Seedling root development, effect

Various assay methods have been used to detect the presence of inhibitory substances. These include some of the classical tests used by investigators of growth-promoting substances—i.e., the various Avena coleoptile assays which utilize intact, decapitated, or isolated cylinders and the split pea stem test. Effects on seed germination and seedling shoot or root growth and development have also been measured in addition to other visible expressions of inhibition. Details of many of these tests have been compiled by Mitchell et al. (99). Tests have been carried out in Petri dishes, with various solution culture techniques, and by sand and soil culture. Effects so measured may or may not be similar to those obtained under field situations— i.e., the establishment of inhibition under controlled conditions pro-... 

It soon became apparent that before a chemical agent could be implicated under field conditions, the subtle nature of the allelopathic effect would have to be carefully elucidated. It should be possible to demonstrate the release of the chemical agent into the soil environment and its accumulation to phytotoxic concentrations. An example of this phenomena is the accumulation of the thiophene, a-terthienyl, in the root zone of common marigolds (e r e c t a ) ( ) If knapweed is allelopathic, is the effect present at all stages of plant development or is the effect most evident at the vulnerable seedling stage ... 

Once clear inhibitory effects were detected on germination and radicle growth of lettuce plants exposed to BOA,12,35 our group developed methodology to show whether there is a detectable BOA effect on the cell cycle progression in lettuce root meristems.13 This allows a more detailed characterization of the putative direct or indirect effect on the meristems of BOA-treated seedlings. 

It is effective for the control of seed-propagated grass and broad-leaved weeds in the seedling and early development stages, but is ineffective against deep-rooted weeds. 

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