摘要:

Summary.The influence of the nitrogen supply on the growth and development of quackgrass (Agropyron repensL. Beauv.) was investigated by growing plants in sand culture at nitrogen levels of 210, 10–5, 5.25 and 2.6 ppm in addition to constant levels of other basic nutrients.When these nutrient regimes were first applied the rate of leaf emergence showed a positive correlation with the nitrogen level. This effect, however, did not persist and the rate subsequently attained was similar at all levels of nutrition. Tiller emergence, on the other hand, was markedly dependent on the nitrogen supply and at 2.6 ppm N was almost completely suppressed. As a result of this effect the production of secondary rhizomes, i.e. those arising from tillers, was correspondingly reduced. There was, however, a slight increase in the number of rhizomes produced from buds on the parent shoot.At 2.6 ppm N the dry weight of the shoots was reduced by approximately 75% as compared with the highest nitrogen level but there was no significant reduction in the weight of the roots or rhizomes. The shoot/root ratio was thus considerably decreased at the lower ni trogen levels.By varying the nitrogen supply it was also possible to control quite precisely the behaviour of the rhizome buds. At 2.6 ppm and 10.5 ppm the buds ceased to grow when 2–6 mm in length, the size attained being determined by the nitrogen level. At 210 ppm, however, the onset of dormancy was eliminated and all of the buds grew out as lateral branches. Bud growth could also be induced at a low nitrogen level (5.25 ppm) by removing the rhizome apex.The significance of these results is discussed in relation to the ecology of the plant and to the problem of apical dominance.Influence de diverses dases d'azote sur la croissarce et le développent d'Agropyron repensL. B

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00318.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Summary.Seeds ofPolygonam persiariawere collected from seven localities during 1962. In 1963 plants of these seven populations were grown in the field and sampled at regular intervals over the period 21st June to 13th August. At all samplings there were differences between populations in total dry weight, in leaf area index and in total nitrogen content, and populations also differed in the date of flowering. The populations also differed significantly in relative growth rate, leaf area ratio, net assimilation rate and relative nitrogen absorption rate. The variations in net assimilation rate did not appear to be closely associated with variations in leaf area index. Certain growth attributes were correlated with the latitude of origin, and it is tentatively suggested that the populations may represent genetically distinct latitudinal ecotypes.Études sur des espèces de mauvaises herbes du genre Polygonum

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00319.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Summary.Nuclear magnetic resonance spectra have shown that isocil, 5‐bromo‐6‐methyl‐3‐isopropyluracil, exists almost entirely in the ‘keto’ form, i.e. that the hydrogen atom is attached to the nitrogen at position one in the ring rather than to the oxygen at position two. Spectra were obtained in deuterated chloroform to avoid solvent interference. This method may be of value in determining structures of other herbicides where‘keto’‐‘enol’equilibria arc believed to exist.Utilisation de la résonance magnétique nucléaire pour la détermination de la structure de l'isocil (5‐brom

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00320.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Summary.From 1959 to 1962 the effects of some triazine and growth regulator herbicides applied pre‐emergence and post‐emergence to maize grown for silage were studied in field experiments on light to medium loam soils at Harper Adams College, Shropshire.Atrazine applied pre‐emergence at 1–1.5 lb/ac gave good control of annual weeds and was superior to simazine at equivalent rates. Soil moisture and rainfall after spraying were found to influence the activity of the triazines, but both were completely tolerated by maize. In 1960, 1961 and 1962 atrazine was much more effective against annual weeds than post‐emergence applications of MCPA and 2,4‐D. However MCPA and 2,4‐D gave adequate control of a range of annual and perennial weeds under favourable conditions in 1959 and 1960 but results were poor in the two following years due to the presence ofresistant and late germinating weeds.The effect of the herbicides on development and yield of ihe maize are discussed.Le désherbage chimiq

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00321.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Summary.A series of field trials was conducted to determine if the tolerance of newly planted strawberry runners to simazine could be increased by placing adsorbents in the vicinily of the root zone at planting time. Powdered steam‐activated charcoal was found to be the most suitable of seven adsorbents tested. Dipping the roots of runners in charcoal before planting was more effective and practicable than placing a similar quantity of charcoal around each runner at planting time. No significant damage was recorded in several trials in which dipped runners were sprayed with simazine at 1 lb/ac within a few days of planting.Although new roots are likely to take up the herbicide as they grow away from the charcoal‐protected area around the plant, the protection provided by the adsorbent appears to be sufficient to enable the young plants to develop satisfactorily.Utilisation d'adsorbants et de simazine sur des fraisiers récemment pl

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00322.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Summary.The effect of pre‐ and post‐emergence applications of neburon on the growth ofPueraria phaseoloidesandCentrosema pubescenshas been tested.Pueraria phaseoloideswas adversely affectcd by both applications, seprately and combined, the effect being greater on a sandy soil than on a clay soil.Centrosema pubescensshowed greater tolerance, and was little affected by post‐emergence treatment but pre‐emergence treatment showed some adverse effect.The check to growth of the legumes could be offset by increased rates of sowing. It appears that neburon might be suitable as a selective herbicide for application in tropical legumes.Le néburon, herbicide sélectif pour les cultures de légumineuses

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00323.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Summary.The concentration of chlorpropham required to reduce primary root clongation by 50% was determined for more than 180 species of dicotyledons in laboratory tests and was found to vary from 0.01 ppm to more than 10 ppm. With certain exceptions, species within a family responded similarly; the Polygonaccae and Caryophyllaceae were the most susceptible and the Compositae were the most tolerant. There was a general correspondence between the test results and the relative susceptibility of species in the field. Tests with different varieties ofBrassies oleraceaandDaucus carotashowed no significant differences in varietal response.Tolérance comparée de quelques dicotylédones au chlorprop

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00324.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Zusammenfassung.Für die in Deutschland als Ackerunkräuter vorkommenden Kamillearten der GattungenAnthemisundMatricariawird ein Bestimmungsschlüssel gebracht, der die Differenzierung dieser Arten im Rosettenstadium ermöglicht.Morphological difference between species of the generaAnthémis ami Matricaria (mayiveeds) at the rosette

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00325.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00326.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1965.tb00327.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY