摘要:

Summary.Seeds niPolygonum lapathifoliumfrom several sources or after certain treatments were subjected to various periods of moist chilling and then incubated for 3 weeks, during which time the numbers that germinated were recorded.Populations from different localities differed in both seed weight and in the response of the seeds to chilling, but no relationships between the response and the environment of the locality of origin were found. Seeds from individual plants and from single inflorescences within populations also varied in both seed weight and germination with and without chilling. Application of dichlorprop to the parent plants was found to affect seed weight and % germination, the effect varying with both population and dose.Etudes sur des espèces de mauvaises herbes du genre Polygonum L.IV.Variations du poids et des modalités de germination des semences chezP. lapathifolium

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01343.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Summary.Pot experiments on the competitive effects of charlock(Sinapis arvensisL.) on oats and wild oat(Avena fatuaL.) on barley had the following results:(1) During the period up to tillering there was an appreciable effect of the weeds on crop growth with depression in plant weight of 10–15% from that in the absence of weeds.(2) The greatest competitive effect occurred up to the middle of shooting of the cereals, when there were depressions in plant weight of 25–32%.(3) After this stage, the competitive effects of the weeds were much less in pots with a high nutrient level, and at low nutrient level there was almost no competitive effect.(4) The reduction in growth at the time of weeding was somewhat less at the low nutrient level than at the high nutrient level, and it is concluded that at the high level the competitive ability of the weeds was favoured more than that of the cereal crops.(5) The cereals were not able to overcome the initial damage caused by the weeds even when the weeds were removed at the beginning of tillering. A partial recovery did how ever occur at the high but not at the low nutrient level.(6) Both combinations, oats with charlock and barley with wild oat, behaved similarly, but some differences could be observed.Compétition entre plantes cultivées et mauvaises herbesII.Action des mauvaises herbes annuelles sur les c

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01344.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Summary.Measurements were made of the time taken for equilibrium to be established during adsorption and desorption under aqueous slurry conditions using monuron, linuron, atrazine and chlorpropham with a variety of adsorbents. An appreciable time was taken for equilibria to be established in adsorption processes, although with one exception, this period was 24 hr or less. Desorption processes were generally rather slower and in seven cases out of eighteen equilibrium was apparently not established in 72 hr. However, in all but two cases it seemed likely that the sorption process was reversible or nearly so.Possible explanations for differences of equilibrium times are discussed together with implications the results might have on the interpretation of leaching phenomena.Vitesse à laquelle est atteint I'équilibre d'adsorption et de désorption dans certains systèmes impliquant des herbic

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01345.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Summary.The experiments reported show that weed competition throughout growth reduced kale yields by up to 89%. Competition until the 4‐leaf stage reduced yields by about 12%. Application of nitrogen had little effect on the actual loss of yield. The same yield could be obtained by controlling weeds from emergence and giving little nitrogen, or by delaying weed control until the 4‐leaf stage and giving a higher level of nitrogen, but kale crops that had suffered weed competition until the 4‐Ieaf stage appeared to be incapable of achieving the same yield as crops clean‐weeded from emergence. Data on nitrogen percentage and content suggest that competition between weeds and kale was not solely for iEffets du desherbage et du taux de fertilisation azoiée sur le rendement et la teneuren azote du chou

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01346.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Summary.Pyrazon (5‐amino‐4‐chIoro‐2‐phenyl‐3(2H)‐pyridazinonc) labelled with tritium in the phenyl ring, was applied to both the root and shoot of seedlings of red beet(Beta vulgaris L., cultivar Detroit Dark Red I, German millet(Setatra italica J.), and tomato(Lycopersicon esculentumMill., cultivar Heinz 1350). Of these species, red best is tolerant, millet is moderately tolerant, and tomato is susceptible to pyrazon.When the roots were exposed to 1–325 ppm3H‐pyrazon in the nutrient solution, the greatest root absorption and transiocation to the shoot was observed in tomato and the least in red beet, while millet was intermediate.Applications to the first true leaf indicated that pyrazon was absorbed by the foliage of all three but that it was not transported basipetally. The absorption and translocation studies indicated that pyrazon mi transported primarily in the xylem.A radioactive metabolite of3H‐pyrazon was detected in the shoots of red beet, but there was no evidence for its presence in the shoots of the other two species. Since this metabolite is radioactive, its structure must contain at least some altered form of the phenyl ring which contained the tritium in the parent molecule. This differentiates it from 5‐amino‐4‐chloro‐pyridazinone, the previously proposed degradation product of pyrazon, since this compound lacks the phenyl ring.On the bash of these results, it is hypothesized that pyrazon will be phytotoxic if a suffic inn mm entration of the unaltered chemical reaches the site of herbicidal action in the shoot.Migration et métabolisme de la pyrazone dans les esp

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01347.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Summary.Picloram was incubated at concentrations of 0, 0·25, 0·5 and 1 ppmw in Regina heavy clay topsoil maintained at moisture‐holding capacity and a t 25° C The herbicide was quantitatively bioassayed at regular intervals. There was a lag period prior to degradation at all concentrations. The duration of the lag period increased as the concentration of picloram in the soil was increased. Al the end of each lag period, the degradation of picloram occurred as a first‐order reaction, i.e. the rate of degradation was independent of the concentration of picloram in the soil. Due to the pronounced variations in the duration of the lag periods with concentration, the assignment of half‐value or half‐life periods to picloram degradation in soil is considered to be of doubtful significance.Etude de la degradation de t'acide 4‐amino‐3,5,6‐trichloropicol

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01348.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01349.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01350.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01351.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1967.tb01352.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY