摘要：

Based on content, hydroponically cultured seedlings were 254, 66, and 13 times more tolerant to than , , and smooth , respectively. , at concentrations that inhibited , did not affect fresh weight accumulations of any species except . However, in , fresh weight accumulation was only half as sensitive to as the leaf content. of 14C-from nutrient solution by 72 h after treatment (HAT) (> > > ) indicates that differential absorption cannot account for selectivity. Shoot:root ratios of 14C recovered from , , , and by 72 HAT were 0.39, 0.84, 1.67, and 2.37, respectively. The limited acropetal translocation in seedlings may account to a small degree for tolerance to . Conversion of to more polar metabolites was rapid in all four species. There were no significant differences among species in the percentage of 14C activity recovered as from root tissue by 72 HAT. Of the 14C activity recovered from shoots of , , , and seedlings by 72 HAT, 46, 59, 35, and 54%, respectively, was . Differences in , distribution, and among the four species were either insignificant or poorly correlated to selectivity, and therefore cannot account for the tremendous differences in sensitivity among these species. These observations indicate, indirectly, that differences at the site of action may account for selectivity.

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