Agriculture Reference
In-Depth Information
Presoak
.
This method allows the seeds to soak in a solution of the herbicide for a predetermined inter-
val. The seeds are then planted and germinated under normal conditions and susceptibility to the herbicide
determined. The advantage of the presoak method is that there is less contamination of facilities, equip-
ment, and waste with the herbicide.
Substrate Imbibition
. Grote (1992) developed the original substrate imbibition test for testing imid-
azolinone tolerant corn and Gutormson (1999) published a 13-step method for testing Roundup Ready
TM
corn. In this method, the germination medium/substrate is soaked with the herbicide followed by placing
the seeds on the moistened medium. This approach allows the seeds to be exposed to the herbicide through-
out the duration of the test. The herbicide concentrations are usually less than those used in the ield since
the non-trait seeds/seedlings must emerge to express non-trait symptoms in their growth and anatomy. The
advantages of the substrate imbibition test are the automation of the method, ease of including a check
sample with each replicate, and less steps to plant. Important disadvantages include the requirement for
dedicated equipment to avoid herbicide toxicity to other seedlings and environmental concerns regarding
the disposal of media containing the herbicides. Tolerant and susceptible corn seedlings are illustrated in
Fig 9.5.
Figure 9.5. Herbicide tolerant corn seedling (left) and susceptible corn seedling (right) (courtesy of Seed
Technologist Training Manual, 2009).
