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

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

 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.

AOSA requirements for orchargrass purity testing

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.

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

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

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

Sample Variety Purity (%) No. MSU Germi nation SSU (%) Germin ation MSU (%) Germi nation SSU + MSU (%) 1Akimidori II Akimidori II Potomac Benchmark plus Potomac NA 6Benchmark plus Potomac Harvester NA 9Benchmark NA 10Dividend VL Mean Preliminary Study

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.

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).

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.

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.

 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. M ATERIALS AND M ETHODS

R ESULTS

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

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.

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

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.

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