1. 2016 Onion Germination Referee Results
Sue Alvarez, Ransom Seed Laboratory
Linda Barbosa, Sakata Seed Company

2. Background
The final count for onions (Allium cepa) is 10 days in AOSA when tested in B, T, or PP (an alternative method is 12 days when planted in S).
For ISTA the final count is 12 days for all media.
In the Canadian M & P the final count is 14 days.
Some onions do not appear to reach the maximum potential germination on 10 days, especially those that have been pelleted and/or treated with certain chemicals. 14 days might be too long, but 12 days may be better than 10 days.

3. Background, cont.
Several analysts discussed this observation at last year’s annual meeting.
After the meeting, a referee was put together as a comparison of the 10 and 12 day final counts for onions.
In addition, some in-house laboratory data was collected using commercial onion samples from three different seed companies.

4. Purpose of referee To compare the AOSA and ISTA final counts of onion.
Results could be used for an AOSA Rules change proposal.
One possible outcome would be to harmonize the ISTA and AOSA rules for onion germination testing.

5. Materials and Methods
Six lots of onion seeds from Sakata Seed Company were selected, of varying quality.
Samples from the six lots were prepared and sent out to nine laboratories from five different states.
Participants were asked to test each sample using 4 replicates of 100 seeds, using their normal media for onions. Participants were asked to state the media and temperature used.
Participants were asked to do a 10 day count as they would for the AOSA final count and to extend the test for two more days and report the 12 day final count.

6. Results Eight labs from 5 states returned results.
Seven of the labs reported using rolled towels at 20°C. The eighth lab did not report the test method.
Results are shown on the following slide.

7. Summary of results: % germination
Lab #
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
10 day
12 day 1
80.25
82.25 75
78.75
77.5
78.25 88
88.75
86.5
87.5
88.5
89.5 2
78.5
77.25
84.75
86.25 92
93.5
87.75
88.25 90 3 79 72 78 83 87 89 86 4
79.75 81
81.75
90.25
91.25 5
70.25 73 70
73.25
90.5 91
92.25 6
76.5 77
85.5
94.25
92.75 7
83.25
90.75
89.75 8
74.75
79.5 80
66.75
84.5
81.5 82
Average
76.34
78.69
75.53
77.88
80.78
89.22
90.13
87.03
88.94
88.19
89.84
Difference
2.35
2.47
0.91
1.91
1.65

8. 10 and 12 day average germination percent

9. Discussion
Overall, the average difference of the six samples and 8 labs was 1.94% between the 10 day and 12 day final counts.
A nearly 2% difference shows that onion germination may not be reaching the maximum potential on the 10 day count.
The evidence supports the idea of harmonizing with ISTA in using the 12 day final count for onions.

10. In-house Data
Onion samples received at Ransom Seed Laboratory from three different seed companies were used to compare 10 and 12 day final counts.
The following table summarizes the results.

11. % Germination of onion samples
10 day
12 day
Difference
2687 92 93 1
2518
80.5
81.5
2519 77 78
2523
85.33
85.67
0.5
2524
89.5 91
1.5
2525
82.75
87.75 5
2527
78.75 82
3.25
2528
89.75
1.25
2530
86.25
86.75
2531
87.67
88.67
3206
84.25
84.75
3219
84.5
85.75
3220
79.5
80.75
2497
35.67
52.33
16.67
Average
80.96
83.49
2.53

12. Discussion, cont.
This in-house data shows an average of 2.53% additional germination by adding the two days to the final count.
These results further support the extension of onion final counts to 12 days and harmonizing with ISTA.

13. Thanks to participating laboratories
AgriSeed Testing
Crookham Company
Eurofins BioDiagnostics
Incotec
MD Seed Analysis
Ransom Seed Lab
Sakata Seed Company
SGS Brookings

14. Special thanks to Sakata Seed Company for providing and preparing the samples.
Questions?
Contact:
Sue Alvarez
Linda Barbosa