Seasonal plasticity more important than population variability in effects on white clover architecture and productivity

2021 ◽  
Author(s):  
Isabelle Nölke ◽  
Bettina Tonn ◽  
Johannes Isselstein
Keyword(s):  
Leaf Area ◽  
White Clover ◽  
Seasonal Pattern ◽  
Total Yield ◽  
Seasonal Effects ◽  
Total Biomass ◽  
Mixed Stands ◽  
The Impact ◽  
The Relationship ◽  
Architectural Traits

Abstract Background and Aims The drivers of white clover (Trifolium repens) architecture and productivity are still imperfectly understood. Our aim was to investigate the impact of genetic background, neighbourhood and season on different architectural traits, clover and total biomass yield as well as the relationship between those traits and yield. Methods We grew eight white clover populations in pure stands and in mixed stands with contrasting mixture partners. Over four consecutive regrowth periods within one year, we measured trait sizes and determined clover and total yield amounts. Key Results The size of the architectural traits differed between populations and changed in response to neighbourhood and season. Population did not affect the sign and degree of those changes. Among the tested factors, season was by far the most important driver of white clover architecture, with the seasonal pattern notably differing between architectural traits. Clover and total yield were positively related to the architectural traits leaf area, petiole length, internode length and specific leaf area. Whereas the direction of the relationship was widely unaffected, its magnitude was clearly altered by neighbourhood and season. Conclusions Our results show that seasonal effects are the key for a deeper understanding of architecture of white clover individuals and to improve productivity of white clover communities.

Interception of light by the foliage of pure and mixed stands of pasture plants

1958 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
RW Brougham
Keyword(s):  
Leaf Area ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Incident Light ◽  
Time Of Day ◽  
Phleum Pratense ◽  
Mixed Stand ◽  
Angle Of Incidence ◽  
Mixed Stands ◽  
Short Rotation

Relationships between light interception and leaf area in the regrowth of pure stands of short-rota,tion ryegrass (Lolium perenne L. x L. multiflorum Lam.), perennial ryegrass (L. perenne), timothy (Phleum pratense L.), white clover (Trifolium repens L.), and a mixed stand of short-rotation ryegrass and white clover, were determined for cloudless conditions. The relationship between light penetration and elevation of the sun was also examined. The leaf area indices at which 95 per cent. of the incident light was intercepted about midday in midsummer mere as follows: short-rotation ryegrass, 7.1 ; perennial ryegrass, 7.1; timothy, 6.5; white clover, 3.5; and the mixed stand, 4.5. The percentage of incident light penetrating through the foliage on cloudless damp in summer changed considerably with time of day. The highest values were recorded at local noon and the lowest 2-3 hours after sunrise or before sunset. These results are attributed to the angle of incidence of the light, and suggest marked seasonal differences in the leaf area required to intercept 95 per cent. of the light. It is suggested that midwinter values are approximately one-half of mid-summer values. The results are discussed in relation to the light-intercepting capacities of the leaves of the different species, plant competition, and pasture management.

Photothermal time describes common ragweed (Ambrosia artemisiifoliaL.) phenological development and growth

Weed Science ◽  
1998 ◽  
Vol 46 (5) ◽  
pp. 561-568 ◽  
Author(s):  
William Deen ◽  
L. Anthony Hunt ◽  
Clarence J. Swanton
Keyword(s):  
Leaf Area ◽  
Mechanistic Model ◽  
Field Conditions ◽  
Total Biomass ◽  
Common Ragweed ◽  
Matter Production ◽  
Growth Room ◽  
Time Accumulation ◽  
The Relationship ◽  
Crop Competition

The ability to predict weed phenological development under field conditions is fundamental to the development of mechanistic weed–crop competition models. We studied how phenological development of common ragweed grown under field conditions could be explained using temperature and photoperiod responses derived from growth room experiments. We also determined the relationship between phenological development and common ragweed leaf area, dry matter production, and partitioning. Phenological development of common ragweed emerging at different times in the field was described by photothermal time based on temperature and photoperiod responses derived from growth room experiments. Estimated dates of phenological events of common ragweed were within 4 d of recorded values. Common ragweed seedling density did not influence phenological development. Common ragweed leaf area development, biomass partitioning, and total biomass were related to photothermal time accumulation. The results of this study are consistent with our hypothesis that phenological development is a major factor influencing the outcome of weed–crop competition. Results obtained from this study can be incorporated into a mechanistic model of weed–crop competition.

The effects of grassland management on nitrogen losses from grazed swards through ammonia volatilization; the relationship to excretal N returns from cattle

1989 ◽  
Vol 112 (2) ◽  
pp. 205-216 ◽  
Author(s):  
S. C. Jarvis ◽  
D. J. Hatch ◽  
Daphne H. Roberts
Keyword(s):  
White Clover ◽  
Ammonia Volatilization ◽  
Grassland Management ◽  
N Losses ◽  
Mineral N ◽  
N Fluxes ◽  
Grazing Period ◽  
The Impact ◽  
The Relationship ◽  
Grazed Swards

SummaryAmmonia (NH3)-N fluxes from three swards, grazed by cattle and with different N managements, were measured using the mass balance micrometeorological method after a 7-day grazing period in the spring of 2 years. At the same time the impact of the sward managements on N returns in dung and urine was examined in housed animals and the effects of the changes in excreted returns on NH3-N losses examined. The treatments were ryegrass swards receiving either 420 or 210 kg N/ha per year, and a mixed ryegrass/white clover sward receiving no mineral N. There was little difference in the faecal N returns between treatments but there were differences in the N returned in urine, thus 74, 60 and 56% of the excreted returns from 420 N, 210 N or grass/clover treatments, respectively, were in urine. The fluxes of NH3-N from the grazed swards were greatest whilst the animals were present and there were large differences between treatments, the ratio of total NH3 losses from 420 N grass to those from 210 N grass and grass/lover being 7·8:1. The NH3-N losses were equivalent (i) to 12,5 and 7 % of the urinary N returns to 420 N, 210 N grass and grass/clover swards, or alternatively (ii) to 9 and 3% of the fertilizer addition to 420 and 210 N swards and 3% of the estimated rate of N2 fixation in the grass/clover sward. Throughout the investigation there was little difference between the effects with the 210 N grass swards and those with grass/clover.

Architectural modelling of maize under water stress

2008 ◽  
Vol 48 (3) ◽  
pp. 335 ◽  
Author(s):  
Colin J. Birch ◽  
David Thornby ◽  
Steve Adkins ◽  
Bruno Andrieu ◽  
Jim Hanan
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Field Experiments ◽  
Leaf Shape ◽  
Leaf Sheath ◽  
Total Biomass ◽  
Maize Crop ◽  
Crop Cycle ◽  
Using Data ◽  
The Impact

Two field experiments using maize (Pioneer 31H50) and three watering regimes [(i) irrigated for the whole crop cycle, until anthesis, (ii) not at all (experiment 1) and (iii) fully irrigated and rain grown for the whole crop cycle (experiment 2)] were conducted at Gatton, Australia, during the 2003–04 season. Data on crop ontogeny, leaf, sheath and internode lengths and leaf width, and senescence were collected at 1- to 3-day intervals. A glasshouse experiment during 2003 quantified the responses of leaf shape and leaf presentation to various levels of water stress. Data from experiment 1 were used to modify and parameterise an architectural model of maize (ADEL-Maize) to incorporate the impact of water stress on maize canopy characteristics. The modified model produced accurate fitted values for experiment 1 for final leaf area and plant height, but values during development for leaf area were lower than observed data. Crop duration was reasonably well fitted and differences between the fully irrigated and rain-grown crops were accurately predicted. Final representations of maize crop canopies were realistic. Possible explanations for low values of leaf area are provided. The model requires further development using data from the glasshouse study and before being validated using data from experiment 2 and other independent data. It will then be used to extend functionality in architectural models of maize. With further research and development, the model should be particularly useful in examining the response of maize production to water stress including improved prediction of total biomass and grain yield. This will facilitate improved simulation of plant growth and development processes allowing investigation of genotype by environment interactions under conditions of suboptimal water supply.

scholarly journals Assessment of ratoonability of short-duration pigeonpea genotypes

1996 ◽  
Vol 127 (3) ◽  
pp. 331-335 ◽  
Author(s):  
Y. S. Chauhan ◽  
C. Johansen ◽  
S. C. Gupta
Keyword(s):  
Leaf Area ◽  
Short Duration ◽  
Cajanus Cajan ◽  
Andhra Pradesh ◽  
Total Yield ◽  
Area Index ◽  
Main Crop ◽  
Relationship Of ◽  
The Relationship ◽  
Crop Maturity

SUMMARYThe extent of variation in ratoonability was examined in a range of recently bred short-duration pigeonpea [Cajanus cajan (L.) Millsp.] genotypes in 1989/90, 1990/91 and 1991/92 at the ICRISAT Asia Center, Andhra Pradesh, India. Traits with which this variation could be associated were assessed. Differences in the total ratoon yield of two flushes were significant among the genotypes in each season. In a few genotypes, ratoon yield constituted 50% of the total yield, which could be as high as 5·6 t/ha. Total ratoon yield was positively correlated with leaf area index in the last 2 years of experimentation. The relationship of total ratoon yield to main crop yield was significantly positive in 1991/92 only. The results suggest that there is a large variation in ratoonability among short-duration genotypes and that high leaf area retention at main crop maturity appears to contribute substantially to this variation.

scholarly journals Plant residues, beneficial microbes and integrated phosphorus management for improving hybrid maize (Zea mays L.) growth and total biomass

2021 ◽  
pp. 16-34
Author(s):  
Amanullah Amanullah ◽  
Asif Iqbal ◽  
Asim Muhammad ◽  
Abdel Rahman Altawaha ◽  
Azizullah Shah ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Faba Bean ◽  
Biomass Yield ◽  
Plant Residues ◽  
Total Biomass ◽  
Phosphate Solubilizing Bacteria ◽  
Area Index ◽  
Hybrid Maize ◽  
The Impact

Phosphorus (P) unavailability and lack of organic matter in calcareous soils in semiarid climates are the major reasons for low crop productivity. This field experiment was conducted at the Agronomy Research Farm of The University of Agriculture Peshawar, during the summer of 2015 to investigate the impact of plant residues (PR) (faba bean, garlic and paper mulberry residues) and phosphorous sources [(60 and 120kg ha-1) from single super phosphate (SSP) and poultry manure (PM)] with (+) and without (-) phosphate solubilizing bacteria (PSB) on the phenological development, growth and biomass yield of hybrid maize “CS-200”. Among the PR, application of faba bean residue was found to delay phenological development (days to tasseling, silking and physiological maturity), improved growth (taller plants, higher leaf area per plant and leaf area index) and produced the highest biomass yield (faba bean>garlic>paper mulberry residues). Application of P at the rate of 120kg ha-1 from the inorganic source (SSP) was more beneficial in terms of better growth and higher biomass yield (120-SSP≥120-PM>60-SSP>60-PM kg P ha-1). The plots with (+) PSB showed enhanced phenological development, produced significantly taller plants with higher leaf area per plant and leaf area index and produced the highest biomass yield. On the basis of these results we concluded that the application of faba bean residues, phosphorus at the rate of 120kg ha-1 either from organic or inorganic sources with the inoculation of seed with PSB improved the growth and total biomass of hybrid maize in the study area.

Accent Policy and Accent Modification Enterprises as Potential Indicators of Intercultural Power Relations: A Call for an Updated Research Agenda

2013 ◽  
Vol 3 (1) ◽  
pp. 22-33 ◽  
Author(s):  
Brynne D. Ovalle ◽  
Rahul Chakraborty
Keyword(s):  
International Relations ◽  
Identity Construction ◽  
Social Theory ◽  
Power Relations ◽  
Linguistic Diversity ◽  
Cultural Organization ◽  
Using Data ◽  
The Individual ◽  
The Impact ◽  
The Relationship

This article has two purposes: (a) to examine the relationship between intercultural power relations and the widespread practice of accent discrimination and (b) to underscore the ramifications of accent discrimination both for the individual and for global society as a whole. First, authors review social theory regarding language and group identity construction, and then go on to integrate more current studies linking accent bias to sociocultural variables. Authors discuss three examples of intercultural accent discrimination in order to illustrate how this link manifests itself in the broader context of international relations (i.e., how accent discrimination is generated in situations of unequal power) and, using a review of current research, assess the consequences of accent discrimination for the individual. Finally, the article highlights the impact that linguistic discrimination is having on linguistic diversity globally, partially using data from the United Nations Educational, Scientific and Cultural Organization (UNESCO) and partially by offering a potential context for interpreting the emergence of practices that seek to reduce or modify speaker accents.

Business: Making Cents of Coding Systems: Billing for Professional Services

2010 ◽  
Vol 20 (1) ◽  
pp. 3-8
Author(s):  
Dee Adams Nikjeh
Keyword(s):  
Professional Services ◽  
Speech Language Pathology ◽  
Coding Systems ◽  
Language Pathology ◽  
Program Funding ◽  
Fee Schedule ◽  
Procedure Codes ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship

Abstract Administrators and supervisors face daily challenges over issues such as program funding, service fees, correct coding procedures, and the ever-changing healthcare regulations. Receiving equitable reimbursement for speech-language pathology and audiology services necessitates an understanding of federal coding and reimbursement systems. This tutorial provides information pertaining to two major healthcare coding systems and explains the relationship of these systems to clinical documentation, the Medicare Physician Fee Schedule and equitable reimbursement. An explanation of coding edits and coding modifiers is provided for use in those occasional atypical situations when the standard use of procedural coding may not be appropriate. Also included in this tutorial is a brief discussion of the impact that the Medicare Improvements for Patients and Providers Act of 2008 (HR 6331 Medicare Improvements for Patients and Providers Act [MIPPA], 2008) has had on the valuation of speech-language pathology procedure codes.

The Need to Belong and the Relationship Between Loneliness and Health

2014 ◽  
Vol 22 (4) ◽  
pp. 194-201 ◽  
Author(s):  
Freda-Marie Hartung ◽  
Britta Renner
Keyword(s):  
Individual Differences ◽  
Social Isolation ◽  
Social Situation ◽  
First Year ◽  
Health State ◽  
Need To Belong ◽  
First Year University ◽  
Perceived Social Isolation ◽  
The Impact ◽  
The Relationship

Humans are social animals; consequently, a lack of social ties affects individuals’ health negatively. However, the desire to belong differs between individuals, raising the question of whether individual differences in the need to belong moderate the impact of perceived social isolation on health. In the present study, 77 first-year university students rated their loneliness and health every 6 weeks for 18 weeks. Individual differences in the need to belong were found to moderate the relationship between loneliness and current health state. Specifically, lonely students with a high need to belong reported more days of illness than those with a low need to belong. In contrast, the strength of the need to belong had no effect on students who did not feel lonely. Thus, people who have a strong need to belong appear to suffer from loneliness and become ill more often, whereas people with a weak need to belong appear to stand loneliness better and are comparatively healthy. The study implies that social isolation does not impact all individuals identically; instead, the fit between the social situation and an individual’s need appears to be crucial for an individual’s functioning.

Investigating the Relationship Between Self-Esteem and Stigma Among Young Adults With History of Suicide Attempts

Crisis ◽  
2016 ◽  
Vol 37 (4) ◽  
pp. 265-270 ◽  
Author(s):  
Meshan Lehmann ◽  
Matthew R. Hilimire ◽  
Lawrence H. Yang ◽  
Bruce G. Link ◽  
Jordan E. DeVylder
Keyword(s):  
Young Adults ◽  
Suicide Attempts ◽  
Self Esteem ◽  
High Risk Population ◽  
High Functioning ◽  
People With Mental Illness ◽  
History Of ◽  
The Individual ◽  
The Impact ◽  
The Relationship

Abstract. Background: Self-esteem is a major contributor to risk for repeated suicide attempts. Prior research has shown that awareness of stigma is associated with reduced self-esteem among people with mental illness. No prior studies have examined the association between self-esteem and stereotype awareness among individuals with past suicide attempts. Aims: To understand the relationship between stereotype awareness and self-esteem among young adults who have and have not attempted suicide. Method: Computerized surveys were administered to college students (N = 637). Linear regression analyses were used to test associations between self-esteem and stereotype awareness, attempt history, and their interaction. Results: There was a significant stereotype awareness by attempt interaction (β = –.74, p = .006) in the regression analysis. The interaction was explained by a stronger negative association between stereotype awareness and self-esteem among individuals with past suicide attempts (β = –.50, p = .013) compared with those without attempts (β = –.09, p = .037). Conclusion: Stigma is associated with lower self-esteem within this high-functioning sample of young adults with histories of suicide attempts. Alleviating the impact of stigma at the individual (clinical) or community (public health) levels may improve self-esteem among this high-risk population, which could potentially influence subsequent suicide risk.

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