Abstract
The phytotoxicity of MCPA (2-methyl-4-chlorophenoxyacetic acid) as related to the translocation and metabolism in maize (tolerant), chickweed (moderately sensitive), and broad bean (sensitive) were examined under controlled environmental conditions. The amount of 14C-MCPA translocated in broad bean and chickweed was significantly greater than in maize. However, retained by the treated leaf was greater in maize than in the other two species. The 14C-MCPA retained by the cuticle wax was less than 1% (of the applied) and the test species did not differ significantly in this respect. The release of 14CO2 from 14C-MCPA was significantly greater in broad bean than in maize and chickweed. The foliar application of MCPA resulted in greater inhibition of 14CO2 fixation and 14C-assimilate translocation in broad bean and chickweed than in maize.
