scholarly journals Phosphite and mycorrhizal formation in seedlings of three Australian Myrtaceae

2000 ◽  
Vol 48 (6) ◽  
pp. 725 ◽  
Author(s):  
Kay Howard ◽  
Bernie Dell ◽  
Giles E. Hardy
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Phytophthora Cinnamomi ◽  
Fold Increase ◽  
Native Plant ◽  
Negative Effects ◽  
Eucalyptus Marginata ◽  
Collar Rot ◽  
The Impact ◽  
Different Levels

Currently in Western Australia, phosphite is being used to contain the root and collar rot pathogen, Phytophthora cinnamomi, in native plant communities. There have been reports of negative effects of phosphite on arbuscular mycorrhiza (AM), so there are concerns that it may have a deleterious effect on other mycorrhizal fungi. Two glasshouse experiments were undertaken to determine the impact of phosphite on eucalypt-associated ectomycorrhizal fungi. In the first experiment, non-mycorrhizal seedlings of Eucalyptus marginata, Eucalyptus globulus and Agonis flexuosa were sprayed to runoff with several concentrations of phosphite, and then planted into soil naturally infested with early colonising mycorrhizal species. Assessments were made of percentage of roots infected with mycorrhizal fungi. There was no significant effect on ectomycorrhizal formation but there was a four-fold increase in AM colonisation of A. flexuosa roots with phosphite application. In the second experiment, E. globulus seedlings mycorrhizal with Pisolithus, Scleroderma and Descolea were treated with different levels of phosphite and infection of new roots by ectomycorrhizal fungi was assessed. There was no significant effect on ectomycorrhizal formation when phosphite was applied at the recommended rate (5 g L–1), while at 10 g L–1 phosphite significantly decreased infection by Descolea.

The long-term ability of phosphite to control Phytophthora cinnamomi in two native plant communities of Western Australia

2001 ◽  
Vol 49 (6) ◽  
pp. 761 ◽  
Author(s):  
K. M. Tynan ◽  
C. J. Wilkinson ◽  
J. M. Holmes ◽  
B. Dell ◽  
I. J. Colquhoun ◽  
...  
Keyword(s):  
Plant Species ◽  
Plant Communities ◽  
Western Australia ◽  
Foliar Application ◽  
Phytophthora Cinnamomi ◽  
Native Plant ◽  
In Planta ◽  
Eucalyptus Marginata ◽  
Application Rates ◽  
The Impact

This study examined the ability of foliar applications of the fungicide phosphite to contain colonisation of Phytophthora cinnamomi in a range of plant species growing in natural plant communities in the northern sandplain and jarrah (Eucalyptus marginata) forest of south-western Australia. Wound inoculation of plant stems with P. cinnamomi was used to determine the efficacy of phosphite over time after application. Colonisation by P. cinnamomi was reduced for 5–24 months after phosphite was applied, depending on the concentration of phosphite used, plant species treated and the time of phosphite application. Plant species within and between plant communities varied considerably in their ability to take up and retain phosphite in inoculated stems and in the in planta concentrations of phosphite required to contain P. cinnamomi. As spray application rates of phosphite increased from 5 to 20 g L–1, stem tissue concentrations increased, as did the ability of a plant species to contain P. cinnamomi. However, at application rates of phosphite above 5 g L–1 phytotoxicity symptoms were obvious in most species, with some plants being killed. So, despite 10 and 20 g L–1 of phosphite being more effective and persistent in controlling P. cinnamomi, these rates are not recommended for application to the plant species studied. The results of this study indicate that foliar application of phosphite has considerable potential in reducing the impact of P. cinnamomi in native plant communities in the short-term. However, in order to maintain adequate control, phosphite should be sprayed every 6–12 months, depending on the species and/or plant community.

scholarly journals Effectiveness of Three Post-Harvest Rehabilitation Treatments for Runoff and Sediment Reduction on Skid Trails in the Hyrcanian Forests

2020 ◽  
Vol 41 (2) ◽  
pp. 309-324
Author(s):  
Meghdad Jourgholami ◽  
Masoumeh Ahmadi ◽  
Farzam Tavankar ◽  
Rodolfo Picchio
Keyword(s):  
Leaf Litter ◽  
Sediment Yield ◽  
Rainfall Intensity ◽  
Regression Equations ◽  
Negative Effects ◽  
Diverse Range ◽  
Straw Mulch ◽  
The Impact ◽  
Different Levels ◽  
Runoff And Sediment Yield

Ground-based skidding operations can lead to soil compaction and displacement, which could cause negative effects on forest soil. Hence, some efforts such as forestry best management practices (BMPs) must be implemented in the prone area to mitigate these possible impacts. Several materials and treatments have been adopted to suppress these adverse effects by increasing the ground cover. However, the effects of mulch treatments on runoff and sediment yield are inconclusive with a diverse range of effectiveness. For these reasons, in this research mulch treatments were tested as to determine how the application of organic mulch amendments such as straw and leaf litter and contour-felled logs would alleviate the runoff and sediment yield on machine operating trails and ensure successful hillslope stabilization. The aims of the study were to analyse and compare the effectiveness of leaf litter (LM) and straw mulch (SM) rate and different distances of contour-felled logs (CFL) to mitigate the runoff and sediment yield, and examine the impact of rainfall intensity on effectiveness of litter mulch, straw mulch, and contour-felled logs. Totally, 30 bounded runoff plots in the machine operating trails and four treatments including litter mulch (LMR1: 0.62, LMR2: 1.24, and LMR3: 1.86 kg m-2), straw mulch (SMR1: 0.45, SMR2: 0.92, and SMR3: 1.34 kg m-2), contour-felled logs (CFL10: 10, CFL20: 20, and CFL30: 30 m), and untreated area were established in triplicate with 4 m width and 100 m length. During the study period, the runoff and sediment yield in the untreated trails (U) were 2.36 mm and 11.84 g m-2. Straw (from 41.5 to 60.6%) and litter mulch (from 38.1 to 55.1%), and contour-felled logs treatments (from 70.8 to 88.1%) significantly decreased the runoff, compared to U treatment. Results show that mulch treatments with three different levels of Litter Mulch Rate, LMR1, LMR2, and LMR3 decreased mean sediment by 46.6, 64.0 and 71.8%, in the treatments with three different levels of Straw Mulch Rate, SMR1, SMR2, and SMR3 decreased mean sediment by 42.9, 62.1, and 69.9%, and in the treatments with three different distances of Contour-Felled Logs, CFL10, CFL20, and CFL30 decreased mean sediment by 90.6, 94.7 and 88.3% comparing to U, respectively. The relationships of the runoff and sediment responses to increasing mulching rate of litter and straw followed as negative logarithmic curves, but the decreasing-increasing trends were observed in runoff and sediment yield as the distance between contour-felled logs increased from 10 to 30 m. Polynomial regression equations were developed for predicting the runoff and sediment yield as a function of the application rate of litter and straw mulch and the distance between contour-felled logs, and rainfall intensity. We concluded that contour-felled logs treatment was more effective than both litter and straw mulch to mitigate the runoff, runoff coefficient, and sediment yield on machine operating trails. As a management measure, it could be possible to propose that the contour-felled logs with a distance of 20 m be prescribed to protect the machine operating trails from the negative effects of surface waterflow.

scholarly journals Corruption and satisfaction with democracy: the conditional role of electoral disproportionality and ballot control

2018 ◽  
Vol 10 (3) ◽  
pp. 393-416 ◽  
Author(s):  
Alessandro Pellegata ◽  
Vincenzo Memoli
Keyword(s):  
Electoral Systems ◽  
Aggregate Level ◽  
Negative Effects ◽  
Empirical Results ◽  
Satisfaction With Democracy ◽  
Level Data ◽  
The Impact ◽  
The Relationship ◽  
Different Levels

Existing literature has analysed the relationship between electoral systems and either corruption or satisfaction with democracy (SWD) focussing on the traditional distinction between majoritarian and proportional systems. This paper, instead, investigates if and how specific aspects of electoral systems moderate the negative effects of corruption perceptions on SWD. We argue that two mechanisms act simultaneously but at different levels. The first mechanism is the relationship between voters and the national government, while the second links single representatives to their constituents. We advance conditional hypotheses that postulate an attenuating effect of disproportionality and a reinforcing impact of personal vote. Empirical results from 35 elections in 33 democracies, using both individual and aggregate-level data, confirm the research hypotheses. More disproportional electoral systems weaken the impact of citizens’ perceived corruption on their democratic satisfaction, while this is strengthened by systems in which the ballot control is mostly in the hand of the voters.

Host response to inoculation and behaviour of introduced and indigenous ectomycorrhizal fungi of jack pine grown on oil-sands tailings

1989 ◽  
Vol 19 (11) ◽  
pp. 1412-1421 ◽  
Author(s):  
R. M. Danielson ◽  
S. Visser
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Oil Sands ◽  
Host Response ◽  
Fold Increase ◽  
Growing Season ◽  
Jack Pine ◽  
Short Root ◽  
Replacement Process ◽  
Shoot Weight

Pinusbanksiana Lamb, seedlings were inoculated with nine mycorrhizal fungi and outplanted on an oil-sands containment dyke that had been amended with muskeg peat. After one growing season, E-strain (Complexipes), Hebeloma sp., Thelephoraterrestris Ehrh.:Fr., and Laccariaproximo Boudier each formed mycorrhizae with greater than 40% of the new short roots within 10 cm of the stem. Cenococcumgeophilum Fr., Pisolithustinctorius (Pers.) Coker & Couch, Astraeushygrometricus (Pers.) Morgan, Lactariusparadoxus Beardslee & Burlingham, and Sphaerosporellabrunnea (Alb. & Schw.:Fr.) Svrcek & Kubika each formed mycorrhizae with less than 6% of the short roots on egressed laterals. Of the introduced fungi, only E-strain was present in substantial quantities after 3 years. The quantity of short roots converted to mycorrhizae by indigenous fungi was 4, 33, and 72% after 1, 2, and 3 years, respectively. The change in mycorrhizal fungi appeared to be a noncompetitive replacement process, in which the original short root resident fungus died in the near absence of mycorrhizal fungi. At the end of the 3rd year, the major indigenous fungi converting short roots to mycorrhizae were E-strain, Tuber sp., Suillus-like spp., Myceliumradicisatrovirens Melin, and an unidentified basidiomycete. Inoculation with E-strain and Thelephoraterrestris resulted in a 2- to 3-fold increase in shoot weight after 2 years compared with uninoculated seedlings.

Direct and Indirect Effects of Income Inequality On Economic Growth Through Political Economy

2019 ◽  
pp. 5-17
Author(s):  
Goksu Aslan
Keyword(s):  
Economic Growth ◽  
Political Economy ◽  
Income Inequality ◽  
Indirect Effects ◽  
Direct Effects ◽  
Negative Effects ◽  
Transmission Channels ◽  
Interaction Terms ◽  
The Impact ◽  
Different Levels

In addition to its direct effects, income inequality may affect economic growth indirectly through various transmission channels. Negative effects may arise from a political economy, socio-political instability, and credit market imperfections. In other words, inequality may have indirect effects on economic growth through these transmission channels. In this article, the focus is on testing the impact of income inequality through the political economy channel, using several types of taxes as the proxy for redistributive pressure. In order to test the possible effects through these channels, income inequality, taxation, and related interaction terms are added into the growth model. The results show that there is a significant negative interaction between income inequality and tax channels. This interaction is also justified with the tax index calculated by the PCA. Marginal effects of the related tax channels are interpreted for different levels of income inequality.

scholarly journals Does Remediation Work for All Students? How the Effects of Postsecondary Remedial and Developmental Courses Vary by Level of Academic Preparation

2017 ◽  
Vol 40 (1) ◽  
pp. 29-58 ◽  
Author(s):  
Angela Boatman ◽  
Bridget Terry Long
Keyword(s):  
Academic Preparation ◽  
Regression Discontinuity Design ◽  
Developmental Courses ◽  
Negative Effects ◽  
Remedial Courses ◽  
Long Term Outcomes ◽  
Academic Preparedness ◽  
The Impact ◽  
Different Levels

We examine the impact of remedial and developmental courses on college students with varying levels of academic preparedness, thus focusing on a wider range of students than previous studies. Using a regression discontinuity design, we provide causal estimates of the effects of placement in different levels of remedial courses on short-, intermediate-, and long-term outcomes at both 2- and 4-year colleges. Similar to other research, we find that remediation has negative effects for students on the margin of needing one developmental course. However, for students with lower levels of academic preparation, the effects of remediation are estimated to be positive in some subjects. These results suggest that remedial courses can help or hinder students differently depending on their incoming levels of academic preparedness. Moreover, our conclusions are largely driven by positive and negative effects observed for students at 2-year institutions, and we discuss several hypotheses that may explain these findings.

scholarly journals Adaptation of Selected Ectomycorrhizal Fungi to Increased Concentration of Cadmium and Lead

2016 ◽  
Vol 23 (3) ◽  
pp. 483-491
Author(s):  
Katarzyna Bandurska ◽  
Piotr Krupa ◽  
Agnieszka Berdowska ◽  
Magdalena Marczak
Keyword(s):  
Heavy Metals ◽  
Ectomycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Colorimetric Method ◽  
Fungal Resistance ◽  
Fruiting Bodies ◽  
Industrial Emissions ◽  
Mineral Salts ◽  
Cadmium And Lead ◽  
The Impact

Abstract Plants together with water and minerals actively take from the soil heavy metals such as cadmium and lead. The negative role of ions of these metals on plant growth and development depends not only on their concentration in the soil, but also on a number of factors that may affect the transport of minerals from the soil to the roots. The harmful effects of xenobiotics getting from the soil to the plants are limited by the organic compounds contained in the soil, soil structure and pH. Particularly noteworthy are biotic factors, such as bacteria and fungi which greatly limit the translocation of heavy metals. Stream of new scientific reports show that the symbiotic combination of fungi with plant roots so called mycorrhizae is a factor that may be important in reducing the impact of soil contamination by heavy metals. Mycorrhiza by filtering solutions of water and mineral salts stop a considerable amount of heavy metals in the internal mycelium or on its surface. It was proved that plants with properly formed mycorrhiza grow better in hard to renew lands, such as salty, sterile soils contaminated with industrial waste. Questions to which answer was sought in this study are: 1) whether mycorrhizal fungi for many years growing in the contaminated areas have managed to adapt to these adverse conditions and 2) do the same species derived from clean areas are less resistant to contamination by heavy metals? Stated problems tried to be solved based on the fruiting bodies of fungi collected from ectomycorrhizal fungi picked from the areas contaminated by industrial emissions and areas free of contamination. The interaction of cadmium and lead ions on the growth of mycelium was examined by plate method and binding of heavy metals in fruiting structures of fungi were done by colorimetric method with use of methylene blue. It has been shown that the fungal resistance, even of the same species, to high concentration of heavy metals varies depending on the origin of symbiont. Isolated fungi from contaminated areas are better adapted to high concentrations of xenobiotics. Ability to bind cadmium and lead to fruiting bodies of fungi varies.

Habitat utilisation by small mammals in a coastal heathland exhibiting symptoms of Phytophthora cinnamomi infestation

2006 ◽  
Vol 33 (8) ◽  
pp. 639 ◽  
Author(s):  
W. Scott Laidlaw ◽  
Barbara A. Wilson
Keyword(s):  
Plant Species ◽  
Small Mammals ◽  
Small Mammal ◽  
Phytophthora Cinnamomi ◽  
Species Abundance ◽  
Structural Factors ◽  
Native Plant ◽  
Mammal Species ◽  
Tea Tree ◽  
The Impact

Phytophthora cinnamomi is a soil-inhabiting ‘water mould’ that is pathogenic to many native plant species in Australia, and has been shown to alter plant species abundance and richness, as well as the structure of vegetation in sclerophyllous vegetation. This study investigated the effects of P. cinnamomi-induced vegetation disturbance and habitat degradation on microhabitat associations of small mammals in a coastal heathland in southern Australia. Seven small mammal species were trapped in a P. cinnamomi-infested heathland community over four years. Trap stations were classified into three disease classes (non-diseased, active disease and post-disease) and structural and floristic aspects of the vegetation were recorded at each station. The mean number of species captured was greatest in non-diseased areas and least in post-disease areas. The total capture frequency of small mammals was lower in post-disease areas except where they were covered by thick stands of tall tea-tree (Leptospermum sp.). Combined small mammal captures were associated with thick vegetation and floristic factors. Captures of Antechinus agilis, Rattus fuscipes, Rattus lutreolus and Sminthopsis leucopus were greatest in non-diseased vegetation and were less frequent in areas of diseased vegetation. A. agilis and R. fuscipes captures were correlated with a floristic factor associated with non-diseased vegetation, while R. lutreolus was associated with structural factors, preferring thick vegetation. The impact on Cercartetus nanus and Isoodon obesulus could not be assessed owing to low captures of these species. Modification of vegetation structure and floristics associated with P. cinnamomi infestation is having a significant impact on the habitat utilised by the small mammal communities in the area. This impact highlights the need to identify and protect those areas that remain free of P. cinnamomi infestation. Continued spread of the pathogen will reduce the area of suitable small-mammal habitat able to support the diverse communities of the eastern Otway Ranges, Victoria, Australia.

The Microflora of Unsuberized Roots of Eucalyptus calophylla R.Br. And Eucalyptus marginata Donn ex Sm. Seedlings Grown in Soil Suppressive and Conducive to Phytophthora cinnamomi Rands. II. Mycorrhizal Roots and Associated Microflora

1979 ◽  
Vol 27 (3) ◽  
pp. 255 ◽  
Author(s):  
N Malajczuk
Keyword(s):  
Electron Microscope ◽  
Mycorrhizal Fungi ◽  
Electron Microscope Study ◽  
Phytophthora Cinnamomi ◽  
Differential Susceptibility ◽  
Eucalyptus Marginata ◽  
Different Types ◽  
Mycorrhizal Roots ◽  
Conducive Soil ◽  
Stimulation Of

Mycorrhizal root development was more frequent in Eucalyptus calophylla than in Eucalyptus marginata in field and pot samples of soil conductive to Phytophthora cinnamomi. Morphologically different types of mycorrhizas were also observed in the two species, which suggested preferential stimulation of mycorrhizal fungi, and this was supported by cross-inoculation experiments with fungal symbionts isolated from mycorrhizal roots and from basidiomycete sporophores. Isolation of bacteria from mycorrhizal roots, and low power electron microscope study of these roots, indicated a significant mycorrhizosphere effect. Populations of bacteria varied quantitatively and qualitatively for different mycorrhizal roots. In suppressive soil few mycorrhizal roots were formed in either species. It is suggested that the different types of mycorrhizal roots and their associated bacterial microflora may contribute to differential susceptibility of the two species to infection by P. cinnamomi in conducive soil.

The More Control, the Better?

2014 ◽  
Vol 26 (2) ◽  
pp. 81-91 ◽  
Author(s):  
Jeeyun Oh ◽  
Mun-Young Chung ◽  
Sangyong Han
Keyword(s):  
Mixed Design ◽  
Negative Effects ◽  
Story Structure ◽  
Content Type ◽  
High User ◽  
User Control ◽  
Rigorous Research ◽  
Control Versus ◽  
The Media ◽  
The Impact

Despite of the popularity of interactive movie trailers, rigorous research on one of the most apparent features of these interfaces – the level of user control – has been scarce. This study explored the effects of user control on users’ immersion and enjoyment of the movie trailers, moderated by the content type. We conducted a 2 (high user control versus low user control) × 2 (drama film trailer versus documentary film trailer) mixed-design factorial experiment. The results showed that the level of user control over movie trailer interfaces decreased users’ immersion when the trailer had an element of traditional story structure, such as a drama film trailer. Participants in the high user control condition answered that they were less fascinated with, absorbed in, focused on, mentally involved with, and emotionally affected by the movie trailer than participants in the low user control condition only with the drama movie trailer. The negative effects of user control on the level of immersion for the drama trailer translated into users’ enjoyment. The impact of user control over interfaces on immersion and enjoyment varies depending on the nature of the media content, which suggests a possible trade-off between the level of user control and entertainment outcomes.

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