bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolution des hydrates de carbone non structuraux chez la morelle jaune (Solatium elaeagnifolium Cav.)
Authors: BOUHACHE M. , BOULET C. , EL KARAKHI F. 
Published: July 2006

Résumé: Summary: ZusammenfassungLes teneurs en hydrates de carbone non structuraux (TNC) des racines, collets et tiges des in‐dividus de la morelle jaune (Solarium elaeagnifolium Cav.) issue des bordures, champ de cotonnier et verger d'oliviers ont été déter‐minées mensuellement pendant une année. Les racines et, dans une certaine mesure, les collets ont été les organes où les réserves glucidiques étaient les plus importantes. Ces glucides ont atteint leur niveau le plus bas au moment de la formation des boutons floraux. La reconstitution des réserves en TNC a lieu entre la floraison et la maturation des fruits sur une durée de 2, 4 et 5 mois pour les individus issus du champ de cotonnier, des bordures et du verger d'oliviers, respec‐tivement. L'évolution des TNC est plus influencée par le stade phénologique de l'espèce que par rhumidité et la température du sol. Les implications de ces réquitals pour définir une stratégic de lutte centre la morelle jaune sont également discutées. Seasonal changes in non‐structural carbohydrates in silver‐leaf nightshade (Solanum elaeagnifolium Cav.)The levels of non‐structural carbohydrates (TNC) in the roots, root collar and stems of S. elaeagnifolium collected from field margins, cotton fields and olive plantations were determined monthly over a period of 1 year. The roots, and to a certain extent the root collar, were the organs with the largest carbohydrate reserves. The carbohydrate level was lowest at the time of flower bud formation. There was a build‐up of TNC reserves between flowering and fruit maturation over periods of 2, 4 and 5 months from plants growing in cotton fields, field margins and olive plantations respectively. Changes in TNC are influenced more by the phenological stage of the plant than by soil humidity or temperature. The implications of these findings in defining a control strategy for this weed are discussed. Saisonale Einlagerung von Kohlenwasserstoffen beim Ölweidenblättrigen Nachtschatten (Solanum eleagnifolium Cav.)Die Gehalte unstrukturierler Kohlenwasser‐stoffe (TNC) des Wurzeln, des Wurzelhalses und des Sprosses von Solanum elaeagnifolium Cav. von Feldrainen, Baumwollfeldern und Olivengärten wurden monatlich über l Jahr hin bestimmt. Die Wurzeln und in bestimmten Maβe der Wurzelhals waren die Pflanzenteile, in denen die Kohlenwasserstoffe die wichtigsten Re‐servesubstanzen waren; sie hatten ihr nie‐drigstes Niveau zur Blütenbildung. Der Wiederaufbau dieser Reservestoffe zwischen der Blüte und der Fruchtreife dauerte bei den Pflanzen auf den Baumwollfeldern, den Feldrainen und den Olivengärten 2, 4 bzw. 5 Monate. Die Kohlenhydratbildung wurde mehrnach den Entwicklungsstadienals durch Boden feuchte und‐temperatur beeinflußt. Die Aspekte dieserUntersuchungsergebnisse für die Bekämpfung dieses Unkrauts werden diskutiert.
Paraquat resistance in a biotype of Vulpia bromoides (L.) S. F. Gray
Authors: PURBA E. , PRESTON C. , POWLES S. B. 
Published: July 2006

Summary: Résumé: ZusammenfassungA biotype of Vulpia bromoides from a lucerne field in Elmhurst, Victoria, Australia was shown to be resistant to paraquat in pot trials. Application of paraquat at 50 g a.i. ha−1 killed all of the plants of a susceptible Vulpia bromoides biotype but only 6% of the resistant biotype. The LD50 for paraquat of the resistant biotype was five‐ to sixfold higher than for the susceptible biotype. The resistant biotype was also resistant to the bipyridyl herbicide diquat, but was susceptible to glyphosate and metribuzin. Application of 100 g a.i. ha−1 paraquat at anthesis completely suppressed seed set of the susceptible biotype and reduced that of the resistant biotype by 95%. Seed set by the paraquat‐treated resistant biotype, however, showed little reduction in germination. This is the fourth species to have been found to be resistant to bipyridyl herbicides in this field, the others being Hordeum glaucum, H. leporinum and Arctotheca calendula. Résistance au paraquat d'un biotype de Vulpia bromoides (L.) S. F. GrayUn biotype de Vulpia bromoides issu d'un champ de luzerne à Elmhurst, Victoria, Australie s'est révélé résistant au paraquat lors d'essais en pots. Des traitements au paraquat 50 g m.a. ha−1 détruisaient toutes les plantes d'un biotype sensible de V. bromoides mais seulement 6% du biotype résistant. La DLV50 du paraquat pour ce biotype était 5 à 6 fois plus élevée que pour le biotype sensible. Le biotype résistant l'était aussi à l'herbicide bipyridyle diquat, mais était sensible au glyphosate et à la métribuzine. Des traitements au paraquat 100 g m.a. ha−1 au stade anthèse supprimaient complètement la production de graines du biotype sensible et réduisait de 95% celle du biotype résistant. Cependant, le pouvoir germinatif des graines issues du biotype résistant traité, n'était que peu réduit. Après Hordeum glaucum, Hordeum leporinum et Arctotheca calendula, c'est la quatrième espèce trouvée dans ce même champ résistante aux herbicides bipyridyles. Paraquatresistenz eines Biotyps von Vulpia bromoides (L.) S. F. GrayEin Biotyp von Vulpia bromoides von einem Luzernefeld in Elmhurst, Victoria, Australien, erwies sich in Topfversuchen als paraquatresistent. Mit 50 g AS ha−1 wurden Pflanzen eines empfindlichen Biotyps abgetötet, jedoch nur 6% des resistenten. Die LD50 des resistenten Biotyps für paraquat war 5‐ bis 6mal höher als die des empfindlichen Biotyps. Der resistente Biotype war auch gegenüber dem Bipyridylherbizid Deiquat résistent, gegenüber Glyphosat und Metribuzin jedoch empfindlich. Nach Anwendung von 100 g AS ha−1 Paraquat vor der Blüte bildeten sich bei dem empfindlichen Biotyp keine Samen aus, bei dem resistenten waren sie um 95% vermindert; die dennoch gebildeten Samen keimten etwas weniger. Dies ist die vierte Pflanzenart, bei der eine Resistenz gegenüber Bipyridylherbiziden beobachtet wurde, die anderen sind Hordeum glaucum. Hordeum leporinum und Arctotheca calendula.
Estimation of economic thresholds for weed control in winter wheat
Authors: ZANIN G. , BERTI A. , TONIOLO L. 
Published: July 2006

Summary: Résumé: ZusammenfassungThresholds for winter wheat weed control have been determined for different herbicides or mixtures effective against individual weed species. For Avena sterilis L. subsp. ludoviciana (Durieu) Nyman the economic threshold was between 7 and 12 plants m−2, for Alopecurits myosuroides Hudson and Lolium multiflorum Lam. it varied between 25 and 35 plants m−2, while for Bromus sterilis L. the values were just under 40 plants m−2. For Galium aparine L. the threshold was as low as 2 plants m−2, while for Vicia sativa L. it was between 5 and 10 plants m−2. Within the same species the different values of economic threshold result from the different costs and efficacy of herbicides. Nitrogen fertilization was important: in its absence, the competitiveness of B. sterilis and G. aparine was negligible, and it was not possible to calculate an economic threshold for some of the treatments which could not be justified economically. Estimation de seuils économiqu.es de désherbage chez le blé d'hiver Les seuils économiques de désherbage du blé d'hiver ont été determinés pour différents herbicides, seuls ou en mélanges, pour plusieurs espèces demauvaises herbes. POUT Avena sterilis L. subsp. ludoviciana (Durieu) Nyman, le seuil économique était compris entre 7 et 12 plantes m−2. PourAlopecurus myosuroides Hudson et Lolium multiflorum Lam., il variait entre 25 et 35 plantes m−2 et était juste au‐dessous de 40 plantes m−2 pour Bromus sterilis L. Pour Galium aparine L., le seuil était2 plantes m−2 et était compris entre 5 et 10 plantes m−2 pour Vicia sativa L. Les différences de seuil pour une même espèce sont dues aux différences de coût et d'ef‐ficacité des herbicides. Le rôle de la fertilisation azotVe Vtait important: en son absence, le pou‐voir compVtitif de B. sterilis et de G. aparineétait négligeable, et il n'était pas possible de calculer de seuil économique pour certains traitements, qui ne pouvaient se justifier économiquement. Bestimmung von wirtschaftlichen Schadensschwel‐lenfiirdie Unkrautbekdmpfung in Winterweizen Für verschiedenen Herbizide und ‐mischungen wurden entsprechend ihrer Wirksamkeit gegenüber bestimmten Unkrautarten Schadensschwellen zur Unkrautbekämpfung inWinterweizen bestimmt. Für Avena sterilis L. spp. ludoviciana (Durieu) Nyman lag die Schadensschwelle zwischen 7 und 12 Pflanzen m−2, fur Alopecurus myosuroides Hudson und Lolium multiflorum Lam. variierte sie zwischen 25 und 35 Pflanzen m−2, während die Werte für Bromus sterilis L. bei knapp 40 Pflanzen m−2 lagen. Bei Galium aparine L. war die Schadensschwelle ganz niedrig, nämlich 2 Pflanzen m−2, während sie für Vicia sativa L. zwischen 5 und 10 Pflanzen m2 betrug. Fiir ein und die‐selbe Art ist die okonomische Schadensschwelle je nach den Kosten und der Wirksamkeit der Herbizide unterschiedlich. Die Stickstoffdün‐gung ist zu beachten: wenn sie fehlt, ist die Konkurrenz durch Bromus sterilis und Galium aparine verachlässigbar, so daß keine gerechtfertigten ökonomischen Schadensschwellen berechnet werden konnten.
Effect of crop density on competition by wheat and barley with Agrostemma githago and other weeds
Authors: DOLL H. , HOLM U. , SØSGAARD B. 
Published: July 2006

SummaryThe effect of Agrostemma githago L. and other naturally occurring weeds on biomass production and grain yield was studied in winter wheat and winter barley. Naturally occurring weeds had only a negligible effect on barley, but reduced wheat grain yield by 10% at a quarter of normal crop density. The interaction between the cereals and A. githago was studied in additive series employing different crop densities. Growth of this weed species was strongly dependent on crop density, which was more important for controlling weed growth than it was for obtaining a normal grain yield. Wheat and especially barley had a better competitive ability than A. githago. Wheat and A. githago utilized resources for growth better when grown in mixture than when grown in pure stands as the relative yield totals were significantly larger than unity.
Losses in grain yield of winter crops from Lolium rigidum competition depend on crop species, cultivar and season
Authors: LEMERLE D. , VERBEEK B. , COOMBES N. 
Published: July 2006

SummaryThe competitive abilities of eight winter crops were compared against Lolium rigidum Gaud, (annual ryegrass), an important weed of southern Australia, as a potential strategy to suppress weeds and reduce dependence on herbicides. Two cultivars of each species were chosen to represent the range of competitive ability within each crop and grown in field experiments in 1992 and 1993. The order of decreasing competitive ability (with the ranges of percentage yield reduction from L. rigidum at 300 plants m−2 in parenthesis) was as follows: oats (Avena sativa L.), 2–14%; cereal rye (Secale cereale L.), 14–20%; and triticale (×Triticosecale), 5–24%; followed by oilseed rape, (Brassica napus L.), 9–30%; spring wheat (Triticum aestivum L.), 22–40%; spring barley (Hordeum vulgare L.), 10–55%; and, lastly, field pea (Pisum sativum L.), 100%, and lupin (Lupinus angustifolius L.), 100%. Differences in competitive ability of cultivars within each species were identified, but competition was strongly influenced by seasonal conditions. Competition for nutrients (N, P and K) and light was demonstrated. L. rigidum dry matter and seed production were negatively correlated with grain yield of the weedy crops. More competitive crops offer the potential to suppress grass weeds while maintaining acceptable grain yields. Ways of improving the competitive abilities of grain legume crops are discussed.
On the inheritance of tolerance to chlorotoluron application in wheat using a very efficient score test
Authors: SIXTO H. , SILVELA L. , ESCORIAL C. , GARCIA‐BAUDIN J.M. , CHUECA M.C. 
Published: July 2006

SummaryWe present a nondestructive, easy to handle, cheap, fast and efficient assay to score wheat responses to herbicides. The application of the assay is illustrated by the reactions of the bread wheat cultivars ‘Castan’ and ‘Recital’ to the urea her‐bicide, chlorotoluron. The results not only confirm the presence of a major tolerant allele controlling the differences in response between the two cultivars, but also, show the contributions of modifier genes present in ‘Castan’, ‘Recital’ and other related cultivars.
Alcoolyse et hydrolyse chimique du chlorimuron éthyle
Authors: SABADIE J. 
Published: July 2006

Summary: RésuméLa coupure de la fonction urée est seule observée au cours de 1'alcoolyse (méthanol ou éthanol) et de l'hydrolyse (pH8) du chlorimuron éthyle à 30°C ou 50°C. La pyrimidinamine est quantitativement formée dans tous les cas accompagnée des carbamates correspondants (alcoolyse) ou du phénylsulfonamide (hydrolyse) quise cyclise facilement en saccharine (pH6). L'hydrolyse du substituant carbéthoxy porté par le noyau aromatique de l'herbicide devient prépondérante en solution alcaline. Les constantes de vitesse du premier ordre cinétique ont été précisées. La déméthylation du chlorimuron éthyle n'a pas été détectée. Alcoholysis and chemical hydrolysis of chlorimuron ethyl Alcoholysis (methanol or ethanol) and hydrolysis (pH8) of the herbicide chlorimuron ethyl at 30°C or 50°C involved only the breakdown of the urea function. The pyrimidinamine is always obtained in high yield along with the corresponding carbamate (alcoholysis) or phenylsulfonamide (hydrolysis). This compound was easily cyclized to saccharin (pH6). In alkaline solution, the carbethoxy substituent of the aromatic ring was preferentially hydrolysed. The first order kinetic constants were characterized. No formation of desmethyl chlorimuron was observed.
Weed communities in intensified cereal‐based cropping systems of the northern Guinea savanna
Authors: WEBER G. , ELEMO K. , LAGOKE S. T. O. 
Published: July 2006

SummaryThe dynamics of weed populations were ana lysed in intensified cereal‐based cropping sys tems of the northern Guinea savanna in Nigeria, A total of four common weed associations were identified through cluster analysis. Five factors describing soil fertility conditions and field his tory best differentiated the weed communities according to a discriminant model. The analysis shows that maize‐based cropping systems with a high frequency of cereal cropping and a low fre quency of noncereal cropping tended to be domi nated by weeds such as Commelina spp. and Kyllinga squamulata. As soil fertility declined, Vernonia spp. and Eclipta prostrata became more important. Increased frequency of noncereal crops in mixed cropping with cereals was associ ated with reduced incidence of weeds such as Leucas martinicensis, Oldenlandia corymbosa, Spermacoce verticillata, Litdwigia hyssopifolia, Celosia laxa, and,Ipomoea spp. Further diversifi cation of cereal‐based systems to obtain a re duced frequency of cereals is likely to increase the incidence of Dactvloctenium aegyptium in crop fields. The information provides guidance for technology development and transfer on weed control for intensifying systems in the northern Guinea savanna of Africa.
A bioassay method for formulation testing and residue studies of sulfonylurea and sulfonanylide herbicides
Authors: STORK P. , HANNAH M. C. 
Published: July 2006

SummaryA bioassay method using the radicles of pea (Pisum sativum L.) and lupin (Lupinus angustifolius L.) was developed for the assessment of trials on herbicides of common use in the sulfonylurea class (chlorsulfuron, triasulfuron and metsulfuron‐methyl) and in the sulfonanylide class (flumetsulam and metosulam). Soils within a range of pH 5.8–8.4 with textures from sand to clay were used in these experiments. The sensitivities of the species were similar in chlorsulfuron and flumetsulam trials and their response range varied with soil type and herbicide, e.g. between 0.75 and 6.0 ng triasulfuron g−1 in the Wimmera grey clay and between 0.125 and 8.0 ng chlorsulfuron g−1 soil in the Mallee sand. The method was demonstrated in a wide range of uses, encompassing tests of the initial bioactivity of formulations of chlorsulfuron and flumetsulam, monitoring the field leaching and persistence of triasulfuron and measuring relative potencies between the classes, using metsulfuron‐methyl and metosulam. The bioassay response provided a high level of reproducibility and precision, which was measurable by the logistic curve‐fitting procedure. In each case, R2 values were >0.90 and lack‐of‐fit tests were clearly non‐significant at the 0.05 level. Chi‐square tests were used to measure differences between ED50's. The method does not require the pre‐germination and selection of seedlings, daily watering or root‐washing and results are obtained 7 days from sowing, providing favourable use for routine analyses and large‐scale trials.
Annual weed distributions can be mapped with kriging
Authors: HEISEL T. , ANDREASEN C. , ERSBØLL A. K. 
Published: July 2006

SummaryThe authenticity of weed distribution maps prepared by the geostatistical estimation method, kriging, was investigated. We concentrated on the total number of weed plants and the dominant weed genus Veronica spp. in a 2.1‐ha field of winter wheat. Different sampling distances were evaluated. Our analyses showed that kriging weed densities based on seedling counts collected in, 0.25.m2 circles in a sampling grid of approximately 10 m × 10 m gave good agreement with actual observations. Reducing the sampling grid to 20 m × 30 m gave poor agreement. New sampling methods combined with positioning devices and injection sprayers are discussed with reference to site‐specific weed management.
Estimating Taylor's power law parameters for weeds and the effect of spatial scale
Authors: CLARK S. J. , PERRY J. N. , MARSHALL E. J. P. 
Published: July 2006

SummaryThe spatial variability of weeds within fields was studied for six sets of count data. Heterogeneity for a given mean population density was measured using the variance of the counts between sample units at different locations; relatively large values of sample variance imply aggregation. The dependence of variance on mean was measured using the relationship known as Taylor's power law, ubiquitous in animal ecology but seldom used for plant populations. This was fitted to an extensive set of plant counts and 69 estimates of its parameters b, an index of aggregation, and log10a were computed. Estimates were corrected for bias when the number of samples was small. Overall, b varied between 1.32 and 2.61, and log10a varied between ‐0.85 and 1.58. agreeing well with previous estimates for both plant and animal populations. Parameter estimates varied with sample size and spatial sample scale, but unpredictably. Parameter values when species counts were combined were compared with individual species analyses. Knowledge of the likely range of these parameters for weed populations provides an important basis for future modelling of the relationship between weed density and crop yield loss.
Measurement and simulation of the movement of thiazafluron, clopyralid and metamitron in soil columns
Authors: COX L. , WALKER A. , HERMOSIN M.C. , CORNEJO J. 
Published: July 2006

SummaryAdsorption and leaching of the herbicides thiazafluron (1,3‐dimethyl‐1(5‐trifluoromethyl‐1,3,4‐thiadiazol‐2‐yl)urea), metamitron (4‐amino‐4,5‐dihydro‐3‐methyl‐6‐phenyl‐1,2,4‐tri azin‐5‐one) and clopyralid (3,6‐dichloropicolinic acid) were studied in one sandy and two silty‐clay soils. Equilibrium adsorption coefficients (Kd) were measured using a batch equilibration procedure, and mobility was studied in repacked columns of the soils under fluctuating saturated/unsaturated flow conditions. Breakthrough curves (BTCs) were consistent with an inverse relationship between leaching and adsorption with greater mobility of the weakly‐adsorbed clopyralid than the more strongly adsorbed thiazafluron or metamitron. The BTC data were used to evaluate the LEACHP simulation model. Following model calibration with respect to hydrological parameters and some of the herbicide degradation rates, the best fits between predicted and observed data were with the less adsorptive and highly mobile clopyralid. In general, the model gave acceptable predictions of the timing of the concentration maxima and the shapes of the BTCs, although earlier breakthrough than that observed was predicted with the less mobile herbicides, thiazafluron and metamitron, in the silty‐clay soils. For metamitron, the total amounts leached were not predicted accurately, suggesting more rapid degradation of the herbicide in the soil columns than in the kinetic studies performed in a 1:1 soil:solution ratio shaken system.
Root growth inhibition of rice by bensulfuron
Authors: YIM KYU‐OCK , BAYER D.E. 
Published: July 2006

SummaryBensulfuron inhibited root growth of waterseeded rice (Oryza sativa L.) plants in a solution culture system. Rice root growth was more sensitive to bensulfuron than was shoot growth. A1 2.5 × 10‐9 M bensulfuron, plant height, number of leaves and number of roots were not significantly affected, while root growth was reduced, Seedlings treated 3 or 4 days after emergence showed a significant reduction of total root length by the second day after treatmeni. Root growth inhibition was proportional to duration of treatment; however, treatment for 2 days was necessary to affect root growth, Bensulfuron decreased the mitotic index and the mitotic height in root tips. At 5 days after treatment, only 0.7% of the cells were dividing and mitotic height was 68% of control
The role of peroxidase in the resistance of sunflower against Orobanche cumana in Russia
Authors: ANTONOVA T.S. , TERBORG S.J. 
Published: July 2006

SummaryWe present the results of a histochemical study comparing seedlings of races C and D of Orobanche cumana Wallr. (syn. O. cernua Loefl.) attacking sunflower (Helianthus annuus L.) in southern Russia. Three groups of O. cumana seedlings were distinguished according to the peroxidase content of the cells in the radicles: (1) those with neither extracellular nor intracellubr peroxidase and whose radicles have a smooth apex (these were classified as non‐infective): (2) those with a high peroxidase content of the nuclei and the cytoplasm layer adjacent to the cell wall, as well as excretion of peroxidase from the apex of the radicles: (3) those with a similarly high peroxidase activity in the parasite cells, but without extracellular excretion. The apices of the radicles of the last two groups are swollen. It is suggested that these belong to O. cumana races C and D respectively. The extracellular peroxidase in O. cumana race C reacts with phenolic compounds, which are lignin precursors of the host, resulting in host resistance due to the formation of lignin layers in sunflowers possessing the Or3 gene for resistance. The absence of extracellular peroxidase in O. cumana race D prevents lignin formation and enables the parasite to attach to the host vascular system. Comparison of these data with the information on the earlier O. cumana races A and B, and older sunflower cultivars, points to a crucial role of peroxidase in the process of breeding new sunflower cultivars and the evolution of new O. cumana races.