnenberg ◽  
Catherine H Mercer ◽  
Christian L Althaus
Keyword(s):  
Sexual Activity ◽  
Gini Coefficient ◽  
Treatment Strategies ◽  
Mycoplasma Genitalium ◽  
Sti Prevention ◽  
Sexually Transmitted ◽  
Gini Coefficients ◽  
The Gini Coefficient ◽  
Hpv Types ◽  
Different Levels

AbstractObjectivesGini coefficients have been used to describe the distribution of Chlamydia trachomatis (CT) infections among individuals with different levels of sexual activity. The objectives of this study were to investigate Gini coefficients for different sexually transmitted infections (STIs), and to determine how STI control interventions might affect the Gini coefficient over time.MethodsWe used population-based data for sexually experienced women from two British National Surveys of Sexual Attitudes and Lifestyles (Natsal-2: 1999-2001; Natsal-3: 2010-2012) to calculate Gini coefficients for CT, Mycoplasma genitalium (MG), and human papillomavirus (HPV) types 6, 11, 16 and 18. We applied bootstrap methods to assess uncertainty and to compare Gini coefficients for different STIs. We then used a mathematical model of STI transmission to study how control interventions affect Gini coefficients.ResultsGini coefficients for CT and MG were 0.33 (95% confidence interval (CI): 0.18-0.49) and 0.16 (95% CI: 0.02-0.36), respectively. The relatively small coefficient for MG suggests a longer infectious duration compared with CT. The coefficients for HPV types 6, 11, 16 and 18 ranged from 0.15-0.38. During the decade between Natsal-2 and Natsal-3, the Gini coefficient for CT did not change. The transmission model shows that higher STI treatment rates are expected to reduce prevalence and increase the Gini coefficient of STIs. In contrast, increased condom use reduces STI prevalence but does not affect the Gini coefficient.ConclusionsGini coefficients for STIs can help us to understand the distribution of STIs in the population, according to level of sexual activity, and could be used to inform STI prevention and treatment strategies.Key messagesThe Gini coefficient can be used to describe the distribution of STIs in a population, according to different levels of sexual activity.Gini coefficients for Chlamydia trachomatis (CT) and human papillomavirus (HPV) type 18 appear to be higher than for Mycoplasma genitalium and HPV 6, 11 and 16.Mathematical modelling suggests that CT screening interventions should reduce prevalence and increase the Gini coefficient, whilst condom use reduces prevalence without affecting the Gini coefficient.Changes in Gini coefficients over time could be used to assess the impact of STI prevention and treatment strategies.

scholarly journals Commentary: Measuring the shape of degree distributions

2013 ◽  
Vol 1 (2) ◽  
pp. 213-225 ◽  
Author(s):  
JENNIFER M. BADHAM
Keyword(s):  
Gini Coefficient ◽  
Degree Distribution ◽  
Fundamental Property ◽  
Standard Measure ◽  
Gini Coefficients ◽  
The Gini Coefficient ◽  
Different Types ◽  
Network Properties ◽  
The Relationship

AbstractDegree distribution is a fundamental property of networks. While mean degree provides a standard measure of scale, there are several commonly used shape measures. Widespread use of a single shape measure would enable comparisons between networks and facilitate investigations about the relationship between degree distribution properties and other network features. This paper describes five candidate measures of heterogeneity and recommends the Gini coefficient. It has theoretical advantages over many of the previously proposed measures, is meaningful for the broad range of distribution shapes seen in different types of networks, and has several accessible interpretations. While this paper focuses on degree, the distribution of other node-based network properties could also be described with Gini coefficients.

scholarly journals Growth and Persistenceof Common Temperature Pasture Species under Low Light and Low R:FR Ratio

2006 ◽  
Vol 27 ◽  
pp. 111-118 ◽  
Author(s):  
NR Devkota
Keyword(s):  
Lolium Perenne ◽  
White Clover ◽  
Dactylis Glomerata ◽  
Dry Weight ◽  
Holcus Lanatus ◽  
Agrostis Capillaris ◽  
Shoot Dry Weight ◽  
Poa Trivialis ◽  
R:Fr Ratio ◽  
Dactylis Glomerata L

The effects of varied PAR and R:FR ratio on tillering and shoot dry weight production of temperate pasture species were evaluated at Massey University New Zealand using split-plot design with four blocks. The main plots were % transmitted PAR (photosynthetically active radiation; mmoles photons m-2 s-1, 400- 700 nm) and R:FR ratios (red to far red ratios) with 2 x 2 factors of PAR and R: FR, i.e. medium (38 and 39%) and low (16 and 17%) PAR-each with two natural (1.33 and 1.34) and two reduced (0.57 each) R:FR ratios. The treatment combination was such that each low and medium PAR level had a natural and a reduced R:FR ratio. PAR levels with natural R: FR ratio were imposed by differing densities of neutral shade cloth (Sarlon) with a layer of clear filter, while low R:FR ratio was created with the use of a blue filter. Nine pasture cultivars of seven pasture species: Dactylis glomerata L., Grasslands Wana (cocksfoot); Dactylis glomerata L., PG 74 (cocksfoot); Dactylis glomerata L., PG 321 (cocksfoot); Lolium perenne L. (perennial ryegrass); Holcus lanatus L. (Yorkshire fog); Agrostis capillaris (browntop); Poa trivialis; Trifolium repens L. (white clover), and Lotus uliginosus (lotus) were grown in pots as subplots with four replicate blocks. Six plants were maintained per pot. Plants were harvested at 61 days after imposing shade. There was no effect of R:FR ratio (P>0.05) on the shoot dry weight per plant, however, significant differences (P<0.05) for PAR, species, and interaction of PAR, species for shoot dry weight was observed. At low PAR, Lolium perenne, Dactylis glomerata (Wana) and Holcus lanatus had the highest and similar yields, whereas the yield of white clover and lotus were similar and less than for all the grass species. Effects of PAR as well as R:FR were significant (P<0.001) for total tillers per plant in the shade. Poa trivialis, Agrostis capillaris and Lolium perenne had the highest number of tillers/plant at the low PAR and low R:FR, but did not contribute to higher shoot dry weight at the low PAR, mainly due to their low weight per tiller. Likewise, SLA was significantly (P<0.01) increased by low PAR but not by low R:FR. Lotus produced a higher (P<0.001) number of branches at the low PAR than white clover. Comparatively better performance of cocksfoot, especially at low PAR, was mainly due to the ability to produce higher leaf area, higher SLA, and more tillers per plant. The results are discussed in terms of the effects of PAR and R:FR on the yield and yield components with respect to the attributes of shade tolerant pasture species. Key words: PAR, R:FR ratio, wana cocksfoot, nui perennial ryegrass, shade J. Inst. Agric. Anim. Sci. 27:111-118 (2006)

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