Improved germination conditions for Norway spruce somatic cotyledonary embryos increased survival and height growth of emblings
2018
Tikkinen, Mikko | Varis, Saila | Peltola, Heli | Aronen, Tuija
Norway spruce is one of the most cultivated tree species in Nordic countries. However, intermittent shortages of improved seeds occur. As a powerful vegetative propagation technology, somatic embryogenesis (SE) could provide an alternative solution for this problem and also shorten the time required to obtain breeding gains. However, there are still large bottlenecks in SE, e.g. in the germination and acclimatization phases, which greatly affect the final outcome of somatic embryo plants (emblings). In this work, we examined the effects of in vitro embryo storage and germination treatments and ex vitro growing techniques on the survival and growth of emblings. The study comprised 32 genotypes from 18 full-sib families in four experiments, testing two different cold storage methods, three durations of in vitro germination, lower inorganic nitrogen content in the germination medium, and two plant-growing techniques. The best treatment combination—cold storage on filter paper, lower nitrogen content in the germination medium and one-week in vitro germination—resulted in an 88% higher survival and 28% higher growth compared to the poorest, reference treatment in the same test year. These emblings could be planted after a nursery period one year sooner than that of the control emblings. The results indicate that Norway spruce emblings germinated for one week in vitro can be transplanted and grown in nurseries without any additional treatments or environmental control differing from seedlings, which is a prerequisite to reach standards for forest regeneration material.
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