The influence of nutrient status on paraquat activity

The effects of nitrogen fertiliser on herbicide doseresponse of weeds were investigated by measuring weed biomass after growth at a range of nitrogen levels and treatment with a range of herbicide doses. Increasing weed biomass at no-herbicide treatment (W 0 ) and the response rate of the dose-response curve (B), with increasing nitrogen were successfully described by the linear model and the exponential model respectively. Conversely, decreasing ED 50 value with increasing nitrogen was well described by the logistic model. A combined model was then developed by incorporating these models into the standard dose-response model to describe the interactive effects of herbicide dose and nitrogen levels on biomass of Brassica napus, Matricaria perforata, Papaver rhoeas and Galium aparine. The model developed allowed the systematic description of increased herbicide performance with increasing nitrogen. The model was also used to predict weed biomass as affected by both herbicide doses and nitrogen levels. The mathematical relationships between herbicide dose-response and nitrogen levels may also be applied to the crop-weed competition model and then to decision making for optimum uses of nitrogen fertiliser and herbicide.

“…The results presented here agree with Lutman et al. (1974) and provide a closer insight into the relationship between nitrogen response and herbicide dose–response of weeds.…”

Section: Discussionsupporting

confidence: 86%

Modelling interactions between herbicide and nitrogen fertiliser in terms of weed response

Kim¹,

Marshall²,

Caseley³

et al. 2006

“…These experiments have shown that when the amount of paraquat available to the leaf was similar over the three nitrogen levels, then the low nitrogen leaves were more susceptible than the high nitrogen ones. Therefore the greater tolerance of the low nitrogen plants sprayed with paraquat found in the earlier whole plant experiments (Lutman et al, 1974) was not due to a greater 'intrinsic' tolerance of the leaves.…”

Section: Discussionmentioning

confidence: 64%

“…In previous experimenls it was shown that the suscepiibilily to paraquat of young cereals and grasses was influenced by their nitrogen status (Lutman et al, 1974). When sprayed with paraquat, plants grown in soils of high nitrogen status were more susceptible than those grown in soils of lower nitrogen status.…”

Section: Introductionmentioning

confidence: 93%

The influence of nitrogen status on the susceptibility of segments of cereal leaves to paraquat

Lutman

Sagar²,

Marshall³

et al. 1975

Self Cite

“…Data from previous experiments showed that plants grown at a high nitrogen status were more susceptible to paraquat than plants grown at a low nitrogen status (Lutman et al, 1974). The results of the experiments described in this paper support the hypothesis that the greater susceptibility of the high nitrogen plants was because they intercepted and retained more paraquat than the low nitrogen plants.…”

Section: Wcttabilitymentioning

confidence: 99%

“…Experiments described in a previous paper (Lutman, Sagar, Marshall & Headford, 1974) indicated that young cereal plants grown under high nitrogen conditions were more susceptible to paraquat than those grown under low nitrogen conditions. In this paper further experiments are described which attempt to explain these results.…”

Section: Introductionmentioning

confidence: 99%

The influence of the nitrogen status of oat plants (Avena sativa L.) on the interception and retention of foliar sprays

Lutman

Sagar

1975

Self Cite

Resum6: ZusammenfassungYoung oat plants grown at a high soil nitrogen level retained more spray tban plants grown at a lower nitrogen level. The greater retention by tbe bigb nitrogen plants appeared to be due both to tbeir greater leaf area and to tbe less vertical angle of tbe leaves.The angles of contact of water droplets on the leaf surfaees were lower for high nitrogen plants. Therefore water droplets hitting tbe surface of the leaves of these plants would be less likely to be reflected and would spread over the leaf surface more readily tban droplets hitting tbe leaves of low nitrogen plants.These results are discussed in relation to earlier work wbich sbowed that high nitrogen plants were more susceptible than those grown at a low nitrogen level to the foliar-applied herbieide, paraquat. * Present address: Weed Research Organization, llcgbroke Hill Varnlon. Oxford. Der Einfluss der Stk!