Search results for "weed"

In vitro secretion of specific antimitochondrial antibodies in primary biliary cirrhosis

1992

Antimitochondrial antibodies are present in the serum of virtually all patients with primary biliary cirrhosis. They have a well-defined antigen reactivity that is diagnostic for the disease. The role of these autoantibodies in the disease process remains to be defined. In this study we show that antimitochondrial antibodies can be produced in vitro by peripheral blood lymphocytes, that the cells producing antimitochondrial antibodies are present in the peripheral blood in a high frequency and seem to be maximally activated. Stimulation with pokeweed mitogen did not augment the in vitro production of antimitochondrial antibodies in patients nor did it induce the production of these antibodi…

Glyphosate residues alter the microbiota of a perennial weed with a minimal indirect impact on plant performance

2021

Abstract Purpose In cold climates, glyphosate residues may linger in soils, with effects on plant–microbe interactions and, consequently, plant performance. Here, we explore the influence of glyphosate residues on the endophytic microbiota (bacteria and fungi) and performance of the perennial nitrogen-fixing weed Lupinus polyphyllus. Methods In a common garden, we grew plants from six populations of L. polyphyllus in glyphosate-treated or untreated control soils, with or without additional phosphorus. We sampled plant microbiota (leaves, roots, nodules) and assessed plant performance based on six traits: height, retrogression probability (i.e. shrinkage), biomass, root:shoot ratio, nodule n…

Gel-electrophoretic description of European populations ofTerellia virens (Loew) (Diptera, Tephritidae); implications for its use as an agent for the…

1991

Allozyme frequencies of 15 enzyme loci, 14 of which were polymorphic, were used to characterize sevenTerellia virens populations originating from three allopatrically distributedCentaurea species. The two populations whose origins were geographically furthest apart, from Israel (onC. iberica) and from Switzerland (onC. vallesiaca), showed relatively high values of genetic distance from the 5 populations sampled in Austria and Hungary (onC. maculosa) (Nei's D>0.07). The latter five displayed a high degree of genetic similarity. No diagnostic (fixed) allelic differences were observed between these three groups ofT. virens populations, but they could be well characterized by significant differ…

PHYTOTOXIC POTENTIAL OF EUCALYPTUS ESSENTIAL OILS FOR WEED CONTROL

2018

The widespread use of synthetic herbicides has resulted in herbicide-resistant weeds, disturbed ecological balance and negative effects on human health. Due to this fact, it is necessary to rely on alternative weed control strategies using natural compounds released by plants, such as essential oils (EOs). EOs have a short half-life since they are biodegradable, and are safer than synthetic compounds, with little damage to the environment, without even contaminating ground water (Topal and Kocaçalıskan 2006). Essential oils from different species contain allelochemical compounds that possess significant phytotoxic activity. Azizi and Fuji (2006) demonstrated that Eucalyptus (family Myrtacea…

Multistage recovery process of seaweed pigments: Investigation of ultrasound assisted extraction and ultra-filtration performances

2017

International audience; The objectives of this study were first to evaluate the performance of seaweed pigments’ recovery through ultrasound assisted extraction (UAE) and ultra-filtration (UF), and second to investigate the membrane fouling mechanism and evidence the threshold flux during filtration. The pigments’ recovery from the extract was performed using 5 kDa and 10 kDa ultra-filtration membranes. Results showed that increasing the extraction temperature in the range of 40–60 °C was proportional to chlorophyll extraction efficiency, while the maximal carotenoid yield was achieved at 50 °C. Ultrasonic power (from 100 W to 300 W) facilitated the extraction of both chlorophylls and carot…

Forage production, N uptake, N2 fixation, and N recovery of berseem clover grown in pure stand and in mixture with annual ryegrass under different ma…

2011

In Mediterranean countries, forage grasses and legumes are commonly grown in mixture because of their ability to increase herbage yield and quality compared with monocrop systems. However, the benefits of intercropping over a monocrop system are not always realized because the efficiency of a grass–legume mixture is strongly affected by agronomic factors. The present study evaluated productivity, N2 fixation, N transfer, and N recovery of berseem clover (Trifolium alexandrinum) grown in pure stand and in mixture with annual ryegrass (Lolium multiflorum) under high or low defoliation frequencies and varying plant arrangements (sowing in the same row or in alternating rows). On average, the b…

Uso di alcuni estratti vegetali come bio-erbicidi

2014

Le infestanti competono con le piante coltivate per la luce, gli elementi nutritivi, l'acqua e lo spazio, e influenzano fortemente le produzioni agrarie sia sotto l'aspetto quantitativo che qualitativo. Normalmente le infestanti riescono ad assorbire e utilizzare l'acqua e gli elementi nutritivi più rapidamente ed efficacemente delle colture principali, accrescendosi più velocemente di queste, fino, talvolta, ad inibirne del tutto lo sviluppo. Nel corso del tempo, alcune infestanti hanno sviluppato meccanismi di resistenza agli erbicidi comunemente utilizzati. Questa acquisizione, unitamente alla necessità di reperire soluzioni al problema della gestione delle infestanti anche in condizioni…

Rare and threatend pondweed communities in anthropogenic water bodies of Opole Silesia (SW Poland)

2007

Characterization of trophic links in an agrosystem : weed seed predation by carabid beetles

2012

Agroecology gives evidence of new perspectives in agriculture, and open doors for alternative weed management approaches through different regulation mechanisms. Seed predation is one of them, and the interest is growing to deepen knowledge, relative to this process. This Phd work aims (i) to describe weed seed predation, the dominant carabid predators and the available resource at a local scale in a common crop (winter wheat); (ii) to study predation profiles of main predators, and the pair-wise correlations between the biological components of the system; (iii) to bring new insights regarding potential regulation of weed communities, through seed predation by carabid beetles. Complementar…

The role of biotic interactions in a prey-predator system : the case of predation and regulation of weed seeds by carabids.

2020

For the transition towards agricultural production systems that are less dependent on herbicides, the use of weed regulation by seed-eating carabids is of great interest. Weed seed predation by carabids is variable and occurs within a complex context of many biotic interactions. This complexity partly explains our current inability to predict levels of in-field weed regulation. In this thesis, I analysed variations in the levels of predation and biological regulation of weeds and determined how they respond to two classes of biotic interactions: 1) the availability of alternative prey; and, 2) intra- and inter-specific interactions between the carabids themselves. Field measurements carried…