The impact of defoliation on nitrogen translocation patterns in the woody invasive plant, Buddleia davidii

2008 ◽  
Vol 35 (6) ◽  
pp. 462 ◽  
Author(s):  
Marc M. Thomas ◽  
Pete Millard ◽  
Michael S. Watt ◽  
Matthew H. Turnbull ◽  
Duane Peltzer ◽  
...  
Keyword(s):  
Invasive Plant ◽  
Control Measure ◽  
Total Biomass ◽  
Invasive Shrub ◽  
Growing Seasons ◽  
Invasive Spread ◽  
Buddleia Davidii ◽  
Induced Changes ◽  
The Impact ◽  
N Remobilisation

The influence of defoliation on nitrogen (N) re-translocation and the source for N remobilisation by the invasive shrub, Buddleia davidii Franch. (buddleia) was determined. Eighty plants were grown over two growing seasons, and half were repeatedly defoliated by removing 66% of their leaf area. During the second season, the N supply was labelled with 15N (10 atom% enrichment), to distinguish the use of stored N (unlabelled) from N taken up by roots (labelled) for growth. Defoliation significantly decreased root (39%) and total biomass (26%). Old leaves were the main source of N for remobilisation which was accelerated and increased (by 50% in the second season) in response to defoliation. In spring, root uptake of N increased by 57% in defoliated plants. Thus, defoliation induced changes in N remobilisation and uptake as compensatory growth increased the demand for N. Continued leaf removal decreased the pool of stored N and caused a significant decline in biomass production, especially in roots (39%) and flowers (31%). This has important implications for the efficacy of defoliation as a control measure, as smaller roots suggest a reduced capacity for uptake of nutrients from the soil and reduced flower production may assist in reducing the invasive spread of the species. These findings clearly show that, although the success of B. davidii is associated, in part, with efficient remobilisation of N from storage, this advantage can be overcome by continued defoliation.

scholarly journals Effects of climate-induced changes in isoprene emissions after the eruption of Mount Pinatubo

2010 ◽  
Vol 10 (3) ◽  
pp. 6871-6894
Author(s):  
P. J. Telford ◽  
J. Lathière ◽  
N. L. Abraham ◽  
P. Braesicke ◽  
C. E. Johnson ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Total Biomass ◽  
Biogeochemical Processes ◽  
Suppression Factor ◽  
Mount Pinatubo ◽  
Warm Event ◽  
Time Period ◽  
Maximum Decrease ◽  
Induced Changes ◽  
The Impact

Abstract. In the 1990s the rates of increase of greenhouse gas concentrations, most notably of methane, were observed to change, for reasons that have yet to be fully determined. This period included the eruption of Mt. Pinatubo and an El Niño warm event, both of which affect biogeochemical processes, by changes in temperature, precipitation and radiation. We examine the impact of these changes in climate on global isoprene emissions and the effect these climate dependent emissions have on the hydroxy radical, OH, the dominant sink for methane. We model a reduction of isoprene emissions in the early 1990s, with a maximum decrease of 40 Tg(C)/yr in late 1992 and early 1993, a change of 9%. This reduction is caused by the cooler, drier conditions following the eruption of Mt. Pinatubo. Isoprene emissions are reduced both directly, by changes in temperature and a soil moisture dependent suppression factor, and indirectly through reductions in the total biomass. The reduction in isoprene emissions causes increases of tropospheric OH which lead to an increased sink for methane of up to 5 Tg/year, comparable to estimated source changes over the time period studied.

scholarly journals Effects of climate-induced changes in isoprene emissions after the eruption of Mount Pinatubo

2010 ◽  
Vol 10 (15) ◽  
pp. 7117-7125 ◽  
Author(s):  
P. J. Telford ◽  
J. Lathière ◽  
N. L. Abraham ◽  
A. T. Archibald ◽  
P. Braesicke ◽  
...  
Keyword(s):  
Total Biomass ◽  
Biogeochemical Processes ◽  
Suppression Factor ◽  
Mount Pinatubo ◽  
Warm Event ◽  
Time Period ◽  
Maximum Decrease ◽  
Exact Size ◽  
Induced Changes ◽  
The Impact

Abstract. In the 1990s the rates of increase of greenhouse gas concentrations, most notably of methane, were observed to change, for reasons that have yet to be fully determined. This period included the eruption of Mt. Pinatubo and an El Niño warm event, both of which affect biogeochemical processes, by changes in temperature, precipitation and radiation. We examine the impact of these changes in climate on global isoprene emissions and the effect these climate dependent emissions have on the hydroxy radical, OH, the dominant sink for methane. We model a reduction of isoprene emissions in the early 1990s, with a maximum decrease of 40 Tg(C)/yr in late 1992 and early 1993, a change of 9%. This reduction is caused by the cooler, drier conditions following the eruption of Mt. Pinatubo. Isoprene emissions are reduced both directly, by changes in temperature and a soil moisture dependent suppression factor, and indirectly, through reductions in the total biomass. The reduction in isoprene emissions causes increases of tropospheric OH which lead to an increased sink for methane of up to 5 Tg(CH4)/year, comparable to estimated source changes over the time period studied. There remain many uncertainties in the emission and oxidation of isoprene which may affect the exact size of this effect, but its magnitude is large enough that it should remain important.

scholarly journals The impact of a native hemiparasite on a major invasive shrub is affected by host size at time of infection

2020 ◽  
Vol 71 (12) ◽  
pp. 3725-3734
Author(s):  
Robert M Cirocco ◽  
José M Facelli ◽  
Jennifer R Watling
Keyword(s):  
Root Biomass ◽  
Isotope Composition ◽  
Nitrogen Concentration ◽  
Host Size ◽  
Quantum Yields ◽  
Total Biomass ◽  
Invasive Shrub ◽  
Ulex Europaeus ◽  
Nodule Biomass ◽  
The Impact

Abstract Many studies have investigated the effect of parasitic plants on their hosts; however, few have examined how parasite impact is affected by host size. In a glasshouse experiment, we investigated the impact of the Australian native hemiparasitic vine, Cassytha pubescens, on a major invasive shrub, Ulex europaeus, of different sizes. Infected plants had significantly lower total, shoot, and root biomass, but the parasite’s impact was more severe on small than on large hosts. When infected, small but not large hosts had significantly lower nodule biomass. Irrespective of size, infection significantly decreased the host shoot/root ratio, pre-dawn and midday quantum yields, maximum electron transport rates, and carbon isotope composition, and the host nodule biomass per gram of root biomass significantly increased in response to infection. Infection did not affect host foliar nitrogen concentration or midday shoot water potential. Parasite biomass was significantly lower on small relative to large hosts, but was similar when expressed on a per gram of host total biomass basis. Parasite stem nitrogen, phosphorus, and potassium concentrations were significantly greater when C. pubescens was growing on small than on large hosts. Our results clearly show that C. pubescens strongly decreases performance of this major invasive shrub, especially when hosts are small. This suggests that C. pubescens could be used most effectively as a native biocontrol when deployed on smaller hosts.

scholarly journals Assessment of Climate Change Impact on Sorghum Production in Machakos County

2018 ◽  
Vol 3 ◽  
pp. 25-45
Author(s):  
Emily Bosire ◽  
Fredrick Karanja ◽  
Gilbert Ouma ◽  
Wilson Gitau
Keyword(s):  
Climate Change ◽  
Production Systems ◽  
Fertilizer Application ◽  
Cycle Duration ◽  
Total Biomass ◽  
Growing Seasons ◽  
Sorghum Production ◽  
Phenological Dates ◽  
Sorghum Grain ◽  
The Impact

The APSIM (Agricultural Production Systems sIMulator) model was used to assess the impact of climate change on sorghum production in the semi arid low lands of Machakos County under three future scenarios of climate change (2010-2039, 2040-2069 and 2070-2099) using two Representative Concentration Pathways (RCPs): RCP 4.5 and RCP 8.5. The APSIM model was calibrated and evaluated using field experimental data obtained from a two-year experiment (2014 to 2015) of sorghum parameters carried out at Kenya Agricultural and Livestock Research Organization (KALRO) in Katumani. Model evaluation shows that APSIM sorghum model was capable in quantifying the response of sorghum to nitrogen (N). The values of root mean square error obtained were low for all the sorghum parameters studied. Higher values of modified index of agreement showed more precise simulation of total biomass and grain yield. The observed and simulated sorghum parameters for both cultivars during the long and short growing seasons depicted good correlation with r2values ranging between 45 % and 99%. Across all the GCMs projected mean changes on phenological dates (days to 50% flowering and physiological maturity) showed a consistent decline for both sorghum varieties during the long and short growing seasons with the application of different rates of fertilizer. These trends were more manifested in the RCP8.5 than RCP4.5 and in the end century (2071-2100) of the simulation. With the RCP8.5 flowering dates reduced by 24 and 28 days and the crop cycle duration shrinked by 35 and 38 days in the end century (2071-2100) for gadam and seredo, respectively. There was slight increase or decrease in biomass for both varieties under climate change with no fertilizer application. However, with application of 50kgha-1N, there was a slight increase of biomass. It has been noted that under changing climate sorghum grain yields will constantly increase for both cultivars over the three future time periods with almost 85.3% increase as we approach the end of the century (2070-2099). The extent of yield change was higher for seredo than for gadam.

Drug Induced Changes in Cell Organelles

1968 ◽  
Vol 26 ◽  
pp. 110-111
Author(s):  
Sarah A. Luse
Keyword(s):  
Clinical Medicine ◽  
Cell Organelles ◽  
Riboflavin Deficiency ◽  
Drug Induced ◽  
New Era ◽  
Health And Disease ◽  
In The Beginning ◽  
Cellular Pathology ◽  
Induced Changes ◽  
The Impact

In the mid-nineteenth century Virchow revolutionized pathology by introduction of the concept of “cellular pathology”. Today, a century later, this term has increasing significance in health and disease. We now are in the beginning of a new era in pathology, one which might well be termed “organelle pathology” or “subcellular pathology”. The impact of lysosomal diseases on clinical medicine exemplifies this role of pathology of organelles in elucidation of disease today.Another aspect of cell organelles of prime importance is their pathologic alteration by drugs, toxins, hormones and malnutrition. The sensitivity of cell organelles to minute alterations in their environment offers an accurate evaluation of the site of action of drugs in the study of both function and toxicity. Examples of mitochondrial lesions include the effect of DDD on the adrenal cortex, riboflavin deficiency on liver cells, elevated blood ammonia on the neuron and some 8-aminoquinolines on myocardium.

Effect of Glycosaminoglycans on Thrombin- and Atroxin-Induced Fibrin Assembly and Structure

1989 ◽  
Vol 62 (04) ◽  
pp. 1057-1061 ◽  
Author(s):  
Marcus E Carr ◽  
Patrick L Powers
Keyword(s):  
Chondroitin Sulfate ◽  
Fiber Diameter ◽  
Lag Phase ◽  
Low Molecular Weight ◽  
Fibrin Gels ◽  
Fiber Size ◽  
Induced Changes ◽  
The Impact ◽  
Fiber Radius ◽  
Turbidity Increase

SummaryThis study was performed to quantitate the impact of several glycosaminoglycans (GAG) on fibrin assembly and structure. Gel formation was monitored as the increase in optical density at 633 nm subsequent to thrombin (2 NIH u/ml) or atroxin (0.10 mg/ml) addition to solutions of buffered fibrinogen (1 mg/ml) or plasma. Gel absorbance was measured as a function of wavelength (400 to 800 nm) and gel fiber diameter and mass/length ratio (μ) were calculated. Chondroitin sulfate A (CSA)shortened the lag phase, enhanced the maximal rate of turbidity increase, and increased the final gel turbidity of fibrin gels formed by thrombin or atroxin. CSA (16 mg/ml) increased fiber μ from 1.3 to 3.1 × 1013 dalton/cm and fiber radius from 6.0 to 8.6 × 10-6 cm in thrombin-induced gels. μ increased from 0.7 to 2.7 × 1013 dalton/cm and fiber radius from 4 to 7.8 × 10-6 cm for atroxin-induced gels. Above 16 mg/ml, CSA caused fibrinogen precipitation in purified solutions but not in plasma. CSA inhibited thrombin-induced plasma clotting of plasma but effects in atroxin-mediated plasma gels paralleled those seen in purified solutions. Chondroitin sulfate B (CSB)-induced changes in fibrin were similar but slightly less dramatic than those seen with CSA. μ increased from 0.9 to 2.0 × 1013 dalton/cm for thrombin-induced fibrin gels and from 0.8 to 2.3 × 1013 dalton/cm for atroxininduced gels. Low molecular weight heparin (Mr = 5100) slowed fibrin assembly and reduced fiber size by 50% in thrombininduced gels. Changes in μ of atroxin-induced gels were much less pronounced (<20%). This study documents pronounced GAGinduced changes in fibrin structure which vary with GAG species and may mediate significant physiologic functions.

Characterizing the effectiveness of COVID-19 mitigation measures: A data-centric approach (Preprint)

2020 ◽  
Author(s):  
Lukman Olagoke ◽  
Ahmet E. Topcu
Keyword(s):  
Control Measure ◽  
Control Measures ◽  
World Health ◽  
Mitigation Measures ◽  
Effective Control ◽  
The World ◽  
Decision Making Processes ◽  
And Performance ◽  
Health Organization ◽  
The Impact

BACKGROUND COVID-19 represents a serious threat to both national health and economic systems. To curb this pandemic, the World Health Organization (WHO) issued a series of COVID-19 public safety guidelines. Different countries around the world initiated different measures in line with the WHO guidelines to mitigate and investigate the spread of COVID-19 in their territories. OBJECTIVE The aim of this paper is to quantitatively evaluate the effectiveness of these control measures using a data-centric approach. METHODS We begin with a simple text analysis of coronavirus-related articles and show that reports on similar outbreaks in the past strongly proposed similar control measures. This reaffirms the fact that these control measures are in order. Subsequently, we propose a simple performance statistic that quantifies general performance and performance under the different measures that were initiated. A density based clustering of based on performance statistic was carried out to group countries based on performance. RESULTS The performance statistic helps evaluate quantitatively the impact of COVID-19 control measures. Countries tend show variability in performance under different control measures. The performance statistic has negative correlation with cases of death which is a useful characteristics for COVID-19 control measure performance analysis. A web-based time-line visualization that enables comparison of performances and cases across continents and subregions is presented. CONCLUSIONS The performance metric is relevant for the analysis of the impact of COVID-19 control measures. This can help caregivers and policymakers identify effective control measures and reduce cases of death due to COVID-19. The interactive web visualizer provides easily digested and quick feedback to augment decision-making processes in the COVID-19 response measures evaluation. CLINICALTRIAL Not Applicable

scholarly journals Exogenous application of growth stimulators improves the condition of maize exposed to soil drought

2021 ◽  
Vol 43 (4) ◽  
Author(s):  
Agnieszka Ostrowska ◽  
Maciej T. Grzesiak ◽  
Tomasz Hura
Keyword(s):  
Plant Growth ◽  
Developmental Stages ◽  
Aminolevulinic Acid ◽  
Stem Elongation ◽  
Development Stage ◽  
Photochemical Activity ◽  
Soil Drought ◽  
Beneficial Effects ◽  
Induced Changes ◽  
The Impact

AbstractSoil drought is a major problem in plant cultivation. This is particularly true for thermophilic plants, such as maize, which grow in areas often affected by precipitation shortage. The problem may be alleviated using plant growth and development stimulators. Therefore, the aim of the study was to analyze the effects of 5-aminolevulinic acid (5-ALA), zearalenone (ZEN), triacontanol (TRIA) and silicon (Si) on water management and photosynthetic activity of maize under soil drought. The experiments covered three developmental stages: three leaves, stem elongation and heading. The impact of these substances applied during drought stress depended on the plant development stage. 5-ALA affected chlorophyll levels, gas exchange and photochemical activity of PSII. Similar effects were observed for ZEN, which additionally induced stem elongation and limited dehydration. Beneficial effects of TRIA were visible at the stage of three leaves and involved leaf hydration and plant growth. A silicon preparation applied at the same developmental stage triggered similar effects and additionally induced changes in chlorophyll levels. All the stimulators significantly affected transpiration intensity at the heading stage.

scholarly journals Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1726
Author(s):  
Nasr H. Gomaa ◽  
Ahmad K. Hegazy ◽  
Arafat Abdel Hamed Abdel Latef
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Stress Gradient ◽  
Growing Season ◽  
Annual Species ◽  
Negative Effects ◽  
Growing Seasons ◽  
Dry Seasons ◽  
The Impact ◽  
Haloxylon Salicornicum

Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.

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