MOVEMENT OF CHEMICALS 
IN PLANTS 
FOLIAR \) 
APPLICATION 
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Figure 3 
MECHANISMS AND SITES OF HERBICIDAL ACTION 
Herbicides modify and control plant growth by inhibiting essential physiological 
processes or by preventing the biosynthesis of metabolites essential to plant growth 
(figure 4). 
Figure 4 represents an over-simplified version of cellular metabolism, Carbohy - 
drates, organic acids, and other products are synthesized through the process of photo- 
synthesis, This food supply may be utilized in respiration to form the high energy 
phosphate bonds of adenosine triphosphate. This energy is then utilized in the biosynthesis 
of many cell constituents, The carbon skeletons synthesized through photosynthesis enter 
into enzyme-catalyzed reactions which lead in step-wise fashion to the production of 
growth-essential metabolites. These compounds are then incorporated into macromolecules 
such as coenzymes, proteins, nucleic acids, and polysaccharides, Macromolecules may 
then be incorporated into highly organized structures suchas microsomes, mitochondria, 
spindle fibers, chloroplasts, and nucleus. 
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