scholarly journals Involvement of Allelopathy in the Invasive Potential of Tithonia diversifolia

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 766 ◽  
Author(s):  
Hisashi Kato-Noguchi
Keyword(s):  
Root Exudates ◽  
Competitive Ability ◽  
Invasive Plant ◽  
Sesquiterpene Lactones ◽  
Plant Residues ◽  
Tithonia Diversifolia ◽  
Native Plant ◽  
Invasive Potential ◽  
Living Tissues ◽  
Germination And Growth

Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae) is native to Mexico and Central America. The species is spreading quickly and has naturalized in more than 70 countries. It has often been recorded as a harmful invasive plant that disturbs native plant communities. Phytotoxic chemical interactions such as allelopathy between invasive plants and native plants have been reported to play an important role in the invasion. Evidence for allelopathy of T. diversifolia has accumulated in the literature over 30 years. Thus, the objective of this review was to discuss the possible involvement of allelopathy in the invasive potential of T. diversifolia. The extracts, root exudates, and plant residues of T. diversifolia inhibited the germination and growth of other plant species. The soil water and soil collected from T. diversifolia fields also showed inhibitory growth effects. The decomposition rate of T. diversifolia residues in soil was reported to be high. Phytotoxic substances such as sesquiterpene lactones were isolated and identified in the extracts of T. diversifolia. Some phytotoxic substances in T. diversifolia may be released into the soil through the decomposition of the plant residues and the exudation from living tissues of T. diversifolia, including its root exudates, which act as allelopathic substances. Those allelopathic substances can inhibit the germination and growth of neighboring plants and may enhance the competitive ability of the plants, make them invasive.

scholarly journals Allelopathy of Knotweeds as Invasive Plants

Plants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 3
Author(s):  
Hisashi Kato-Noguchi
Keyword(s):  
Plant Species ◽  
Mycorrhizal Fungi ◽  
Invasive Plant ◽  
Native Plants ◽  
Rhizosphere Soil ◽  
Arbuscular Mycorrhizal ◽  
Plant Residues ◽  
Japanese Knotweed ◽  
Plant Parts ◽  
Germination And Growth

Perennial herbaceous Fallopia is native to East Asia, and was introduced to Europe and North America in the 19th century as an ornamental plant. Fallopia has been spreading quickly and has naturalized in many countries. It is listed in the world’s 100 worst alien species. Fallopia often forms dense monospecies stands through the interruption of the regeneration process of indigenous plant species. Allelopathy of Japanese knotweed (Fallopia japonica), giant knotweed (Fallopia sachalinensis), and Bohemian knotweed (Fallopia x bohemica) has been reported to play an essential role in its invasion. The exudate from their roots and/or rhizomes, and their plant residues inhibited the germination and growth of some other plant species. These knotweeds, which are non-mycorrhizal plants, also suppressed the abundance and species richness of arbuscular mycorrhizal fungi (AMF) in the rhizosphere soil. Such suppression was critical for most territorial plants to form the mutualism with AMF, which enhances the nutrient and water uptake, and the tolerance against pathogens and stress conditions. Several allelochemicals such as flavanols, stilbenes, and quinones were identified in the extracts, residues, and rhizosphere soil of the knotweeds. The accumulated evidence suggests that some of those allelochemicals in knotweeds may be released into the rhizosphere soil through the decomposition process of their plant parts, and the exudation from their rhizomes and roots. Those allelochemicals may inhibit the germination and growth of native plants, and suppress the mycorrhizal colonization of native plants, which provides the knotweeds with a competitive advantage, and interrupts the regeneration processes of native plants. Therefore, allelopathy of knotweeds may contribute to establishing their new habitats in the introduced ranges as invasive plant species. It is the first review article focusing on the allelopathy of knotweeds.

Germination and growth inhibitory sesquiterpene lactones and a flavone from Tithonia diversifolia

1994 ◽  
Vol 36 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Narayan C. Baruah ◽  
Jadab C. Sarma ◽  
Nabin C. Barua ◽  
Soneswar Sarma ◽  
Ram P. Sharma
Keyword(s):  
Sesquiterpene Lactones ◽  
Tithonia Diversifolia ◽  
Growth Inhibitory ◽  
Germination And Growth

Planting native trees to restore riparian forests increases biotic resistance to non-native plant invasions

2021 ◽  
pp. 1-24
Author(s):  
Chad F. Hammer ◽  
John S. Gunn
Keyword(s):  
United States ◽  
Ecosystem Service ◽  
Invasive Plant ◽  
Biotic Resistance ◽  
The United States ◽  
Tree Regeneration ◽  
Tree Planting ◽  
Plant Colonization ◽  
Native Plant ◽  
Native Trees

Abstract Non-native invasive plant species are a major cause of ecosystem degradation and impairment of ecosystem service benefits in the United States. Forested riparian areas provide many ecosystem service benefits and are vital to maintaining water quality of streams and rivers. These systems are also vulnerable to natural disturbances and invasion by non-native plants. We assessed whether planting native trees on disturbed riparian sites may increase biotic resistance to invasive plant establishment in central Vermont in the northeastern United States. The density (stems/m2) of invasive stems was higher in non-planted sites (x̄=4.1 stems/m2) compared to planted sites (x̄=1.3 stems/m2). More than 90% of the invasive plants were Japanese knotweed (Fallopia japonica). There were no significant differences in total stem density of native vegetation between planted and non-planted sites. Other measured response variables such as native tree regeneration, species diversity, soil properties and soil function showed no significant differences or trends in the paired riparian study sites. The results of this case study indicate that tree planting in disturbed riparian forest areas may assist conservation efforts by minimizing the risk of invasive plant colonization.

INHIBITION OF RESPIRATION, GERMINATION, AND GROWTH BY SUBSTANCES ARISING DURING THE DECOMPOSITION OF CERTAIN PLANT RESIDUES IN THE SOIL

1958 ◽  
Vol 36 (5) ◽  
pp. 621-647 ◽  
Author(s):  
Z. A. Patrick ◽  
L. W. Koch
Keyword(s):  
Plant Residues ◽  
Toxic Substances ◽  
Root Cells ◽  
Toxic Activity ◽  
Root Rots ◽  
High Soil Moisture ◽  
Heat Stable ◽  
Tobacco Seedlings ◽  
Ph Range ◽  
Germination And Growth

Substances capable of markedly inhibiting the respiration, germination, and growth of tobacco seedlings were obtained after residues from timothy, corn, rye, or tobacco plants had been allowed to decompose under appropriate conditions in the soil. Bio-assay tests, based on manometric methods, made it possible to determine some of the conditions under which the decomposition gave rise to phytotoxic by-products and to obtain rapidly an accurate measure of the degree of their toxicity. Among the factors influencing the production of the toxic products, the species and stage of maturity of plant material added, the water content and pH of the soil, and length of decomposition period seemed most important. Substances capable of reducing the respiration of tobacco seedlings by 50 to 90% were consistently obtained when any of the abovementioned plant residues had been decomposing for 15 to 25 days under conditions of high soil moisture and when the pH of the soil solution was below 5.5 throughout this period. Timothy gave rise to substances possessing the highest toxic activity, followed by corn, then rye, and finally tobacco. Aqueous extracts of unamended soil or of macerated plant tissues prepared either before decomposition had taken place or when decomposition was inhibited by autoclaving the soil were not toxic.The toxic substances, obtained by water extraction, exhibited an inhibiting effect on respiration of tobacco seedlings after an exposure of less than one hour and also induced darkening and necrosis of root cells. Some extracts affected the cells of the apical meristem most severely while others affected only the cells of the elongation region.While the toxic substances have not been identified, they were relatively nonspecific in their action, affecting tobacco, timothy, and barley in approximately the same manner and in many instances possessed also antifungal activity. They were soluble in water, insoluble in petroleum ether, stable in acid, and most active in the pH range 4.5 to 5.8. They were precipitated by alkali and the activity was markedly reduced when readjusted to the acid range. They were also heat stable and did not lose their activity in storage at 1°–3 °C. provided they were covered by a layer of toluene.Because of their rapid production and the marked injurious effects exerted on various plants it is believed that these toxins may perform a significant role in the field as the primary cause of some root rots and in predisposing plants to attack by organisms not normally regarded as pathogenic.

scholarly journals HERBICIDAL EFFICACY OF ROOT EXUDATES OF RICE (ORYZA SATIVA L.) ON BARNYARD GRASS (ECHINOCHLOA CRUS-GALLI L.)

2016 ◽  
Vol 3 (1) ◽  
pp. 26-29
Author(s):  
Prabhakaran J ◽  
Kavitha D
Keyword(s):  
Root Exudates ◽  
Oryza Sativa L ◽  
Dry Weight ◽  
Significant Inhibition ◽  
Rice Cultivars ◽  
Weed Species ◽  
Underground Part ◽  
Barnyard Grass ◽  
Crop Field ◽  
Germination And Growth

A laboratory study was conducted to assess the herbicidal potential of root exudates of three rice cultivars (ADT-36, BPT and IR-20) against germination and growth of common crop field weed, barnyard grass (Echinochloa crus-galli L.). Various concentrations (5, 10, 15 and 20%) of root exudates were prepared from the underground part of rice cultivars from the postharvest rice fields. The studies revealed that all the three rice cultivars were exhibited significant inhibition on growth and development of weed species. Among the rice cultivars, ADT-36 exhibited the greatest inhibition on the seed germination (86%), seedling growth(83%), dry weight (81%) of barnyard cross than BPT and ADT-36. The percentage of inhibition on concentration depends. The order of inhibition of the rice cultivars was ADT-36 > BPT > IR-20 on barnyard grass.

scholarly journals Are declines in insects and insectivorous birds related?

The Condor ◽  
2021 ◽  
Author(s):  
Douglas W Tallamy ◽  
W Gregory Shriver
Keyword(s):  
Plant Species ◽  
Invasive Plant ◽  
Bird Species ◽  
Insect Herbivores ◽  
Native Plant ◽  
Insectivorous Birds ◽  
Population Declines ◽  
Native Plant Species ◽  
Host Plant Specialization ◽  
Scale Population

Abstract A flurry of recently published studies indicates that both insects and birds have experienced wide-scale population declines in the last several decades. Curiously, whether insect and bird declines are causally linked has received little empirical attention. Here, we hypothesize that insect declines are an important factor contributing to the decline of insectivorous birds. We further suggest that insect populations essential to insectivorous birds decline whenever non-native lumber, ornamental, or invasive plant species replace native plant communities. We support our hypothesis by reviewing studies that show (1) due to host plant specialization, insect herbivores typically do poorly on non-native plants; (2) birds are often food limited; (3) populations of insectivorous bird species fluctuate with the supply of essential insect prey; (4) not all arthropod prey support bird reproduction equally well; and (5) terrestrial birds for which insects are an essential source of food have declined by 2.9 billion individuals over the last 50 years, while terrestrial birds that do not depend on insects during their life history have gained by 26.2 million individuals, a 111-fold difference. Understanding the consequences of insect declines, particularly as they affect charismatic animals like birds, may motivate land managers, homeowners, and restoration ecologists to take actions that reverse these declines by favoring the native plant species that support insect herbivores most productively.

scholarly journals Interactive effects of climate change and plant invasion on alpine biodiversity and ecosystem dynamics

2021 ◽  
Author(s):  
◽  
Justyna Giejsztowt
Keyword(s):  
Climate Change ◽  
New Zealand ◽  
Plant Species ◽  
Climate Warming ◽  
Plant Invasion ◽  
Invasive Plant ◽  
Ecosystem Dynamics ◽  
Interactive Effects ◽  
Native Plant ◽  
Competition For Pollination

<p>Drivers of global change have direct impacts on the structure of communities and functioning of ecosystems, and interactions between drivers may buffer or exacerbate these direct effects. Interactions among drivers can lead to complex non-linear outcomes for ecosystems, communities and species, but are infrequently quantified. Through a combination of experimental, observational and modelling approaches, I address critical gaps in our understanding of the interactive effects of climate change and plant invasion, using Tongariro National Park (TNP; New Zealand) as a model. TNP is an alpine ecosystem of cultural significance which hosts a unique flora with high rates of endemism. TNP is invaded by the perennial shrub Calluna vulgaris (L.) Hull. My objectives were to: 1) determine whether species-specific phenological shifts have the potential to alter the reproductive capacity of native plants in landscapes affected by invasion; 2) determine whether the effect of invasion intensity on the Species Area Relationship (SAR) of native alpine plant species is influenced by environmental stress; 3) develop a novel modelling framework that would account for density-dependent competitive interactions between native species and C. vulgaris and implement it to determine the combined risk of climate change and plant invasion on the distribution of native plant species; and 4) explore the possible mechanisms leading to a discrepancy in C. vulgaris invasion success on the North and South Islands of New Zealand. I show that species-specific phenological responses to climate warming increase the flowering overlap between a native and an invasive plant. I then show that competition for pollination with the invader decreases the sexual reproduction of the native in some landscapes. I therefore illustrate a previously undescribed interaction between climate warming and plant invasion where the effects of competition for pollination with an invader on the sexual reproduction of the native may be exacerbated by climate warming. Furthermore, I describe a previously unknown pattern of changing invasive plant impact on SAR along an environmental stress gradient. Namely, I demonstrate that interactions between an invasive plant and local native plant species richness become increasingly facilitative along elevational gradients and that the strength of plant interactions is dependent on invader biomass. I then show that the consequences of changing plant interactions at a local scale for the slope of SAR is dependent on the pervasion of the invader. Next, I demonstrate that the inclusion of invasive species density data in distribution models for a native plant leads to greater reductions in predicted native plant distribution and density under future climate change scenarios relative to models based on climate suitability alone. Finally, I find no evidence for large-scale climatic, edaphic, and vegetative limitations to invasion by C. vulgaris on either the North and South Islands of New Zealand. Instead, my results suggest that discrepancies in invasive spread between islands may be driven by human activity: C. vulgaris is associated with the same levels of human disturbance on both islands despite differences in the presence of these conditions between then islands. Altogether, these results show that interactive effects between drivers on biodiversity and ecosystem dynamics are frequently not additive or linear. Therefore, accurate predictions of global change impacts on community structure and ecosystems function require experiments and models which include of interactions among drivers such as climate change and species invasion. These results are pertinent to effective conservation management as most landscapes are concurrently affected by multiple drivers of global environmental change.</p>

Reduced competitive ability in an invasive plant

2004 ◽  
Vol 7 (4) ◽  
pp. 346-353 ◽  
Author(s):  
Oliver Bossdorf ◽  
Daniel Prati ◽  
Harald Auge ◽  
Bernhard Schmid
Keyword(s):  
Competitive Ability ◽  
Invasive Plant
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