bluuebunny/crossref_metadata_2025_split huggingface dataset:
Competition between annual weeds and vining peas grown at a range of population densities: effects on the crop
Authors: LAWSON H. M. 
Published: July 2006

SummaryCompetition between annual weeds and vining peas (Pisum sativum L.) at five target population densities between 11 and 194 plants/m2 was examined by means of periodic destructive sampling of weedy and weed‐free plots. A further area of each plot was cut and vined to assess yields. Weeds impaired vegetative development, particularly by reducing tillering in low density crops. This resulted in weedy plots having fewer pods per plant at harvest but a lower proportion of flat pods than weed‐free plots. Weeds had no effect on numbers or weights of peas in full pods nor on tenderometer values of samples of vined peas.Adverse effects of weeds on the growth of individual crop plants decreased with increasing crop density. However, at lower crop densities many of the additional pods on weed‐free plots contributed little to vined yield, while at higher densities, direct or indirect effects of weeds increased the problem of maintaining sufficient photosynthetic area during pod swelling to prevent pod abscission and poor ovule development. Regression analysis of yield on crop density and of yield on numbers of pods per plant showed that vined yield per hectare was reduced by weeds by a constant amount across the range of densities and numbers of pods examined. Vining throughput was also reduced in weedy as compared with weed‐free crops, even on high density plots where little or no weed vegetation remained at harvest.In general, weed presence had effects similar to those caused by increasing crop density, but without the additional contribution to yield made by extra plants. Higher density crops suppressed weeds very effectively but were no less vulnerable to yield loss than those of lower density; they therefore merit just as much attention to effective weed control as crops suffering more visibly from competition by weeds.
Response of teff (Eragrostis tef(Zucc.) Trotter) to 2, 4‐D and MCPA at various growth stages
Authors: MERSIE WONDIMAGEGNEHU , PARKER C. 
Published: July 2006

SummaryTeff (Eragrostis tef (Zucc.) Trotter) cv.DZ‐01‐ 354 was sprayed at one‐, three‐, four‐, five‐ and six‐leaf stages with 2.4‐D (amine salt) and MCPA (potassium salt) each at 0.75 and 1.5 kg a.e. ha−1. Teff was also grown in different temperature regimes to see the relation between apical and vegetative development. Photomicrographs were made to determine the stage of development of the growing point and dry matter measurements were made to assess the effects of the herbieide. Teff sprayed at the one leaf stage was killed by both herbieides. At the three‐ and four‐leaf stages 2, 4‐D at both rates and MCPA at 1.5 kg a.i. ha−1 caused severe leaf deformities and reduced dry weights. Less severe effects were noted at the five‐leaf stage indicating that teff was then more tolerant to these herbicides. This coincided with a fully elongated shoot apex. However, when sprayed at the six‐leaf stage there was evidence of herbicide‐induced panicle deformities. Teff was more susceptible to 2, 4‐D than to MCPA and both affected the roots more than the shoots. A close correlation was found between leaf number and the development of shoot apex under all the different temperature and day length conditions.
Etudes préliminaires sur la concurrence entre Solanum nigrum ssp. eu‐nigrum L. (morelle noire) et Lycopersicon esculentum Mill. (tomate) en culture repiquée
Authors: MAILLET J. , ABDEL‐FATAH H. 
Published: July 2006

SummaryL'accroissement de production des tomates (Lycopersicon esculentum Mill.) de conserverie en semis direct et l'utilisation d'herbicides sélectifs ont entraîné la prolifération de Solanum nigrum L. dans le Sud‐est de la France. Les estimations réalisées sur le terrain ont montré l'action préjudiciable de faibles populations de morelles; un essai a été mis en place afin de déterminer un seuil de nuisibilité. Dans les conditions d'essai, une droite de régression a pu être tracée en fonction de la densité de morelle/m linéaire et du logarithme du rendement.
The influence of climatic factors on metoxuron activity on Bromus sterilis L.
Authors: BLAIR A.M. , RICHARDSON W.G. , WEST T.M. 
Published: July 2006

SummaryMetoxuron was more active when Bromus sterilis L. (sterile brome) plants were kept under cool (10/6°C day/night) compared with warm (26/16°C) temperatures after spraying. The effect of warmer temperatures required exposure for more than 3 days. Metoxuron activity was unaflected by a cold exposure (0/‐2°C or 4/2°C) for a 24‐h period shortly before or after spraying.Greater damage occurred when plants were kept in high relative humidity (r.h.) (95/98% r.h. day/nighl) after spraying than at 75/86% r.h. or at 50/75% r.h. Increasing soil moisture from 11.5 to 21.5 g water 100 g−1 dry soil also resulted in increased metoxuron activity. Metoxuron was less active under severe shading.There was little evidence in these studies that metoxuron activity resulted from foliar uptake. Results are discussed with reference to field reports of metloxuron use against B. sterilis. L.
Dégradation catalytique du propyzamide déposé sur bentonite
Authors: BASTIDE J. , COSTE C. M. , SABADIE J. 
Published: July 2006

RésuméLa dégradation du propyzamide a étéétudiée après dépôt sur diverses bentonites homioniques. Les meilleures activités sont obtenues avec les bentonite Ag + et Cu++ qui provoquent la dégradation du propyzamide selon un processus en deux étapes. La présence d'humidité provoque l'apparition d'un processus secondaire compétitif.
Absorption and translocation of 14C‐3,6‐dichloropicolinic acid in Cirsium arvense (L.) Scop.
Authors: O'SULLIVAN P. A. , KOSSATZ V. C. 
Published: July 2006

SummaryExperiments were conducted in a growth cabinet to investigate the absorption and translocation of 14C‐3, 6‐dichloropicolinic acid by Cirsium arvense (L.) Scop. (Canada thistle, creeping thistle), a sensitive species. Applications were made, either to the middle four leaves of 12‐cm‐tall vegetative plants grown under low (40%) and/or high (>95%) relative humidity (r.h.), or to four upper or lower leaves of 30‐cm‐tall flowering plants grown under low r.h. Following application to vegetative plants, absorption and translocation of 14C‐3,6‐dichloropicolinic acid was rapid and was approximately doubled by high r.h. High r.h. increased the amount of radioactivity retained by the treated leaves or translocated to the shoots but did not affect greatly the amount retained in the roots. The herbicide was highly mobile, with over half of that absorbed, translocated out of the treated leaves after two days. The apex accumulated most of the radioactivity, while approximately 8% was recovered from the roots. The absorption and translocation patterns were similar to those reported in the literature for picloram in C. arvense. Absorption of 3,6‐dichloropicolinic acid was greater in vegetative than in flowering C. arvense plants, and placement of herbicide on lower leaves tended to decrease the amount of radioactivity recovered from shoot apex and increase the amount recovered from the roots. Approximately 15% of the applied radioactivity could not be recovered from treated plants by 2 days after treatment.
The influence of water solubility on the movement and degradation of simazine in a fallow soil
Authors: NICHOLLS P. H. , BRIGGS G. G. , EVANS A. A. 
Published: July 2006

SummaryThe movement and degradation of simazine in the field during winter and summer were measured and compared with simulations using a simple model. The model only simulated simazine behaviour closely when water solubility was taken into account. Relationships between water solubility, melting point, soil adsorption and octan‐1‐ol/water partition coefficient indicate that, at agricultural rates of application, water solubility will only have an important influence on behaviour for relatively polar chemicals with high melting points.
Mechanism of action of asulam in celery tissue cultures
Authors: HEWERTSON N. A. , COLLIN H. A. 
Published: July 2006

SummaryThe mechanism of action of the phenylsulphonyl carbamate herbicide (asulam) was examined in celery tissue cultures to see whether the mechanism involved an inhibition of folic acid synthesis. When asulam was included in the nutrient medium, growth of the celery cultures was reduced but not entirely inhibited even at a concentration of 250 μm. Growth was also reduced if a phenylcarbamate herbicide (barban), or sulphanilamide were included in the medium. The addition of folic acid, or 4‐amino benzoic acid, which is a precursor of folic acid, almost totally reversed the inhibitory effect of the asulam and sulphanilamide, but not of barban, whereas the addition of thymidine, methionine, serine or adenine, all of which are formed from folic acid, did not reverse the inhibitory effect of asulam, sulphanilamide or barban. Nevertheless the removal of the growth inhibition of asulam by folic acid or 4ABA suggested the mechanism of action of asulam was similar to that of a sulphanilamide. This mechanism of action in celery cell cultures appears to be similar to that found for asulam in intact plants of a range of species.
Selectivity factors relative to asulam for Senecio jacobaea L. control in Medicago sativa L. II. Metabolism*
Authors: HARPER DELBERT R. , APPLEBY ARNOLD P. 
Published: July 2006

SummaryMetabolism of 14C asulam applied with surfactant was studied in Senecio Jacobaea L. and Medicago saliva L. Plants were harvested 48, 96 and 144 h after treatment and extracted with acetone. The aqueous residue of the acetone extract was partitioned with ethyl acetate and the 14C activity in the ethyl‐acetate phase, the aqueous phase and the plant residue was determined. A significant amount of 14C activity was not extracted by acetone from either species. This amount increased with time in M. sativa but remained relatively constant in S. jacobaea. More 14C activity was found in the aqueous phase than in the ethyl‐acetate phase in M. sativa while the reverse was true in S. jacobaea. Significantly lower amounts of free asulam were identified in M. sativa than in S. jacnbaea. Still, results of these and previous studies on retention, uptake and translocation do not completely account for differences in sensitivity found in greenhouse and field applications. Other possible explanations for selectivity are discussed.
Effects of application method on the performance of some soil‐applied herbicides. I. Glasshouse experiments
Authors: ADDALA M. S. A. , HANCE R. J. , DRENNAN D. S. H. 
Published: July 2006

SummaryChlortoluron, propyzamide, terbutryne and nitrofen were applied to the soil in pots with a rotary atomizer at 301 ha−1, with a conventional hydraulic nozzle at 400 1 ha−1 at several doses, or as discrete 2‐μl drops applied with a microsyringe at 2‐cm spacings. The test plants were Alopecurus myosuroides, Stellaria media, Chenopodium album, Avena fatua, perennial ryegrass and radish. Chlortoluron, propyzamide and terbutryne had the same activities following the rotary atomizer or conventional spray application but the rotary atomizer application of nitrofen was less effective against A. fatua than the conventional spray treatment. Chlortoluron, propyzamide and terbutryne showed appreciable activity applied as drops 2 cm apart at rates equivalent to 2 kg ai ha−1, on plants growing equidistant from the drops, but nitrofen showed no activity under these circumstances.The activity of chlortoluron was investigated at different soil moisture contents; it was more active when applied to moist soil than to dry soil which was not wetted for at least 10 h. Application method did not affect this response
Growth and patterns of resource allocation in Eupatorium odoratum L. in the secondary successional environments following slash and burn agriculture (Jhum)
Authors: SAXENA K. G. , RAMAKRISHNAN P. S. 
Published: July 2006

SummaryBiomass, nitrogen, phosphorus and potassium in Eupatorium odoratum L. (Asteraceae), an abundant early successional perennial weed, were studied in seral stages after slash and burn. Increment in individual biomass and nutrient uptake declined with increasing time after fallow. A higher proportion of the available resources was allocated to the supporting organs but a lower proportion to the photosynthetic organ in the older fields compared to recently fallowed fields. The allocation of biomass to reproduction, and also nutrient content, decreased during seral development. However, cost of reproduction to the plants (considered as the proportion of increment in biomass or nutrient uptake during the current growing season) was much higher in the older fields than the younger ones. Growth was adversely affected by low nutrient availability in soil in the recently fallowed fields but the allocation pattern remained unaffected. Biomass was not allocated in the same manner as nutrients. A higher proportion of nitrogen and phosphorus compared to that of biomass and potassium was devoted to reproduction in all the fields.
Response of three winter wheat cultivars to difenzoquat
Authors: PALLETT K. E. 
Published: July 2006

SummaryThe response to difenzoquat of the three winter wheat cultivars, Hobbit, Maris Huntsman and Score is compared. In an experiment in which plants with three to four leaves were sprayed with 0, 1, 2 and 4 kg ai ha−1 difenzoquat Maris Huntsman was most tolerant while Score appeared least tolerant. Difenzoquat reduced the main shoot height and lamina length, and increased tiller number. At the high doses the main shoot was often killed, particularly in Hobbit and Score, which showed stunting and tillering with the 1‐kg dose. DNA synthesis, monitored by 14C‐thymidine incorporation in excised meristematic segments, and 14C‐difenzoquat penetration and translocation were compared in the three cultivars. 1 × 10−4m difenzoquat inhibited DNA synthesis by 7·9, 29·3 and 45·5% in Maris Huntsman, Score and Hobbit respectively. This is likely to contribute to the different responses of Maris Huntsman and Hobbit as 14C‐difenzoquat penetration and translocation were similar. However, there was a greater accumulation of 14C activity in the apical meristem of Score, which is likely to contribute to the greater susceptibility of this cultivar, as is the greater inhibition of DNA synthesis and higher level of spray retention.
A mathematical modelling approach to the study of the economics of controlling Rumex obtusifolius in grassland
Authors: DOYLE C. J. , OSWALD A. K. , HAGGAR R. J. , KIRKHAM P. W. 
Published: July 2006

SummarySynthesizing data from several sources, a simplified mathematical model of dock (Rumex obtusifolius) reproduction, growth and competition with grass has been constructed. Using the model, an attempt has been made to study the short‐ and long‐term economic implications of controlling dock infestation in a grassland conservation system by use of the herbicide asulam. The sensitivity of the results has been tested in respect of assumptions about the efficacy of asulam in controlling docks and the economic values attached to grass and dock dry‐matter production. However, given the large number of assumptions necessitated by the limited availability of data and in the absence of any means of validating the model, extreme care is needed in interpreting the results. Nonetheless, while the model cannot be used to derive practical recommendations it can and does provide some useful insights into herbicide control of docks. However, confident economic predictions of the value of controlling docks in grassland await further experimental work on the population dynamics of docks, the factors influencing the effectiveness of herbicides and the nutritive value of docks.
Measurement of phytotoxicity of commercial and unformulated soil‐applied herbicides
Authors: STREIBIG J.C. 
Published: July 2006

SummaryThe relative potencies of analytical‐grade lenacil (99% ai) and its commercial formulation, Venzar® (80% ai), technical‐grade ethofumesate (96%) and its commercial formulation Nortron® (21% ai) were evaluated using oats (Avena sativa L. cv. Selma) as test plant.In all experiments the dose‐response curves of the pure herbicide and its commercial product were parallel. The average potency of Venzar relative to lenacil, assayed twice in a sandy loam, was 0⋅80 and thus equal to the expected 0⋅80. The average potency of Nortron relative to ethofumesate, assayed in a sandy loam and a loamy sand, was 0⋅25 and close to the expected value of 0⋅21.The implication of using the technique of parallel‐line assay in herbicide studies is discussed and its potential use in other contexts than the present one is suggested.
Role of temperature in regulating timing of germination in soil seed reserves of Lamium purpureum L.
Authors: BASKIN J. M. , BASKIN CAROL C. 
Published: July 2006

SummaryFresh seeds of Lamium purpureum L. were dormant at maturity, and when buried and exposed to natural seasonal temperature changes they exhibited an annual dormancy/non‐dormancy cycle. During burial in summer, fresh seeds and those that had been buried for 1 year afterripened and thus were non‐dormant by September and October; light was required for germination. During autumn and winter seeds re‐entered dormancy, and during the following summer they became non‐dormant again. Dormant seeds afterripened when buried and stored over a range of temperatures, becoming conditionally dormant at low (5, 15/6°C) and non‐dormant at high (20/10, 25/15, 30/15 and 35/20°C) temperatures. Conditionally dormant seeds germinated to high percentages at 5, 15/6 and 20/10°C, while non‐dormant seeds germinated to high percentages additionally at 25/15, 30/15 and 35/20°C. Low temperatures caused non‐dormant seeds to re‐enter dormancy, while high temperatures caused a sharp decline in germination only at 30/15 and 5°C. The temperature responses of L. purpureum seeds are compared to those of L. amplexicaule L.
Residualwirkung von Chlortriazin‐Herbiziden im Boden an drei rumänischen Standorten. II. Prognose möglicher Folgekulturen bei Atrazinrükständen im Boden
Authors: PESTEMER W. , GHINEA L. , RADULESCU VALERIA 
Published: July 2006

ZusammenfassungVon drei Versuchsstationen in Rumänien, die unterschiedliche Klima‐ und Bodeneigenschaften aufweisen, wurden 1982 120 Tage nach Applikation von 3 kg Atrazin ha−1 in Mais (Zea mays L.) Proben aus 0–10 cm Bodentiefe auf ihre Gesamtrückstände und pflanzenverfügbaren Anteile mit einer Wasserextraktions‐ und Biotestmethode untersucht. An einem Standort wurden zudem die gleichen Bestimmungen 3,5 Jahren nach Anwendung von 100 kg AS ha−1 durchgeführt.In Abhängigkeit von der unterschiedlichen Atrazinverlustrate und der prozentualen Verfügbarkeit bei den drei Standorten konnten 30–120 μg 1−1 Boden an potentiell pflanzenverfügbarem Atrazin ermittelt werden.In Langzeit‐Biotesten in Hydroponik wurde die Aktivität dieser Konzentrationen auf die für Rumänien wichtigsten Folgekulturen nach Maisanbau—Sonnenblume, Winterweizen, Sojabohne und Lein—überprüft. Die ED50‐ Werte und die Einteilung der Wirkung in fünf Aktivitätskategorien erfolgte mit der Probit‐Analyse, wobei die Sonnenblume mit 22 μg 1−1 die höchste und die Sojabohne mit 78 μg 1−1 die niedrigste Empfindlichkeit zeigte.Mit Hilfe der ermittelten Verfügbarkeitswerte kann für jeden Standort anhand einer Verträglichkeitsliste abgelesen werden, ob und wie stark Atrazin‐Rückstände mögliche Nachbaukulturen zu schädigen vermögen.
A competition index for Orobanche crenata Forsk effects on broad bean (Vicia faba L.)
Authors: MESA‐GARCÍA J. , GARCÍA‐TORRES L. 
Published: July 2006

SummaryThe influence of broomrape (Orobanche crenata Forsk) infection levels on commercial broad bean (Vicia faba L.) crops was investigated and an equation relating yield losses to O. crenata density was derived. O. crenata growth was weakly and negatively related to the final height or shoot number of the broad bean plant. O. crenata decreased seed yield mainly by reducing the number of pods. The number of seeds per pod was also decreased by O. crenata infection when competition occurred at late‐crop growth stages when most of the pods had already developed. Bean unit seed weight was only weakly affected by infection. Correlation coefficients between O. crenata number and broad‐bean seed yield per plant were significant at P=0·05 and greater than 0·70 in most locations. On average, about four O. crenata per broad‐bean plant decreased seed yield by half. An estimation of the percentage of losses in any field can be calculated from the equation:%loss = 100 × 0·124 × OcN.where OcN is the average final number of emerged O. crenata per plant.
Effects of fluazifop‐butyl on shoot growth and rhizome buds of Elymus repens (L.) Gould
Authors: CHANDRASENA J. P. N. R. , SAGAR G. R. 
Published: July 2006

Summary:A series of glasshouse experiments was conducted to evaluate the activity of fluazifop‐butyl, butyl 2‐[4‐(5‐trifluoromethyl‐2‐pyridyloxy)phenoxy] propionate, against Elymus repens. Foliar applications of doses 0·25–1·0 kg ha−1 consistently gave better control than did soil applications. The most obvious phytotoxic symptoms were chlorosis and necrosis, beginning with the youngest leaves 5–6 days after spraying, which spread to all leaves within 2 weeks. Translocation was measured by defoliating plants at different times after spraying and assessing regrowth and by evaluating rhizome‐bud viability. At low doses (0·125 and 0·25 kg ha−1) translocation to rhizomes occurred mainly between 6 and 48 h. When fluazifop‐butyl was sprayed at a dose range of 0·125–1·0 kg ha−1, at least 90% of the rhizome buds had accumulated a lethal dose within 72 h of spraying. In another experiment, with a dose of 0·25 kg ha−1, 31, 72 and 92% of rhizome buds were found to be non‐viable when sampled 2, 24 and 48 h respectively after spraying. At 1·0 kg ha−1 all the buds had accumulated sufficient herbicide to prevent sprouting 48 h after spraying.
Atrazine metabolism in resistant and susceptible biotypes of Chenopodium album L., Chenopodium strictum Roth., and Amaranthus powellii S. Wats.
Authors: KHAN S. U. , WARWICK S. I. , MARRIAGE P. B. 
Published: July 2006

SummaryThe metabolism of atrazine was studied in resistant and susceptible biotypes of Chenopodium album L., Chenopodium strictum Roth., and Amaranthus powellii S. Wats. Both biotypes metabolized atrazine by N‐dealkylation, hydroxy lation at the 2‐position and conjugation. In addition, binding of mono‐N‐dealkylated atrazine with plant constituents to form nonextractable (bound) residues was also observed. Although parent atrazine levels were similar in the shoots and roots of both biotypes of the three weed species, the resistant biotype in each case contained a higher level of polar conjugates and bound residues in the plant tissues. In contrast, presence of a phytotoxic metabolite, namely 2‐chloro‐4‐amino‐6‐isopropylamino‐s‐triazine, was only observed in the susceptible biotype of the three weed species.