bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of root‐ and shoot‐acting growth retardants on a grass/clover sward
Authors: PARR T. W. , MARRS R. H. , BOORMANR L. A. , PLANT R. A. 
Published: July 2006

SummaryThe effects of six grass growth retardants, maleic hydrazide (±2,4‐D), mefluidide, paclobutrazol, EL500 and a mixture of mefluidide with paclobutrazol on a grass/clover sward were compared over a 3‐year period. Maleic hydrazide, which is the most commonly used retardant, gave poor levels of growth control except when used with 2,4‐D. Greatest growth suppression, a 38% reduction in dry matter production from May to July, was obtained from a mixture of mefluidide and paclobutrazol. Differences were observed between the effects of the shoot‐acting retardants, maleic hydrazide and mefluidide and the root‐acting retardants, paclobutrazol and EL500. Shoot‐acting retardants were less effective in wet weather and lasted for a shorter period than root‐acting retardants. They also increased compensatory growth after a period of growth suppression, and increased the proportion of clover in the sward.
Dégradation catalytique de carbamates herbicides déposés sur bentonites homoioniques. V. Cas du CEPC
Authors: SABADIE J. , COSTE C. M. 
Published: July 2006

SummaryLe CEPC se dégrade lentement à 20 °C et en phase sèche au contact de divers supports minéraux: gel de silice et bentonites homoioniques (Bentonite Prolabo, MontmoriMonite K 10; Cu2+, Zn2+, Fe3+ et Ag+). L'hydroxylation de l'atome de chlore terminal est généralement prépondérante tandis que la cyclisation en oxazolidone ou l'hydrolyse de la fonction carbamate demeurent limitées. La formation intermédiaire d'isocyanate n'a pas été observée. La sélectivité de la conversion est principalement influencée par la nature et l'acidité du support, le métal de saturation et la méthode d'imprégnation.
Physiological activity spectra of existing graminicides and the new herbicide 2‐(2‐benzothiazolyl‐oxy)‐N‐methyl‐N‐phenylacetamide (mefenacet)
Authors: FEDTKE C. 
Published: July 2006

Summaryinhibitory activities of existing graminicides on root regeneration from monocotyledonous (oat) and dicotyledonous (soybean) plant cuttings in the light, in the dark and on algal growth were compared with the respective inhibitory activities of the new herbicide 2‐(2‐benzothiazo‐lyl‐oxy)‐N‐methyl‐N‐phenylacetamide (mefenacet). The mefenacet activity spectrum resembled that of the α‐chloroacetamide herbicides. Herbicide groups of other structure‐activity can be distinguished by their distinct activity spectrum. The mono‐oxygenase inhibitors piperonyl but‐oxide (PBO) and 1‐aminobenzotriazole (ABT) were found to antagonize the inhibitory activities of herbicides from the thiolcarbamate, α‐chloroacetamide, and oxyacetic acid amide structure groups in the oat rooting and leaf growth tests. The critical evaluation of the presently available information on graminicide and safener mode of action suggests the concept that lipid biosynthesis on the physiological level and mono‐oxygenase type enzymes on the biochemical level may hold the target sites for many of the graminicides and safeners discussed.
Germination of proximal and distal seeds of Poa trivialis L. from contrasting habitats
Authors: FROUD‐WILLIAMS R. J. , FERRIS R. 
Published: July 2006

SummarySeeds of Poa trivialis L. were collected from one grassland and two arable habitats. Seeds from the grassland population were less dormant than the arable populations. Distal (upper) seeds were consistently more dormant than proximal (basal) seeds. Dry storage at 4°C and 15°C for 4 weeks after shedding resulted in a slightly greater loss of dormancy than storage at 23°C. Germination was enhanced by subjecting seeds stored at 15°C to repeated hydration and dehydration cycles. Germination of P. trivialis seeds was density‐dependent. Germination of distal seeds was particularly impaired at high densities. The ecological implications of these results are discussed in relation to seed survival strategies.
Establishment of Senecio jacobaea L. from seed in grassland and in boxed swards
Authors: WATT T. A. 
Published: July 2006

SummaryThe effects of a high or a low level of nitrogen fertilizer and the presence or absence of a grass‐suppressing herbicide (propyzamide) upon the establishment of Senecio jacobaea L. (common ragwort) in three sizes of bare soil patch in a perennial ryegrass sward (Lolium perenne L.) were investigated both in boxed swards and in the field.
Influence of tillage, straw disposal system and seed return on the population dynamics of Alopecurus myosuroides Huds. in winter wheat
Authors: MOSS S. R. 
Published: July 2006

Summary Alopecurus myosuroides Huds. was studied over a 2‐year period in winter wheat established after tine cultivations or direct drilling. Straw was removed by baling or spread and burnt. Seed production was either allowed or prevented by cutting and removing all vegetation at the end of the first year. Cultivation differences had no consistent effect on plant or seed populations. Straw burning destroyed about 50% of seeds and encouraged the germination of surviving seeds. Weed populations in the crop were lower on burnt than on baled areas. Where seed shedding was allowed, populations of seeds in soil and plants increased by up to nine‐fold per year. Straw burning resulted in smaller population increases. Seed decline in the soil averaged about 80% per year, so that less than 6% of the weed seeds sown were still viable after 2 years’burial in the soil. Most of the seed decline occurred between July and October and was slightly greater on burnt than on baled areas. Only part of this seed loss was accounted for by germination and emergence of seedlings during summer and autumn. Plants emerging in the crop represented less than 26% of viable seeds present in the soil at time of drilling the crop. Few seedlings emerged in spring. The viability of shed seeds varied with year and with weed density. High infestations were associated with lower seed viability and also fewer heads per plant.
Glyphosate effects on Canada thistle (Cirsium arvense) roots, root buds, and shoots
Authors: CARLSON S. J. , DONALD W. W. 
Published: July 2006

SummaryGlyphosate† was sprayed at 0009–1·12 kg a.i. ha−1 on the foliage of large potted glasshouse‐grown Canada thistle [Cirsium arvense (L.) Scop.], which had extensive, well‐developed roots. Increasing the glyphosate rate progressively reduced the total number of visible adventitious root buds plus emerged secondary shoots per plant proportionately more than root biomass, 10 days after treatment. Cortical tissue of thickened propagative roots became soft, water‐soaked, darkened, and some regions decomposed, exposing strands of vascular tissue. Lateral roots completely decomposed. When thickened roots were segmented to stimulate secondary shoot emergence from root buds 10 days after foliar treatment, Fewer secondary shoots emerged than expected from the number of visible adventitious root buds present on both control and herbicide‐treated plants. Increasing the rate of glyphosate also reduced the regrowth potential of root buds proportionately more than root biomass. Regrowth potential was measured as the number of emerged secondary shoots 35 days after segmenting unearthed roots from plants that had been sprayed 10 days earlier. When foliar‐applied at 0·28 kg ha−1, glyphosate decreased the regrowth potential of root buds to zero in 2 and 3 days, as measured by secondary shoot dry weight and number, respectively, even though root fresh weight was unchanged 3 days after foliar treatment. These dose‐response and time‐course experiments demonstrate that glyphosate did not reduce root biomass as much as it decreased root bud numbers and secondary shoot regrowth potential from root buds.
Relations entre la vitesse de dégradation du propyzamide et les propriétés physicochimiques des sols
Authors: BARRERE C. , BASTIDE J. , COSTE C. M. 
Published: July 2006

RésuméL'étude de la dégradation du propyzamide est réalisée dans 29 sols, dans des conditions de température et d'humidité constantes. Une relation est trouvée entre la vitesse de dégradation et la résistivité des sols. Un apport d'engrais dans les sols entraine une diminution de la résistivité qui se traduit par un ralentissement de la vitesse de dégradation.
Weeding and nitrogen effects on farmers' wheat crops in semi‐arid Morocco
Authors: TANJI A. , REGEHR D. L. 
Published: July 2006

SummaryThe effects of three weeding systems with and without top‐dressed nitrogen were examined in 40 experiments on bread wheat and durum wheat planted by farmers in the Chaouia (semi‐arid area of Morocco) in 1984–1985 and 1985–1986 growing seasons. In both years, hand‐weeding to simulate collection of forage reduced weed numbers by 30% and removed 63% of the weed dry weight. Treatment with 2, 4‐D removed 66% of the weeds and reduced weed dry weight by 82%, in 1985–1986. Hand‐weeding for forage produced 427 kg ha−1 weed dry matter in both years, but wheat grain yields were 179 kg ha−1 lower than with 2.4‐D treatments. Over both years, the cost of each kg weed forage was 0·43 kg grain yield loss. Without weeding grain yields were 130 kg ha−1 lower than 2, 4‐D treatments. Weed control with 2,4‐D increased wheat grain yields over both non‐weeded and hand‐weeded treatments by an average of 154 kg ha−1. Overall, there were no significant effects of nitrogen on wheat or weed yields nor interactions between top‐dressed nitrogen and weeding systems. A total of 157 weed species belonging to 29 botanical families were identified on the 40 experimental sites over both years; 89% were dicotyledons. Papaver rhoeas L. (common poppy), 2, 4‐D susceptible plant, was the most annual weed in wheat fields in Chaouia.
Influence of time of emergence of wild oat on competition with wheat
Authors: MARTIN M. P. L. D. , FIELD R. J. 
Published: July 2006

SummaryThe influence of time of emergence of wild oat (Avena fatua L.) on its competition with wheat (Triticum aestivum L.) was studied, using boxes that allowed separation of root and shoot competition. The relative yield total for mixtures of wild oat and wheat, grown under different forms of competition and with different wild oat sowing times, was very close to unity, indicating that the two species competed fully for limiting resources. Wild oat was more competitive than wheat when the two species were sown simultaneously, due largely to its greater root competitive ability; the two species had similar shoot competitive abilities. When wild oat was sown 3 or 6 weeks later than wheat, wheat was more competitive than wild oat and the production of wild oat panicles was prevented. This was mainly the result of greater root competitive ability of the wheat, although shoot competitive ability was also greater. The effects of root and shoot competition were additive. It is concluded that in order to prevent the return of wild oat seeds to the soil, and hence obtain long‐term benefit, it is necessary to control the wild oat seedlings emerging within the first 3 weeks after drilling a wheat crop.
Selectivity of 2,4‐D in Solanum ptycanthum Dun. and Lycopersicon esculentum Mill.
Authors: HALL J. C. , SWANTON C. J. 
Published: July 2006

SummaryIn controlled environmental studies, a marked difference was observed between the growth pattern of tomato and eastern black nightshade plants that received doses of 2,4‐D ranging from 28 to 952 g a.e. ha−1. The highest dose of 2,4‐D reduced the dry weight of eastern black nightshade and tomato by approximately 15 and 50%, respectively, when compared with controls. Although the height of both species was reduced by all doses of 2,4‐D, eastern black nightshade plants produced secondary shoots, which compensated for any potential loss in dry weight that otherwise may have occurred. Tomato plants did not produce secondary shoots. After application of 14C‐2,4‐D to tomato and eastern black nightshade, the pattern of 14C absorption and translocation was similar in both plant species. However, there was significantly more radioactivity recovered in tomato (72%) than in eastern black nightshade (52%) plants, 72 h after treatment. Assay radioactivity in the nutrient solution of hydroponically grown plants indicated that 7·0 and 27·9% of the applied radioactivity was exuded from the roots of tomato and eastern black nightshade, respectively, within 72 h after treatment. Assay of plant extracts by thin layer chromatography revealed that the amount of radioactivity that remained as unaltered 2,4‐D was 73 and 49% in tomato and eastern black nightshade, respectively, 72 h after treatment. Thus the greater tolerance of eastern black nightshade appeared to be due to greater rates of 2,4‐D metabolism and/or greater rates of herbicide elimination by root exudation.
Effect of narrow‐leaved hawk's‐beard (Crepis tectorum L.) on yield and quality of lucerne hay and seed yield of creeping red fescue
Authors: PESCHKEN D. P. , DARWENT A. L. 
Published: July 2006

SummaryNarrow‐leaved hawk's‐beard (Crevis tectorum L.) occurs in all provinces of Canada, but is particularly abundant in the northern portions of the agricultural regions of the three prairie provinces and British Columbia. The losses in yield in terms of quantity and quality due to narrow‐leaved hawk's‐beard were investigated in fields of lucerne (Medicago sativa L.) used in the dehydration industry and in experimental plots. The effect of hawk's‐beard on creeping red fescue (Festuca rubra L.) seed yield in the Peace River Region of British Columbia was also investigated. In the lucerne, the average percentage of hawk's‐beard in the total biomass over the 3 years of the study was only 2⋅5%, with a minimum of 1⋅2% in one year and a maximum of 5⋅5% in another year. In the lucerne vs hawk's‐beard plots, yields on plots free of hawk's‐beard were not significantly higher than on those with hawks'‐beard. Although excellent control was achieved in creeping red fescue (Festuca rubra L.) by the use of the herbicide 2, 4‐DB, yields of seed were not significantly increased. Therefore, narrow‐leaved hawk's‐beard seems to be an excellent colonizer but a weak competitor and contributed little to crop losses in lucerne and creeping red fescue.
Efficacy of chemical weed control in spring cereals in Finland
Authors: SALONEN J. , ERVIÖ L.‐R. 
Published: July 2006

SummaryA national survey was conducted in Finland from 1982 to 1984 to determine the main weed species in spring cereals and the efficacy of herbicides on Finnish farms. The most common dicotyledonous weeds producing the highest biomass in spring cereals were Chenopodium album L., Galeopsis spp. L., Stellaria media (L.) Vill. and Lapsana communis L. The main grass weed was Elymus repens (L.) Gould. The average reduction of weed biomass by herbicide treatment was 75%. More reliable efficacy was obtained with herbicide mixtures than with MCPA alone.
Influence of glumes, soil and environmental conditions on germination of Ischaemum afrum (J.F. Gmel.) Dandy seeds
Authors: TAYALLA O. E. , BABIKER A. G. T. , MANSI M. G. , BESHIR N. H. H. 
Published: July 2006

SummaryStudies on the germination of Ischaemum afrum seeds showed that low temperature, presence of glumes and both low and excessive soil moisture contents were conducive to delayed and low germination. The inhibitory effect of the glumes was more pronounced in freshly harvested seeds. Germinability of seeds on the soil surface was poor, but shallow burial in soil increased germination.
Dynamique de quelques dicotylédones adventices en culture de céréale. I. Relation flore levée—stock semencier
Authors: INRA P. DEBAEKE 
Published: July 2006

RésuméLa connaissance du rapport flore levée/stock de semences du sol est nécessaire à la prévision des infestations de mauvaises herbes. Des travaux antérieurs ont montré que ce rapport (ou taux de levée) est en moyenne faible mais pourtant variable entre espèces, années et sites expérimentaux. Cette étude tente d'expliquer la variabilityé du taux de levée annuel, pour quelques dicotylédones à stock assez persistant, au sein de cultures de céréales d'hiver ou de printemps, labourées ou non. La dynamique de la levée et le stock de semences viables sont enregistrées à partir de populations adventices naturelles au cours de deux années successives et sur 26 parcelles cultivées, appartenant an champ d'essai de Grignon, situé dans le Bassin Parisien. Les résultats montrent une relative constance intra‐ et inter‐annuelle du taux de levée pour des conditions voisines d'implantation de la céréale. La variation résiduelle est expliquée pour une même espèce par la distribution verticale des semences dans la couche labouré et peut‐être par l'âge moyen du stock. La variabilityé inter‐spécifique du taux de levée est à relier à la taille de la semence, à la période de germination de l'espéce mais aussi au mode d'estimation de la viabilité des semences; cependant l'utilisation de la radiographie industrielle aux rayons X a permis de compenser l'insuffisance des tests de germination et de réduire partiellement cette variabilité. De très faibles taux de levée sont observés enfin en l'absence de labour. Un modèle statistique simple est proposé pour rendre compte de la variabilité de ce taux, pour la flore dicotylédone annuelle, en culture d'hiver labourée.
Analysis of growth and resource allocation
Authors: HUNT R. 
Published: July 2006

SummaryAt UCPE we are exploring high‐level, ecologically based models of growth and resource allocation in herbaceous plants, including weed species. In them, allocation is driven by variables from Plant Strategy Theory, such as below‐and above‐ground‘environmental stress'. A‘hyperbolic’model is described in which the allocation of resources into above‐and below‐ground plant parts is jointly controlled by (i) the absolute amounts of below‐and above‐ground stress that the plant‘perceives'; (ii) the ratio of below‐ground to above‐ground stress; and (iii) by the maximum growth potential of the plant itself. The inputs to the model are the fraction of its maximum potential that the plant attains and its root‐shoot allometric growth coefficient. The outputs from the model are indices of the above‐and below‐ground stresses‘perceived’by the plant. The latter arc otherwise particularly difficult to estimate when growth and allocation are being controlled simultaneously by several suboptimal environmental variables, as happens in many crop weed systems.
Quantitative determination of broomrape (Orobanche spp.) seeds in vetch seeds
Authors: JACOBSOHN R. , MARCUS RUTH 
Published: July 2006

Summary: Résumé: ZusammenfassungA method was developed by which the presence of broomrape (Orobanche spp.) seeds in vetch seeds was determined quantitatively. The broomrape seeds are washed out of the vetch seeds by a combination of two sieves. The vetch seeds remain on the top sieve and the broomrape seeds are collected on the lower sieve with square openings of 100 μm, which do not permit passage of the broomrape seeds. An appropriate statistical method for estimating the true mean number of broomrape seeds per sample in a large vetch seeds lot is presented and discussed. Détermination quantitative des graines d' orobanche dans des graines de vesce.Une méthode permettant de dénombrer la présence de graines d'orobanche dans un lot de graines de vesce a été mise au point. Les graines d'orobanche sont séparées de celles de vesce par une succession de deux tamis. Les graines de vesce sont maintenues sur le tamis supérieur et les graines d'orobanche sont collectées sur le tamis le plus bas avec une maille de 100 μm qui ne permet pas le passage des graines d'orobanche. Une méthode statistique appropriée pour estimer la quantité réelle d'orobanches dans un grand lot de semences de vesce est présentée puis discutée. Quantitative Bestimmung von Orobanche‐Samen in Wicken‐SaatgutEs wurde eine Methode entwickelt, mit der Orobanche‐Samen in Wicken‐Saatgut quantitativ erfasst werden können. Zum Trennen der Samen wurden 2 Siebe verwendet, wobei die Wicken‐Samen im oberen, die Orobanche‐Samen im unteren mit einer Maschenweite von 100 μm gesammelt wurden. Eine statistische Methode für die Schätzung der Orobanche‐Samenmenge in grossen Wicken‐Saatgutpartien wurde vorgestellt und diskutiert.
Photosynthetic capacity of intact leaves of resistant and susceptible cultivars of Brassica napus L. to atrazine
Authors: van OORSCHOT J. L. P. , van LEEUWEN P. H. 
Published: July 2006

SummaryThe rate of photosynthesis in intact leaves attached to plants of an atrazine‐resistant cultivar of Brassica napus L. was compared with that in leaves of an atrazine‐susceptible, rather isogenic cultivar, in a number of irradiance series. The resistant cultivar had been obtained from the susceptible cultivar by crossing the resistant biotype of Brassica campestris L. with the susceptible cultivar of B. napus, and using the fourth back‐cross for comparison. At a natural CO2 concentration (360 cm3 m−3) the rate of photosynthesis of leaves of the atrazine‐resistant cultivar was significantly (17–21%) less than that of leaves of the susceptible cultivar, over the whole range of irradiances up to 250 W m−2 At the enriched CO2 concentration of 1500 cm−3 m−3 this reduction in rate amounted to 9–12%.
Effect of time of weed removal on growth and yield of potato
Authors: THAKRAL K. K. , PANDITA M. L. , KHURANA S. C. , KALLOO G. 
Published: July 2006

SummaryThe effects of weed removal at five dates after planting the crop were examined and compared with weed‐free and unweeded controls. The results revealed that the total weed population increased up to 6 weeks after planting and then decreased drastically in both the years. Total dry weight of weeds (at weeding and at haulm‐cutting) was greatest in the unweeded control, followed by weeding at 10 weeks after planting. In both years, maximum yield was obtained where plots were kept weed‐free, followed by weeding at 4 and 6 weeks after planting. The remaining treatments, including weeding at 2 weeks after planting, resulted in significant reductions in tuber yield. In unweeded control plots the tuber yield of potato was reduced by 40–43%.
Absorption, translocation and metabolism of pyridate in a tolerant crop (Zea mays) and two susceptible weeds (Polygonum lapathifolium L. and Chenopodium album L.)
Authors: GAILLARDON P. , GUICHAOUA J. C. , GASQUEZ J. , SCALLA R. 
Published: July 2006

SummaryAbsorption, translocation and metabolism of 14C‐pyridate were compared in tolerant maize. moderately susceptible Polygonum lapathifolium and susceptible Chenopodium album. Foliar absorption was limited in all species, but comparatively higher penetration levels were observed in younger leaves of dicotyledonous species. The absorbed radioactivity was not very mobile and translocation appeared mainly sym‐plastic. Herbicide selectivity could not be explained on the basis of absorption and transport. Chenopodium and P. lapathifolium degraded pyridate and formed unstable water‐soluble conjugates that easily released a phytotoxic metabolite. By contrast, more stable unidentified water‐soluble metabolites were found in maize. That metabolic difference could explain the selectivity of pyridate.
Relative importance of crop seed, manure and irrigation water as sources of weed infestation
Authors: DASTGHEIB F. 
Published: July 2006

SummaryThree possible sources of field contamination by weed seeds were studied during 1983–86 in two areas of Fars Province, Iran. These sources were crop seed, irrigation water and sheep manure. Manure was found to be the most important, adding almost 10 million seeds ha−1 at each application. Farmer‐saved seed of wheat, the main crop of the area, added an average of 182,000 weed seeds ha−1. Irrigation water added no more than 120 seeds ha−1, but was able to carry seeds over long distances without affecting viability.