bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seed dormancy and seedling emergence studies in Avena fatua L
Authors: PETERS N. C. B. 
Published: July 2006

Summary:Studies were made of seedling emergence of three phenotypes of Avena fatua L. with dif ferent coloured lemmas (fA, fB, fC) originally collected from one site. Each phenotype was grown under the same conditions in 1975 and the resulting seed buried 25 mm deep in soil im mediately after collection. The soil was either left uncultivated (all phenotypes) or cultivated monthly (phenotype fA only). Seedling emergence was assessed weekly and the number of remaining viable seeds was determined at the end of three years. Seeds of different lines of A. fatua (fA phenotypes) obtained from separate locations were grown under the same conditions in 1983, buried and seedling emergence moni tored for 85 months.Without cultivation, overall emergence (mean of three phenotypes) in successive autumns and springs was 9%, 18%, 9%, 33%, < 1%, 14% and <1%. A further 3% of viable seeds were recovered at the end of the experiment. Periodicity of emergence was the same for all phenotypes. Actual numbers of seedlings emerging in each of the periods varied between phenotypes. Total emergence of seed from the inner zone of panicles was significantly less than that from the outer zone, although there was little difference between the two zones in each of the natural emergence periods. Cultivation increased emergence, particularly from secondary seed in the first spring after burial, but did not changes its periodicity. By the second spring seed numbers had declined, and seedling counts were similar from cultivated and non‐cultivated soil. No viable seed remained in the cultivated soil after three years. Emergence from the two lines of fA was very different. Seedling emergence occurred after hot dry con ditions, or in warm periods immediately after periods of chilling, particularly those below 4°C.
Fate of fluroxypyr in soil
Authors: LEHMANN R. G. , LICKLY L. S. , LARDIE T. S. , MILLER J. H. , BALDWIN W. S. 
Published: July 2006

Summary:Fluroxypyr‐MHE (methylheptyl ester) was applied to small field plots containing Londo sandy loam soil. After 30 days, fluroxypyr had degraded to about 60% of the initial concentration, but was still the main component, while after 120 and 366 days the methoxypyridine metabolite was the main component in the soil. At 30, 120, and 366 days, lettuce, turnips, green beans, soybeans, and wheat were planted and grown with no observed injury. Residues of 14C in the edible crop fractions were indistinguishable from 14C in control plants exposed to 14CO2, while residues in plant greens and chaff were low (0.1–0.2 mg kg−1), with little evidence of fluroxypyr and no evidence of metabolite uptake. These results indicate that the methoxypyridine metabolite, if present in the soil, does not harm and is not taken up into the plants.
Dégradation chimique ou microbiologique des sulfonylurées dans le sol. I. Cas du sulfbméturon méthyle
Authors: CAMBON J. P. , ZHENG S. Q. , GERAP J. BASTIDE 
Published: July 2006

Résumé: Summary: ZusammenfassungLa Vitesse de transformation du sulfométuron méthyle dans un sol, et en solution au même pH, a été mesurée à différentes temperatures. Aussi bien en solution que dans le sol, la relation d'Arrhénius est bien vérifiée dans la gamme de température étudiée 20°C‐75°C. L'énergie d'activation calculée est respectivement de 94 kJ mol−1 et de 117 kJ mol−1 dans le sol et en solution. Du fait que la loi d'Arrhénius est vérifiée dans le sol jusqu'à 70°C, un mécanisme de dégradation est proposé: la dégradation chimique. L'analyse des produits formés dans un sol stérile et non stérile a été réalisée a partir du sulfométuron méthyle marqué au 14C sur le cycle pyrimidine. Dans les deux sols le métabolite principal retrouvé est la 2‐amino‐4,6‐diméthyl‐pyrimidine. Aucune différence significative n'est mise en évidence entre le sol sterile et non stérile. Chemical or microbial degradation of sulfonylurea herbicides in soil. I. Sulfometuron methyl The rates of degradation of sulfometuron methyl in a soil and in aqueous solution at the same pH were measured at different temperatures. The Arrhenius relationship was verified between 20°C and 75°C. The calculated activation energy in soil and in solution was 94 kJ mol−1 and 117 kJ mol−1, respectively. From the fact that the Arrhenius relationship is followed up to 70°C, it is proposed that the mechanism of degradation in the soil is chemical. Analysis of the metabolites formed in sterile and non‐sterile soil was performed using sulfometuron methyl labelled with 14C in the pyrimidine ring. In both soils the main metabolite isolated was 2‐amino‐4,6‐dimethylpyrimidine. No significant difference has been observed between sterile and non‐sterile soils. Chemischer oder mikrobiologischer Abbau von Sulfonylharnstoffen im Boden. I. Sulfometuronmethyl Die Abbaurate von Sulfometuron‐methyl wurde in einem Boden und in wäßriger Lösung mit gleichem pH‐Wert bei verschiedenen Temperaturen untersucht. Die Gültigkeit der Arrhenius‐Gleichung wurde zwischen 20 und 75°C überprüft, mit Aktiviemngsenergien von 94 oder 117 kJ mol−1 für den Boden bzw. die Lösung. Aus dem linearen Abbau im Boden bis zu 70°C wurde auf chemischen Abbau geschlossen. Bei der Analyse der Abbauprodukte von 14C‐Sulfometuron‐methyl (markiert am Pyrimidin‐Ring) in sterilisiertem und nicht sterilisiertem Boden wurden keine signifikanten Unterschiede festgestellt und hauptsächlich das 2‐Amino‐4,6‐dimethylpyrimidin gefunden.
Interrelated effects of temperature, light and oxygen on Amaranthus caudatus L. seed germination
Authors: GUTTERMAN Y. , CORBINEAU F. , CÔME D. 
Published: July 2006

Summary: Résumé: ZusammenfassungThe aim of this study was to investigate the effects of temperature, light and oxygen on the germination of Amaranthus caudatus (var. viridis) seeds. At the highest temperature studied (35°C), seed germination was found to be most rapid and highest in both the dark and the light. Germination was inhibited by continuous white light. The lower the temperature, the greater the inhibitory effect of light. The far‐red and blue spectral regions were the most effective in light inhibition. The light effect was also dependent on the percentage of oxygen in the atmosphere around the seeds; it was less marked in O2‐enriched atmospheres. Light/ oxygen dependency resulted from the action of the seed coat and endosperm. Scarified seeds were much less sensitive to light and hypoxia than non‐scarified seeds. Effets combinés de la température, de la lumière et de I'oxygène sur la germination des graines d'Amaranthus caudatus L.Le but de ce travail était d'étudier les effets de la température, de la lumiere et de I'oxygène sur la germination des graines d'Amaranthus caudatus (var. viridis). A la temperature la plus élevée utilisée (35°C), la germination était la plus rapide et la plus complète tant à la lumière qu'à 1'obscuritè. La germination était inhibée par la lumière blanche continue. Plus la temperature était basse, plus 1'effet inhibiteur de la lumière était important. Les radiations rouge sombre et bleues du spectre étaient les plus in‐hibitrices. L'effet de la lumière dépendait aussi de la teneur de 1'atmosphère en oxygène; il était moins marqué dans des atmosphères enrichies en oxygène. L'interaction lumière/oxygène provenait du tégument et de 1'albumen. Les graines scarifiées étaient beaucoup moins sensibles à la lumière et a 1'hypoxie que les graines non scarifiées. Wechselwirkungen von Temperatur, Licht und Sauerstoff auf die Keimung der Samen von Amaranthus caudatus L.Sowohl im Dunkeln als auch im Licht keimten die Samen von Amaranthus caudatus (var. viridis) bei 35°C, der höchsten Temperatur der Versuche, am schnellsten und meisten. Durch weiβes Dauerlicht wurde die Keimung gehemmt. Je niedriger die Temperatur, desto hölier die Hemmung durch Licht. Im entfernt roten und blauen Spektralbereich war die Lichthemmung am stärksten. Die Wirkung des Lichts hing auch vom Sauerstoffgehalt der die Samen umgebenden Luft ab: Bei O25‐Anreiche‐rung war sie weniger deutlich. Die Licht/ Sauerstoff‐Wechselwirkung wurde von der Samenschale und dem Endosperm beeinfluβt: Geritzte Samen waren gegenüber Licht und O2‐Mangel viel weniger empfindlich als ganze.
Réactivité de l'herbicide chlorsulfuron; synthèse et structure de ses produits de dégradation
Authors: SABADIE J. 
Published: July 2006

Résumé: Summary: ZusammenfassungDes conditions opératoires appropriées permet‐tent de transformer sélectivement le chlorsulfuron en différents produits précédemment observés au cours de sa dégradation chimique. Leurs structures ont été précisées. Reactivity of the herbicide chlorsulfuron: synthesis and structure of its degradation products By selecting appropriate experimental conditions it was possible to convert chlorsulfuron into the various breakdown products observed as a result of chemical degradation. Proposed structures for these compounds are presented. Reaktionen des Herbizids Chlorsulfuron: Synthese und Struktur seiner Abbauprodukte Durch angepaβte Versuchsbedingungen konnte Chlorsulfuron in verschiedene Abbauprodukte überführt werden, wie sie bei seinem chemischen Abbau beobachtet werden. Ihre Struk‐turen wurden genau bestimmt.
Photosynthetic and accessory pigments inCuscuta campestrisYuncker and some host species
Authors: DINELLI G. , BONETTI A. , TIBILETTI E. 
Published: July 2006

Summary: Résumé: ZusammenfassungPhotosynthetic and accessory pigments (chlorophyll a and b, a and ß carotenes and xanthophylls) were evaluated inCuscuta campestrisYuncker during the course of its biological cycle, taking into account both autotrophic and heterotrophic phases, and different parts of the parasite. Chloroplast activity inC. campestriswas measured and comparisons were made with the chloroplast activity inBeta vulgarisL. andConvolvulus arvensisL. The effects of parasitization ofC. campestrison the main and accessory photosynthetic pigments ofB. vulgariswere also evaluated.Finally, a hypothesis was formulated to explain the different distribution of pigments in different parts and at different stages of the growth cycle inC. campestrisand its chloroplast activity.Pigments photosynthétiques principaux et accessoires chez Cuscuta campestris Yuncker et des espèces hôtesLes pigments photosynthétiques principaux et accessoires (chlorophylles a et b, α et β carotènes, xanthophylles) ont été déterminés chezCuscuta campestrisYuncker durant son cycle biologique. Les phases auttorophes et hétérotrophes ont été prises en compte et les mesures ont porté sur différentes parties des plantes. L'activité chloroplastique a été déterminée chezC. campestriset a été comparéà celles deBeta vulgarisL. et deConvolvulus arvensisL. Les conséquences du parasitisme deC. campestrissur les pigments principaux et accessoires deB. vulgarisont aussi étéétudiées.Enfin, une hypothèse a été avancée pour expliquer les différences de distribution des pigments dans les différentes parties deC. campestrisà divers stades de son cycle biologique, ainsi que son activité chloroplastique.Photosynthese‐ und akzessorische Pigmentre inCuscuta campestrisYuncker und einigen WirstspflanzenartenBeiCuscuta campestrisYuncker wurden im Verlaufe ihres Lebenszyklus die Photosynthese‐ und akzessorischen Pigmenten (Chlorophyll a und b, a‐ und ß‐Karotin, Xanthophylle) sowohl in autotrophen als auch heterotrophen Phasen und in verschiedenen Pflanzenteilen untersucht. Die Chloroplastenaktivität wurde gemessen und mit der vonBeta vulgarisL. undConvolvulus arvensisL. vergleichen. Die Wirkung der Parasitierung vonCuscuta campestrisauf die Photosynthese‐Pigmente vonBeta vulgariswurd erfaßt. Eine Hypothese über die Chloroplastenaktivität und zur verschiedenen Verteilung der Pigmente in den verschiedenen Pflanzenteilen und in verschiedenen Entwicklungsstadien vonCuscuta campestriswurde formuliert.
Dégradation du chlorsulfuron et du metsulfuron méthyle en présence d'acides humiques
Authors: SABADIE J. 
Published: July 2006

Résumé: Zusammenfassung: SummaryAprès dépôt sur de l'acide humique solide, le chlorsulfuron et le metsulfuron méthyle se dégradent à 25°C selon le schéma d'hydrolyse précédemment observé en solution aqueuse: hydrolyse simultanée de la fonction urée et du substituant méthoxy. La présence d'eau accélère notablement la conversion et favorise l'hydroxylation de la molécule. L'addition de méthanol provoque la méthanolyse de la fonction urée.La forte affinité des composés hydroxylés intermédiaires pour la matière humique sèche a été mise en évidence. Abbau von Chlorsulfuron und Metsulfuron‐methyl in Gegenwart von Huminsäuren Nach Anlagerung an feste Huminsäure wurden Chlorsulfuron und Metsulfuron‐methyl bei 25°C in derselben Weise hydrolysiert, wie vorher in wäßriger Lösung beobachtet, nämlich mit simultaner Hydrolyse der Harnstoff‐ und der Methoxygruppe. Durch Feuchtigkeit wurde die Reaktionsrate beachtlich erhöht und die Hydrolyse gefördert. Zugabe von Methanol leitete die Méthanolyse der Harnstoffgruppe ein. Es wurde eine hohe Affinität der intermediären Hydrolyseprodukte zu trockener Huminsubstanz beobachtet. Degradation of chlorsulfuron and metsulfuron methyl in the presence ofhumic adds The chemical degradation of chlorsulfuron and metsulfuron methyl on solid humic acid was investigated at 25°C. Hydrolysis followed the same pathway as that observed previously in aqueous solution: simultaneous hydrolysis of the urea function and of the methoxy radical. Moisture enhanced the rate of reaction and favoured hydroxylation of the molecule. Methanolysis of the urea function was induced by methanol.A high affinity between dry humic material and hydroxylated intermediate compounds was observed.
Mauvaises herbes des céréales de la Chaouia (Maroc). II. Aspect écologique.
Authors: TALEB A. , MAILLET J. 
Published: July 2006

Résumé: Summary: ZusammenfassungLa répartition régionale des espèces adventices des céréales de la Chaouia est conditionnée par deux facteurs prépondérants: la nature du sol et le climat régional qui permettent d'établir cinq grands groupes écologiques. II existe une bonne correspondance avec les groupes phytosociolo‐giques déjàétablis par ailleurs, mais cette appro‐che permet de mieux mettre en évidence les transitions qui existent sur le terrain. Les risques liés à une évolution des techniques culturales sont appréciés en fonction des groupes d'espèces actuels. Weeds of cereals in Chaonia (Morocco) II. Ecological aspects.The regional distribution of weeds of cereals in Chaonia is controlled by two major factors, soil type and climate, which allows five large ecological groups to be defined. There is a good correlation between these and groupings established in other ways but this approach shows more clearly the transitions which occur on the ground. The risks associated with agricultural development can be evaluated with reference to the species currently present. Unkräuter des Getreides im Gebiet von Chaouia (marokko) II. Ökologische Aspekte Die regionale Verteilung der Ackerwildpflanzen den Getreides im Gebiet von Chaouia ist durch 2 entscheidene Faktoren bestimmt: die Boden‐arten und die regionalen Klimabedingungen, die 5 große ökologische Gruppen sich entwickeln lassen. Es besteht eine gute übereinstimmung mil den bereits andernorts beschriebenen pflan‐zensoziologischen Gruppen, mit deren Hilfe die naturräumlichen übergange deutlich heraus‐gearbeitet werden können. Die Wahrschein‐lichkeit agrotechnisch bedingter Entwicklungen der aktuellen Artengruppen wird abgeschätzt.
Variation in the annual dormancy cycle in buried seeds of the weedy winter annual Viola arvensis
Authors: BASKIN J. M. , BASKIN C. C. 
Published: July 2006

SummarySeeds of Viola arvensis collected in different years and in different months within those years were buried in soil under natural seasonal temperature cycles, and changes in their germination requirements monitored. Seeds were dormant at maturity in May or June, but nondormant by autumn. During winter, some seeds entered dormancy, while others entered conditional dormancy, i.e. retained the ability to germinate at 15/6 and 20/10oC but not at other thermoperiods. Dormant and conditionally dormant seeds became nondormant the following summer. Seeds collected in 1981 exhibited an annual dormancy:nondormancy cycle, while those collected in 1982 exhibited an annual conditional dormancy:nondormancy cycle. The type of dormancy cycle found in these seed lots during their first year of burial persisted in subsequent years. Thirty–five and 36% of seeds collected in May 1983 and 1986, respectively, were conditionally dormant the following May, while only 5 and 9% of those collected in the same field in June 1983 and 1986, respectively, were conditionally dormant. Dormant seeds collected in 1981,1982 and 1984 and buried at 5oC during summer germinated to 0, 33 and 0% respectively, at 15/6oC in autumn. After the 1982 seeds became nondormant during summer, only 25% entered conditional dormancy when buried at 5oC, but after the 1981 and 1984 seeds became nondormant, 100% entered conditional dormancy at 5oC. Thus, the persistent seed bank of V. arvensis at a population site may consist of seeds with an annual dormancy:mondormancy cycle and others with an annual conditional dormancy:nondormancy cycle. This is the first report of the two types of annual seed dormancy cycles in the same species.
A method to obtain fast and uniform emergence of weeds for field experiments
Authors: KEMPENAAR C. , SCHNIEDERS B.J. 
Published: July 2006

SummaryIn studies on competition between crops and weeds it may be desirable to manipulate time of emergence, density and spatial arrangement of weeds. This requires a method to obtain a fast and uniform emergence of weeds. Two planting methods were compared that differed in the medium (agar or blotting paper) on which seeds were germinated, and in the method of transplanting the seeds (with or without the medium). In wet soil, emergence started earlier when seeds were germinated on agar and subsequently planted with agar. Root tips of seeds germinated on blotting paper may have been damaged to a greater extent during transplanting, because root tips tended to grow into the blotting paper. The duration, heterogeneity and final level of emergence were not affected by the planting method. In dry soil in a greenhouse experiment, the final level of emergence was much less when seeds were planted using the blotting paper method than when they were planted using the agar method. The agar may have provided a small source of water which reduced dehydration of emerging plants. The results were similar for the three species studies, namely, Chenopodium album L., Senecio vulgaris L. and Solanum nigrum L.
Germination behaviour in seeds of Diplotaxis erucoides and D. virgata
Authors: PEREZ‐GARCIA F. , IRIONDO J.M. , MARTINEZ‐LABORDE J.B. 
Published: July 2006

SummaryThe seed germination behaviour of four populations each of Diplotaxis erucoides (L.) DC. and D. virgata (Cav.) DC, two weedy Brassicaceae species widely distributed in the Mediterranean region, was studied under controlled light, temperature and moisture conditions. Germination rates in D. virgata were generally higher at alternating (25/15^C) and low (15^C) temperatures, whereas in D. erucoides optimal germination rates were achieved at higher temperatures (25^C). No correlation between seed weight and germination was found in either species. In D. virgata, the geographic origin of the seed had an important effect on germination percentage. Great germination variability was found among the populations and even among seeds belonging to the same population. In this species, the application of gibberellic acid stimulated germination, especially in the populations with higher dormancy levels. Dormancy was found in mature D. virgata seeds but not in those of D. erucoides. In both species, germination percentages decreased after a certain period of storage at low temperatures. This period varied depending on the species and the population considered.
A comparison of the dynamics of root growth and biomass partitioning in wild oat (Avena fatua L.) and spring wheat
Authors: BINGHAM I. J. 
Published: July 2006

SummaryThe dynamics of early root growth and dry matter partitioning were compared in spring wheat (Triticum aestivum L.) and wild oat (Avena fatua L.) grown in solution culture. Total root length was greater in wheat than wild oat throughout the experiment; a result of a greater number of seminal axes and greater production of lateral root length per axis. The final number of adventitious roots was greater in wheat than in wild oat, but their length was similar. Relative growth rates were also similar as was shoot:root dry weight ratio and rate of root respiration. However, wheat used the dry matter partitioned to its roots more efficiently, producing a greater specific root length (SRL, length per unit weight). Caution must be exercised when relating these results to plants growing and compet‐ing in the field, but three general points are raised. First, the initial number of seminal axes can have a profound effect on the rate of early root development; second, the adventitious root system of wild oat is not inherently more vigorous than that of wheat; and third, future studies should compare SRL of wheat and wild oat in the field. If differences similar to those in the present study are found they may contribute to the greater competitive ability of wheat.
Etendue de distribution et degré d'infestation des adventices dans la rotation cotonnière au Nord‐Cameroun
Authors: Le BOURGEOIS T. , GUILLERM J. L. 
Published: July 2006

Résumé: SummaryL'étude des adventices dans la rotation cotonnière au Nord‐Cameroun a porté sur l'observation de 180 parcelles à trois époques du cycle cultural. L'analyse floristique qualitative met en évidence une flore de 280 espèces, réparties en 141 genres appartenant à 42 families botaniques, dont les mieux représentées sont les Poaceae, Fabaceae, Cyperaceae et Asteraceae. L'analyse floristique quantitative réalisée en fonction des saisons et des trois régions phytogéographiques de la zone d'étude montre que les espéces les plus fréquentes sont Ipomoea eriocarpa R. Br., Digitaria horizontalis Willd. et Commelina benghalensis L. et que les mauvaises herbes qui posent des problèmes majeurs d'infestation dans les cultures annuelles sont C. benghalensis, D. horizontalis et Striga hermonthica (Del.) Benth. Weed distribution and abundance in cotton rotation in northern Cameroon This weed study in cotton rotation in northern Cameroon concerns observations of approximately 180 fields on three occasions during the crop season. Qualitative floristical analysis shows a flora of about 280 species, in 141 genus among 42 botanical families in which the commonest representatives are Poaceae, Fabaceae, Cyperaceae and Asteraceae. Quantitative floristical analysis was carried out in relation to the three seasons and the three phyto‐geographical areas of the region. It shows that the more frequent species are Ipomoea eriocarpa R. Br., Digitaria horizontalis Willd. and Commelina benghalensis L., and the weeds that cause most damage in annual crops are C. benghalensis, D. horizontalis and Striga hermonthica (Del.) Benth.