Agriculture Reference
In-Depth Information
daily to a predetermined weight. Shoot and root length of intact plants was measured with a
ruler after the Whirl-Pak® bag was opened and soil was washed away with water.
plastic beads
Whirl-Pak
®
bag
sugar beet plant
soil
Figure 1. Diagram of a sugar beet bioassay in a Whirl-Pak® bag.
Using this simple laboratory bioassay technique, sugar beet response to pyroxsulam in
the range from 0 to 3.45 μg/kg and to pyroxasulfone in the range from 0 to 276 μg/kg
was
evaluated. The optimal duration of sugar beet growth required for significant inhibition due to
pyroxsulam was 4 days and due to pyroxasulfone was 7 days. Measuring both roots and
shoots of sugar beet showed that pyroxsulam inhibits primarily root length while
pyroxasulfone inhibits mainly shoot length and that both of these parameters correlate well
with the respective herbicide concentration (Figure 2).
Figure 2. Sugar beet root and shoot response to (a) pyroxsulam obtained by the 4-day bioassay, and (b)
pyroxasulfone obtained by the 7-day bioassay.
