摘要:

SummaryThe mechanism of action of the phenylsulphonyl carbamate herbicide (asulam) was examined in celery tissue cultures to see whether the mechanism involved an inhibition of folic acid synthesis. When asulam was included in the nutrient medium, growth of the celery cultures was reduced but not entirely inhibited even at a concentration of 250 μm. Growth was also reduced if a phenylcarbamate herbicide (barban), or sulphanilamide were included in the medium. The addition of folic acid, or 4‐amino benzoic acid, which is a precursor of folic acid, almost totally reversed the inhibitory effect of the asulam and sulphanilamide, but not of barban, whereas the addition of thymidine, methionine, serine or adenine, all of which are formed from folic acid, did not reverse the inhibitory effect of asulam, sulphanilamide or barban. Nevertheless the removal of the growth inhibition of asulam by folic acid or 4ABA suggested the mechanism of action of asulam was similar to that of a sulphanilamide. This mechanism of action in celery cell cultures appears to be similar to that found for asulam in intact plants of a range of speci

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00573.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummarySenecio jacobaeaL. andMedicago sativaL. plants grown in a glasshouse were treated with foliar applications of aqueous solutions of asulam. Retention on foliage, uptake and translocation were measured in both species. Retention was greater inS. jacobaeathan inM. sativawhen no surfactant was added and similar when surfactant was added. Addition of surfactant modified spray distribution and increased asulam uptake inM. salivabut did not in S.jacobaea. S. jacobaeatranslocated over twice as much asulam from the treated area asM. sativa.These data suggest that surfactant should not be added for maximum selectivity. Differences in species response to asulam treatments are partially, but not entirely, explained by differences in retention, uptake and translocation.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00574.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryMetabolism of14C asulam applied with surfactant was studied inSenecio JacobaeaL. andMedicago salivaL. Plants were harvested 48, 96 and 144 h after treatment and extracted with acetone. The aqueous residue of the acetone extract was partitioned with ethyl acetate and the14C activity in the ethyl‐acetate phase, the aqueous phase and the plant residue was determined. A significant amount of14C activity was not extracted by acetone from either species. This amount increased with time inM. sativabut remained relatively constant inS. jacobaea.More14C activity was found in the aqueous phase than in the ethyl‐acetate phase inM. sativawhile the reverse was true in S.jacobaea.Significantly lower amounts of free asulam were identified inM. sativathan inS. jacnbaea.Still, results of these and previous studies on retention, uptake and translocation do not completely account for differences in sensitivity found in greenhouse and field applications. Other possible explanations for selectivity are discus

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00575.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryChlortoluron, propyzamide, terbutryne and nitrofen were applied to the soil in pots with a rotary atomizer at 301 ha−1, with a conventional hydraulic nozzle at 400 1 ha−1at several doses, or as discrete 2‐μl drops applied with a microsyringe at 2‐cm spacings. The test plants wereAlopecurus myosuroides, Stellaria media, Chenopodium album, Avena fatua, perennial ryegrass and radish. Chlortoluron, propyzamide and terbutryne had the same activities following the rotary atomizer or conventional spray application but the rotary atomizer application of nitrofen was less effective againstA. fatuathan the conventional spray treatment. Chlortoluron, propyzamide and terbutryne showed appreciable activity applied as drops 2 cm apart at rates equivalent to 2 kg ai ha−1, on plants growing equidistant from the drops, but nitrofen showed no activity under these circumstances.The activity of chlortoluron was investigated at different soil moisture contents; it was more active when applied to moist soil than to dry soil which was not wetted for at least 10 h. Application method did not affect th

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00576.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryPlots sown with a range of test species were treated with chlortoluron, nitrofen, propyzamide or terbutryne applied at several doses either by rotary atomizer (30 1 ha−1), conventional hydraulic nozzle (250 1 ha−1) or dribble bar (with orifices spaced at 2‐cm intervals) (520 1 ha−1). The performance of chlortoluron, propyzamide and terbutryne was similar with all the methods used, regardless of soil and weather conditions. Vertical movement in the soil was similar for each application method. Horizontal variability following dribble‐bar application was measured for chlortoluron and was very large across short distances but weed control was as uniform as with the other application methods.In a further experiment, the phytotoxicity of chlortoluron applied by each of the three methods was less in a seed bed prepared by minimum tillage following straw burning than in a ploughed and cultivated seed bed. Activity following minimum tillage and straw baling was intermediate. This difference in phytotoxicity probably resulted from greater adsorption in the surface layers of the minimal cultivation t

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00577.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00578.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

RásumáLes définitions d' ‘adventicee’ et de ‘mauvaise herbee’ en Français, de ‘weede’ en Anglais et de ‘Unkraute’ en Allemand ont été relevées dans la bibliographie. La difficulté de trouver une seule définition satisfaisante pour ‘weede’ et ‘Unkraute’ est insurmontable puisque ces mots ont deux sens et doivent par conséquent avoir deux définitions distinctes: (i) adventice, weed, Unkraut (sens écologique): plante qui croit spontanément dans les milieux modifiés par l'homme; (ii) mauvaise herbe ou malherbe, weed, Unkraut (sens

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00579.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryBiomass, nitrogen, phosphorus and potassium inEupatorium odoratumL. (Asteraceae), an abundant early successional perennial weed, were studied in seral stages after slash and burn. Increment in individual biomass and nutrient uptake declined with increasing time after fallow. A higher proportion of the available resources was allocated to the supporting organs but a lower proportion to the photosynthetic organ in the older fields compared to recently fallowed fields. The allocation of biomass to reproduction, and also nutrient content, decreased during seral development. However, cost of reproduction to the plants (considered as the proportion of increment in biomass or nutrient uptake during the current growing season) was much higher in the older fields than the younger ones. Growth was adversely affected by low nutrient availability in soil in the recently fallowed fields but the allocation pattern remained unaffected. Biomass was not allocated in the same manner as nutrients. A higher proportion of nitrogen and phosphorus compared to that of biomass and potassium was devoted to reproduction in all the fields.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00580.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryThe patterns of herbaceous vegetation development and weed potential following slash and burn clearing after different lengths of time between the cultivation cycles are described. The early stages of secondary succession following burning tended to conform closely to the ‘initial floristic compositione’ model under shorter cycles of 4 and 6 years between cultivation, but the ‘relay floristicse’ model was found to be more applicable to the cycles of 10 and 20 yearse’ duration. Weed population, in terms of density, biomass and germinable seeds present in the soil, was significantly higher after cycles of 4 and 6 years compared to 10‐ and 20‐year cycles. In all the cycles, however, weed population declined sharply after a year of cropping with an effective weeding programme follo

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00581.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryBuried populations of dormant and non‐dormant wild oat (Avena fatua) seed persisted less than 2 years, depth of burial having very little influence on their survival. The mode of seed disappearence, however, was closely related to their depth in the soil. Seed exhaustion through germinationin situincreased with increasing depth in the soil, whereas exhaustion through non‐viability increased with decreasing depth. Physical and induced dormancies are apparently not capable of supporting prolonged persistence ofA. fatuaseeds in soil. The lack of prolonged persistence ofA. fatuaseeds in Colorado derives from a lack of genetically programmed embryonic dormancy in these populations and makesA. fatuaeasier to control in Colorado than in other cereal‐growing regions south of the 43rd parallel because it dramatically reduces the survival of seeds in the soil. The most effective non‐chemical control of this grass weed is achieved by means of the shallowest cultivations possible, carried out as late as p

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1984.tb00582.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY