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The objective of this work was to develop a methodology for standardizing the Accelerated Aging test (AA) for J. nigra seeds. After different aging treatments, seeds were subjected to the standard germination test the results of which were expressed as the percentage of normal seedlings. Germination velocity index and mean time of maximum germination were also determined. Our results showed that storage at high temperature and relative humidity deteriorates black walnut seeds to the extent that their germination capacity is lost in only seven days. Bigger seeds had a higher percentage of normal seedlings and vigor, both under favorable storage conditions and when subjected to accelerated aging treatments. This work has clearly shown that vigor of J. nigra seeds should be assessed using AA periods no longer than 72 h. The most frequent abnormality observed in AA testing was seedlings with stubby roots and no secondary roots. [ABSTRACT FROM AUTHOR]

The objective of this work was to quantify changes in the germination capacity ofJuglans nigraseeds following storage and then artificial stratification. Seeds were stored at 5 and –20 °C under 5% and 14% internal moisture content (IMC) for 0, 8, 10, and 12 months under conditions with oxygen or under vacuum. Germination percentage (GP) was affected by storage temperature, IMC, and storage period. Seeds stored with 5% IMC succeeded in germinating regardless of the temperature. Seeds stored with 14% IMC did not germinate (–20 °C) or germinated during storage (5 °C). The GP was reduced with the time of storage in seeds at –20 °C and 5% IMC and this effect was avoided in storage under vacuum. In conclusion, the germination capacity of black walnut seeds did not change for up to 12 months at low above-zero temperature and low IMC (5 °C, 5% IMC), being the most cost-effective alternative for long-term storage of black walnut seeds in commercial nurseries. Vacuum storage avoided the decrease of around 50% in average germination capacity of seeds stored for a year at –20 °C. [ABSTRACT FROM PUBLISHER]