Germination changes in Picea abies seeds at water-based pretreatments.

摘要

Water-based pretreatments are used to reduce the great variety in germination parameters of conifer seeds. However, treatment results of Norway spruce seeds are frequently unsatisfactory. The aim of this work was to study changes in the germination parameters of spruce seeds during the multiphased pretreatment chain and the impact of seed structures on these changes. Furthermore we studied the effect of storage on germination indices of pretreated spruce seeds. Seeds were extracted using the ordinary method by sprinkling water on the cones or restricting that amount of water sprinkled on the cones. Cleaned and dried seeds were stored at -3 degrees C for three months prior to IDS-treatment. The changes in germination parameters were studied using germination tests and radiography. Seed structures were observed using SEM. In general germination parameters of seed lots increased during the pretreatment chain despite the opening of the seed coat, which occurred in fungi-infected seeds already at the extraction phase. The seed coat usually opened from the micropyle almost as far as the edge of the nucellar cap. The IDS-treatment succeeded well, and the germination parameters in the best fractions were 13-28% better than in the seed batches prior to IDS-treatment. The germination indices remained nearly unchanged during one year's storage at -18 degrees C. This indicates that the large nucellar cap typical for spruce seeds protected the megagametophyte and the embryo during pretreatment phases and short-term storage. The results also pointed out how pretreatments should be improved to get them better adapted for spruce seeds.