CHANGES IN DORMANCY AND VIGOR OF PICEA-ABIES SEEDS DURING OVERWINTERING AND DRY STORAGE

The changes of dormancy and vigor during natural overwintering and dur ing simultaneous dry storage were studied using Norway spruce (Picea a bies (L.) Karat.) seeds from individual trees. Dormancy was evaluated by studying germination response to light and moist chilling at 12 and 21 degrees C. A dormancy reducing germination at 12 degrees C in dark ness was induced in seed during overwintering and during 5 months of s torage at 6% moisture content and 5 degrees C. Light released that dor mancy effectively. Moist chilling was unable to substitute for Light i n most seeds. Simultaneously with induction of light requirement, the seeds ripened during overwintering (either via dormancy relief or invi goration), as indicted by the increased germination rate at 12 degrees C in light and by the disappearance of the negative chilling effects. Moist chilling decreased germination time as much or more in seeds co llected in winter than in autumn-collected seeds, in which the chillin g effect was small or negative. No evidence on dry afterripening in st orage was found. According to leachate conductivity and accelerated ag ing tests, the effect of overwintering on seed vigor was either insign ificant or negative. The results are useful in developing proper pretr eatment and management procedures for seeds used for seedling producti on or direct seeding.