Heartwood production in a 35-year-old black walnut progeny test
2002
Woeste, K.E.
A 35-year-old black walnut (Juglans nigra L.) progeny test was evaluated for growth and production of heartwood. The test trees, which were open-pollinated progeny of select females in seven states, were planted on a good-quality, uniform site in Wabash County, central Indiana, U.S.A. Increment cores were used to estimate the amount of heartwood at 1.3 m above ground level. There were significant differences among open-pollinated families (alpha = 0.10) for both area of heartwood and percent area of heartwood. Narrow-sense heritability estimates for these traits were moderate (0.40 and 0.27), indicating opportunity for gain from selection. Faster growing trees had more heartwood and a higher percentage of heartwood area in cross section. Genetic correlations indicated that the rate and amount of heartwood formation is closely related to diameter growth.
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