Problems in testing native Asteraceae species

Example:  Artemisia tridentata (Big sagebrush)

As mentioned briefly, Artemisia tridentata (Big sagebrush) is an example of a native species - listed in the AOSA Rules for both purity and germination – which presents testing problems.  This species is a native shrub commonly occurring on dry soils of valleys and slopes in the western United States.  The pure seed unit definition listed for Artemisia tridentata in the AOSA Rules, PSU #27, does not work well for this species.  Part of the problem is that many of the seed units have attached floral remnants which are tedious to remove, and many lots of this species include obviously empty achenes.

2003 Artemisia Seed Testing Workgroup

In 2003, the AOSA commissioned an Artemisia Seed Testing Workgroup to work on some of the problems encountered for this species.  The group met in Salt Lake City Utah on March 26-27, 2003.  The group came up with a list of recommendations including harvesting, conditioning standards and methods, sampling, testing, and seed laws/end user requirements.

Artemisia tridentata

In 2004, the subject of the joint AOSA/SCST (Society of Commercial Seed Technologists) referee project for the Southwest (Region IV) was Artemisia tridentata.  The three purposes stated for this referee project were

1. to compare ISTA and AOSA definitions for Artemisia pure seed;

2. to assess consistency of Artemisia pure seed determination among labs; and

3. to assess consistency of Artemisia PLS (pure live seed) determination among labs. 

Two lots were sampled and sent out to labs.  The results from 14 participants were presented at the June, 2004, annual AOSA/SCST meeting in Tunica, Mississippi.  The report stated the results in part as follows:

“Using a 5% probability of error, statistically significant differences were only found in PSU results for sample 2.  AOSA and ISTA results were not significantly different for any other test on these two samples …”

“It is possible that insufficient sample sizes were tested to examine this issue adequately.  However, larger sample sizes would likely reduce participation.  It is unclear whether the wording for ISTA pure seed would improve consistency of pure seed determination.”