bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF CULTIVATION ON THE NUMBERS OF VIABLE WEED SEEDS IN SOIL
Authors: ROBERTS H. A. , DAWKINS PATRICIA A. 
Published: July 2006

Summary. In a 6‐year experiment with a naturally occurring population of viable weed seeds, the numbers in the top 9 in. of soil decreased exponentially from year to year in the absence of further seeding. The rates of loss were equivalent to 22% per year in undisturbed soil, 30% per year on plots dug twice a year (March and September) and 36% per year on those dug four times a year (March, June, September, December). Seed numbers of individual species also decreased exponentially, although not all at the same rates.On the dug plots, the numbers of seedlings that emerged each year decreased exponentially once the regimes had become established. The proportions of the viable seeds which gave rise to seedlings in the course of a year were 7 % on plots dug twice and 9 % on those dug four times a year; although there was some variation, these proportions remained much the same from year to year. On undisturbed soil the number of seedlings that emerged declined rapidly, and in the 4th year represented no more than 03% of the viable seeds still present in the top 9 in. of soil.
THE PHOTOLYTIC DEGRADATION OF PICLORAM
Authors: HALL R. C. , GIAM C. S. , MERKLE M. G. 
Published: July 2006

Summary. The effects of sunlight and ultraviolet light (253.7 nm) on 4‐amino‐3,5,6‐trichloropicolinic acid (picloram) in a basic aqueous solution were investigated. Electron‐capture gas chromatography determinations showed that approximately 20% of a 2 × 10−2 M concentration of picloram was degraded for each 48‐hr exposure to ultraviolet light of an intensity of 200 μW/cm2. Decomposition by sunlight was slower and more variable.Precipitation of the degradation products with AgNO3 indicated that two chloride ions were liberated for each molecule of picloram that was degraded. Titrations indicated that acids were formed in the degradation process, and ultraviolet spectra showed that the pyridine nucleus was destroyed. Chromatograms of the methylated decomposition products showed that at least five products were formed.The effect of the addition of a free radical scavenger, hydroquinone, on the rate of decomposition was investigated but no definite conclusions could be drawn.La dégradation photolytique du piclorame
TRANSLOCATION STUDIES WITH ENDOTHAL‐14C IN POTAMOGETON NODOSUS POIR.
Authors: THOMAS T. M. , SEAMAN D. E. 
Published: July 2006

Summary. Plants of Potamogeton nodosus, a submersed aquatic, were treated with the di‐sodium salt of 7‐oxabicyclo(2,2,l)heptane‐2,3‐dicarboxylic acid‐14C (endothal‐14C). Gross radioautographs showed that the 14C label moved from mature photosynthesizing leaves and accumulated in the apices and developing secondary plants. Similar results were obtained with mid‐leaf, stem (internode) and winter‐bud applications. No move‐ment of radioactivity occurred following root treatment. The results indicate symplastic translocation of endothal‐14C when applied to the leaf, stem or winter bud. It is suggested that endothal can cause the death of plants by direct injury to root tissues subsequent to absorption.Recherches sur la migration de l'endothal‐14C dans le Potamogeton nodosus Poir.
THE EFFECTS OF SHOOT REMOVAL ON THE RHIZOME CARBOHYDRATE RESERVES OF COUCH GRASS (AGROPYRON REPENS (L.) BEAUV.)
Authors: TURNER D. J. 
Published: July 2006

Summary. Three box experiments examining the effects of shoot removal on rhizome carbohydrate reserves are reported.During summer in England the optimum frequency of hand defoliation for maximum loss of carbohydrate was 10–14 days. As in previous experiments, high levels of soil nitrogen sometimes increased the rate of carbohydrate loss from 9‐in. rhizome pieces. This result was obtained when nitrogen was supplied as a nitrate, an ammonium salt, or urea.Repeated applications of 2 or 4 oz/ac paraquat over a period of about 60 days reduced carbohydrate reserves to about 50% of the level obtained with the same number of hand clippings. It is suggested that paraquat may have been translocated to the rhizomes, the carbohydrate content of which may have been reduced by an effect of the paraquat on the respiration rate.When plants which had been subjected to different methods and frequencies of defoliation were uprooted and buried beneath 2 in. of soil, there was a connection between the rhizome carbohydrate content at the time of burial, the ability of the plants to regenerate, and the rate at which new carbohydrate reserves built up during the following two months.
GROWTH AND SPRAY RETENTION OF WILD OAT AND FLAX IN RELATION TO HERBICIDAL SELECTIVITY*
Authors: HIBBITT C. J. 
Published: July 2006

Summary. The growth of wild oat (Avena fatua L.) was accompanied by an increase in the amount of spray retained per plant and per unit weight of plant, probably because the projected area (plan view) increased as the plant became larger. Flax (Linum usitatissimum L.) retained a fairly constant volume of spray per plant from the 8‐leaf to the 35–40‐leaf stages, so that the spray retained per unit plant weight decreased considerably as the plants grew. This was related to the decrease in projected area as a proportion of the whole. There was also a difference in retentivity between the cotyledons and true leaves; the cotyledons retained ten to twenty times more spray per unit weight. These results suggest that maximum selectivity would be achieved by spraying at an advanced stage of growth.Wild oat at the 3‐leaf stage retained more than half the aqueous spray in the two leaf axils, while flax retained most on the cotyledons. Distribution was shown to be a probable reason for selectivity. Addition of a surfactant greatly increased retention by both species, but although the effect of a spray on wild oat might thereby be increased, under certain conditions injury to flax might be increased and the margin of selectivity reduced.Croissance et retention des bouillies herbicides par la folle‐avoine et le lin en rapport avec la sélectivité
THE HERBICIDAL ACTIVITY OF 2‐AMINO‐3‐CHLORO‐1,4‐NAPHTHOQUINONE
Authors: HAGIMOTO H. 
Published: July 2006

Summary. An investigation was made of a now herbicide, 2–amino‐3–chloio‐1,4–naphthociuinone (ACNQ,), which appears to be promising for the control oi Echinochloa crus‐galli (L.) Beauv. in transplanted paddy rice [Oryza sativa L.).In pot experiments in the glasshouse, seedlings of Echinochloa at different stages of growth were killed by ACNQ, at doses equivalent to 2–4 kg/ha (applied as granules) if they were submerged, but not if the shoots emerged above water. Activity was increased more by raising the level of water in the pot than by increasing the dosage. Emergent rice seedlings were little affected by ACNQ, up to 8 kg/ha, and the observed selectivity is considered to be due mainly to differences in plant height in relation to depth of water.In laboratory experiments with rice seedlings grown without soil, the activity of ACNQ again increased with the depth of solution. Conversely, at a standard solution depth, there was a reduction in damage with advancing stage of growth, and the chemical had little effect once the leaf tip was above the solution surface.The rate of leaching of ACNQ. through a sandy soil was slow and, at a dose of 2 kg/ha, persistence was about 15 days.In evaluating new herbicides for paddy rice it is suggested that screening tests arc necessary on submerged as well as non‐submerged plants. Activité herbicide de la 2–amino‐3–chloro‐1,′4–naphtoquimne. I. Activité herbicide et profondtur de de l'eau
THE EFFECTS OF DIFFERENT LEVELS OF NITROGEN UPON CIRSIUM ARVENSE (L.) SCOP. PLANTS GROWN FROM SEEDS AND ROOT FRAGMENTS
Authors: HAMDOUN A. M. 
Published: July 2006

Summary. Growth of Cirsium arvense plants was little affected by nitrogen level for the first 3 weeks of treatment, but differences between levels became apparent later. Shoot dry weight increased more than root dry weight at nitrogen levels of 35 ppm or more. The growth responses to nitrogen were similar in pattern in plants grown from seed and from root fragments, but growth was greater in fragment‐derived plants. Effets de l'azote à diverses concentrations sur des plantes de Cirsium arvense (L.) Scop, issues de sentences ou de fragments de racinesRésumé. La croissance de plantes de Cirsium arvense fut peu affectée par la concentration en azote pour les trois premieres semaines de traitement mais des différences selon les concentrations se manifestérent par la suite. Le poids sec de la partie aćrienne s'accrut plus que le poids sec des racines a des concentrations en azote de 35 ppm ou plus. Les reactions de croissance provoquées par l'azote se déroulérent selon un processus analogue pour les plantes issues de semences et pour celles provenant de fragments de racines, mais dans ce dernier cas, la croissance fut plus importante. Wirkung verschieden hoher Stickstoffgaben auf Cirsium arvense (L.) Scop, bei Aufwuchs aus Samen sowie aus WurzelfragmentenZusammenfassung. Das Wachstum von Cirsium arvense zeigte wenig Abhangigkeit von der Höhe der Stickstoffgabe während der ersten drei Wochen nach der Applikation, wohl aber spater. Durch Stickstoffgaben von 35 ppm und mehr wurde das Spross‐Trockengewicht stärker gefördert als das Wurzel‐Trockengewicht. Die Reaktion auf Stickstoff entsprach bei atjs Samen gezogenen Pflanzen weilgehend derjenigen von Pflanzen, die aus Wurzelfragmenten hervorgegangen waren, doch war das Wachstum bei den vegetativ vermehrten Pflanzen allgemein stärker.
AVAILABILITY TO PLANTS OF PARAQUAT ADSORBED ON SOIL OR SPRAYED ON VEGETATION*
Authors: DAMANAKIS M. , DRENNAN D. S. H. , FRYER J.D. , HOLLY K. 
Published: July 2006

Summary. Paraquat adsorbed on peat soils was available to plants in amounts as low as l/25th of their Strong Adsorption Capacity (SAG). In Begbroke soil the paraquat was available to plants only near the SAG. Paraquat sprayed at usual doses on the surface of peat soils and not incorporated reduced growth of seedlings of Lolium perenne L. placed on the surface. Seeds sown 6 mm below a sprayed surface were only affected in one soil at a high rate of application.Hypocotyl uptake of adsorbed paraquat took place only with applications of more than 82 kg/ha in a peat soil and 230 kg/ha in Begbroke soil.Paraquat on litter of sprayed plants was found to be available to plants through root uptake. Living leaves can also adsorb paraquat from sprayed leaves if they are in contact.Disponibilité our les plantes du paraquat adsorbé sur le sol ou appliqué sur la végitationRésumé. Le paraquat adsorbé sur des sols tourbeux fut disponible pour les plantes en quantités n'atteignant que 1/25 de leur capacité brute d'adsorption (GBA). Dans le sol de Begbroke, le paraquat ne fut disponible pour les plantes qu'au voisinage de la CBA. Le paraquat appliqué aux doses usuelles à la surface de sols toturbeux, et non incorporé, réduisit la croissance des plantules de ray‐grass placées sur cette surface. Les semences semées á 6 mm de profondeur sous une surface traitée furent affectées dans un sol seulement et á une dose d'application élevée.L'absorption par I'hypocotyle de paraquat adsorbé se produisit seulement avec des applications à des doses supéieures à 82 kg/ha dans un sol tourbeux et 230 kg/ha dans un sol de Begbroke.Le paraquat sur une litiére de plantes traitées se montra disponible pour les plantes par absorption racinaire. Les feuilles vivantes peuvent aussi adsorber le paraquat de feuilles traitées si elles sont en contact avec elles.Pflanzenverfugbarkeit von im Boden adsorbiertem oder auf PJlanzen gespritztem ParaquatZusammenfassung. Im Moorboden adsorbiertes Paraquat war fur Pflanzen verfügbar in Mengen um 1/25 der Kapazität zur festen Adsorption (Strong Adsorption Capacity, SAG). In Begbroke‐Böden war Paraquat für Pflanzen nur ungefähr in der Höhe des SAG verfügbar. In normalen Aufwandmengen atif die Oberfläche von Moorboden gespritztes und nicht eingearbeitetes Paraquat verminderte das Wachstum von Keimpflanzen von atif der Oberfläche ausgesätem Lolium perenne L. Scchs Millimeter unterhalb der Ober‐flache eingesáte Samen wurden nur in einem Boden bei hoher Herbizidkonzentration beeinflusst.Hypocotyle Aufnahme von adsorbiertem Paraquat erfolgte nur bei Aufwandmengen von mehr als 82 kg/ha in Moorböden und 230 kg/ha in Begbroke‐Boden.Paraquat an Rückständen von behandelten Pflanzen war durch Wurzelaufnahmc für andere Pflanzen verfügbar. Ausserdem können lebende Blatter Paraquat von behandelten Blättern adsorbieren, sofern sie in Kontakt mit dicaen stehen.
SEASONAL DIFFERENCES IN KILL OF TWO KENYA BUSH SPECIES AFTER FOLIAR HERBICIDE TREATMENT
Authors: IVENS G. W. 
Published: July 2006

Summary. In a series of foliar spray treatments on the deciduous Acacia drepanolobium Sjöstedt, a mixture of picloram+2,4‐D lulled a large proportion of the trees in May, the latter part of the principal rainy season, moderate numbers in November‐December, the subsidiary rains, and small numbers during the two intervening dry seasons. An ester formulation of 2,4,5‐T was generally less effective, but similar seasonal variations in kill occurred. At the time of maximum susceptibility, the rate of shoot extension growth was declining and new leaves were fully extended, but still succulent.With the evergreen Tarchonanthus camphoratus L., the effectiveness of spraying was related directly to the growth rate of the shoots. The percentage kill was highest following application of picloram+2,4‐D in May‐July, the late long rains and first half of the long dry season, but low during the November‐December rains and short dry season. T. camphoratus is susceptible to foliar herbicide treatment over a longer period than A. drepanolobium, presumably because of its different seasonal growth characteristics.
STUDIEN ZUR VERTEILUNG VON 14C‐MARKIERTEM 2,4‐D IN VERSCHIEDEN EMPFINDLICHEN UNKRÄUTERN
Authors: SANAD A. J. , Und F. MÜLLER , RADEMACHER B. 
Published: July 2006

SummaryStudies of the absorption and translocation of 14C‐2,4‐D in Chenopodium album L., Galinsoga parviflora Cav., Datura stramonium L. and Galium aparine L. in relation to their susceptibility gave the following results:In G aparine (resistant) there was little transport of 2,4‐D applied to the leaves, and a probable relationship between resistance and the immediate binding of the 2,4‐D in the treated leaf. D. stramonium (relatively resistant) transported 2,4‐D in considerable amounts alter uptake through the leaf, while C. album (very susceptible) and G. parviflora (susceptible) were intermediate in respect of 2,4‐D translocation. No relationship between susceptibility of these four species and 2,4‐D uptake and translocation from the leaves could be established.After application to the root systems of the four species, 2,4‐D was taken up and translocated in the shoot to varying extents. In G. aparine much 2,4‐D was taken up and translocated. In contrast to leaf application, the herbicide was not immediately converted into a strongly‐held immobile form. In C. album, G. parviflora and D. stramonium, however, no 2,4‐D was translocated in the shoot. There was thus no correlation between susceptibility and shoot transport of 2,4‐D in the four species studied. Distribution du 2,4‐D marqué au 14C dans des espèces de mauvaises herbes présentant des sensibilités diverses
THE CHEMICAL CONTROL OF BARLEY GRASS IN DRYLAND LUCERNE
Authors: SOUTHWOOD O. R. 
Published: July 2006

SummaryIn a field trial, different doses of five herbicides applied in autumn and late winder were compared for the control of barley grass (Hordeum leporium Link) in dryland Lucerne.Diuron at 1·1, 2·2, and 4·5 kg/ha and atrazine at 1·1 kg/ha were more effective in increasing Lucerne production than linuron at 4·5 kg/ha and various rates of dalapon and paraquat. Autumn application generally resulted in greater Lucerne production than late winter application. Most treatments reduced the amount of barley grass in the Lucerne. Diuron and atrazine also eliminated reduced the amount of barley grass in the Lucerne.Atrazine, diuron and linuron had a strong residual effect and reduced the density of subterranean clover and barley grass in the autumn following treatment.
THE USE OF THREE SIMPLE, RAPID BIOASSAYS ON FORTY‐TWO HERBICIDES*
Authors: And B. A. KRATKY , WARREN G. F. 
Published: July 2006

SummaryThree rapid bioassays were tested on forty‐two herbicides having several different modes of action. A 50% or greater inhibition of growth was found at 1 ppm with thirty‐one herbicides in one or more of the bioassays. Of the remaining eleven herbicides, seven were detected at 10 ppm, two at 20 ppm and two at 30 ppm.The techniques used were a Chlorella bioassay, a root bioassay with sorghum, oat and cucumber and a shoot bioassay with sorghum and oat. The duration of the bioassays was 1, 2 and 4 days respectively. As a general rule, the Chlorella bioassay was especially sensitive to photosynthetic and respiratory inhibitors but not sensitive to herbicides with other modes of action, whereas the root and/or shoot bioassays were sensitive to most of the herbicides except the photosynthetic inhibitors. The use of the three bioassays simultaneously is suggested as a possible method for primary screening of herbicides.
EFFECTS OF ANNUAL DRESSINGS OF NITROGEN FERTILIZER ON WILD OAT INFESTATIONS
Authors: WATKINS F. B. 
Published: July 2006

SummaryNitrogen fertilizer in three forms, urea, sulphate of ammonia and calcium ammonium nitrate, was applied at three rates, 26, 52 and 104 kg N/ha, early (January) and late (May) during land preparation for three consecutive barley crops, to determine the effect of fertilization on wild oat populations.On the fertilized areas there was significantly greater germination of wild oats prior to sowing than on the unfertilized areas, with calcium ammonium nitrate and sulphate of ammonia tending to be more effective in stimulating germination than urea. Despite the destruction of these heavy populations of wild oat seedlings by cultivation prior to sowing, in‐crop infestations of the weed were still heavy. Late‐applied nitrogen by comparison with the early application tended to produce greater numbers of wild oat panicles in the crop, particularly at the lower fertilizer rates.The overall effect after three annual dressings of nitrogen was one of greatly increased wild oat seed reserves in the soil. These had increased five‐fold in no‐nitrogen plots, six‐fold in early‐fertilized plots and eight‐fold in late‐fertilized plots.It was concluded that annual dressings of nitrogen fertilizer on winter cereals in wild‐oat‐infested areas led to an increase in the population of the weed. Some suggestions are made as to why nitrogen fertilizer stimulated wild oats to germinate, and the overall results are discussed in the light of the agricultural situation of the Darling Downs.
DEVELOPMENT OF CYNODON DACTYLON (L.) PERS.*
Authors: HOROWITZ MENASHE 
Published: July 2006

Summary. Early development of Cynodon dactylon (L.) Pers, was studied on one‐node rhizome fragments planted at successive dates over a year. Aerial growth followed the changes in external temperature; in the cool season tops grew very slowly but remained alive. New rhizomes were formed only at temperatures exceeding 15–20°C. Flowering occurred in the warm season from May onwards. No relationship was found between flowering and rhizome formation. The age of plants forming new rhizomes decreased from 5 months for the January planting to less than 2 months for the May‐September plantings. Rhizome bud germination was maximal between 23 and 35°C, slow below 20°C and inhibited at 10°C.The weight ratio of tops to subterranean parts of established plants was near 1 in winter, declined in March‐April and remained at 0·5–0·6 from May onwards.An established sward of C. dactylon was sampled from September to November of the following year. Dry weight was lowest from January to mid‐April, rose in spring and decreased in late summer. Almost no rhizomes were found deeper than 45 cm. Underground parts from the 0–15, 15–30 and 30–45 cm horizons constituted 62, 26 and 12% of the total weight, respectively; rhizomes formed more than 90% of the total underground dry weight. In the warm season the dry weight of the subterranean organs amounted to 2, 0·7 and 0·4 kg/m3 of soil in the three horizons, respectively.Percent dry matter in tops and subterranean parts was about 35–45% in the winter and 50–65% in the warm season. Up to 2% reducing sugars was found in various parts of the plants. The water‐soluble sugar content of rhizomes was high in November‐December, decreased in late winter, rose again in spring, and decreased in late summer.Percent germination of rhizome buds fluctuated greatly during the year, but complete dormancy was never recorded. Newly‐formed rhizomes showed a high germinative capacity. Similar germination percentages were found on fragments with one node and those with several nodes. Développement du Cynodon dactylon (L.) Pers.
STUDIES ON THE BIOLOGY AND CONTROL OF VAUCHERIA DICHOTOMA FOUND IN FRESHWATERS IN BRITAIN
Authors: DOWIDAR A. R. , ROBSON T. O. 
Published: July 2006

Summary. Vaucheria plants collected from a ditch near Crowland and from the River Cherwell at Oxford in the first week of October 1970 were identified as V. dichotoma Ag. A nutrient medium is described which allows the growth and the production of organs of sexual reproduction of this alga. Preliminary studies on the control with diquat show that it must be exposed to a concentration of 2 mg/1 for 6 h for the herbicide to be effective. The presence of mud reduces the rate at which chlorophyll disintegrates and hastens the inactivation of diquat. Etudes sur la biologie et la destruction de Vaucheria dichotoma. Ag. dans les eaux doucei de Grande‐Bretagne
FATE OF SEEDS OF SOME ANNUAL WEEDS IN DIFFERENT DEPTHS OF CULTIVATED AND UNDISTURBED SOIL
Authors: ROBERTS H. A. , FEAST PATRICIA M. 
Published: July 2006

Summary. Freshly‐collected seeds of twenty species of annual weeds were uniformly mixed with 2.5, 7.5 or 15 cm of soil confined in cylinders sunk in the ground outdoors. The soil was either cultivated four times a year or left undisturbed, seedling emergence was recorded, and after 5 years the numbers of viable seeds remaining were determined.Total seedling emergence from seeds incorporated to 2·5, 7·5 and 15 cm amounted to 75, 65 and 54% respectively of those added when the soil was cultivated, and 58, 36 and 21% where it was left undisturbed. The corresponding numbers of viable seeds remaining after 5 years were 2·3, 4·0 and 7·7% respectively for cultivated soil, and 6·8, 16·5 and 31·6% of the seeds initially added and then not disturbed. Individual species varied in their responses to increasing depth of incorporation and to cultivation; these differences are discussed in relation to the dormancy characteritics of the seeds.Devenir des semences de quelques mauvaises herbes annuelles à différentes profondeur dans un sol cultivé et non cultivé