Mass Production Alternatives for Fast-Growing Spruce Hybrids

A reciprocal crossing program of Picea glauca and P. omorika, and P. mariana and P. omorika with adequate intraspecific control crosses was carried out. Yields of full seed/cone ranged from 0 to 2.6 for the P. glauca-P. omorika combination. These low seed sets and a-9-day difference in female receptivity rule out producing this hybrid via seed. The full seed/cone yields of the P. mariana-P. omorika combinations averaged approximately half the yield of the intraspecific crosses. However, receptivity of the two species is well synchronized and in spite of reduced yields, mass production via seed is a practical option. A seed orchard design is outlined and a 4-acre grafted orchard may produce at least 75,000 plantable seedlings on 6- to 8-year-old grafts. Results of a rooting trial of selected hybrid seedlings are described. A practical mass production program for the P. glauca-P. omorika combination based on rooted cuttings-is described. The program would be based on juvenile selection among 4-year-old seedlings, cloning, and the simultaneous establishment of clonal trials and hedges. The hedges would be a source of cuttings for future mass production--a hedge 400 feet long by 5 feet high would produce a minimum of 20,000 cuttings annually.

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Author(s): Hans Nienstaedt

Publication: Tree Improvement and Genetics - Lake States Forest Tree Improvement Conference - 1977