Seed Provenance and Substrate as Significant Factors on Picea abies (L.) Karst. Production

Picea abies (L. ) Karst. is commonly cultivated in Italy for sale as Christmas trees. Experiments were carried out to investigate the emergence and growth of three seed provenances of Picea to different levels of organic material. Mature seeds were collected from forests enrolled in the ”Libro Nazionale Boschi da Seme” (L.N.B.S.). Three certified seed provenances “Gran Bosco di Salbertrand”, “Pezzel e Fochino”, and “Val di Fiemme” were studied. The collected seeds were subjected to chilling treatment (4°C for 21 days), then were sown on benches in greenhouse. Two levels of organic material (manure) were used to achieve a total organic C content of 6.26% for substrate 1 and 9.82% for substrate 2. After 12 weeks, the seedlings were transferred in pots and placed in a shaded (50% light reduction) outdoors for one year. The seedling growth performance was significantly influenced by provenances and substrates (P<0.05). The interactions between substrate and provenance were evident 15 days after sowing. “Val di Fiemme” showed a better growth performance than the other ones, 91% and 47% of seedling emergence for substrate 1 and substrate 2, respectively. On the other hand, “Pezzel e Fochino” displayed the worst performance, 25% and 20% on the respective substrates. Furthermore, seedling growth was favoured by a lower organic material in medium (substrate 1). In fact, the stem height of seedlings ranged from 2.4 to 4.2 cm on substrate 1, and from 2.1 to 3.2 cm on substrate 2. “Val di Fiemme” seedlings showed the highest stem height 3.7 and 3.2 cm for substrate 1 and substrate 2, respectively, and this provenance appeared to be more resistant to pathogens. “Pezzel e Fochino” seedlings exhibited the lowest growth on both substrates while “Gran Bosco di Salbertrand” showed a growth of 4.3 cm and 2.6 cm on substrate 1 and 2, respectively. Among provenances, seedlings grown in pots exhibited differences in early growth, fresh and dry weights. “Gran Bosco di Salbertrand” and “Pezzel e Fochino” seedlings reached stem heights of 14.7 and 13.8 cm, respectively, whereas, “Val di Fiemme” attained a height of only 10 cm. However, the biomass values were similar in spite of the linear growth differences. The results demonstrated that both provenance and level of organic C in the substrate are significant factors for a large-scale production of Picea as Christmas trees.