EXPERIMENTS ON THE RELATIVE SUSCEPTIBILITY OF WEEDS TO AUXIN HERBICIDES

1962 ◽  
Vol 40 (11) ◽  
pp. 1401-1409 ◽  
Author(s):  
J. R. Hay

Sections of stems of Silene cucubalus, Galeopsis tetrahit, and Phaseolus vulgaris were cultured under sterile conditions in media containing inorganic salts, sucrose, agar, and the herbicides 2-methyl, 4-chlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, or 2-(2,4,5-trichlorophenoxy)propionic acid. The herbicide which gave the most effective control of a species under field conditions was also the most active in inducing root formation and proliferation on stem sections of that species. The response of the sections to these auxin herbicides diminished as the plants from which the sections were taken became more mature. The amount of herbicide recovered from treated shoots of these species was not correlated with susceptibility. It is postulated that susceptibility to these materials depends upon (i) the affinity of the species for the molecular configuration of the herbicide and (ii) the relative amount and functional importance of the susceptible tissues at the time of treatment.

1987 ◽  
Vol 70 (5) ◽  
pp. 874-878 ◽  
Author(s):  
James Fleeker

Abstract Two solid-phase enzyme immunoassays were developed to measure 2,4-dichlorophenoxyacetic acid (2,4-D), using 2 sets of structurally distinct immunogens and enzyme ligands. The 2,4-D analog, 2-methyl- 4-chlorophenoxyacetic acid (MCPA), gave a similar response with both methods, whereas other phenoxy herbicides cross-reacted differently. In method A, the aromatic moiety of 2,4-D was distal from the carrier protein and labeled enzyme, whereas in method B, the acetic acid portion of the herbicide was distal. The use of both methods to screen for this herbicide in ground water and municipal and river water reduced the number of false-positive responses. Water sources having a low background response could be monitored with either method alone. When a concentration step, with disposable C18 extraction columns, was used, the limit of sensitivity was 5 ng/L,. Method A was the more sensitive of the 2 methods with a limit of detection of 10 j*g/L without the concentration step


2009 ◽  
Vol 92 (6) ◽  
pp. 1773-1779 ◽  
Author(s):  
Robin C Boro ◽  
K Vikas Singh ◽  
C Raman Suri

Abstract The generation of specific and sensitive antibodies against small molecules is greatly dependent upon the characteristics of the hapten-protein conjugates. In this study, we report a new fluorescence-based method for the characterization of hapten-protein conjugates. The method is based on an effect promoted by hapten-protein conjugation density upon the fluorescence intensity of the intrinsic tryptophan chromophore molecules of the protein. The proposed methodology is applied to quantify the hapten-protein conjugation density for two different chlorophenoxyacetic acid pesticides, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenoxybutyric acid (2,4-DB), coupled to carrier protein. Highly sensitive anti-2,4-D and anti-2,4-DB antibodies were obtained using these well-characterized hapten-protein conjugates. The generated antibodies were used in an immunoassay format demonstrating inhibitory concentration (IC50) values equal to 30 and 7 ng/mL for 2,4-D and 2,4-DB, respectively. Linearity was observed in the concentration range between 0.1500 ng/mL with LODs around 4 and 3 ng/mL for 2,4-D and 2,4-DB, respectively, in standard water samples. The proposed method was successfully applied for the determination of the extent of hapten-protein conjugation to produce specific antibodies for immunoassay development against pesticides.


Nature ◽  
1964 ◽  
Vol 204 (4961) ◽  
pp. 884-885 ◽  
Author(s):  
E. W. THOMAS ◽  
B. C. LOUGHMAN ◽  
R. G. POWELL

1967 ◽  
Vol 45 (7) ◽  
pp. 1011-1017 ◽  
Author(s):  
Harold M. Etter

The uptake and subsequent distribution of 32P among the root, stem, and leaf tissues of bean seedlings growing in complete or phosphate-free nutrient and its incorporation into organic phosphorus fractions was studied. Plants growing in complete nutrient took up, retained, translocated, and incorporated less activity than those growing in phosphate-free solution. These results are discussed in relation to phosphate pools which appear to be present in bean seedlings. Fifty and 70 h after spraying with 5 p.p.m. 2,4-dichlorophenoxyacetic acid (2,4-D), no marked changes were observed in the uptake or distribution pattern of the 32P as compared to controls.


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