摘要:

Summary.The effectiveness of pre‐emergence applications of 2,4‐D for weed control in maize was studied In five experiments, in comparison with other herbicide treatments. 2,4‐D‐aimne applied before crop emergence gave satisfactory weed control if the subsequent conditions were wet, but post‐emerge nee applications only killed some species (Chenopodium albumandAtriplex patula.) A combination of 2,4‐D‐amine, applied pre‐emergence to a moist soil and subsequently as a foliar spray, controlled completely C.album, A. patula, Stellaria mediaandVeronicaspp. Pre‐emergence applications of simazine gave better weed control with less need for rain soon after application. OnlyA. patulawas usually resistant. Pre‐emergence treatments of atrazine killed all weeds whilst linuron controlledS. media, A. patula., C. albumandSonchus oleraceusbut notVeronicaspp.Irrigation experiments showed that weed competition for water was largely responsible for the depressions in the early growth of maize when the conditions were dry. Final yield largely reflected the degrees of weed control attained by the herbicidal treatments. Only 2,4‐D applied pre‐emergence, and followed by heavy rain caused a direct depression in yield.Effects des herbicides sur la productivityé du mals fourrage avec référence particuliére aux applications

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01240.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.Linuron, 2,4‐D‐aniine, propachlor, pyriclor and cypromid, singly and mixture with atrazine, were compared with atrazine and fluromidine alone for effectiveness of weed control in maize on Oxford clay soil. Pre‐emergence applications were made under wet conditions and atrazine, even at 0·28 kg/ha a.i. gave an excellent control of three main weeds,Stellaria media, Veronicaspp. andPolygonum aviculare, and at 0·56 kg/ha also killedAethusa cynapium.Fluromidine was comparable with atrazine, but linuron,2,4‐D‐amine, propachlor and pyriclor were less effective. Post‐emergence treatments were less satisfactory. High doses of atrazine were needed for good weed control.Acynapiumwas resistant to pyriclor and cypromid andP. aviculareto fluromidine. 2,4‐Daminewas ineffective, but atrazine/2,4‐D‐amine mixtures were more effective than the individual components for the control ofP. aviculare.Pyriclor, at 0·56 kg/ha pre‐emergenceand cypromid at 2·24 kg/ha post‐emergence directly reduced the yield of the crop.Utilisation de I'atrazine à faible dose, seule et en mélange avec d'autres herbicid

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01241.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.Studies on the physiological effects of dalapon inCynodon dactylon(L.) Pers. were carried out. Field and glasshouse experiments showed that dalapon is freely translocated in the aerial organs and from these to the rhizomes. No transformation of the herbicide was detected during 72 h following application. In rhizomes as well as in stolons, dalapon caused growth inhibition and necrosis of buds while root growth was apparently not affected. This differential susceptibility was confirmed by culturing node explants in nutrient solution containing dalapon. Although dalapon killed aerial organs, most rhizomes were capable of recovery even when a high dose was applied. These results are discussed.Effets physiologiqius du dalapon surCynodon dactylon (L.)Pers.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01242.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The growth ofAgropyron repensseedlings, or of clones derived from them, raised from seeds collected from different areas was compared; the growth of seedlings raised from seeds from single spikes and from seeds of a cross of two clones was also compared.The number and length of shoots and the amount of rhizome produced differed between seedlings from different areas. Seedlings with a large weight of rhizomes often had a small weight of shoots. Many of the differences found between seedlings from different areas were confirmed by comparing clones established from some of them. Comparisons of both seedlings and clones showed that the percentage of shoots that developed spikes differed between genotypes; clones with the least weight of rhizome tended to have most weight of spikes. Large variations also occurred between clones established from seedlings from a given area, particularly in the way their dry weight was partitioned between primary and secondary shoots and in the time the spikes emerged.The amount of rhizome per seedling varied greatly between seedlings from seeds from single spikes and from seeds from a cross of two clones. There was some evidence of a negative correlation between per cent shoot and per cent rhizome dry weight with seedlings from single spikes and between number of shoots and number of rhizomes per seedling with seedlings from a cross of two clones.Variation en croissance de plantules issues de semences et de clones d'Agropyron repens (L)Beauv.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01243.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The residues remaining in the soil from repeated annual application of simazine at 2–8, 5–6, and 22–4 kg/ha to uncropped plots on a loam soil were measured by chemical or bioassay methods at various intervals after treatment.The total simazine residue present 12 months after the last of three treatments with 2–8 kg/ha and 8 months after the last of five treatments with 5–6 kg/ha was less than 10% of the annual dose. This rapid decomposition is considered consistent with the soil and climatic conditions. In contrast a much larger residue (a mean value of 1·7 kg/ha) was found on plots sampled 21/2 years after the last of two annual applications of simazine at 22·4 kg/ha and the reduction in the amount of residue during the next 12 months was only of the order of 25%.In all treatments the highest concentration of simazine was found in the surface layers of the soil but measurable residues were detected to 60 cm depth, 31/2 years after the last 22·4 kg/ha application.There was considerable variation in the total residues recovered between replicate plots and between different positions on the same plots in all treatments regardless of the depth of the sample. The possible causes of this variation are discussed.Persistance et pénétration de fortes doses de simazine dans un

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01244.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The adsorption of acid, n‐butyl, and iso‐octyl ester forms of 2,4‐D (2,4‐ dichloiophenoxyacetic acid) was studied for several Canadian prairie soils. Thekvalues for the acid ranged from 0·09 to 1·30 and were correlated to the soil organic matter and not to the clay content. TheQ, values (μg adsorbed/g of organic matter) for the acid were 7–2±l. The n‐butyl and the iso‐octyl esters hydrolysed to the acid form in the aqueous medium and this process was accelerated in the presence of the moist soil. Consequently, thekvalues for the esters, using slurry type adsorption experiments, or their distribution coefficients, using leaching columns, could not be determined. It was concluded that the adsorptive behavior of the two esters in moist soil was similar to that of the acid form.Comportement des formes actde, et ester du 2,4‐D quant à leur ads

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01245.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The metabolism of monuron in excised leaves of bean (Phaseolus vulgarisL., var. Black Valentine) and corn (Zea maysL., var. Batam Cross) were studied with carbonyl‐14C‐labelled monuron. The metabolic conversions of monuron in both plant species were exponential and followed first order reaction kinetics. The metabolism of monuron can be divided into two major pathways: demethylation and hydroxylation. At a monuron concentration of 16 ppm the hydroxylation was dominant in the bean leaves. As the concentration of monuron was increased the participation of the hydroxylation pathway became less probably due to the inhibition of enzymes involved by monuron. The demethylation pathway was not affected by higher monuron concentration. In the corn leaf, however, sequential demethylation was always the major pathway of monuron transformation and there was no inhibitory effect observed on either pathways as the concentration of monuron increased. The following radioactive metabolites were found in the alcohol extract of bean and com leaves receiving carbonyl‐14C‐labelled monuron:N′‐(4‐chlorophenyl)‐N‐methylurea,p‐chlorophenylurea, two polypeptide complexes of monuron, one polypeptide complex ofN′‐(4‐chlorophenyl)‐N‐methylurea and β‐D‐glucosides ofN‐(2‐hydroxy‐4‐chlorophenyl) urea,N′‐(2‐hydroxy‐4‐chlorophenyl)N‐methylurea, andN′‐(2‐hydroxy‐4‐chlorophenyl)‐N,N‐dimethylurea. In addition, one minor radioactive peak was found only in the alcohol extract of corn leaves, which yielded four unidentified radioactive metabolites after acid or enzyme hydrolysis with β‐glucosidas

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01246.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.Some investigations were carried out on the adsorption of paraquat by a range of organic materials which included an organic soil, various humic fractions from that soil, model polymers prepared by the oxidative coupling of benzoquinone, the ion exchange resins Zeo‐Karb 216 and 226, and Amberlite XAD‐2. The time required for the adsorption process to reach equilibrium ranged from about 3 h (for the soil and humic preparations) to about 48 h (for the more highly cross‐linked materials). Adsorption by Amberlite XAD‐2, a cross‐linked polystyrene resin, was very small, presumably because it lacked ion‐exchange sites.The results suggested that particle diffusion control was operating and the different equilibrium times reflected different degrees of molecular complexity within the adsorbents.Temperature, within the 20°–70°C range, did not affect the adsorption equilibrium, and this is indirect evidence for ion exchange as the primary adsorption mechanism. No evidence was found for decomposition of paraquat in the adsorption systems studied.Quelques interactions physico‐chimiques du paraquat avec des inatéaux de sol organique et des composes modéles I. Effets de la température, du temps et de la dégradation sur I'

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01247.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The adsorption equilibria of paraquat were investigated on a range of organic materials including an organic soil, various humic fractions of that soil, model polymers prepared by the oxidative coupling of benzoquinone, ion‐exchange resins (Zeo‐Karb 216 and 226) and a polystyrene resin (Amberlite XAD‐2). Isotherms were prepared for adsorption on the H+and on some of the Ca2+saturated materials. Measurement of the counter‐ion in solution at equilibrium, and correlation of the adsorption with exchange capacity for H+adsorbents showed that ion exchange was the primary adsorption mechanism. Significant amounts of non‐exchange adsorption were also detected, especially at low concentrations, but generally the results followed the Rothmund‐Kornfeld isotherm equation fairly accurately. The Rothmund‐Kornfeld plots for the Ga2+forms were complicated by the hydrolysis by water of some of the exchange sites. Other types of isotherm equations were tested and found to be unsatisfactory.Desorption of paraquat with HCl from organic soil preparations was less than expected, and the isotherms did not conform to the Rothmund‐Kornfeld or to the mass action equations. The probable reasons for this behaviour arc discussed.Quelques interactions physico‐chimiques du paraquat avec des matériaux de sol organique et des composés modèlesII. Adsorption, désorption et équilibre dans l

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01248.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.A laboratory method is described for studying the effects of introducing herbicides into the vascular tissues oiPopuluscuttings. Of sixteen herbicides tested in this way, MCPA and picloram were the most phytotoxic. Ester formulations of growth regulator herbicides were less active than water soluble amine or inorganic salts. The phytotoxic effects of the latter were increased by supplying water to the cuttings before or after treatment or by applying the herbicide in a relatively large volume of water. A non‐ionic surfactant did not increase the effects of injected MCPA salt, approximately similar amounts of which moved both upwards and downwards in cuttings from the point of introduction.Expériences en laboratoire sur des boutures dePopulus × euroamericana“I‐78” traités avec des

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1973.tb01249.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY