bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiological responses of maize and sorghum to four different safeners for metazachlor
Authors: EKLER Z. , STEPHENSON G. R. 
Published: July 2006

SummaryThe ability of the herbicide safeners, BAS‐145138 (1‐dichloroacetyl‐hexahydro‐3,3,8a‐trimethyl‐pyrrolo(1,2a)pyrimidin‐6(2H)‐one), dichlormid (N,N‐diallyl‐2,2‐dichloroacetamide), flurazole (phenylmethyl ester), and MG‐191 (2‐dichloromelhyl‐2‐methyl‐1,3‐dioxolane) for preventing metazachlor injury to maize (Zea mays L.) and sorghum (Sorghum bicolor L.) seedlings were compared with their effects on 14C‐metazachlor metabolism to a glutathione (GSH) conjugate, effects on non‐protein thiol contents (mainly GSH) and effects on Glutathione S‐transferase (GST) activity in these two species.Sorghum shoot growth was reduced by 41% and maize shoot growth was reduced by 54%, by metazachlor concentrations in vermiculite nutrient culture of 0·6 μM and 7·5μM, respectively. In this system, all four compounds had significant activity as safeners for metazachlor in both sorghum and maize seedlings. BAS‐145138 and flurazole were the most effective safeners in maize and sorghum, respectively. In the absence of safeners, the rate of non‐enzymatic conjugation of metazachlor and GSH was much greater than the enzymatic rate. However, the rate of enzymatic conjugation of metazachlor with GSH was increased by safener treatment in both maize and sorghum. Safener effectiveness was highly correlated with increases in 14C‐metazachlor uptake and metabolism in both species. Safener effectiveness was more highly correlated with safener effects on GST activity in maize or sorghum when 14C‐metazachlor was used as the substrate than when the non‐specific CDNB (1‐chloro‐2,4‐dinitrobenzene) was used as the substrate. Safener effectiveness was also strongly correlated with safener effects on GSH levels in sorghum, but not in maize, possibly because of the greater importance of non‐enzymatic conjugation of metazachlor with GSH in sorghum as compared to maize.
Response of maize (Zea mays L.) inbred lines and hybrids to chlorsulfuron
Authors: LANDI P. , VICARI A. , CATIZONE P. 
Published: July 2006

SummaryTwenty inbred maize lines, raised in a growth chamber, were treated with 0 or 1 ng g−1 of chlorsulfuron which caused a variable reduction in root‐length. In a second experiment, all crosses (reciprocals included) among two tolerant lines (T: Va85 and Mes44) and two susceptible lines (S: B73 and B79) were raised in a growth chamber together with the parental lines and exposed to 0,0×5 or 1 ng g−1, The interaction of reciprocal effects x rates was not significant for all traits, The T × S hybrids showed an intermediate response between the T × T and S × S responses for root‐length and dry weight. Interaction (hybrids vs. parental lines) × rates was not significant for all traits. These results indicate that susceptibility to chlorsulfuron is not controlled by extra‐nuclear factors and that additive gene actions prevail. Four crosses (one T × T, two T × S and one S × S) were further investigated at nine rates from 0 to 1 ng g−1. The responses confirmed the intermediate behaviour of T×S hybrids, resulting in a GR20 of 0×07, 0×55 and 0×94 ng g−1 for S × S, T × S and T × T, respectively. In a third experiment, the four crosses previously considered were grown in the field with parental lines and treated at five rates from 0 to 1·12 g a.i. ha−1. Effects on shoot height and dry weight were consistent with root effects found in growth chamber experiments.
Einfluß des Zersetzungsgrades organischer Sub‐stanzen auf die Keimung von Striga hermonthica (Del.) Benth
Authors: COMBARI A. , PINEAU R. , SCHIAVON M. 
Published: July 2006

Résumé:De la poudre de cellulose ou des fragments de paille de blé sont mélangées á un substrat inerte (sable stérilisé). A l'issue de différents temps d'incubation (0 á 8 semaines) du substrat ainsi amendé des graines de sorgho sont semées et une extraction des exsudats racinaires et produits de décomposition des matiéres organiques est réali‐sée aprés deux semaines de culture. L'influence de ces extraits sur la germination de graines de Striga hermonthica (Del.) Benth. est la suivante: dans tous les cas, on assiste á une réduction importante du taux de germination au terme de 4 á 6 semaines d'incubation des produits organiques. Un effet stimulant de l'apport de paille est toutefois noté dans les premiéres semaines de sa dégradation. Une meilleure connaissance des mécanismes et processus de stimulation et d'inhibition liés aux apports de matiére organique devrait permettre une rationalisation des amendements en pays d'Afrique tropicale séche.
A model of the effects of cultivation on the vertical distribution of weed seeds within the soil
Authors: COUSENS R. , MOSS S. R. 
Published: July 2006

Summary:A matrix model was constructed for the prediction of vertical seed movement within the soil. This was inserted into a model of the life‐cycle of Alopecurus myosuroides in order to predict seed population dynamics. Parameter values were obtained from published sources and from a single field cultivation experiment using coloured plastic beads. In simulations, stability of vertical distribution was reached sooner under ploughing than under rigid tine cultivation. Stable distributions were very different for the two cultivation methods, being reached by damped oscillations in the case of ploughing and asymptotically in the case of rigid tine cultivation.
The use of thermal calendar models to improve the efficiency of herbicide applications in Sorghum halepense (L.) Pers
Authors: GHERSA C. M. , SATORRE E. H. , VAN ESSO M. L. , PATARO A. , ELIZAGARAY R. 
Published: July 2006

Summary:The dynamics of sprout emergence and rhizome populations of Sorghum halepense (L.) Pers. were followed in two field experiments. In addition, the herbicide dalapon was applied at various stages during rhizome development and the degree of control was evaluated. Rhizome biomass oscillated during the growth cycle, whereas the number of rhizome sprouts increased asymptotically until mid‐summer. Observed values were compared against those predicted from a thermal calendar model. The dynamics of the rhizome population was predicted accurately in both experiments, but only in one of them was the prediction of the sprout emergence satisfactory. The degree of control differed markedly between herbicide applications at various intervals during population development. Best results were obtained from applications when rhizome biomass was at a minimum. The time of minimum biomass was predicted by a thermal calendar model. The advantages of using the thermal calendar model to determine the time of herbicide application, and the possible influence of the distribution of the rhizome population in the soil profile on the predictions of the model, are discussed.
Efficacy of five different formulations of clopyralid on Cirsium arvense (L.) Scop, and Polygonum convolvulus L
Authors: KLOPPENBURG DAVID J. , HALL J. CHRISTOPHER 
Published: July 2006

Summary:Experiments were conducted in a controlled environment growth room to compare the phytotoxicity of five formulations of clopyralid and to determine the effect of post‐treatment simulated rainfall applications on the efficacy of these formulations. Clopyralid, formulated as the acid, monoethanolamine salt, potassium salt, 2‐ethylhexyl ester or 1‐decyl ester was applied to Cirsium arvense or Polygonum convolvulus at the 8–10 and 4–6 leaf stage of development, respectively.Based on the shoot and root dry weight data from both species, the 2‐ethylhexyl ester was consistently less phytotoxic than the other four formulations. With respect to Cirsium arvense shoot and root dry weight, there was no difference in efficacy between the acid, monoethanolamine salt, potassium salt and 1‐decyl ester. Root dry weight changes of Polygonum convolvulus did not correlate well with an increase in dose of the five formulations. Maximum increase in stem diameter of Polygonum convolvulus occurred after application of 100 g a.e. ha−1 of the acid, monoethanolamine salt, potassium salt and 1‐decyl ester whereas with the 2‐ethylhexyl ester, the maximum increase occurred after application of 200 g a.e. ha−1. Simulated rainfall was applied 3, 6, 9 or 12 h after application of 200 g a.e. ha−1 of the five clopyralid formulations to both species. Rainfall reduced the efficacy of clopyralid, regardless of the formulation or species. The 2‐ethylhexyl ester was less efficacious than the other four formulations, irrespective of the timing of simulated rainfall.
Growth behaviour and leaf morphology of Philippine strains of Sphenoclea zeylanica showing differential response to 2,4‐D
Authors: MERCADO B. L. , DE DATTA S. K. , MIGO T. R. , BALTAZAR A. M. 
Published: July 2006

Summary:The germination and growth of three strains of gooseweed (Sphenoclea zeylanica Gaertn.) that showed susceptibility, moderate susceptibility, and tolerance for foliar‐applied 2,4‐D isobutyl ester were studied in the laboratory and greenhouse. The plants were isolated from samples collected from major rice (Oryza sativa L.) growing areas in the Philippines. The seeds of all three strains possessed dormancy; light stimulated germination but did not completely overcome dormancy. Without N application, stem elongation and leaf production did not differ among the strains. With 60 kg N ha−1, the susceptible and moderately susceptible strains responded better than the tolerant strain, the difference being apparent at 6 weeks after emergence. Measurements of the leaf cuticle showed significant differences among the strains starting at the 8‐ to the 10‐leaf stage, a trend that paralleled their response to 2,4‐D. Adding a surfactant to the spray formulation nullified the differential responses. Implications for managing the weed and correlations with current field observations are discussed.
Weed flora of dryland crops in the Córdoba region (Spain)
Authors: HIDALGO B. , SAAVEDRA M. , GARCIA‐TORRES L. 
Published: July 2006

Summary:In a study of the weed flora of dryland crops in the Córdoba region (southern Spain) in 1983 and 1984, a total of 256 species from 41 families was identified in the 201 fields surveyed. The families with the highest numbers of species were Compositae, Gramineae, Leguminosae and Cruciferae. Therophytes represented 79% of the biological spectrum, with hemicryptophytes and geophytes more especially in the spring‐sown crops. At the early and late crop growth stages about 4% and 8%, respectively, of the fields had severe or very severe infestations. The seasonality of the crop had a marked influence on the weed flora, mainly due to the relationship of its phenological cycle with well defined climatic periods and to soil management practices. Cluster analysis clearly differentiated typically autumn‐spring and spring‐summer floras as well as a set of common species.
The influence of Agral 90 surfactant on the activity of imazamethabenz in wild oats (Avena fatua L.)
Authors: SMITH A.M. , CHOW P.N.P. 
Published: July 2006

Summary:The influence of the nonionic surfactant, Agral 90, on the activity of imazamethabenz in wild oats (Avena fatua L.) was investigated in glasshouse and laboratory trials. Agral 90 significantly increased the efficacy of imazamethabenz against wild oats at a range of growth stages; a significant decrease in activity of both imazamethabenz alone or with Agral 90 was observed following application to plants possessing tillers. At 0.1 kg ha−1, the growth of tillers was significantly reduced by imazamethabenz plus Agral 90. The retention of imazamethabenz on wild oat foliage was significantly increased by Agral 90 incorporation; Agral 90 also facilitated retention of imazamethabenz on the tillers. The absorption and translocation of imazamethabenz were significantly enhanced by Agral 90; greater amounts of the labelled material were found in all regions of the plant except the tillers which existed at the time of application.
Utilisation de I'isoproturon, seul et en association avec d'autres matiires en actives, en post levée à I'automne at en printemps, sur blé et orge d'hiver. II. Effets secondaires sur I'activiti de la déshydrogénase, la transformation de V azote et la décomposition des chaumes dans le sol
Authors: BERGER B. , HEITEFUSS R. 
Published: July 2006

Zusammenfassung:In einem zweijährigen Feldversuch auf zwei Standorten wurde der Einfluß von Isoproturon, allein und in Kombination mit Dinoseb–acetat und Bifenox, auf die Dehydrogenaseaktivität, den Stickstoffumsatz und den Strohabbau im Boden nach einer Anwendung im Nachauflauf Winter (NA–W) und Nachauflauf–Frühjahr (NA–F) zu Winterweizen und Wintergerste untersucht. Isoproturon rief vorübergehend geringe Stimulationen aber auch Hemmungen der Dehydrogenaseaktivität um maximal 40% und des Stickstoffumsatzes um 70–90% hervor. Dinoseb–acetat führte zu Reduktionen der allgemeinen Stoffwechselaktiviät um bis zu 30%. Die Ammonium– und Nitritkonzentrationen lagen zeitweise um mehr als 100%über den Kontrollwerten. Im Labor hatte Isoproturon bei den zu diesen Terminen herrschenden Temperatur– und Feuchtebedingungen nur in wenigen Fällen einen Einfluß auf die Dehydrogenaseaktivität, nach Applikation dereinfachen Aufwandmenge von Dinoseb–acetat war die Aktivität aber um bis zu 50% reduziert. Im Sandboden waren die Herbizideffekte deutlicher ausgeprägt als im Lehmboden. Ein Einfluß der Behandlungstermine auf die durch die Herbizide bedingten veränderten mikrobiellen Aktivitäten wurde nur in den Freiland–versuchen deutlich.
Enhanced degradation of some soil‐applied herbicides
Authors: WALKER A. , WELCH SARAH J. 
Published: July 2006

Summary:In a field experiment involving repeated herbicide application, persistence of simazine was not affected by up to three previous doses of the herbicide. With propyzamide, there was a trend to more rapid rates of degradation with increasing number of previous treatments. Persistence of linuron and alachlor was affected only slightly by prior applications. In a laboratory incubation with soil from the field that had received four doses of the appropriate herbicide over a 12–month period, there was again no effect from simazine pretreatments on rates of loss. However, propyzamide, linuron and alachlor all degraded more rapidly in the previously treated than in similar untreated soil samples. Propyzamide, linuron, alachlor and napropamide degradation rates were all enhanced by a single pretreatment of soil in laboratory incubations, whereas degradation rates of isoproturon, metazachlor, atrazine and simazine were the same in pretreated and control soil samples.
Uptake, translocation and fate of 2,4‐D and chlorsulfuron in Silene vulgaris (Moench) Garcke
Authors: WALL D. A. , HALL J. C. , MORRISON I. N. 
Published: July 2006

Summary:Experiments were conducted to examine the up take, translocation and metabolism by S. vulgaris of two distinctly different herbicides: 2,4‐D, a phenoxyalkanoic acid with growth regulator activity to which this species exhibits complete tolerance, and chlorsulfuron, a sul‐fonylurea to which S. vulgaris is highly sensitive. Despite their structural dissimilarities 2,4‐D and chlorsulfuron was readily absorbed by S. vulgaris with 65 and 69%, respectively, of the applied dosage being absorbed within 72 hours after treatment. Approximately 35% of the 2,4‐D and 10% of the chlorsulfuron label was translocated out of the treated leaf after 72 hours. Neither herbicide accumulated in the terminal bud. Seventy‐two hours after treatment 63% of the recovered 14C remained as unaltered 2,4‐D in S. vulgaris, while in tomato, a 2,4‐D sensitive species, 65% of the recovered 14C remained as intact herbicide. In S. vulgaris approximately 86% of the radioactivity remained as intact chlorsulfuron 72 hours after treatment compared to 12% in the tolerant wheat. The tolerance of S. vulgaris to 2,4‐D could not be accounted for by limited absorption, translocation nor metabolic degradation of the herbicide. The sensitivity of S. vulgaris to chlorsulfuron would appear to be related to the inability of this species to metabolize the herbicide molecule.
Influence of 1‐aminobenzotriazole (ABT) derivatives on the toxicity of EPTC to monocotyledonous plants
Authors: BARTA I. Cs. , DUTKA F. 
Published: July 2006

Summary:The effect of l‐aminobenzotriazole (ABT) and EPTC mixtures on plant growth was investigated in greenhouse experiments by presowing application in sand. The concentration of ABT for 50% shoot growth inhibition (I50) was about 1 mM in the monoctyledons investigated. Both subtoxic and toxic doses of ABT were antagonists of EPTC in maize (Zea mays L.) However, subtoxic doses of ABT were syner‐gists of EPTC in wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and oat (Avena sativa L.). No correlation between ABT and EPTC sensitivity of monocotyledonous plants was found. Some of the C‐ and N‐substituted ABT derivatives (e.g. N‐methyl or N‐benzyl‐ABT) completely reversed the effect of toxic dose of EPTC in maize. These results are considered as indirect evidence for the hypothesis that oxidation by cytochrome P‐450 enzymes is the biochemical target of EPTC and is involved in the mode of action of EPTC safeners.
Soybean yield and yield components as influenced by canopy heights and duration of competition of velvetleaf (Abutilon theophrasti Medik.)*
Authors: BEGONIA G. B. , ALDRICH R. J. , SALISBURY C. D. 
Published: July 2006

Summary:Soybean yields, pod and branch numbers were inversely related to the height of velvetleaf (Abutilon theophrasti). This effect was attributed to increasing interception of light with increasing height of A. theophrasti. Reduction; in soybean yield and yield components were greater if A. theophrasti was maintained at various heights for only 3 weeks rather than 6 weeks following soybean emergence. This effect was attributed to a longer duration of light competition by the weed. Even when the A. theophrasti canopy was kept 25% below that of soybean for 4 weeks, soybean yields, pod and branch numbers decreased when the weed was allowed to regrow during the remainder of the season, but not if the weed was removed after the initial 4‐week clipping period. No reduction in seed yields, pod and branch numbers was noted if A. theophrasti plants 25% shorter than soybeans were removed or allowed to resume growth after the initial 6 or 8 weeks of clipping. Soybean seed size was slightly affected by A. theophrasti canopy height and duration of competition.
Reduction of growth and reproduction of Cyperus esculentus by specific crops
Authors: LOTZ L.A.P. , GROENEVELD R.M.W. , HABEKOTTÉ B. , VAN OENE H. 
Published: July 2006

Summary:To assess the potential contribution of growing highly competitive crops to control Cyperus esculentus in the Netherlands, the influence of silage maize, hemp, winter barley and silage winter rye on emergence, growth and reproduction of this weed was studied in two field experiments. Growth and reproduction of C. esculentus (determined both as tuber production per plant and density of the weed in the subseuent crop maize) was reduced by each crop, compared to plots in which no crop was grown. In hemp, hardly any tuber production was observed. By growing a green manure crop after harvest of the winter barley the tuber production of the weed was reduced to about 40% of that in winter barley followed by fallow. Decreasing the light regime in a greenhouse experiment in the same order as was observed in the crops winter barley, maize and hemp, caused a similar reduction of tuber production to that found in the field. Therefore, it is suggested that competition for light is the main factor explaining the observed crop effects on the population dynamics of the weed. It is concluded that growing competitive crops as hemp in rotation may effectively complement chemical control of C. esculentus.
Effects of nitrogen fertilizer and emergence date on root and shoot competition between wheat and blackgrass
Authors: EXLEY D. M. , SNAYDON R. W. 
Published: July 2006

Summary: Résumé: ZusammenfassungCompetition between wheat and blackgrass (Alopecurus myosuroides Huds.) was studied in two experiments, where the effects of root competition and shoot competition were separated using an additive design. The effects of the following factors on root and shoot competition were investigated: weed density, N fertilizer, crop sowing date (October and November) and weed emergence date (October to April). Root competition generally affected the growth of both wheat and blackgrass more than did shoot competition, although shoot competition affected the survival of blackgrass more than did root competition. N fertilizer partially alleviated the effects of root competition, but did not affect shoot competition. Later sowing of either wheat or blackgrass, relative to the other, reduced the competitive ability of the later‐sown species, particularly under conditions of root competition. Effets de la fertilisation azotée et de la date de levée sur la compétition racinaire et foliaire entre le ble et le vulpin La compétition entre du blé de printemps et du vulpin (Alopecurus myosuroïdes) a étéétudiée dans deux essais, ou les effets de la competition racinaire et de la compétition aérienne ont été séparés en utilisant un systéme additif. Les effets des facteurs suivant ont étéétudiées pour les deux sortes de compétition: densité d'adventices, fertilisation azotée, date de semis (octobre et novembre) et date de levée de l'adventice (octobre—avril). La compétition racinaire a affecté généralement la croissance du blé et du vulpin de façon plus conséquente que la compétition aérienne, bien que la compétition aérienne affectât plus la survie du vulpin que la compétition racinaire. La fertilisation azotée a partiellement réduit les effets de la compétition racinaire, mais n'a pas affecté la compétition aérienne. Le semis plus tardif, soit du blé, soit du vulpin, par rapport à l'autre, a réduit la competitivite de l'espéce semée le plus tardivement, spécialement sous les conditions de competition racinaire. Einfluß von Stickstoffdüngung und Keimperiode auf die Wurzel‐ und Sproβkonkurrenz zwischen Weizen und Acker‐Fuchsschwanz Die Konkurrenz zwischen Sommerweizen und Acker‐Fuchsschwanz (Alopecurus myosuroides Huds.) wurde in 2 Versuchen untersucht, in denen mit einer additiven Versuchsanordnung die Wirkung der Wurzel‐ und der Sproßkonkurrenz unter den Faktoren Unkrautdichte, N‐ Düngung, Saatzeit (Oktober und November) und Keimperiode des Unkrauts (Oktober bis April) getrennt erfaßt wurde. Die Wurzelkonkurrenz beeinflußte das Wachstum sowohl des Weizens als auch des Acker‐Fuchs schwanzes mehr als die Sproßkonkurrenz, während auf die Weiterentwicklung des Acker‐Fuchsschwanzes die Sproßkonkurrenz mehr als die Wurzelkonkurrenz wirkte. Eine spätere Aussaat entweder des Weizens oder des Unkrauts verminderte die Konkurrenzkraft der später ausgesäten Art, besonders hinsichtlich der Wurzelkonkurrenz.