摘要:

Summary:In 962 field trials in different crops, the size of a number of weed species was investigated. The weeds were ranked according to their size on a single occasion. The ranks of the species were examined relative to two weed species,Viola arvensis and Matricaria inodora. The ranking was, however, independent of which of the two species were used as standard. The correlation between the rankings withViola arvensisas standard, and the rankings withMatricaria inodoraas standard werer= 0‐93 for spring sown crops, andr= 0.84 for autumn sown crops.Sinapis arvensiswas the largest weed species in spring sown crops, with a weight of 14.5 times that ofViola arvensis, followed byBrassica napus, Galeopsisspp.,Thlaspi arvenseandAmsinckiaspp.Viola arvensis. Veronicaspp. andLamiumspp. were the smallest weed species in spring sown crops.Galium aparinewas the largest species in autumn sown crops, whereas spring germinating species such asPolygonumspp. were among the smallest. The ranks ofViola arvensis, Myosotis arvensis, Lapsana communis, Matricaria inodoraandLamiumspp. were almost identical in spring sown crops and in autumn sown crop

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01736.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

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

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01737.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Summary:Chlorsulfuron, giyphosate and imazaquin were evaluated in pot and field studies for their efficacy in controlling broomrape (Orobanche ramosaL.) in tomato (Lycopersicon esculentumMill.) in Northern Greece. All herbicides were applied four to five weeks after tomato transplanting, when the crop was at early flowering stage and broomrape had started to develop underground attachments. The number of emerged broomrape shoots and underground attachments were less affected by herbicide treatments than the dry weight, suggesting that the herbicides suppress the growth of broomrape rather than kill its underground organs. In the pot experiments, chlorsulfuron applied at 5 g AI ha−1was the most effective treatment for broomrape control and the least toxic to the crop. Imazaquin and glyphosate applied at 37 and 180 g AI ha−1, respectively, controlled broomrape but imazaquin reduced crop yield. In the field, similar rates of glyphosate and higher rates of imazaquin were not toxic to the crop but were less effective on broomrape. Chlorsulfuron applied at 10 g AI ha−1controlled broomrape emergence by 88%. When the herbicide was applied twice (5+10 g AI ha−1), it gave complete control of broomrape but delayed crop maturity. The yield of tomato was not increased as a result of these treatments because of low broomrape infestation and a short competition

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01738.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Summary:Emergence ofAvena fatuaandA. sterilisssp.ludovicianainfesting winter cereals during two years and at two sites in Aragon began after sowing in late October and continued for 23 weeks, with 75% of seedlings appearing in the first 9 weeks. The start of emergence was associated with a fall in minimum air temperature to below 9°C and a maximum of less than 20°C. Soil moisture was not limiting, and during winter flushes of seedlings tended to be associated with rises in mean temperature. In contrast with results from other latitudes,A. fatuaemerged mainly in autumn at the same time asA. sterilisssp. ludovician

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01739.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Résumé:L'imazaquine, un herbicide systémique, appliqué sur les feuilles dePhaseolus aureusparasité parCuscuta lupuliformisest transporté dans la cuscute et fortement accumulé dans la partie apicale des tiges de ce parasite. Des résultats similaires sont obtenus avec le couple soja—Cuscuta australis. L'herbicide est rapidement dégradé dans le soja, mais actif sur la cuscute dont il inhibe la division cellulaire. La systémie phloémienne de l'imazaquine, sa sélectivité physiologique vis à vis du soja ainsi que son efficacité sur la cuscute font que cet herbicide est un produit prometteur pour la lutte curative contre la cuscute dans le soja, comme le montrent les essais préliminaires

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01740.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Résumé:La répartition spatiale du potentiel semencier a été analysée à partir de données simulées et de données réelles provenant d'une parcelle expérimental. Trois types d'approches statistiques ont été comparés quant à leur capacitéà déterminer la structure spatiale de populations: (1) l'ajustement de la distribution des fréquences observées à une distribution théorique (Poisson et Binomiale négative); (2) le calcul d'indices basé sur la moyenne (m) et la variance (V) d'échantillonnage (rapport V/m, la ‘mean crowding’ et l'indice d'agrégation de Lloyd); (3) le calcul d'un coefficient d'autocorrélation (le I de Moran) permettant de prendre en compte la position géographique des prélèvements. Au vue des résultats obtenus à partir des données simulées, il apparait que seul le coefficient d'autocorrélation est adaptéà la description des structures spatiales. Appliqué aux données réelles, il a permis de définir la

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01741.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

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 sample

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01742.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Résumé:Neuf espfècesd'Eragrostisannuelles, adventices des cultures du Nord Cameroun sont différenciées à partir de quelques critères de l'appareil végétatif:E. viscosa, E. namaquensis, E. gangetica, E. turgida, E. pilosa, E. tremula, E. aspera, E. ciliaris, et E. cil

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1991.tb01743.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY