摘要:

SummaryThe activity of GR7 andStrigagermination stimulant(s) fromEuphorbia aegyptiacaBoiss. showed adequate persistence (6–8 days) in acidic soils (pH 5·0–6·3), but residual activity was short (1–3 days) in alkaline soils. The compounds tended to lose activity at a faster rate in the alkaline clay Gezira soil (pH 7·8), than in its sandy equivalent (pH 8·1). In solution, pH had no influence on initial activity, but residual action was reduced more rapidly by alkalinity and high temperature. However, the rate of loss of activity in solution was slower than

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00778.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryGermination in the laboratory of seeds ofBarbarea strictaandB. vulgariswas inhibited by 20–200 mg l−1chlormequat chloride or daminozide. Seeds treated with chlormequat and then washed with water and kept on moist quartz sand remained dormant for up to 1 year, but dormancy could be broken at any time by treatment with gibberellic acid. Similar results were obtained withCapsella bursa‐pastorisandThlaspi arvense.In contrast, germination of other weed species, such asSpergula arvensisandMatrkaria perforata, took place in the presence of chlormequat and daminozide in concentrations of 5000–10000 mg 1−1. The relevance of the results to the duration of seed dormancy in the soil is

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00779.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

RésuméLa dégradation chimique du N‐phenylcarbamate de propyne‐2 yle a étéétudiée à 20°C après dépôt sur diverses argiles homoioniques (Bentonit Prolabo, Montmorillonite K 10; Cu2+, Ag+Zn2+, Fe3+) Seuls le cuivre et l'argent sont actifs et les vitesses de conversion sont généralement plus faibles que celles précédemmentl observées avec le Chlorbufame. Un processus de dégradation suivant deux voies parallèles a pu étre mis en évidence: cyclisation en oxazolidinone ou hydrolyse de la fonction carbamate. La sélectivité observée dépend de la méthode d'imprégnation de la nature du support et du cation de saturation. La formation d'isocyanate intermédiaire au cours de l'hydro

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00780.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryPathways of chlortoluron metabolism were compared in excised leaves of four tolerant species, namely wheat (Triticum aestivumvar Clement),Bromus sterilis, Galium aparineandVeronica persica.The herbicide was principally detoxified by hydroxylation of the ring methyl in wheat and byN‐dealkylation inVeronica persica.Both pathways were involved inBromus sterilisandGalium aparine.Kinetic study of the degradation showed that capacity to form non‐toxic conjugates could, at least partially, explain the tolerance of these species to chlortoluron. In plants treated with 1‐aminobenzotriazole, a cytochrome P‐450 enzyme inactivator,N‐dealkylation of chlortoluron was little or not affected, but ring methyl hydroxylation was strongly inhibited. This suggests that at least two distinct enzymatic systems could participate in this metabolism. Moreover, cytochrome P‐450 enzymes could be involved in the ring methyl hydroxylati

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00781.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryThe feasibility of achieving selective wild oat (Avena fatuaL.) control in a stand of the Australian oat (Avena sativaL.) cv. Savena I was examined. Diclofop‐methyl was applied at rates of 0·4–0·7 kg a.i. ha−1at the three‐ and five‐leaf stages ofA. fatua(84–132 culms m2). Although all rates of diclofop‐methyl caused initial chlorosis and necrosis to the crop, the subsequent control ofA. fatuapermitted increased crop tillering.Avena fatuacontrol and crop yield response were maximized when diclofop‐methyl was applied at the three‐leaf stage. Crop grain yield was increased by as much as 32% and 22% during 1984 and 1985, respectively. In the absence ofA. fatuacompetition, crop shoot dry weight at ear emergence was reduced only where diclofop‐methyl was applied at 0·6 or 0·7 kg ha−1. However, final grain yield was not reduced by any treatment. Only 11 of 240 cultivars or lines tolerated diclofop‐methyl, and none reached the level attained by Savena I and a closely related Australian line [(Irwin × (West × New Zealand Cape/42)) × West]/24. The nature of the inheritance of diclofop‐methyl tolerance was examined (1983–1985) by crossing and backcrossing (BC) Savena I with four diclofop‐methyl susceptible, but agronomically superior, lines. Inheritance of diclofop‐methyl tolerance appeared to be controlled by two genes, with susceptibility being dominant t

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00782.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryGlyphosate†was sprayed at 0009–1·12 kg a.i. ha−1on 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 p

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00783.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ZusammenfassungFür die 6 untersuchten tropischen SegetalartenAgeratum conyzoides, Blechum brownei, Crassocephalum crepidioides, Mikania micrantha, Paspalum conjugatumundP. paniculatumlag 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 conyzoidesundC. crepidioideshatten 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 myosuroidesundChenopodium album, lagen bei 5 (Minimum), 15–25 (Optimum) bzw. 40°C (Maximum). Die Keimung vonA. conyzoides, C. crepidioidesundM. micranthawurde bereits ab einem osmotischen Potential von ‐ 1 bar negativ beeinflusst. Bei ‐ 4,7 bar keimte von den 6 tropischen Arten nur nochP. paniculatumin geringem Umfang, währendAL myosuroidesundCh. albumbis ‐4,7 bar nicht beeinträchtigt wurden. Nach einjähriger trockener Lagerung keimten alle 6 tropischen Arten nur unter Lichteinfluss. Nach 20 Monaten keimten C.crepidioidesundP. p

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00784.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryInterspecific competition between wheat (Triticum aestivumL.) andChenopodium albumL., was studied in pots using the replacement series design of de Wit. Competitive interference for phosphorus, and to some extent for nitrogen, between the two species was noted. This played a major part in limitation of growth of wheat plants byC. album, whereas wheat exhibited greater non‐competitive interference in restricting potassium uptake by the weed. Increasing interference from the weed resulted in significant reductions in wheat grain size and yiel

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00785.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1988.tb00777.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY