Wennstrom U, Bergsten U, Nilsson JE
Early seedling growth of Pinus sylvestris after sowing with a mixture of stand and orchard seed in dense spacings
Canadian Journal of Forest Research-Revue Canadienne De Recherche Forestiere: 2001 31:1184-1194
Effects on early seedling growth of seeding stand and orchard seed of Pinus sylvestris L. in different mixtures (100, 75, 50, 25, and 0% of orchard seed) at 4-cm target spacing were quantified in one nursery and one field experiment during a 2- and 5-year period, respectively. In the field experiment, 50% mixtures at 8- and 12-cm target spacing were also studied. Seedlings from orchard seeds (OS) had in general higher growth rate than seedlings from stand seed (SS). In the nursery experiment, OS were 25% taller, had 41% larger above-soil biomass, and 18% larger root biomass than SS after 2 years when sown separately. However, root/shoot ratio was 26% less and the slenderness value (height/diameter ratio) was 11% greater for OS in comparison with SS. Stand seed in high competition, compared with low competition (mixture 75% vs. mixture 0%), were 11% taller, had 15% greater slenderness value, and 25% less root biomass after 2 years. OS had 9% greater slender value in mixture 100% compared with the 25% mixture. In the field experiment, the tallest OS in each plot were 22% taller and the largest OS had 103% larger stem volume than the tallest or largest SS when sown separately after 5 years. After a height-selection thinning to one seedling per plot at year five, 79% of the seedlings in 50% mixtures would be OS. Seedlings sown in 12-cm spacing were 69% taller and had 527% larger stem volume than seedlings in 4-cm spacing after 5 years. The investigation supports that orchard and stand seed could be direct seeded in a mixture. Low dosages of the more expensive orchard seeds could be used to obtain growth advantages. Stand seeds should be added to increase the number of seedlings to the desired spacing.
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