Research Branch

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Protocols for rating seed orchard seedlots in British Columbia

Author(s) or contact(s): J.H. Woods, M.U. Stoehr, and J.E. Webber
Source: Research Branch
Subject: Seeds and Pollen
Series: Research Report
Other details:  Published 1996. Hardcopy is available.


Seed genetic quality affects reforestation success and plantation value. This is recognized in the Silviculture Practices Regulations of the Forest Practices Code Act of British Columbia, which require that available seed sources of the highest genetic quality be used to reforest Crown land. This report describes procedures for rating the genetic quality of seed orchard seedlots.

The genetic quality of a seedlot encompasses its genetic worth, adaptation to the target zone, and genetic diversity. Adaptability and diversity are considered during orchard design, and must meet minimum standards. These standards must be set out in the orchard working plan and approved as part of the orchard licensing procedure. Genetic worth is a function of the proportional gametic contribution of individual clones in the seed orchard and of the supplemental pollen used.

Different seed orchards require different levels of monitoring and control to produce seedlots of high genetic quality. A system for categorizing orchards based on orchard genetic potential, pollen contamination risk, and the genetic quality of contaminant pollen is presented. Protocols are provided to collect information about clonal gametic contributions, contaminant pollen, phenology of orchard receptivity, start of orchard pollen shed, and effectiveness of supplemental mass pollination. These protocols include formulae for estimating seedlot genetic worth, percent contamination, and effective population size. A method for estimating genetic quality attributes for controlled-cross seedlots is also presented.

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Updated October 24, 2008