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Title: Age trends in Douglas-fir genetic parameters and implications for optimum selection age.

Author: Johnson, G.R.; Sniezko, R.A.; Mandel, N.L.;

Date: 1997

Source: Silvae Genetica. 46: 349-358.

Publication Series: Scientific Journal (JRNL)

Description: rends in genetic variation were examined over 51 progeny test sites throughout western Oregon. Narrow sense heritabilities for height and diameter showed an increasing trend to age 25, the oldest age examined. Before age 10, height heritabilities were relatively unstable. Type B site-site genetic correlations increased slowly with age for height and remained relatively stable for diameter. Age-age correlations by using the log of the age ratios (LAR). Optimum selection age was calculated for a 60-year rotation by using two measures of efficiency: gain per year and discounted gain. the optimum selection age for height tended to be 2 to 3 years earlier than for diameter. Gain per year was maximized at age 10 for height and age 13 for diameter.

Keywords: heritability, age-age correlations, Type B genetic correlation, gain efficiency, Pseudotsuga menziesii (MIRB.) FRANCO

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Johnson, G.R.; Sniezko, R.A.; Mandel, N.L. 1997. Age trends in Douglas-fir genetic parameters and implications for optimum selection age. Silvae Genetica. 46: 349-358.


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