The growth regulator, glyphosine [N,N-bis(phosphonomethyl)glycine], and other possible metabolites of glyphosine and glyphosate [N-(phosphonomethyl)glycine] [glycine, sarcosine, and aminomethylphosphonic acid (AMPA)] were tested individually (0.5 mM) or as a mixture (each at 0.5 mM) for their effects on growth, extractable phenylalanine ammonia-lyase (PAL) activity, hydroxyphenolic-compound production, chlorophyll and anthocyanin contents, and on soluble-protein levels in soybean [Glycine max (L.) Merr. ‘Hill’] seedlings. Most chemical treatments caused some inhibition of growth either on fresh weight accumulation or on root elongation in the light and dark over 72 h. Glyphosine was generally the most inhibitory and caused the greatest inhibition on axis dry-weight accumulation. Glyphosine significantly increased extractable PAL activity in axes of light- and dark-grown soybeans to a lesser extent than did glyphosate. AMPA had some inhibitory effects on extractable PAL activity whereas other compounds had little influence on the enzyme. These compounds had little effect on total soluble protein in axes or on soluble protein in PAL preparations from 12 to 72 h in light-or dark-grown seedlings. No in vitro effect of the chemicals on PAL activity was found at concentrations up to 0.5 mM. Hydroxyphenolic compound levels increased within 24 to 72 h (per gram fresh weight basis) in light- or dark-grown soybean axes treated with glyphosine, AMPA, or a metabolite mixture (AMPA, sarcosine, and glycine). Anthocyanin content was decreased by glyphosate and to a lesser extent by glyphosine, but was increased by AMPA and the mixture. Glyphosate significantly increased the chlorophyll a/b ratio and decreased total chlorophyll, but glyphosine decreased the chlorophyll content to a lesser degree.

This study was conducted to evaluate the mobility of 14C-metolachlor over 1 yr for three seasons when applied preemergent to undisturbed field lysimeters with and without soybean representing cropped and noncropped zones, respectively. Leachate was collected weekly and analyzed for total 14C, metolachlor, and metabolites. Lysimeters were removed, sectioned, and analyzed for 14C. Sixty and 90 days after treatment (DAT), there was less soil water in lysimeters with soybean. Recovery of 14C in lysimeters decreased with time and ranged from 54 to 74% 30 DAT followed by a slower rate of loss with 35 to 49% remaining 365 DAT. Comparable amounts of total 14C were observed in soybean lysimeters as in fallow lysimeters 30, 60, and 90 DAT. 14C distribution in the lysimeters, however, was quite different. Sixty and 90 DAT, 14C mobility in soybean lysimeters was less than in fallow lysimeters. Also, less leachate was collected from soybean lysimeters, which resulted in later appearances and lesser amounts of 14C in the leachate. Cumulative leachate from lysimeters with and without soybean 365 DAT contained 2% and 10 to 18% of the applied 14C, respectively. Peak concentrations of 14C in leachate from fallow columns occurred about 90 DAT and were two to 19 times higher than 14C concentrations in leachate from soybean lysimeters. Metolachlor concentrations in leachate were well below the National Health Advisory level for drinking water in all cases. Apparent volatilization losses of 14C amounted to 26 to 46% of the applied 14C-metolachlor 30 DAT. These results suggest that herbicide mobility is different in cropped vs. fallow sites and possibly in intra- and interrow crop positions.