ELITE AND SUPER ELITE SITKA SPRUCE:
2007 UPDATE


Some of the earliest plantings of Improved Stock (at Kersehope) have now been felled by the FC Research Branch to assess the actual results in terms of volume outturn and timber quality. In summary the overall volume increased by about 30% as compared to QCI with about 40% more green logs. There was no reduction in the percentage of timber passing C16 or C24 despite the fact that the Improved SS then available had not been screened for density.

Based on these results the material currently available by veg prop will give at least 20% more volume without loss of density and an 80% increase in the proportion of green logs.

Introduction: All forms of genetically improved Sitka Spruce are drawn from the same General Breeding Population of 240 genetically superior individuals. The Forestry Commission has determined their superiority by progeny testing crosses from over 1800 plus trees selected from stands of QCI throughout the UK in the 1960's. (Lee 1999).

Planting stock: At present, genetically improved Sitka Spruce planting stock is either raised from seed collected in a seed orchard or propagated from cuttings taken from young mother plants. Seed-based stock (Elite Sitka) is less labour intensive to produce and is consequently cheaper to buy. Vegetatively propagated plants (SuperElite Sitka) start as tip cuttings 8-10 cm long taken by hand from mother plants in February. They are 'struck' in modular cells in a misted polytunnel and form a root system by late July. They are then transplanted into the field in late August. It is the cost of creating these rooted cuttings which makes SuperElite Sitka more expensive than the seed-based Elite stock. However, by way of compensation, Super Elite stock has a superior genotype and appears to establish more quickly.
Genetic Gain:Because seed orchards take 10 to 15 years to produce commercial quantities of seed their level of genetic improvement lags behind that available from vegetatively propagated stock. For example our 2007/08 crop of A12 Elite 2+1 transplants has a predicted genetic gain of 19 per cent in diameter and 8 per cent in form relative to unimproved stock from the Queen Charlotte Islands although there is an 11% loss in timber density.

By comparison, our current crops of '20:20' (+20% volume, +20% form, -0% density) SuperElite transplants have expected gains of 22 per cent in diameter and 18 per cent in form with no loss of timber density.

Brian McCamon (Nursery Manager)
inspecting Super Elite Sitka


Establishment gains. For many years now customers have reported that vegetatively propagated planting stock establishes more quickly than seed-based plants with lower consequent weeding costs. We have always attributed this to the relative youthfulness of SuperElite stock and their compact, fibrous root systems which are lifted with less damage and loss than seed-based transplants. Hannerz (1999) writing on veg-prop Norway Spruce agrees and also reports improved resistance to damage by spring frosts and weevils.

Lee, S. 1999. Predicted gains from Sitka spruce production populations. FC Info note 26.

Hannerz, M. 1999. Cuttings- a superior plant type. Skogforst News No 1 .

For more information contact us via E-mail us or call one of our Staff.

Links to Catalogue Field Grown Conifers Cell Grown Conifers
Christie Elite Nurseries Ltd. Forres, Moray, IV36 3TW, Scotland

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