bluuebunny/crossref_metadata_2025_split huggingface dataset:
Utilisation des chlorelles pour le dosage biologique de l'atrazine dans le sol
Authors: LEFEBVRE‐DROUET E. , CALVET R. 
Published: September 2010

RésuméL'utilisation d'une culture de chlorelles dans des conditions expérimentales bien définies permet le dosage de I'atrazine bioactive du sol sans extraction préalable. La mise au point a été effectuée avec un matériau non adsorbant (sable). Des concentrations d'atrazine de 0.10μg g−1 de sable peuvent ainsi être détectées. et dosées avec précision à partir de 0.45 μg g−1 de sable. Des exemples d'application sont donnés pour des terres de composition très différentes. La comparaison avec la méthode utilisant les plantules d'avoine montre que la méthode proposée conduit à des résultats du même ordre de grandeur.
Movement of fluometuron and 36Cl− in soil under field conditions: computer simulations
Authors: GRAHAM‐BRYCE I.J. , NICHOLLS P.H. , BAKER R.J. , HANCE R.J. , EMBLING S.J. , HILL D. 
Published: September 2010

SummaryThe movement of chloride ion and the movement and degradation of fluometuron in two soils of contrasting texture and structure was predicted with a simulation model which included terms for the degradation of fluometuron as a function of temperature and moisture. The simulated distributions of soil water, chloride ion and fluometuron were compared with the observations reported in a previous paper (Hance, Embling, Hill, Graham‐Boyce & Nicholls, 1981), Soil waler contents and fluometuron distribution were simulated reasonably accurately. Movement of chloride to below 30 cm in both soils and degradation of fluometuron in the WRO sandy loam soil were not well simulated. The discrepancies between observed and predicted water contents and chloride distribution show the importance of measuring dynamic as well as static water properties. Therefore refined simulation models may need to account for pore continuity, soil particle movement and mobile and immobile categories of water.
Measurement of weed species diversity in crop/weed competition studies
Authors: TOPHAM P. B. , LAWSON H. M. 
Published: September 2010

SummaryData on dry matter accumulation by weeds in the presence or absence of two densities of vining peas was used to compare six diversity indices as measures of changes in the structure and behaviour of the weed flora. Analysis of variance was carried out for each index and the residuals were examined for skewness, kurtosis and heteroscedasticity. Indices based on species number (richness) and species evenness were found to be effective and reliable over the wide range of data examined and permitted new information to be derived. They showed that while increasing competition from the pea crops suppressed weed growth and reduced the number of species recorded at successive sampling dates, there was no selection pressure and species evenness was not reduced.
The control of Holcus lanatus in perennial ryegrass swards by asulam.
Authors: KIRKHAM F. W. , HAGGAR R. J. , WATT T. A. 
Published: September 2010

SummaryAsulam was evaluated in three fields experiments for the control of Yorkshire fog (Holcus lanatus L.) in perennial rygrass(Lolium perenneL). It was used in 1976 on a 3 year‐old ryegrass/timothy (Phleum pratense L.) sward in comparison with propyzamidc, in 1977 on a 9 year‐old ryegrass pasture grazed at two stocking rates and in 1978 on an intensively managed ryegrass dominant sward. Asulam at 1.75 kg ha−1 gave good selective control in all the field experiments and was more effective under higher than lower slocking rates. In laxly grazed swards it was most effective when sprayed in October. Propyzamide also controlled H. lanatus and increased yields of while clover (Trifolium repens L.) even at 0.25 kg ha−1 but it damaged the sown grasses and increased the growth of broad‐leaved weeds.
Threshold level and seed production of velvetleaf (Abutilon theophrasti Medicus) in maize
Authors: ZANIN G. , SATTIN M. 
Published: September 2010

SummaryFour tests were carried out in 1980 and 1981 to determine: (a) the economic threshold density of Abutilon theophrasti Medicus (velvetleaf) in maize, and (b) seed production with varying densities of infestation, both in the presence and in the absence of maize. The infestation was artificially created, and the density of the weed ranged from 0 to 80 plants m−2. The economic threshold, calculated using the Cousens (1987) model, varied between 0⋅3 plants m−2 and 2⋅4 plants m−2, depending on the variables considered. The presence of maize reduced the seed‐rain of A. theophrasti by 50%. This seed‐rain reached its maximum level at 20–30 plants m−2 in maize, and at 30–35 plants m−2 in weed monoculture. However, with only 4–5 plants m−2 in competition with maize, A. theophrasti produced 8–10 thousand seeds m−2. The usefulness of threshold density in weed management is debatable when one considers the ecological characteristics of the A. theophrasti seed, and the great capacity of seed production of this weed.
Preventing stump regrowth with a herbicide‐applying tree cutter
Authors: JOHANSSON T. 
Published: September 2010

SummaryTen‐year‐old birches (Betula spp.) and 15‐year‐old aspens (Populus tremula L.) in field were cut and treated by the 'selective cutter', which also wetted the mantle area of the stump. Twenty per cent glyphosate, applied at the rate of 0⋅38 ml per cm stump diameter and 10% imazapyr at 0⋅14 ml per cm stump diameter, effectively killed the stumps or prevented sprouting. The cutter worked adequately.
Seeds in a rainforest soil and their relation to shifting cultivation in the Ivory Coast
Authors: de ROUW ANNEKE , van OERS CATHARINA 
Published: September 2010

SummaryIn the Taï region of the Ivory Coast, mature forest is felled and burned and a crop of rice is grown; forest is then allowed to regenerate for 20 or more years before being cropped again. The top 10 cm of soil beneath a 21‐year‐old forest prior to felling contained 2000 viable seeds m−2 of mainly woody species of previous successional stages no longer represented in the vegetation. Seedling emergence was greater in full sunlight than under leaf canopy, especially for herbaceous species of open habitats. Burning destroyed almost half of the seeds, but overall germination of those that survived was advanced by about 2 weeks. Germination of some common pioneer species was enhanced by the fire. Provided that burning took place and the rice was planted immediately, vegetation arising from the seed bank did not present a problem. The density never exceeded 70 seedlings m−2 and little or no weeding was required. Species present at densities greater than 1 seedling 10 m−2 were all recorded in the seed bank.
Uptake, translocation and phytotoxicity of root‐absorbed haloxyfop in soybean, Festuca rubra L. and Festuca arundinacea Schreb
Authors: AGUERO‐ALVARADO R. , APPLEBY A.P. 
Published: September 2010

Summary:The concentrations of haloxyfop in nutrient solution required to reduce the total plant dry weight of soybean (Glycine max L. Merr. ‘Evans’), red fescue (Festuca rubra L. ‘Pennlawn’), and tall fescue (Festuca arundinacea Schreb. ‘Houndog’) by 50% (GR50) were determined. The GR50) values for soybean, red fescue and tall fescue were 76 μM, 3μM and 0.4 μM, respectively. The reduction in growth in roots and shoots of soybean was similar. In contrast, the relative reduction in root tissue weight was greater than that for foliar tissue in both grass species. The amount of 14C‐haloxyfop in soybean roots or shoots was higher than in red fescue or tall fescue. Red fescue accumulated less haloxyfop in the foliage than in the roots. On the other hand, similar amounts of 14C‐haloxyfop accumulated in both organs in both soybean and tall fescue. 14C‐haloxyfop appeared to be actively absorbed by the roots of all species. Soybean absorbed more nutrient solution, but utilized it less on a per gram dry matter produced basis than the grass species. Differences in the uptake and translocation of haloxyfop by roots do not account for differences in tolerance between species. However, a higher level of retention of haloxyfop in the roots of red fescue than in tall fescue may provide the former with an additional selectivity advantage under conditions where there is significant root exposure to the herbicide.
Homoclime analysis and the prediction of weediness
Authors: PANETTA F. D. , MITCHELL N. D. 
Published: September 2010

Summary:Homoclime analysis of three weed species of potential significance to agriculture in New Zealand was undertaken. Using the Bio‐climate Prediction System computer program (BIOCLIM), climatically suitable regions in New Zealand were estimated for Homeria flaccida Sweet, Chondrilla juncea L. and Emex australis Steinh., on the basis of their respective distributions in Australia. These estimates indicated that the current eradication campaign for Homeria is warranted, owing to the existence of extensive areas with a suitable climate on both of New Zealand's main islands. For Homeria, most of the known occurrences fell within regions predicted to be climatically suitable. For Chondrilla, only very small areas were predicted to be climatically suitable, due to the generally low temperatures that prevail during its reproductive period. This suggests that the designation of Chondrilla as a quarantine pest may be unwarranted. Much of the land in the interior of the North Island was estimated to be climatically suitable for Emex. However, invasion has not occurred, despite the presence of this weed in New Zealand for over 100 years. The failure of Emex to invade perennial pastures is probably a result of its poor competitiveness, since climatic and edaphic characteristics appear to be suitable over large areas. It is concluded that homoclime analysis can be used to identify regions at risk of invasion by a species which has been weedy elsewhere, when potentially modifying factors such as soils, land use/management practices and competitive interactions are taken into account.
The interaction between planting depth of four winter wheat cultivars, Alopecurus myosuroides Huds. and Bromus sterilis L. and their susceptibility to post‐emergence applications of isoproturon and chlorotoluron
Authors: BLAIR A. M. , MARTIN T. D. , BRAIN P. , COTTERILL E. G. 
Published: September 2010

Summary:Seeds of four winter wheat cultivars, Slejpner, Galahad, Avalon and Penman, were sown at depths ranging from 6–75 mm in soil in pots, and isoproturon or chlorotoluron was then applied to the soil surface. For chlorotoluron‐treated plants (both pre‐ and post‐emergence) the dose required to produce a 50% effect (ED50) was unaffected by depth of planting. In contrast, for isoproturon applied pre‐emergence, the ED50 for both Avalon and Slejpner was strongly affected by sowing depth. Although chlorotoluron was much more active in a second experiment when applied post‐emergence to Slejpner wheat, the ED50 for both herbicides increased with greater depth of sowing. Protection of wheat from isoproturon damage by deeper planting was enhanced if the adsorption capacity of the soil was raised from Kd 0.5 to 2.0 by incorporation of activated charcoal in the soil. Isoproturon entry into plants (as measured by the effect on rate of photosynthesis) was slower in those that had been sown deeper and were growing in more adsorptive soils, but there was no obvious relationship between these observations and isoproturon distribution in the soil profile. In nutrient culture the four wheat cultivars responded similarly to a range of doses of isoproturon. The chlorotoluron‐sensitive cultivars, Slejpner and Galahad, were damaged by much lower doses of chlorotoluron than were Avalon and Penman. Bromus sterilis L. responded similarly to wheat with regard to its interaction with isoproturon and planting depth. Alopecurus myosuroides Huds., however, was less damaged by isoproturon when the zone above the seed was protected from the herbicide by growing the shoot through a plastic straw.
The influence of leaf blade, nutrients, water and light on the promotion of axillary bud growth of isolated single‐node stem segments of Paspalum distichum L
Authors: LIU S.H. , HSIAO A.I. , QUICK W.A. 
Published: September 2010

Summary:The presence of the leaf blade for 5 days or longer on isolated single‐node stem segments of Paspalum distichum with an adequate supply of nutrients, water and light, produced better axillary bud growth than was observed on those segments without the leaf blade. Presence or absence of the leaf blade had no effect on segments in distilled water. Segments in Hoagland's solution of any strength exhibited significantly more growth than those in distilled water. In one‐half or full‐strength Hoagland's solution, segments generally showed signifi cantly more growth than segments in lower strength solutions. Segments subjected to flooding, daily watering, submergence or hydro‐ponic treatments exhibited significantly more growth than the segments that were watered every 3 days. Segments with the leaf blade retained, and those exposed to constant light, showed significantly better growth than segments without an attached leaf blade, or without light. It is concluded that the interactions between leaf blade, water, nutrients and light, which favoured photosynthesis and reduced transpiration, increased axillary bud growth. This interaction may provide a survival mechanism for isolated stems of P. distichum, assisting its rapid spread in wetlands.
Germination of seeds from plants of Avenafatua L. treated with glyphosate
Authors: SHUMA J. M. , QUICK W. A. , RAJU M. V. S. , HSIAO A. I. 
Published: September 2010

SummaryGlyphosate was applied at four rates under greenhouse conditions to Avena fatua L. plants at four stages of seed development. Application at anthesis completely prevented the formation of viable seeds. Application five days after anthesis (DAA) of the terminal floret of the panicle significantly reduced seed production at all herbi‐cide rates used, and at 1.76 kg a.i. ha‐1 no viable seeds were produced. When applied 10 DAA, only the highest rate of glyphosate resulted in substantial reduction in number of primary seeds, but seed viability suffered at all herbicide levels. Glyphosate applied 15 DAA still produced a significant decrease in primary and secondary seed production and biomass. Both the viability and the germination rate of seeds from treated plants were significantly affected. When the herbicide was applied to plants 5 DAA, no viable seeds were produced by plants surviving the highest rate, and all rates significantly reduced germination. Glyphosate applied 10 DAA significantly suppressed germination, with 1.76 kg a.i. ha‐1 being the most effective rate. When applied to plants 15 DAA, only the highest rate of glyphosate significantly affected the overall germination of both primary and secondary seeds, but the normal imposition of dormancy was partially blocked in seeds from plants treated with 0.44 and 0.88 kg a.i. ha‐1. These findings are relevant to chemical summerfallow and crop desiccation practices.
Dégradation de l'isoproturon et disponibilité de ses résidus dans le sol
Authors: PERRIN‐GANIER C. , SCHIAVON M. , PORTAL J.‐M. , BABUT M. 
Published: September 2010

RésuméLa disponibilité et la dégradation de l'isoproturon dans le sol au cours du temps ont étéévaluées pendant 140 jours dans une expérience de laboratoire en conditions contrôlées à l'aide de la molécule marquée au 14C sur le cycle. L'état de dégradation de la matière active a été suivi: après 65 jours, l'isoproturon extractible ne représente plus qu'une très faible part (0,6%). Le monodéméthyl‐isoproturon est mesurable dès le 15ème jour (2,6%). La mesure du 14CO2 provenant de la dégradation du cycle benzénique et dégagé au cours du temps donne un total de 13,6% d'isoproturon minéralisés durant l'incubation. Parallèlement, les quantités de résidus extractibles (par l'eau puis par le méthanol) ou subsistant dans le sol quelle que soit leur forme (dosage par combustion) ont été successivement mesurées. Après 140 jours, 72% de la radioactivité apportée se trouve sous forme non extractible dans le sol. La demi‐vie de la matière active isoproturon extractible est estimée à 14 jours.
An assessment, using a modelling approach, of inbreeding as a possible cause of reduced competitiveness in triazine‐resistant weeds
Authors: MADDEN A. D. 
Published: September 2010

SummaryIt is widely assumed that organisms that evolve resistance to a triazine suffer from a fitness deficit in the absence of that herbicide. Arguments for this view are examined, and previously published evidence is discussed. A simple model was developed to examine the genetics of resistance in triazine‐resistant plants, based on the assumption that a founder effect is in operation. The model examined the hypothesis that the extent to which plants in the sprayed population are related will increase rapidly under continual selection, even when there is a significant input of genes from non‐selected populations. The possible consequences of the above hypothesis on the validity of competition experiments are discussed.
Dégradation du chlorimuron‐éthyle déposé sur divers minéraux et sur acides humiques
Authors: SABADIE J. 
Published: September 2010

RésuméLa dégradation chimique du chlorimuron‐éthyle et du chlorimuron a étéétudiée à 30°C au contact de quatre solides minéraux secs (kaolin, silice, bentonite H+, montmorillonite K10) et d'acides humiques solides. Dans tous les cas, on observe la coupure de la fonction sulfonylurée de la molécule conformément au processus précédemment observé en solution aqueuse acide. La cyclisation en saccharine du phényl‐sulfonamide formé n'est observée qu'au contact des minéraux peu acides (kaolin, silice) tandis que la pyrimidamine. autre produit d'hydrolyse, présente une certaine affinité pour les solides minéraux plus acides (bentonite H+, montmorillonite K10) et les acides humiques.
Discovery of an isolate of Fusarium oxysporum with potential to control Striga hermonthica in Africa
Authors: CIOTOLA M. , WATSON A. K. , HALLETT S. G. 
Published: September 2010

SummaryNative fungi of West Africa were evaluated as a means to control Striga hermonthica (Del.) Benth., a troublesome parasitic weed of several gramineous crops. An isolate of Fusarium oxysporum, grown on sorghum straw and incorporated into pots, successfully prevented all emergence of S. hermonthica, and resulted in a 400% increase of sorghum dry weight. The fungus inhibited germination and attachment of S. hermonthica to sorghum roots in Plexiglas root chambers. Several crop species, including sorghum, inoculated with the fungus showed neither any disease symptoms nor any reduction in biomass.
Impact of post‐emergence herbicides on weed community diversity within conservation‐tillage systems
Authors: DERKSEN D. A. , THOMAS A. G. , LAFOND G. P. , LOEPPKY H. A. , SWANTON C.J. 
Published: September 2010

SummaryThe influence of herbicides on weed community dynamics is an issue of agroecological concern. A field study was initiated in 1986 with zero‐, minimum‐, and conventional‐tillage systems. In 1989 and 1990, the fourth and fifth years of study, weed community diversity and relative composition were assessed prior to and following the application of post‐emergence non‐residual herbicides. Weed communities were assessed at the level of tillage system to balance the effect of different crop sequences and crop‐herbicide combinations within each comparison. In general, herbicides did not reduce community diversity when compared by Shannon's H’and dominance‐diversity curves. An increase in species richness and evenness, as assessed by Shannon's E and Margalef's DMG occurred in some cases. Differences in relative community composition among tillage systems were apparent before the application of herbicides, but disappeared following herbicide application. The use of herbicides in this study reduced weed densities, maintained weed diversity, and inhibited community changes that were due to changing tillage systems.
Growth and yield responses of Italian ryegrass (Lolium multiflorum) to diclofop‐methyl and ozone
Authors: MARTÍNEZ‐GHERSA M A , OLSZYK D , RADOSEVICH S R 
Published: September 2010

SummaryWe evaluated the combined effects of diclofop‐methyl herbicide application and the air pollutant ozone (O3) on diclofop‐methyl‐resistant and ‐susceptible biotypes of Italian ryegrass (Lolium multiflorum). We conducted two experiments, one with a long vegetative growth period and the other with a short vegetative growth in late spring with seed production in summer. As expected, because of its phytotoxicity, the herbicide alone reduced total vegetative biomass, leaf area, tiller number and seed production at most sampling periods in susceptible plants for both experiments. However, it had variable effects on resistant plants, including a positive effect on seed production. Ozone alone delayed vegetative biomass accumulation and reduced leaf area and seed biomass in both experiments. However, the effects of O3 on some parameters were altered by herbicide rate and/or biotype. Especially notable was a greater reduction in seed biomass because of O3 in resistant than in susceptible plants with no herbicide. If these apparent differential responses to herbicide and O3 stress of susceptible and resistant plants are confirmed and persist over time, evolutionary tradeoffs may occur. For example, the frequency of resistant plants in a population may be altered in response to interactions between herbicides and other anthropogenic stresses.
Apera spica‐venti population dynamics and impact on crop yield as affected by tillage, crop rotation, location and herbicide programmes
Authors: MELANDER B , HOLST N , JENSEN P K , HANSEN E M , OLESEN J E 
Published: September 2010

Summary Apera spica‐venti is a winter annual grass and, increasingly, a severe weed problem in autumn‐sown crops. Non‐inversion tillage has become more common in Denmark in recent years, but may accentuate problems with A. spica‐venti. These problems may be avoided, if selected preventive and cultural weed management practices are adopted. To this end, we conducted a 4‐year field study investigating the effects of crop rotation, tillage method, location and limited herbicide input on A. spica‐venti population dynamics and crop yield. Additionally, detailed studies were performed on the fate of A. spica‐venti seeds when incorporated to different soil depths. The location with a lighter soil texture, cooler climate and higher rainfall favoured A. spica‐venti growth and consequently crop yield loss, especially in the crop sequence comprised only of autumn‐sown crops and with non‐inversion tine tillage. Incorporating A. spica‐venti seeds in the soil improved their survival, explaining the higher A. spica‐venti proliferation seen with tine tillage as opposed to direct drilling. The rotations including an even mixture of spring‐ and autumn‐sown crops did not lead to noteworthy changes in the A. spica‐venti population, irrespective of tillage method. Thus, in many regions, management of A. spica‐venti will require rotations that balance autumn‐ and spring‐sown crops.