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

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.

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.

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.

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.

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.

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

10 and 12 day average germination percent

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.

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.

% 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

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.

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

Special thanks to Sakata Seed Company for providing and preparing the samples. Questions? Contact: Sue Alvarez SueRSL@silcom.com Linda Barbosa lbarbosa@sakata.com