bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interference of Sinapis arvensis L. and Chenopodium album L. in spring rapeseed (Brassica napus L.)
Authors: BLACKSHAW R. E. , ANDERSON G. W. , DEKKER J. 
Published: July 2006

SummaryInterference of Sinapis arvensis L. (wild mustard) and Chenopodium album L. (lamb's‐quarters) in spring rapeseed (Brassica napus L.) was studied under field conditions in 1983 and 1984. Both weed species interfered with rapeseed early in the growing season, causing significant reductions in rapeseed dry weight by June of each year. Sinapis arvensis caused greater rapeseed grain yield reductions than did C. album. With weed densities of 20–80 plants m−2, rapeseed grain yield reductions ranged from 19 to 77% with S. arvensis but only 20 to 25% with C. album. Rapeseed yield reductions caused by mixtures of both weed species ranged from being less than to being equal to the sum of reductions caused by each weed alone, depending on the weed density and year of study. Both weed species were prolific seed producers capable of returning large quantities of seed to the soil. With weed densities ranging from 10–80 plants m−2, S. arvensis produced 5700–30 100 seeds m−2 while C. album produced 3100–63 600 seeds m−2.
Lack of prevention of chlorsulfuron‐induced inhibition by amino acids
Authors: GIARDINA MARIA CARMELA , DE AGAZIOand MARINA , GREGO S. 
Published: July 2006

SummaryThe amino acids valine and isoleucine, which had been indicated by Ray (1984) as antidotes against growth inhibition of pea plants induced by chlorsulfuron, were ineffective in preventing the damage induced by chlorsulfuron on the plasma membrane of maize roots as measured by K+ uptake. In addition, in seedlings of two corn genotypes and three pea genotypes grown in culture solution containing chlorsulfuron, growth inhibition was not alleviated by valine and isoleucine. However, in agreement with Ray's results, acetolactate synthase, the key enzyme of the biosynthesis of valine and isoleucine, was inhibited in vitro by chlorsulfuron in both maize and pea. It is suggested that the chlorsulfuron mechanism of action involves several sites.
Establishment and growth of Senecio jacobaea L. and Senecio erucifolius L. in grassland
Authors: WATT T. A. 
Published: July 2006

Summary Senecio erucifolius L. (hoary ragwort) has become conspicuous on roadside verges in southern England. Like Senecio jacobaea L. it is poisonous, so it might be a threat to animal production. In boxed swards the growth of S. jacobaea was less adversely affected by the greater competition from grass with a high level of nitrogen fertilizer than was the growth of S. erucifolius. Also, young S. jacobaea plants showed a much greater ability to regrow after their shoots had been cut at ground level. In a range of grassland managements S. jacobaea established better from seed than did S. erucifolius. Establishment of both species on molehills was poor because of the likelihood that the seedlings would be disturbed or even buried by fresh mole activity. Ten months after sowing, seedlings of S. jacobaea had persisted well in the higher nitrogen environment of ex‐cow‐dung patches, whereas S. erucifolius had not. Under intensive sheep grazing, in the absence of fertilizer, transplants of S. erucifolius had much greater root dry weights than did those of S. jacobaea. Also, in regrowth after cattle grazing on a fertilized sward, S. jacobaea plants had greater shoot dry weights than did S. erucifolius. Thus, although S. erucifolius can establish from seed in bare patches in an intensively grazed sward it is likely to be less persistent than S. jacobaea if the gaps are ex‐dung patches or if nitrogen fertilizer is applied.
Prognose‐Modell zur Erfassung des Rückstandsverhaltens von Metribuzin und Methabenzthiazuron im Boden und deren Auswirkungen auf Folgekulturen
Authors: PESTEMER W. , AUSPURG B. 
Published: July 2006

ZusammenfassungDas Abbauverhalten von Methabenzthiazuron und Metribuzin wurde unter Freilandverhältnissen in einem sandigen Lehm mit Hilfe eines Computermodells simuliert, welches vor allem den dominierenden Einfluss von Temperatur und Feuchtigkeit auf den Abbau berücksichtigt, der vorher in Laborversuchen ermittelt wird. Hier ergaben sich in Abhängigkeit von den Inkubationsbedingungen (10–30°C, 20–90% WKmax.) fü Metribuzin Halbwertszeiten von 11–60 Tagen und für Methabenzthiazuron (MBT) von 42– > 1200 Tagen. Darauf aufbauend lässt sich für Freilandverhältnisse aus den täglichen Wetter‐aufzeichnungen für einen vorgegebenen Zeitraum der Herbizidabbau vorhersagen. Bei der Simulation des Metribuzin‐ und MBT‐Abbaus von Anfang Mai bis Ende August bzw. Anfang Oktober 1983 ergaben sich Halbwertszeiten von 21 bzw. 66 Tagen. Die im Freiland ermittelten Zeiten für eine 50%ige Konzentrationsabnahme betrugen 15 bzw. 62 Tage. Die potentiell pflanzenverfügbaren Anteile eines Gesamtrückstandes wurden aus den jeweiligen Verteilugskoeffizienten (Kd‐Werte), bei Berûcksichtigung des pflanzenverfügbaren Wassergehaltes im Boden, berechnet. Sie betrugen im verwendeten Boden für Metribuzin 77% und für MBT 16% des Gesam‐trückstandes.Aus der Kombination der Modelle lassen sich, aufbauend auf dem ermittelten‘no‐observable‐effect‐level’(NOEL) und der simulierten Abbaukurve, Inaktivierungszeiten für die einzelnen Herbizide und Folgekulturen ableiten. Diese lagen z.B. bei Metribuzin zwischen ca. 3 (Möhre) und 13 Wochen (Buschbohne) und bei MBT zwischen 0 (Buschbohne) und 12 Wochen (Möhre).Eine Kombination derartiger Modelle gibt einen Überblick sowohl über den Verbleib von Herbiziden im Boden als auch ihre Phytotoxizität gegenüber Kulturpflanzen und ist für eine praktische Anwendung hinreichend genau.
Nature of resistance to Striga hermonthica (Del.) Benth. parasitism in some Sorghum vulgare (Pers.) cultivars
Authors: EL HIWERIS S.O. 
Published: July 2006

SummaryTen Sorghum vulgare (Pers.) cultivars varying in tolerance to Striga hermonthica (Del.) Benth. parasitism were grown with or without Striga infection. Endodermal thickening, pericycle lignification and silica crystal deposition were studied microscopically and measured for infected and non‐infected sorghum cultivars. Although differences in the root character measurements were statistically significant they were not closely related to the response of the plant to infection. Low stimulant producing cultivars showed low or medium root cell thickening. The cv. Framida had both low stimulant production and high root cell thickening and was the best of the tolerant cultivars. High stimulant producing, tolerant cultivars generally showed heavy or intermediate cell thickening. The high stimulant producing, susceptible cultivar Debaikri also showed intermediate root cell thickening.‘Antibiosis', measured by the content of phenolic compounds in the plant, was then studied. Varietal differences in quality and quantity of phenolic substances in the roots and shoots of sorghum cultivars infected or non‐infected with Striga were observed. Infection increased total phenolic contents in both shoot and root extracts. Differences in the total phenolic content in the shoot of non‐infected cultivars did not reflect tolerance to Striga infection. The total phenolic acid content of the root extracts was closely related to the response of the host plant to Striga infection, tolerant cultivars having greater total phenolic acid content than susceptible ones.
Phenology and growth of Orobanche crenata Forsk (broomrape) in four legume crops
Authors: ARJONA‐BERRAL A. , MESA‐GARCIA J. , GARCIA‐TORRES L. 
Published: July 2006

SummaryStudies were conducted in the field in 2 years comparing the phenology and growth of Orobanche crenata (Forsk) (crenate broomrape) in lentils (Lens esculenta L.) cv. Castellana, peas (Pisum sativum L.) cv. Orix, vetch (Vicia sativa L.) cv. comun and broadbean (Vicia faba L. cv. Alameda. First attachment of O. crenata to these crops took place 9–14 weeks after mid‐November planting and earlier after later plantings, Differences in the first O. crenata attachment dates and in the duration of the underground growth period of O. crenata were much greater between years for any given crop than between crops in a given year: both attributes were apparently affected more by seasonal climatic conditions than by crop species, Furthermore, there was no consistent relationship found between crop growth stages and time after first attachment of the parante. This occurred in lentils and vetch while they were vegetative, in peas at late vegetative‐early flowering stages, and at widely varying growth stages in broadbean, depending on planting dates and years. The maximum number of O. crenata plants successfully attached to each individual crop plant decreased in the order: peas > broadbean > lentil > vetch, with 21, 14, 10 and 8 per plant, respectively, averaged over the two seasons. Similarly, plant parasites: host dry weight ratio were 1.0, 0.7, 0.3 and 0.2 For each of these crops, respectively.
Seed detachment in Avena fatua L.
Authors: YEUNG E. C. , CHINNAPPA C. C. , CHEN F. S. C. 
Published: July 2006

Summary: Résumé: ZusammenfassungSoon after the development of the inflorescence and prior to anthesis, the future detachment point of the floret of Avena fatua L. is formed. This zone is denoted initially by files of cells that will eventually become the future break‐point where a scar is formed. The edge of the future scar (at the articulation zone) is composed of small cells, which, despite the retention of prominent primary wall material, have highly lignified secondary walls. The grain will break from the rachilla in the region of these small cells. The centre of the future scar is composed mainly of thin‐walled parenchyma cells with large intercellular air spaces. Underneath the future break‐point, the stalk is composed of a solid core of vascular elements and lignified cells. These features are absent in the cultivated out (Avena sativa L.). Le détachement de graines d' Avena fatua L.Sitôt après le développement de l'inflorescence avant l'anthèse, le point de détachement de la fleur d'Avenu fatua L. est formé. Cette zone est marquée au départ par des rangées de cellules qui deviendront le futur point d'abscission où une cicatrice se forme. Le bord de la future cicatrice (à la zone d'articulation) est composé de petites cellules qui. malgré le maintien d'une première barrière saillante, ont lignifié des parois secondaires. Le centre de la future cicatrice est composé principalement de parenchyme à cloisons fines avec des espaces intercellulaires larges. A proximité du futur point d'abscission, la tige est composée d'un noyau solide d'éléments vasculaires et de cellules lignifiées. Les caractéristiques énoncées ci‐dessus sont absentes chez l'avoine cultivée (Avenu sativa L.). Ueber die Ablösung der Samen bei Avena fatua L.Bei Avena fatua L. wird bald nach der Entwicklung der Infloreszenzen, aber vor ihrer vollen Ausbildung, die spätere Ablösungsstelle der Blüte angelegt. Diese Zone ist anfänglich durch Zellreihen gekenntzeichnet, welche sehliesslich die Bruchstelle darstellen und wo eine Narbe gebildet wird. Der Rand der zukünftigen Narbe besteht aus kleinen Zellen, welche, obwohl noch auflällig viel primäres Zellwandmaterial enthaltend, stark verholzte sckundäre Zellwände aufweisen. Der Same bricht im Bereiche dieser kleinen Zellen aus der Aehrchenachse (Rachilla). Das Zentrum der zukünftigen Abbruchnarbe besteht aus dünn wandigem Parenchym mit grossen Interzellularräumen. Unterhalb der späteren Abbruchstelle ist die Aehrchenachse aus einem dichten Gewebe aus Gefässelementen und verholzten Zellen aufgebaut. Beim Kulturhafer (Avena sativa L.) fehlen die oben beschriebenen Elemente.
Spread of proso millet (Panicum miliaceum L.) in Ontario, Canada. I. Rate of spread and crop susceptibility
Authors: McCANNY S. J. , BOUGH MARGUERITE , CAVERS P. B. 
Published: July 2006

SummaryThe infestations of two biotypes of Panicum miliaceum L. were monitored over a 5‐year period (1981–1985) as they occurred in two townships in southwestern Ontario, Canada. On average, 16·5% of the cultivated fields in Hullett township were infested with the black‐seeded biotype while 12·9% of the fields in North Norwich township were infested with the golden‐seeded biotype. Neither population showed clear signs of increasing. The two biotypes were similar in their ability to persist as adult infestations. The black‐seeded biotype showed a greater potential for colonizing uninfested fields. The crops grown in this region showed different susceptibilities to infestation by P. miliaceum. Corn (maize) fields were susceptible while most grain fields were resistant to infestation. White beans were susceptible to infestation by the black‐seeded biotype. Wheat and oat crops were more resistant to infestation by the golden‐seeded biotype than to those of the black‐seeded biotype.
Carrot microtubules are dinitroaniline resistant. I. Cytological and cross‐resistance studies
Authors: VAUGHAN M. A. , VAUGHN K. C. 
Published: July 2006

SummaryTreatment of both tolerant and susceptible species with dinitroaniline herbicides results in root swelling typical of mitotic disrupters, however, no root swelling was observed in carrots treated with saturated solutions of all the dinitroaniline herbicides tested, with the exception of oryzalin treatments at ≥ 10−5 M. These levels of treatment are 100–1000 times the levels that caused root‐tip swelling, even in tolerant plants. This properly classifies carrot as dinitroaniline‐resistant rather than merely tolerant. Cross‐resistance was noted to the structurally related mitotic disrupter, hexanitrodiphenylamine, and to the structurally unrelated herbicide, amiprophos‐methyl. No resistance was noted to a number of other mitotic‐disrupting herbicides. Both immunofluorescence and electron microscopy indicate that the microtubules of carrot roots were unaffected by dinitroaniline treatment. All organized microtubule configurations (cortical, pre‐prophase bands, spindle, and phragmoplast) were observed in the treated material.
Ecological implications of traditional weeding and other imposed weeding regimes under slash‐and‐burn agriculture (jhum) in northeastern India
Authors: SWAMY P. S. , RAMAKRISHNAN P. S. 
Published: July 2006

SummaryTraditional weeding in slash‐and‐burn agriculture (jhum) in northeastern India involves the retention of a certain proportion of weed biomass in situ. By comparing this weed management practice with total weeding and no weeding, the economic and ecological efficiency of this agroecosystem has been assessed. It is concluded that traditional weeding has little effect on the yield potential of the crop mixture compared with total weeding but it could lead to conservation of soil resources by up to about 20%. Indeed, harvested weed biomass put back into the system is an efficient way of recycling resources under stress.
Les principales mauvaises herbes des vergers dans la région maritime de Syrie
Authors: SOUFI Z. 
Published: July 2006

RésuméA partir de 51 relevés effectués au printemps 86 dans les vergers de la région maritime syrienne, une liste exhaustive de 370 espèces de mauvaises herbes a étéétablie. Les notions d'abondance et de fréquence ont permis de dégager 54 espèces considérées comme les principales. Plusieurs aspects concernant ces principales mauvaises herbes sont représentés: analyse floristique, spectre biologiques et appartenance biogéographique.
Multivariate analysis in weed science
Authors: POST B. J. 
Published: July 2006

SummaryWeed species in arable ecosystems are adapted to the conditions produced by agricultural management. In order to give preventive and curative guidelines to weed management one needs to predict the composition of the weed vegetation after certain (soil) cultivation measures. Dormancy mechanisms of seeds in the seedbank and the environmental conditions in the furrow before and after cultivation are usually such that the vegetation composition is heterogeneous. Multivariate analyses enable us to describe and classify weed vegetation and to analyse its relationship to environmental factors.
Experimental methods in plant competition research in crop‐weed systems
Authors: CONNOLLY J. 
Published: July 2006

SummaryThe implications of recent studies on the inappropriatness of replacement series and additive methods in competition studies, and some possible alternatives, are discussed in the context of weed research, Replacement series are usually inadequate to assess competitive interactions and can be misleading. In particular they may be biased in favour of the larger species. Many of the criticisms of replacement series also apply to additive experiments. Response models relating yield per individual to the densities of the species in the mixture provide methodology for answering many questions about mixtures. This paper proposes a framework for using these models to: (i) measure the effect of weed species on yield per individual and yield per unit area for the crop and weed species; (ii) develop methods of biological control of weeds both within a seaons and over seasons, based on the interference between crop and weed species and the population biology of the weed species; (iii) establish a cost‐benefit analysis of certain of the biological weed‐control programmes. The inclusion of the effect of relative emergence time and management practices in response models is considered as well as experimental design for crop‐weed experiments.
Modelling the effects of weeds on crop production
Authors: KROPFF M. J. 
Published: July 2006

SummaryIn most quantitative studies on interplant competition, static regression models are used to describe experimental data. However, the generality of these models is limited. More mechanistic models for interplant competition, which simulate growth and production of species in mixtures on the basis of the underlying physiological processes, have been developed in the past decade. Recently, simulation models for competition between species for light and water were improved and a detailed version was developed for sugarbeet and fat hen (Chenopodium album L.). The model was validated with data sets of five field experiments, in which the effect of fat hen on sugarbeet production was analysed. About 98% of the variation in yield loss between the experiments (which ranged from –6 to 96%) could be explained with the model. Further analysis with the model showed that the period between crop and weed emergence was the main factor causing differences in yield loss between the experiments. Sensitivity analysis showed a strong interaction between the effect of the variables weed density and the period between crop and weed emergence on yield reduction. Different quantitative approaches to crop‐weed competition are discussed in view of their practical applicability. Simulations of experiments, where both the weed density and the period between crop and weed emergence were varied over a wide range, showed a close relation between relative leaf cover of the weeds shortly after crop emergence and yield loss. This relation indicates that relative leaf cover of the weeds accounts for both the effect of weed density and the period between crop and weed emergence. This relation has the potential to be developed into a powerful tool for weed‐control advisory systems.
Effects of tropical weeds on yield in white yam (Dioscorea rotundata Poir)
Authors: UNAMMA R. P. A. , AKOBUNDU I. O. 
Published: July 2006

SummaryThe effects of tropical weeds on the yield of while yam were studied outdoors in wooden boxes. When the foliage and roots of weeds were in physical contact with the crop until harvest (full interference), tuber yield of yam was reduced by 76–79% of that obtained under weed‐free conditions over 3 years of study. When there was no physical contact between roots of crop and weeds, the leachate from the weed zone caused tuber yield reductions of 42, 40 and 38% in 1978, 1979 and 1980, respectively, when it was applied to the yam zone. This leachate also reduced leaf area index (LAI) in the yam crop but the adverse effects on yam root and shoot biomass were less pronounced. This technique made it possible to separate competitive interference from allelopathic interference of tropical weeds with the yam crop.
Chemical control of nodding thistle (Carduus nutans L.) in New Zealand pastures
Authors: POPAY A. I. , BUTLER J. H. , MEEKLAH F. A. 
Published: July 2006

SummaryBroadcast sprays of several herbicides were applied at different times of the year at several sites in Hawkes Bay, Canterbury and Otago. For good thistle control, date of application was more important than types of herbicide. In Hawkes Bay, applications made in April, May and June tended to be the most effective. Under slightly cooler Canterbury conditions, April, September and October were the best application dates. In the Otago trials, spring emergence of thistle seedlings meant that the most consistent results came from September or October applications. At all sites, applications made in July or August were relatively ineffective, probably because of low winter temperatures and slow thistle growth rates. MCPA (potassium salt) at 1·0 kg ha−1 was the standard herbicide used in all experiments. MCPA at 0·5 kg ha−1, MCPB (sodium salt) at 0·5 and 1·0 kg ha−1 and 2,4‐D at 0·5 kg ha−1 did not kill as many thistles as MCPA at 1·0 kg ha−1. MCPA at 1·5 kg ha−1 and MCPB (butyl) ester + clopyralid at 0·5 + 0·015 or 1·0+0·03 kg ha−1 gave consistently better control than MCPA at 1·0 kg ha−1 2,4‐D at 1·0 or 1·5 kg ha−1, MCPB at 1·5 or 2·0 kg ha−1, and MCPA + MCPB at 0·33 + 1·0 or 0·67 + 0·5 kg ha−1 gave results very similar to MCPA at 1 kg ha−1. Thistle control varied between sites and years. Some of the variation may have been due to different proportions of first and second year thistles present at spraying, and to variation in genetically determined herbicide susceptibility. Chemical control of thistles was short term only, because of dormant seeds in the soil.
Field persistence of chlorsulfuron and DPX‐L5300 in relation to rotational crops
Authors: ELEFTHEROHORINOS I. G. , KOTOULA‐SYKA ELENI 
Published: July 2006

SummaryA pot bioassay procedure, based on root growth of pre‐germinated maize was used to study residual phytotoxicity of chlorsulfuron and DPX‐L5300 methyl‐([4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl(methyl) carbamoyl]sulphamoyl)benzoate under field conditions. The results indicate that residual bioactivity of both herbicides, applied either pre‐or post‐emergence at 5, 10, 20 and 40 g a.i. ha−1, was increased with increasing rate of application. Chlorsulfuron persisted longer than DPX‐L5300, and both herbicides, when applied pre‐emergence, persisted longer than when applied post‐emergence. Pot bioassay did not detect any residues eight months after either application. Maize and sunflower, planted as rotational field crops eight months after pre‐emergence application, were not injured by either herbicide. Also, these crops were not affected when planted four months after post‐emergence application of any of the DPX‐L5300 rates or 5 or 10 g a.i. ha−1 of chlorsulfuron, but their fresh weight was significantly reduced where 20 or 40 g a.i. ha−1 of chlorsulfuron were applied.
Physiological studies of mecoprop‐resistance in chickweed (Stellaria media L.)
Authors: BARNWELL P , COBB A. H. 
Published: July 2006

SummaryGlasshouse experiments have confirmed that resistance to mecoprop is present in a biotype of Stellaria media. Resistant plants were less vigorous than the susceptible population and ED50 values were calculated as 3·92 and 0·18 kg a.i. ha−1 respectively. The physiological basis of mecoprop resistance was investigated by studying the responses of each biotype in two experimental systems, namely explant stem elongation and ethylene evolution. These studies have discounted differential ethylene evolution as the basis of resistance but have indicated altered elongation growth in resistant plants. This observation suggests the possibility of reduced mecoprop binding in resistant plants, although the role of mecoprop metabolism remains to be elucidated.