bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of temperature and photoperiod on growth and development of Parthenium hysterophorus L.
Authors: WILLIAMS J. D. , GROVES R. H. 
Published: July 2006

Summary:Germination, growth and flowering were investigated in Parthenium hysterophoms (Asteraceae), a species introduced to Australia and at present occurring as a weed in central Queensland. Combinations of day/night temperature regimes from 15/4 to 36/31 and day length of 10, 13 and 16 h in controlled conditions were examined to find the effects of any environmental restraints to growth and development. Results showed that individuals are able to germinate, grow and flower over a wide range of temperatures and photoperiods and established plants can survive at least one mild frost of — 2.We conclude that the potential distribution of P. hyslerophorus in Australia is much wider than at present. Future distribution of the species may be limited seasonally by the inability of seed to germinate in soils of low water potential and by the inability of seedlings to establish and grow at low light intensities.
Effect of ammonium sulphate and other additives upon the phytotoxicity of glyphosate to Agropyron repens (L.) Beauv
Authors: TURNER D. J. , LOADER M. P. C. 
Published: July 2006

Summary:In several pot and field experiments additions of 1–10% w/v ammonium sulphate and/or 0.1–2.5% w/v surfactant increased the phytotoxicity to A. repens of sprays containing 0.2–0.5 kg/ha glyphosate. There were similar results with technical glyphosate‐isopropylamine salt and formulated ‘Roundup’. Higher ammonium sulphate concentrations were sometimes antagonistic. Additions of ammonium sulphate without surfactant generally had less effect on phytotoxicity. While several surfactants increased glyphosate activity the order of effectiveness of these products varied according to whether or not ammonium sulphate was also present. When used alone, relatively hydrophilic non‐ionic or cationic products had more effect. In mixtures with ammonium sulphate, however more lipophilic surfactants gave superior results. Ammonium sulphate (5%) with a lipophilic cationic surfactant (0.5% Ethomeen C12) enhanced the effects of very low volume controlled‐drop applications as well as conventional medium volume sprays. In a field trial 0.25 kg/ha glyphosate applied with those additives in 20 l/ha of spray had as much effect on bud viability as l kg/ha applied conventionally.
Weed control in irrigated dry seeded rice
Authors: GHOBRIAL GEORGE I. 
Published: July 2006

Summary:Large losses in grain yields due to weed competition were found in studies conducted in irrigated dry seeded rice at Gezira Research Station, Sudan. These losses could exceed 50%. Weed competition lowered panicle number per unit area by 37%, number of filled grains per panicle by 13%, and weight of 1000 grains by 4%. Tillering was the critical growth phase most affected by weed competition.Grain yields were increased as number of hand weedings increased. The best yield (4.1 t/ha) was obtained from 3–4 weedings carried out at 15, 30, 45 and 60 days after rice emergence.Oxadiazon (0.5 kg/ha) gave good residual weed control of the dominant weed species, Phyllanthus niruri L., Leucas urticifolia L., Heliotropium F.W.Andr. and Echinochloa colona (L.) Link, for 6–7 weeks. The combination with continuous flooding from 6 weeks after rice emergence gave excellent weed control during the entire season, and comparable or even better yields than frequently weeded rice.
Joint action of root‐absorbed mixtures of DPX‐4189* and linuron in Sinapis alba L. and barley
Authors: STREIBIG J.C. 
Published: July 2006

SummaryThe joint action of DPX‐4189* (2 chloro‐N‐[(4‐methoxy‐6‐methyl‐1, 3, 5‐triazin‐2‐yl)‐aminocarbonyl] benzenesulfonamide) and linuron (N‐[3, 4‐dichlorophenyl]‐N‐methoxy‐N‐methylurea) mixtures, applied in fixed ratios of 1:15 and 1:30, was assessed using water culture experiments in growth chambers.The dose‐response curves of DPX‐4189 were fiat compared with these of linuron. At Gr50‐level (the dose required to reduce dry matter by 50% relative to the untreated control), DPX‐4189 was 12‐fold more potent in Sinapis alba than was linuron, whereas the potencies of the two compounds were almost similar in barley. The selectivity indices (Gr80[barley]/Gr20[S. alba]) of DPX‐4189 and linuron were 3.1 and 1.8.In both species the mixtures were less active than expected from an additive dose model, and the detracted efficacy of the mixtures was of almost similar magnitude. The results indicated that if S. alba is regarded a weed, the loss of bioactivity of the mixtures may be compensated by some increase in dose rate without injuring the barley crop.
Improvement of carpet grass (Axonopus affinis Chase) pasture by fertilization and oversowing with the aid of selective herbicides
Authors: MARTIN R. J. 
Published: July 2006

SummaryAn experiment was done to determine the effect of spring and autumn application of asulam and dalapon, nitrogen fertilizer and oversown white clover (Trifolium repens L.) on the productivity of subtropical pasture dominated by carpet grass (Axonopus affinis Chase). Assessments were made of pasture yield, botanical composition, weed invasion and recolonization by pasture species during the 12‐month period following herbicide application. Both herbicides decreased the yield of carpet grass and increased that of the more productive paspalum (Paspalum dilatatum Poir.) except after autumn application when the yield of paspalum was greatly reduced by dalapon. White clover became established only on plots treated with herbicide and only after autumn application. Clover yields were greatest on plots treated with dalapon. Asulam was considered to be the most suitable herbicide for altering the balance between carpet grass and paspalum because dalapon initially reduced paspalum yield after autumn application and delayed recovery of total pasture. In addition, dalapon permitted greater invasion by broadleaf weeds. This work showed that herbicides have a potential role for speeding up botanical changes in unproductive carpet grass pasture and further refinement of the technique might provide a useful tool for increasing pasture productivity.
Field emergence and temperature requirements for germination in Solanum sarrachoides Sendt.
Authors: ROBERTS H. A. , BODDRELL JUNE E. 
Published: July 2006

SummaryEmergence of Solanum sarrachoides began in late April, reached a peak in May or June and ceased in September. This pattern closely resembled that for S. nigrum L., whereas almost all seedlings of S. dulcamara L. emerged in April. Fresh seeds of S. sarrachoides were dormant but developed a capacity for germination at 25 and 30°C and at alternating (16 h low/8 h high) temperatures of 4/25, 10/25, 10/30 and 20/30°C when stored dry. kept moist at 4°C or buried in the field. Buried seeds also became capable of germinating at 10. 15 and 20°C and the temperature range for germination was widest during April‐June. Induced dormancy developed during August and the range narrowed. The consistent seasonal emergence pattern appears to be associated with cyclic changes in the dormancy status of buried seeds.
A second survey of cereal weeds in central southern England
Authors: CHANCELLOR R.J. , FROUD‐WILLIAMS R.J. 
Published: July 2006

SummaryA survey of grass weeds of cereals in central southern England made in 1981 was repeated in 1982 between 28 June and 23 July. Dicotyledonous weeds were also assessed in 1982. A total of 1021 fields were surveyed, 702 in winter wheat. 198 in winter barley and 121 in spring barley. A total of twenty‐four grass weeds were found and their levels of infestation were scored. The most frequently found grass weeds were the same as in 1981. In all cereals combined, these were Elymus (Agropyron) repens in 35% of fields, Avena fatua in 32%, Alopecurus myosuroides in 26% and Poa trivialis in 24%. Sixty‐three species of dicotyledonous weeds were recorded and of these, eighteen species occurred in 2% or more of fields. The eight most frequent were Viola arvensis, Galium aparine, Stellaria media, Myosotis arvensis, Polygonum aviculare, Convolvulus arvensis, Bilderdykia (Polygonum) convolvulus and Lamium purpureum. Most species were fairly uniform in distribution, but Galium aparine, Convolvulus arvensis and Cirsium arvense were most frequent in the east while Viola arvensis was least frequent there. The cereals varied in weediness, 32% of winter barley, 23% of spring barley and only 7% of winter wheat fields had no weeds recorded.
Activity of extracts from Euphorbia species on the germination of Striga species
Authors: IBRAHIM N. E. , BABIKER A. G. T. , EDWARDS W. G. , PARKER C. 
Published: July 2006

SummaryAqueous extracts of fifteen Euphorbia species induced germination of Striga hermonthica (Del.) Benth. seeds to varying extents. Extracts from E. supina Raf., E. pilulifera Jacq., E. acalyphoides Hochst. ex. Boiss, E. prunifolia (Jacq.) Hort. Schoent., E. hirta L., E. aegyptiaca Boiss, E. splendens Boj., and E. granulata Forsk, were the most active. Extracts from E. acalyphoides and E. pilulifera were inhibitory at high concentrations. Undiluted extracts from E. pilulifera, E. aegyptiaca and E. hirta induced haustorial initiation. The stimulatory substance(s) were widely distributed in plants of E. aegyptiaca. Extracts from E. aegyptiaca also stimulated seed germination and haustorial initiation in a range of Striga species and strains.
Influence of soil moisture on isoproturon activity against Alopecurus myosuroides
Authors: BLAIR A.M. 
Published: July 2006

Summary Alopecurus myosuroides Huds. (blackgrass) in sandy loam soil in pots was treated at the three‐leaf stage with formulated isoproturon. Damage to plants resulted mainly from herbicide entry via the soil. When the soil moisture levels were maintained close to 50, 100 and 150% of field capacity (FC) throughout the experiment damage increased with the amount of water in the soil. After spraying plants raised at field capacity, change to 150 or 50% FC resulted in more and less damage respectively. Water applied to the soil surface compared with sub‐irrigation caused more damage. A delay of up to 21 days between spraying plants in soil at field capacity and surface watering did not reduce damage provided the time interval between the onset of surface watering and assessment remained constant. A delay of 7 days between spraying isoproturon onto plants in dry soil (50% FC) and increasing the moisture to field capacity by surface watering decreased the damage to A. myosuroides. These results are discussed with reference to the soil moisture distribution in soil columns and rainfall patterns under field conditions.
Studies on the site of uptake by plants of chlortoluron and terbutryne
Authors: ADDALA M. S. A. , HANCE R. J. , DRENNAN D. S. 
Published: July 2006

SummaryExperiments were done to observe the pattern of early root development of radish (Raphanus raphatnistrum L.) and perennial ryegrass (Lolium perenne L.), the mobility of chlortoluron following application to the soil surface, the effect of protecting the subterranean shoots of four plant species on their response to chlortoluron and terbutryne and the relative quantities of 14C‐labelled chlortoluron taken up by radish and Avenu fatua from root and shoot zone exposure. Both chlortoluron and terbutryne appear to be able to enter the plants examined, Alopecurus myosuroides, Stellaria media, perennial ryegrass and radish, through roots and shoots. It is suggested that shoot uptake is relatively more important for plants like perennial ryegrass than for those whose roots develop more quickly and invade the soil above the seed, such as radish. The quantities of radioactive chlortoluron taken up from soil containing 400 ng g−1 showed that less than 3 ng per plant could reduce A. fatua fresh weight by 17–40% while over 30 ng per plans had little effect on radish. By comparison 2 kg ha−1 chlortoluron applied to the soil surface of pots which were sub‐irrigated for 3 weeks gave a concentration of 170 ng g−1 in the layer of soil 10–12 mm from the surface. It is suggested that for shallow germinating species with herbicides of physical and phytotoxic properties similar to chlortoluron, the solvent action of rainfall, together with diffusion, is enough to allow the transport of toxic quantities to the target plant although any leaching action is likely to increase activity.
Selective regulation of germination and growth of annual weeds by crop residues
Authors: PURVIS C. E. , JESSOP R. S. , LOVETT J. V. 
Published: July 2006

SummaryResidues from mature, harvested crops of sorghum (Sorghum bicolor Moench.), sunflower (Helianthus annuus L.), oilseed rape (Brassica napus L.), wheat (Triticum aestivum L.) and field pea (Pisum sativum L.), exhibited selective effects on weed germination and growth under field conditions. Weed species in the study included Avena fatua L., Avena sterilis ssp. ludoviciana (Durieu) Nyman, Echinochloa crus‐galli (L.) Beauv., Phalaris aquatica L., Phalaris paradoxa L., Lolium perenne L., Vulpia myuros (L.) Gmel., Hibiscus trionum L., Polygonum aviculare L., Bilderdykia convolvulus (L.) Dumort. and Lamium amplexicaule L. All crop residues tested, and in particular wheat and pea residues, promoted the germination and growth of A. fatua and A sterilis ssp. ludoviciana. Other grass weeds, however, were inhibited by the presence of crop residue, the extent of inhibition being dependent on residue type. Germination response of dicotyledonous weed species was also a function of residue type, H. trionum numbers were significantly higher in plots where oilseed rape, sorghum or sunflower residue had been incorporated, while L. amplexicaule was inhibited by these residue types and stimulated by pea and wheat residues.
Long‐ and short‐term effects of vapour of the herbicide 2,4‐D butyl on the growth of tomato plants
Authors: BREEZE V. G. , WEST C. J. 
Published: July 2006

SummaryAn airflow system has been used to expose tomato plants to a range of concentrations of vapour of the herbicide 2,4‐D butyl, from 5 to 50 ng l−1. Experiments carried out at an air temperature of 20°C indicate that only short periods (less than 2.5 h) are required to produce symptoms of phytotoxicity at concentrations less than 5 ng l−1, or approximately 2.5% of the saturated vapour pressure of the herbicide. A 5‐h period of exposure to approximately 5 ng l−1 reduced the dry weight and dry matter content of the tomato plants after 7 weeks by 18% and 9%, respectively, compared with the control. Phytotoxicity symptoms were shown by the plants in proportion to the vapour concentration during the period of exposure to herbicide. Rates of photosynthesis of treated plants had begun to decline within an hour of the commencement of exposure, slightly after leaf movement was first observed.
Metribuzin metabolism as the basis for tolerance in barley (Hordeum vulgare L.)*
Authors: GAWRONSKI S. W. , HADERLIE L. C. , STARK J. C. 
Published: July 2006

SummaryMetabolism of 14C‐5 (ring)‐metribuzin was studied in Steptoe (tolerant) and Morex (susceptible) barley (Hordeum vulgare L.) cultivars, 1, 4, and 8 days following a single application to roots. Both cultivars contained similar ether‐soluble metribuzin metabolites and five water‐soluble metabolites. Water‐soluble compounds increased from 12 to 53% of the total 14C recovered for Steptoe and 5–17% for Morex between 1 day and 8 days, respectively, whereas the percentage of ether‐soluble metabolites decreased. Ninhydrin reacting compounds were the major water‐soluble metabolites in the leaf blades 8 days after treatment. On a d.p.m. mg−1 dry weight basis, Steptoe leaves had five times more water‐soluble material than Morex leaves and half the quantity of ether‐soluble compounds. Metribuzin comprised 83 and 89% of the ether‐soluble compounds in leaves of Morex and Steptoe, respectively, at 8 days. Terminal radioactivity comprised between 19% and 26% of total radioactivity for both cultivars as early as 1 day after application, with little change over 8 days. Rapid metabolism of metribuzin to non‐phytotoxic water‐soluble conjugates and terminal residues was the major mechanism responsible for the differential tolerance between these two barley cultivars.
Fungal infestation of seeds from seven populations of wild oats (Avena fatuaL.) with different dormancy and viability characteristics
Authors: MORTENSEN K. , HSIAO A. I. 
Published: July 2006

SummarySeeds from seven genetically inbred pure lines of wild oats (Avena fatuaL.) with different levels of dormancy and viability were analysed for seed‐borne fungi. All lines had fungi on the seeds. The predominating fungi wereAlternaria alternataandCladosporium herbarum, of which the latter was non‐pathogenic and the former only weakly pathogenic on seedlings of wild oats.Drechslera avenacea, Cochliobulus sativusandFusariumspp., frequently isolated, were pathogenic onA. fatua.OnlyD. avenaceawas host specific toA. fatuaand cultivated oatsAvena sativa. Cochliobolus sativusandFusariumspp, were equal or more pathogenic on seedlings of wheat (Triticum aestivumL.), barley (Hordeum vulgareL.), oats and rye (Secale cerealeL.) than on seedlings ofA. fatua. Drechslera avenaceaoccurred on a significantly higher percentage of seeds fromA. fatualines, AN 51 and AN 474, than from the other lines. Other fungi isolated occurred randomly on allA. fatualines. There was no relationship between low viability of seeds and fungi carried on the seeds.
Untersuchungen zur Keimungsbiologie von sechs tropischen Segetalarten
Authors: SAUERBORN J. , KOCH W. 
Published: July 2006

ZusammenfassungFür die 6 untersuchten tropischen Segetalarten Ageratum conyzoides, Blechum brownei, Crassocephalum crepidioides, Mikania micrantha, Paspalum conjugatum und P. paniculatum lag die untere Temperaturgrenze bei der Keimung im Bereich von 10 bis 15(20)°C, die maximale bei ≤ 40°C, das Optimum zwischen 20 und 35°C. Ageratum conyzoides und C. crepidioides hatten etwas geringere Ansprüche an die Keimtemperatur als die übrigen Arten, was ihre vergleichsweise stärkere Verbreitung in Höhenlagen erklärt. Die Keim‐temperaturen der beiden Vertreter aus den gemässigten Breiten, Alopecurus myosuroides und Chenopodium album, lagen bei 5 (Minimum), 15–25 (Optimum) bzw. 40°C (Maximum). Die Keimung von A. conyzoides, C. crepidioides und M. micrantha wurde bereits ab einem osmotischen Potential von ‐ 1 bar negativ beeinflusst. Bei ‐ 4,7 bar keimte von den 6 tropischen Arten nur noch P. paniculatum in geringem Umfang, während AL myosuroides und Ch. album bis ‐4,7 bar nicht beeinträchtigt wurden. Nach einjähriger trockener Lagerung keimten alle 6 tropischen Arten nur unter Lichteinfluss. Nach 20 Monaten keimten C. crepidioides und P. paniculatum auch in Dunkeln.
Spread of proso millet (Panicum miliaceum L.) in Ontario, Canada. II. Dispersal by combines
Authors: McCANNY S. J. , CAVERS P. B. 
Published: July 2006

SummarySeeds of proso millet (Panicum miliaceum L.) are moved between and within fields on combine harvesters. The dispersal of seeds of two biotypes of P. miliaceum by combine harvesters was quantified. The golden‐seeded biotype of this weedy annual grass was known to have larger seeds and to experience less seed shattering than the black‐seeded biotype. An average of 3·3% of the seeds on the plants of the black‐seeded biotype was carried more than 50 m by combines, while 0·9% of the golden seeds were carried the same distance. The densities of the seed rain within 50 m of the weedy patches were 3·7 seeds m−2 for the black‐seeded biotype and 9·7 seeds m−2 for the golden‐seeded biotype. This difference was proportional to the difference in the number of seeds in the respective source patches. The numbers of seeds deposited at various points within 50 m of source patches were close to uniform for both biotypes. There was, however, a significant difference (P < 0·05) in the distributions of the seeds of the two biotypes.
Mathematical modelling in agricultural science
Authors: FRANCE J. 
Published: July 2006

SummaryA simple initial classification of types of models is given and the essential role of models in science, especially in agricultural science, is reviewed. Empirical models are contrasted with mechanistic models, and these are related to the levels of aggregation considered, and crucially, to the difference between description and understanding. Examples of mechanistic models to simulate aggregated biochemical systems and to interpret experimental data, with reference to nutrition and metabolism in animals, are presented. Requirements for successful modelling in an agricultural context are discussed, followed by consideration of the problems and promise of linking the modelling viewpoint into a biological research programme. Finally, the ranges of possible objectives and potential contributions of mathematical modelling in agricultural science are explored.
Veränderungen der Vegetation durch experimentelle Erdgasbehandlung
Authors: PYŠEK PETR , PYŠEK ANTONÍN 
Published: July 2006

ZusammenfassungDie Veränderungen der Vegetation, die durch experimentelle Erdgasbehandlung hervorgerufen wurden, sind in den Jahren 1978–84 in Mittelböhmen untersucht worden. Das verwendete Erdgas enthielt 93,8% Methan, 3,6%Äthan, 0,8% Propan, 0,25% Butan, 0,3% Kohlendioxid. Die getesteten Kulturpflanzen wurden auf Parzellen von 60·5 m angebaut, bei denen das Erdgas durch unterirdische Sonden in den Boden eingebracht wurde. Darüber hinaus wurden die Reaktionen der Unkrautarten untersucht.Die Wirkungen auf der Populationsebene bestanden in Wachstumshemmung und Verminderung der Individuenzahl bei den meisten Arten. BeiMedicago sativa, Brassica oleraceavar.acephala, Secale cereale, Lolium multiflorum, Beta vulgarisundZea mayswurden Farbveränderungen beobachtet. Auffällige phänologische Veränderungen wurden beiSolanum tuberasum, Helianthus annuusandZea maysfestgestellt (Verzögerung des Austreibens und des Blühbeginns), Für einen typischen Effekt des Erdgases kann eingeschränkte oder sogar fehlende Reprodutionsfähigkeit angesehen werden, was besonders fürAllium cepa, Triticum aestirum, Hordeum distichon, Trifoliumsp. div.,Medicago sativaund die meisten Unkrautarten gilt. Oftentstanden verschiedene Organdeformationen (Solanum tuberosum, Beta vulgaris).Einzelpflanzen vonChenopodium albumundMedicago sativa, die in der Umgebung der Erdgas‐ausströmung wuchsen, hatten eine erhöhte Stomatazahl. Es wurden auch Veränderungen im Verlauf der Reflektionskurven beiTrifolium pratensesubsp.sativumbeobachtet. Am Ort der stärksten Erdgaswirkung kam es im Vergleich mit der Kontrolle zu auffälligem Abfall der Reflektion im infraroten Bereich des Spektrums. Der Unterschied entstand und verstärkte sich allmählich im Verlauf der Vegetationsperiode mit steigendem Einfluss des Gases.Die Deckungsgrad‐ und Dichtereduktion und Veränderungen in der Artenzusammensetzung (Rückgang der empfindlichen Arten) können für cine allgemeine Folge der Erdgaswirkung auf Gesellschaftsebene gehalten werden. Die ersten Wirkungen wurden etwa 15–30 Tage nach Versuchsbeginn beobachtet, was etwa einer Menge von 80–150 m3Gas pro Parzelle entspricht.