1. Comparison of Orchardgrass (Dactylis glomerata)
National Referee
Comparison of Orchardgrass (Dactylis glomerata)
purity test results with and without
applying the factoring procedure to the multiple seed units
2013

2. Outline Why do we need to investigate this change?
AOSA requirements for orchargrass purity testing.
Preliminary study.
National Referee
Comclusions

3. Why do we need to investigate this change?
The current factoring method does not reflect the true quality of seeds in the bag as traded. It artificially increases the inert matter content.
To achieve global harmonization in testing OG across labs and countries.
The current AOSA factoring procedure places the US OG growers in unnecessary disadvantage compared to the growers in any other country in the world who test their seeds using ISTA rules.
To increase objectivity and efficiency in testing.

4. AOSA requirements for orchargrass purity testing
Uniform Blowing Procedure
B. Factoring of Multiple Seed Units (~16% inert matter)

5. Preliminary Study
A study was conducted to compare the effect of Factoring vs. no-factoring on:
Purity
Germination
The study was based on data from 600 orchardgrass samples collected over 3 years from OSU seed services database.

6. Effect of factoring MSU on purity and germination tests of 229 OG
Samples tested in 2008
Preliminary Study Results
2008

7. Effect of factoring MSU on purity and germination
tests of 197 OG samples tested in 2009
2009

8. Effect of factoring MSU on purity and germination tests of 219 OG
Preliminary Study Results
Effect of factoring MSU on purity and germination tests of 219 OG
Samples tested in 2010

9. Preliminary Study
Germination of single seed units (SSU), MSU, and mixture of both in 10 random orchardgrass samples
Sample
Variety
Purity
(%)
No.
MSU
Germi
nation SSU
Germin
ation MSU 
nation
SSU + MSU 1
Akimidori II
90.50
263 98 94 95 2
88.27
309 96 93 3
Potomac
90.13
273 86 89 4
Benchmark plus
89.63
332 5
87.93
311 91 81 NA 6
81.51
257 80 7
87.23
228 83 82 88 8
Harvester
86.14
658 9
Benchmark
89.84
329 10
Dividend VL
78.86
241 85 87
Mean
320 92

10. Conclusions
Eliminating factoring of multiple seed units increases pure seed results by approximately 2%.
Multiple seed units found in the heavy fraction have high and similar planting value as single seed units.

11. National Referee Objectives
Compare the effect of applying factoring vs. no-factoring procedure of MSU on purity test results of OG across labs.
Compare the time used to complete OG purity tests with and without applying the factoring procedure across labs.
Investigate the possibility of eliminating the factoring procedure in OG purity testing (AOSA Rules 3.7. Table 3B).

12. Materials and Methods
Six OG blind samples representing different varieties, inert matter contents (2.2% to over 10%) production regions (Oregon & Denmark), and growing seasons (2010 & 2011).
Nine labs from CA, ID, VA, UT, OR, NC, IL, and Canada who have General blowers calibrated with AOSA master calibration samples participated in the study.
Nine labs completed the purity tests and six completed the germination tests.

13. Materials and Methods
First, the pure seed content of each sample were determined using the current AOSA factoring procedure (sec 3.7 AOSA Rules vol. 1).
Afterwards, the purity components of each sample were mixed back, and the same samples were used to determine the pure seed contents without applying the factoring procedure.

14. Materials and Methods
When determining the pure seed content without applying the factoring procedure, single and multiple seed units in heavy fraction after the sample has been blown, were considered pure seed units.
Multiple seed units were not separated and factored.
Crop and weed seeds in the blowings and in the heavy portion were separated, weighted and recorded as usual.

15. Results

16. Variation between methods & among labs
Pure seed test results of two orchardgrass samples (No. 1 & 2) separated in nine laboratories with and without applying the factoring procedure.

17. Variation between methods & among labs
Pure seed test results of two orchardgrass samples (No. 3 & 4) separated in nine laboratories with and without applying the factoring procedure.

18. Variation between methods & among labs
Pure seed test results of two orchardgrass samples (No. 5 & 6) separated in nine laboratories with and without applying the factoring procedure.

19. Time Saving
Mean time to complete purity tests of six orchardgrass samples tested eight laboratories with and without applying the AOSA factoring procedure.

20. Conclusions
The elimination of the factoring procedure resulted in an average increase of 1.89% in pure seed content.
The consistency in test results in the no-factoring method was similar to the current factoring method.
The no-factoring method does not introduce any change to the germination test.
Purity testing without factoring saves an average of 43% of the time compared to the current factoring method.

21. Conclusions Other advantages include: simplifies testing process,
global harmonization in testing OG, and
makes US growers more competitive in the global market.