32 SEED TESTING INTERNATIONAL www.seedtest.org RULES DEVELOPMENT • Discussion and Conclusion The cold test consisting of 7 d at 10 °C and 5 d at 25 °C clearly identified the same seed lots as high or low vigour in six laboratories from four coun- tries. The repeatability and reproducibility of the cold test for maize shown in this comparative test indicate that a cold test carried out at 10 °C for 7 d followed by 5 d at 25 °C using sand can be applied as a vigour test for this species. Germination tol- erance tables could be used to check outliers. Cold test results were consistent with field emergence results as previously obtained in Italy, where more seed lots were used to obtain signif- icant correlations with the same method of 7 d at 10 °C in sand (Noli et al., 2008). Factors influencing cold test results have been described in literature. Former comparative tests have shown that CT in sand presented fewer outliers than CT in soil, and that the method was less variable between different regions in the world than between different laboratories from the same region, especially for in-house methods (Nijenstein and Kruse, 2000). Even though it would have been preferable to use more than three seed lots in some field trials, the differences between three lots were very clear, in both their CT result and their field emergence percentage in all three locations (Arras, Chappe and Saint Mathurin sur Loire). In addition, the same lots emerged well, or poorly in each location. The CT also clearly identified differences in seed lot performance in the better conditions of Haut-Mauco. Thus, the test can identify possible differences in emergence in a wide range of environments. Acknowledgements We gratefully acknowledge Jean-Louis Laffont (ISTA Statistics Committee) for his great input in statistical analysis and Cassandre Chupeau (GEVES) for her helpful analyses on pluriannual data using R. We are grateful to Kirk Remund, Michael Kruse and Takayuki Okuda for reviewing the test plan and validation report. We also warmly thank all participants to the comparative tests in 2023 and 2024, namely: Nelly Boinot, Thierry Brunel, Catherine Champion, Erik van Egmond, Dorothée Jouany, Carey Matthiessen, Enrico Noli, Sandrine Pierre, Sandrine Stievenard and Raphaël Suaud. We thank Limagrain and Mas Seeds for providing seed lots and carrying out field trials. A special thanks to the ISTA Vigour Committee who improved the validation report with many comments and constructive support, especially to the former Chair Alison Powell, who did great revisions through the review process. References 1. ISTA (2025). International Rules for Seed Testing. International Seed Testing Association, Wallisellen, Switzerland. 2. Nijenstein, J.H. and Kruse, M. (2000). The potential for standardisation in cold testing of maize (Zea mays L.). Seed Science and Technology, 28, 837–851. 3. Noli, E., Casarini, E., Urso, G. and Conti, S. (2008). Suitability of three vigour test procedures to predict field performance of maize seed in early sowing. Seed Science and Technology, 36, 168–176. Method p_avg s_Lab s_Lot × Lab s_r f_r s_R Excluded samples % f_R f_Miles 7 d @ 10 °C + 5 d @ 25 °C in sand moistened at 14% 86 0 1.57 4.32 0.89 2.67 0 1.1 1.66 Table 4. Repeatability/reproducibility estimates using linear mixed model Figure 4. Mean cold test results per laboratory for six maize seed lots
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