Leaf growth and senescence rates of three pasture grasses and wheat

2013 ◽  
Vol 64 (7) ◽  
pp. 660 ◽  
Author(s):  
Helen G. Daily ◽  
Peter A. Lane ◽  
Shaun N. Lisson ◽  
Kerry L. Bridle ◽  
Stuart A. J. Anderson ◽  
...  
Keyword(s):  
Life Cycle ◽  
Prescribed Burning ◽  
Linear Models ◽  
Growth Models ◽  
Leaf Growth ◽  
Leaf Length ◽  
Grass Species ◽  
Leaf Position ◽  
Turnover Rates ◽  
Leaf Turnover

A glasshouse study was conducted under ideal conditions to determine leaf appearance, elongation, and senescence rates along with life span and leaf length characteristics of four grass species: wheat (Triticum aestivum L.), brown back wallaby grass (Rytidosperma duttonianum (Cashmore) Connor and Edgar), phalaris (Phalaris aquatica L.), and annual ryegrass (Lolium rigidum Gaud.). This study provided a comprehensive characterisation of leaf turnover rates for the entire life cycle of these grasses, some of which are poorly characterised. Importantly, leaf senescence rate has been captured in the same conditions as the other leaf rates of the life cycle. Leaf position proved to be a significant explanatory variable in each of the leaf turnover rates. The relationships between leaf position and the components of leaf turnover were most commonly represented by non-linear models. Further studies may be necessary to validate these statistical models to field situations. However, this information will be useful to calibrate the senescence algorithms of plant growth models in agricultural decision support tools, which may then be applied to simulation studies including the assessment of grass curing for planning activities such as resource allocation, wildfire suppression, and execution of prescribed burning programs by fire management agencies.

scholarly journals Effects of leaf length and development stage on the triple oxygen isotope signature of grass leaf water and phytoliths: insights for a proxy of continental atmospheric humidity

2019 ◽  
Vol 16 (23) ◽  
pp. 4613-4625 ◽  
Author(s):  
Anne Alexandre ◽  
Elizabeth Webb ◽  
Amaelle Landais ◽  
Clément Piel ◽  
Sébastien Devidal ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Climate Model ◽  
Isotope Composition ◽  
Leaf Growth ◽  
Development Stage ◽  
Mean Value ◽  
Leaf Length ◽  
Leaf Water ◽  
Grass Species ◽  
Leaf Biomass

Abstract. Continental relative humidity (RH) is a key climate parameter, but there is a lack of quantitative RH proxies suitable for climate model–data comparisons. Recently, a combination of climate chamber and natural transect calibrations have laid the groundwork for examining the robustness of the triple oxygen isotope composition (δ′18O and 17O-excess) of phytoliths, that can preserve in sediments, as a new proxy for past changes in RH. However, it was recommended that besides RH, additional factors that may impact δ′18O and 17O-excess of plant water and phytoliths be examined. Here, the effects of grass leaf length, leaf development stage and day–night alternations are addressed from growth chamber experiments. The triple oxygen isotope compositions of leaf water and phytoliths of the grass species F. arundinacea are analysed. Evolution of the leaf water δ′18O and 17O-excess along the leaf length can be modelled using a string-of-lakes approach to which an unevaporated–evaporated mixing equation must be added. We show that for phytoliths to record this evolution, a kinetic fractionation between leaf water and silica, increasing from the base to the apex, must be assumed. Despite the isotope heterogeneity of leaf water along the leaf length, the bulk leaf phytolith δ′18O and 17O-excess values can be estimated from the Craig and Gordon model and a mean leaf water–phytolith fractionation exponent (λPhyto-LW) of 0.521. In addition to not being leaf length dependent, δ′18O and 17O-excess of grass phytoliths are expected to be impacted only very slightly by the stem vs. leaf biomass ratio. Our experiment additionally shows that because a lot of silica polymerises in grasses when the leaf reaches senescence (58 % of leaf phytoliths in mass), RH prevailing during the start of senescence should be considered in addition to RH prevailing during leaf growth when interpreting the 17O-excess of grass bulk phytoliths. Although under the study conditions 17O-excessPhyto do not vary significantly from constant day to day–night conditions, additional monitoring at low RH conditions should be done before drawing any generalisable conclusions. Overall, this study strengthens the reliability of the 17O-excess of phytoliths to be used as a proxy of RH. If future studies show that the mean value of 0.521 used for the grass leaf water–phytolith fractionation exponent λPhyto-LW is not climate dependent, then grassland leaf water 17O-excess obtained from grassland phytolith 17O-excess would inform on isotope signals of several soil–plant-atmosphere processes.

scholarly journals Leaf growth under temperature and light control

2009 ◽  
Vol 55 (No. 12) ◽  
pp. 551-557 ◽  
Author(s):  
J. Repková ◽  
M. Brestič ◽  
K. Olšovská
Keyword(s):  
Leaf Growth ◽  
Leaf Length ◽  
Leaf Expansion ◽  
Main Stem ◽  
Leaf Position ◽  
Temperature Sum ◽  
Air Temperatures ◽  
Strong Relation ◽  
Accumulated Temperature ◽  
Leaf Appearance

Dynamics of crop growth and photosynthesis are two main processes that are of major importance for adaptation of plants to their environment. Two experiments were carried out during 2005 and 2006 with sun and shaded barley plants. The results showed that leaf area increased with leaf position on the main stem up to leaf position 5 for sun and leaf position 6 for shaded plants, and then declined towards flag leaves. Air temperature affected leaf appearance, mainly at the beginning of the growing season. A positive correlation between leaf expansion duration (LED) and accumulated temperature sum was measured for both variants, LED linearly increased with temperature sum. Leaf expansion rate (LER) showed a similar dependence on accumulated air temperatures in both light variants. A strong relation was found between soil temperature and LER for the first four leaves of the main stem of shaded plants in 2006. In shaded environment the higher LER was associated with lower accumulated irradiance sum when light restriction supported an increase of leaf elongation and final leaf length.

scholarly journals The ATXN2 Orthologs CID3 and CID4, Act Redundantly to In-Fluence Developmental Pathways throughout the Life Cycle of Arabidopsis thaliana

2021 ◽  
Vol 22 (6) ◽  
pp. 3068
Author(s):  
Zaira M. López-Juárez ◽  
Laura Aguilar-Henonin ◽  
Plinio Guzmán
Keyword(s):  
Arabidopsis Thaliana ◽  
Life Cycle ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Leaf Growth ◽  
Transcriptome Profiling ◽  
Developmental Pathways ◽  
Model Organisms ◽  
Key Factors

RNA-binding proteins (RBPs) are key elements involved in post-transcriptional regulation. Ataxin-2 (ATXN2) is an evolutionarily conserved RBP protein, whose function has been studied in several model organisms, from Saccharomyces cerevisiae to the Homo sapiens. ATXN2 interacts with poly(A) binding proteins (PABP) and binds to specific sequences at the 3′UTR of target mRNAs to stabilize them. CTC-Interacting Domain3 (CID3) and CID4 are two ATXN2 orthologs present in plant genomes whose function is unknown. In the present study, phenotypical and transcriptome profiling were used to examine the role of CID3 and CID4 in Arabidopsis thaliana. We found that they act redundantly to influence pathways throughout the life cycle. cid3cid4 double mutant showed a delay in flowering time and a reduced rosette size. Transcriptome profiling revealed that key factors that promote floral transition and floral meristem identity were downregulated in cid3cid4 whereas the flowering repressor FLOWERING LOCUS C (FLC) was upregulated. Expression of key factors in the photoperiodic regulation of flowering and circadian clock pathways, were also altered in cid3cid4, as well as the expression of several transcription factors and miRNAs encoding genes involved in leaf growth dynamics. These findings reveal that ATXN2 orthologs may have a role in developmental pathways throughout the life cycle of plants.

Dynamic Predictive Model for Growth of Bacillus cereus from Spores in Cooked Beans

2017 ◽  
Vol 81 (2) ◽  
pp. 308-315 ◽  
Author(s):  
Vijay K. Juneja ◽  
Abhinav Mishra ◽  
Abani K. Pradhan
Keyword(s):  
Bacillus Cereus ◽  
Growth Rates ◽  
Linear Models ◽  
Growth Models ◽  
Maximum Growth ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
Growth Data ◽  
Three Phase ◽  
Primary Model

ABSTRACT Kinetic growth data for Bacillus cereus grown from spores were collected in cooked beans under several isothermal conditions (10 to 49°C). Samples were inoculated with approximately 2 log CFU/g heat-shocked (80°C for 10 min) spores and stored at isothermal temperatures. B. cereus populations were determined at appropriate intervals by plating on mannitol–egg yolk–polymyxin agar and incubating at 30°C for 24 h. Data were fitted into Baranyi, Huang, modified Gompertz, and three-phase linear primary growth models. All four models were fitted to the experimental growth data collected at 13 to 46°C. Performances of these models were evaluated based on accuracy and bias factors, the coefficient of determination (R2), and the root mean square error. Based on these criteria, the Baranyi model best described the growth data, followed by the Huang, modified Gompertz, and three-phase linear models. The maximum growth rates of each primary model were fitted as a function of temperature using the modified Ratkowsky model. The high R2 values (0.95 to 0.98) indicate that the modified Ratkowsky model can be used to describe the effect of temperature on the growth rates for all four primary models. The acceptable prediction zone (APZ) approach also was used for validation of the model with observed data collected during single and two-step dynamic cooling temperature protocols. When the predictions using the Baranyi model were compared with the observed data using the APZ analysis, all 24 observations for the exponential single rate cooling were within the APZ, which was set between −0.5 and 1 log CFU/g; 26 of 28 predictions for the two-step cooling profiles also were within the APZ limits. The developed dynamic model can be used to predict potential B. cereus growth from spores in beans under various temperature conditions or during extended chilling of cooked beans.

scholarly journals Eco-Taxonomic Study of Family Poaceae (Gramineae)

2020 ◽  
Vol 10 (2) ◽  
pp. 63-75
Author(s):  
Muhammad Nauman Khan ◽  
Sajjad Ali ◽  
Tabassum Yaseen ◽  
Sami Ullah ◽  
Akhtar Zaman ◽  
...  
Keyword(s):  
Life Cycle ◽  
Rating Scale ◽  
Cynodon Dactylon ◽  
Species Abundance ◽  
Leaf Size ◽  
Research Area ◽  
Scientific Basis ◽  
Grass Species ◽  
Native Flora ◽  
Over Exploitation

Background: The study of species diversity, its conservations and extinction can be done by using systematics in plant biodiversity. Poaceae is a very diverse grass family with great economic importance as it contains crops like rice, maize, oats, wheat, etc. Objectives: The current study was undertaken in district Charsadda during 2017-18 in flowering season to collect different grass species from the area. Methodology: Grass specimens were gathered, preserved, mounted and then identified from the available literature/native flora (Flora of Pakistan). Ecological parameters like habitat, class, life cycle and biological spectra were determined. A total of 51 taxa comprised of 34 genera, 5 subfamilies and 11 tribes of grasses were collected from the District Charsadda. The subfamily Panicoideae was the leading family with highest number of genera, taxa and tribes, followed by Pooideae. Results: The biological spectrum showed that in the life-form class, therophyte had the highest number of species 32 (62.74%), followed by hemicryptophyte having 13 species (25.49%). In the Leaf size class, microphylls were dominant with 24 species (47.05%) followed by nanophylls having 14 species (27.45%). The adaptational survival of plants showed that 32 species (62.74%) were terrestrial and 19 species (37.25%) were amphibious in our study. The Life-cycle class depicted that 33 species (64.70%) were annual, 17 species (33.33%) were perennial and 1 species (1.960%) was annual or perennial. The Palatability class showed that 35 species (68.62%) were highly palatable, followed by less-palatable 11 species (21.56%), non-palatable 2 species (3.921%) and moderately palatable 3 species (5.882%). The Abundant class were determined through species rating scale in ecology Acfor (Abundant Common Frequent Occasional Rare) scale to describe species abundance in a given area; 26 species (50.98%) were occasional, 12 species (23.52%) were frequent, 7 species (13.72%) were rare, 5 species (9.803%) were common and only 1 species cynodon dactylon (1.960%) was abundant in the whole area and present everywhere in the research area in every season. Conclusion: It has been concluded from the study that unwise collection, over-grazing, over-exploitation, over-consumption and overutilization are major biotic factors, which affect the diversity of the grasses in the area and affect the populations’ sustainability on the earth crust. Therefore, the study aims to document and explore wild grasses from the area, which might help in future researches. This survey will be helpful in identifying plant wealth and status for their exploitation on systematic approaches and scientific basis.

Reliability Growth Models for Defect Prediction

2011 ◽  
pp. 3263-3267
Author(s):  
Norman Schneidewind
Keyword(s):  
Risk Factors ◽  
Life Cycle ◽  
Growth Models ◽  
Numerical Results ◽  
Defect Prediction ◽  
Reliability Growth ◽  
Software Measurement ◽  
Requirements Change ◽  
Code Metrics

In order to continue to make progress in software measurement as it pertains to reliability, there must be a shift in emphasis from design and code metrics to metrics that characterize the risk of making requirements changes. By doing so, the quality of delivered software can be improved because defects related to problems in requirements specifi- cations will be identified early in the life cycle. An approach is described for identifying requirements change risk factors as predictors of reliability problems. This approach can be generalized to other applications with numerical results that would vary according to application.

Maturity in Outsourcing Relationships

2010 ◽  
pp. 98-117
Author(s):  
Hans Solli-Sæther ◽  
Petter Gottschalk
Keyword(s):  
Life Cycle ◽  
Information Systems ◽  
Product Life Cycle ◽  
Growth Models ◽  
It Outsourcing ◽  
Growth Stages ◽  
Stage Model ◽  
Stages Of Growth ◽  
Systems Planning ◽  
Living Organisms

Stages of growth models have been used widely in both organizational research and information technology management research. According to King and Teo (1997), these models describe a wide variety of phenomena – the organizational life cycle, product life cycle, biological growth, stages of growth in information systems, growth model for integration between business planning and information systems planning, electronic commerce evolution, stages of knowledge management technology, and a number of other interesting developments in time perspectives. These models assume that predictable patterns (conceptualized in terms of stages or levels) exist in the growth of organizations and organizational parts, the sales levels of products, and the growth of living organisms. These stages are (1) sequential in nature, (2) occur as a hierarchical progression that is not easily reversed, and (3) evolve a broad range of organizational activities and structures. This chapter starts with an introduction to stages of growth models. In the following sections we present the three-stage model for the evolution of IT outsourcing relationships (Gottschalk & Solli-Sæther, 2006). The three stages are labelled cost stage, resource stage, and partnership stage respectively. Theory-based benchmark variables for measuring maturity in IT outsourcing relationships are presented, followed by the stage hypothesis and a description of how benchmark variables are used to indicate characteristics at each stage of growth. Finally in this chapter, we present results from an exploratory study testing the stage model. The purpose of this chapter is to develop a framework for improved understanding of the current situation in an IT outsourcing relationship in terms of a specific stage, to develop strategies for moving to a higher stage in the future, and to learn from earlier stage experience.

DROUGHT SURVIVAL OF SELECTED FORAGE GRASSES COMMONLY SEEDED IN THE NORTHERN GREAT PLAINS

1982 ◽  
Vol 62 (4) ◽  
pp. 949-955 ◽  
Author(s):  
PAT O. CURRIE ◽  
RICHARD S. WHITE
Keyword(s):  
Great Plains ◽  
Leaf Growth ◽  
Basal Area ◽  
Grass Species ◽  
Northern Great Plains ◽  
Severe Drought ◽  
Forage Grasses ◽  
Drought Tolerant ◽  
Drought Survival ◽  
Moisture Conditions

Prolonged drought between 1979 and 1981 killed or severely reduced stands of a number of grass species presumably adapted and frequently recommended for seeding rangelands in the Northern Great Plains. The drought damage took place on recently planted as well as established 2 years or older seedings. Cultivars of the intermediate-pubescent wheatgrass complex were killed or most severely damaged. Damage was also severe on seeded stands of the native green needlegrass, western and thickspike wheatgrasses and big bluegrass. Crested wheatgrass was only moderately drought tolerant, but two cultivars of Russian wild ryegrass established well even with adverse moisture conditions in the seeding year. Altai wild ryegrass seedlings established well but did not survive the drought. An established stand of Vinall Russian wild ryegrass increased in basal area and produced leaf growth and seedstalks during the most severe drought periods. These periodic droughts are sporadic in occurrence but need to be considered in reference to species recommendations for range seedings in the Northern Great Plains.

scholarly journals Effects of a New Herbicide (Aminocyclopyrachlor) on Buffalograss and Forbs in Shortgrass Prairie

2012 ◽  
Vol 26 (3) ◽  
pp. 455-459 ◽  
Author(s):  
Keith R. Harmoney ◽  
Phillip W. Stahlman ◽  
Patrick W. Geier ◽  
Robert Rupp
Keyword(s):  
Growth Regulator ◽  
Dry Matter ◽  
Leaf Growth ◽  
Growing Season ◽  
Grass Species ◽  
Dry Matter Yield ◽  
Native Grass ◽  
Synthetic Auxin ◽  
Shortgrass Prairie ◽  
And Control

Herbicides used to control many forb species in pastures may injure desirable native grass species. Buffalograss, a major component of shortgrass rangeland, often is injured by some growth regulator herbicides, such as 2,4-D and dicamba. Aminocyclopyrachlor (formerly known as DPX-MAT28 and herein termed ACPCR), a new synthetic auxin herbicide chemistry for control of broadleaf weeds, was investigated for injury to buffalograss and control of forbs in shortgrass prairie at varying rates of application. In the season of application, ACPCR at rates of 140 g ai ha−1or less caused buffalograss injury that was either negligible or short-lived, and visual estimates of grass injury were 8% or less at the end of the growing season. At ACPCR rates of 280 g ha−1, more injury was evident at 3 wk after treatment (WAT) than at the end of the season if adequate precipitation was available for new leaf growth. When precipitation was lacking, evidence of injury persisted through to the end of the season when treated at the greatest rate of ACPCR. Buffalograss injury was mainly in the form of browned leaf tips, but total buffalograss dry matter yield was not different between any treatments in either year. The year after treatment, no buffalograss injury was evident from any of the herbicide rates. Final forb control was 97% or greater each year for ACPCR at the 140 and 280 g ha−1rates. In this experiment, rates as low as ACPCR at 140 g ha−1provided excellent forb control and maintained buffalograss productivity.

Analysis on on the Leaf Growth and Changes of Photosynthetic Characterization by Leaf Position in ‘Changhowon Hwangdo’ Peach

2013 ◽  
Vol 22 (4) ◽  
pp. 361-365
Author(s):  
Ik Koo Yoon ◽  
◽  
Seok Kyu Yun ◽  
Ji Hae Jun ◽  
Eun Young Nam ◽  
...  
Keyword(s):  
Leaf Growth ◽  
Leaf Position
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