摘要:

Summary:The effects of picloram formulated with a nonionic surfactant (X‐77) and of the surfactant alone on the ultrastructure of leaf cells of velvet mesquite (Prosopis velutinaWoot.) and catclaw [Acacia greggii var. ariznica(Gray) Isely] were examined The surfactant induced temporary protrusions from chloroplasts in both species. A proliferation of rough endoplasmic reticulum (RER) was noted in velvet mesquite within 8h of application of the herbicide and in catclaw with in 27 h. By 72h after treatment. both species exhibited distortions of organelles with more severe symptoms in catclaw. the species more sensitive to the herbicide Leaf abscission occurred subsequently and was more pronounced in catclaw than in mesquitelIt is known that RER proliferation is induced by ethylene and that ethylene evolution is stimulated by picloram. The present study suggests that the interaction between these two chemicals was similar in the two plant species studie

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01531.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Changes in ihe species composition of a ryegrass pasture were examined over a 2 year period from a spring establishment. Seed of S23 perennial ryegrass was sown in main plots, eilher broadcast or drilled, at rates of 15, 25 or 35 kg/ha in a field experiment at Oxford. The whole area was oversown withfour weed grasses (Agrostis siolonifera.Holcus lanatus. Poa annuaandP trivialis). Five cultural and three herbicide treatments were applied across the plots. These consisted of three levels of nitrogen (0. 50 and 100 kg N per ha), two companion species (Italian ryegrass and white clover) and 2.4‐D, benazolin and methabenzihiazuron applications.Ten weeks after sowing, broad‐leaved weeds accounted for nearly half the lotal dry‐matter yield, except where controlled by the three herbicides. Grass yields were nol increased by herbicide treatment. The only cultural treatment checking broad‐leaved weeds was ihe 35 kg/ha seeding rale.Seven months after sowing, the only treatment which had decreased the abundance of weed grasses was melhabenzthiazuron especially againsiA. stoloniferaandPoaspp. Two years afler sowing, perennial ryegrass had only 34% ground cover and had been replaced largely byH. lanatus(38%),Poaspp, (15%) andA. stolonifera(7%), Where methabenzthiazuron had been used the ryegrass ground cover was 48%. with lessP. trivialisandA. stolonifera.butH. lanatuswas nol altered. White clover decreasedH. lanatuscover.In two supplementary pot experiments, methabenzthiazuron sprayed pre‐emergence damaged perennial ryegrass unless the seed was covered with at least 4 mm of soil. OnlyH. lanatmand F. rubra outof sixteen grasses were relatively resistant to methabenzihiazuron when applied at ihe tillering stage, confirming that this herbicide has potential for preventing the ingress of many unsown grasses in

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01532.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Glyphosate at 2 kg/ha was more effective in reducing regrowth of purple nutsedge (Cyperus rotundusL.) scapes at 90% than at 50% relative humidity (r.h.), and more effective at −2 bars than at −11 bars of plant water potential. Regrowth of treated plants subjected to water potentials of −1 to −8 bars was reduced 54–60% while at −11 bars growth inhibition was only 34%. A time interval of as little as 8 h between application and excision was sufficient to give 47% reduction in regrowth at 90% r.h. None of the treated plants, except those clipped immediately after application, produced new shoots from the basal bulb, while all the untreated control plants produced one or more new shoots. Experiments using14C‐glyphosate substantiated these results. Three times more14C‐label was translocated into the underground parts of nutsedge at 90% than at 50% r.h. Twice as much translocated at −2 bars than at −11 bars

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01533.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Bei den mit 10‐monatigen Schafböcken durchgeführten Versuchen wurden folgende Ergebnisse erhalten:Die Ausscheidungsrate (Versuehsdauer 96 Stunden nach Verfutterung) der Samen von lOverfutterten Weidepflanzenarten betrug beiMedicago sativa55,5%,Phteum pratense53,4%,Coronitta varia42,8%,Lotus cornicutatus34,8%,Agrostis alba32,9%,Trifotium repens24,5%,Stipaviriduta16,6%,Vicia sativa9,3%,Hordeum nodosum1,4%,Onobrychis sativa0,8%.Ausscheidungszeiten: Ohne bestimmte zeitliche Regelmäßigkeiten wurden die Samen vonHordeum nodosumim Verlauf der 96‐stündigen Versuehsdauer ausgeschieden. BeiMedicago sativawurde ein Ausscheidungsmaximum bei 62 Stunden, beiPhteum pratensebei 86 Stunden festgestellt. Bei den anderen 7 Samenarten lag das Ausscheidungsmaximum zwischen 38–48 Stunden.Wahrend bei 8 Samenarten eine Verminderung der Keimfähigkeit nach Passieren des Verdauungstrakts im Vergleich zu frischen Samen festgestellt wurde, konnte man eine Erhöhung des Keimwertes beiAgrostis atbaundHordeum nodosumfeststellen.Keimfahig waren die Samen vonVicia sativabis zu einer Ausscheidungszeit von 38 Stunden,Onobrychis sativabis 48 Stunden. Samen vonHordeum nodosumwaren keimfahig bis zu einer Ausscheidungszeit von 62–96 Stunden,Trifotium repens24–86 Stunden. Bei den restlichen 6 Arten waren die Samen auch nach 96‐stündiger Verweildauer im Verdauungstrakt zumindest noch teilweise keimfähig.Nach 3‐monatiger Mistgärung waren die Samen vonVicia sativa, Hordeum nodosumundOnobrychis sativavollig vernichtet. Bei den restlichen 7 Samenarten betrug die Keimpotenz beiCoronitta varia6,8%,Lotus cornicutatus6,1%,Trifotium repens5,1%,Phteum pratense4,9%,Medicago sativa4,6%,Agrostis alba3,2

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01534.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Barban was combined with benzoylprop ethyl, flamprop methyl, or flamprop isopropyl, and the eflects of the combinations on wild oat control and crop yield were assessed, tn greenhouse experiments, the interaction in all three combinations was synergistic, following application at the 2‐ or 4‐leaf stage of wild oats. Under field conditions, combinations of barban + benzoylprop ethyl applied at the 2‐ or 4‐leaf stage of wild oats were as eflective for wild oat control and wheat yield response as barban at 028 kg/ha applied at the 2‐leaf or benzoylprop ethyl at 14 kg/ha applied at the 4‐leaf stage of wild oats. Mixtures of barban + flamprop methyl applied at the 2‐ or 4‐leaf stage of wild oats provided excellent wild oat control and wheat yield increases. Mixtures of barban + flamprop isopropyl applied at the 2‐ or 4‐leaf stage of wild oats provided comparable wild oat control and barley yield increases to barban (028 kg/ha) applied at the 2‐leaf or flamprop isopropyl (14 kg/ha) applied at the 4‐

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01535.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:The literature on various aspects of the biology of Johnson grass. Sorghum halepense (L.) Pers. is reviewed. Topics discussed include its distribution, cytology, taxonomy, life cycle, variability and the dormancy and germination of its seeds and rhizomes.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01536.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Eighty comparisons were made between the numbers of weed seedlings emerging after seedbed preparation and the numbers of apparently viable seeds extracted by sieving and flotation from samples of the top 10 cm of soil. When soil moisture was adequate, the total seedling numbers represented 3–6% of the numbers of seeds; when dry weather followed cultivation, the percentages were lower than this. The percentages were relatively high forPoa annuaL. andStellaria media(L.) Vill. but low forChenopodium albumL. andPapaverspp. Relatively high numbers of seeds ofPotygonum aviculareL. gave rise to seedlings in early spring but few appeared on seedbeds prepared after mid‐May; the reverse was true forAphanes arvehsisL. It is suggested that data of this kind could provide a basis for predicting weed floras following cultivation at any time of year from determinations of seed numbers made at the start of the y

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01537.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01538.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY