Oilseed rape is a new, but rapidly expanding, crop in Iran. Use of seed stored for more than one year and limited seed testing services have led to emergence problems. Tests of physiological germination (radicle emergence) are sometimes used as an assessment of seed quality and are the topic of this investigation. The physiological germinations of 20 seed lots of oilseed rape stored over several years and tested at 8, 10, 13 and 20°C, were maintained at a high level except at 8°C. Older seeds from earlier years produced significantly fewer normal seedlings (higher abnormals). The mean germination time (MGT; the reciprocal of rate of germination) of the lots was highly and negatively correlated with the percentage of normal seedlings produced at all temperatures, the slower the germination the fewer the normal seedlings, that is, the more abnormals. Close relationships of percentage normal seedlings with MGT and early counts of physiological germination at 10, 13 and 20°C suggested a potential quick method of estimating the percentage of normal seedlings. The relative differences in the MGTs of the lots were maintained at all temperatures although the slower germinating lots were particularly slow at 8 and 10°C. MGT is also the mean lag period between the start of imbibition and radicle emergence. Longer lag periods may be needed for older seeds to repair deterioration before physiological germination can be achieved. We suggest that an increase in abnormals in older seed results from incomplete repair.

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