Abstract
Alloxydim-sodium (ADS), sodium salt of methyl 3-(1-allyloxyaminobutylidene)-6, 6-dimethyl-2, 4-dioxocyclohexyl carboxylate, is a highly selective post-emergence graminicide. It was more than 100 times more active on corn than soybean in post-emergence treatment. The absorption, translocation and metabolism of 14C-ADS were studied to clarify the mechanism of the selectivity between corn and soybean. No great differences in the rate of the absorption by leaf were found between the two species at 1, 4, and 24 hours after treatment. Approximately 80% of the absorbed radioactivity was detected in the treated leaf 24 hours after treatment in both plants. In other parts, the highest 14C-concentration was in the stem for corn and in the first leaf for soybean. However, there was no great difference in radioactivity between the stem of corn and the second leaf of soybean, which have meristematic region respectively. The meristematic region was considered as a site of action of ADS in gramineous plant. A metabolism study was also conducted. TLC analysis of plant extracts from both corn stem and soybean leaf up to 168 hours after treatment with 14C-ADS revealed no evidence of ADS metabolism in corn and soybean. The selective action of ADS in corn and soybean cannot be accounted for by differences in its foliar absorption, translocation or metabolism in these species.
