The relationship between the bleaching pattern on radish cotyledons and hydrophobicity of herbicidal 3-phenoxybenzamides

When herbicidal 3-phenoxybenzamides were applied to radish seeds, the expanded cotyledons were bleached to different extents. The bleached states of cotyledons were classified into three patterns, A, B and c according to the extent of bleaching. compounds with lower hydrophobicity (log Kow 2.57-3.89, Kow: octanol/water partition coefficient) caused total bleaching of both cotyledons (pattern A), while more hydrophobic compounds bleached only partially: one cotyledon was bleached completely and the other only at the marginal area (pattern B, log Kow 4.35, 4.43) or both cotyledons were bleached partially (pattern C, log Kow 4.78, 5.01). It was suggested that the bleaching patterns varied according to the difference in mobility due to hydrophobicity