Research note

The Genetic Control of Ring Width, Wood Density and Tracheid Length in the Juvenile Core of Pinus patula

Published in: South African Forestry Journal
Volume 169, issue 1, 1994, pages: 15–20
DOI: 10.1080/00382167.1994.9629661
Author(s): R.D. BarnesForest Research Centre, Zimbabwe, J.S. Birks, United Kingdom, G. BattleForest Research Centre, Zimbabwe, L.J. MullinForest Research Centre, Zimbabwe

Abstract

Controlled crosses were made between six Pinus patula Schiede & Deppe plus trees selected in plantations. Six full-sib families and two commercial checks were planted in randomised complete block thrice-replicated progeny tests at two sites in Zimbabwe. At 7,5 years, the tests were thinned and sample discs taken at breast height from six trees per plot. Ring width, basic density and tracheid lengths were assessed for each of rings 1 to 6, corresponding to years 2 to 7. All three traits were found to be under genetic control and the differences between the treatments were best expressed in the fourth year and on the harshest site. Genotype-environment interaction effects were absent for basic density and ring width but were pronounced for tracheid length. Juvenile-mature correlations were high for all three traits. Basic density was negatively correlated with ring width and tracheid length but ring width and tracheid length also tended to be inversely related. One generation of selection for various external morphological traits and productivity increased growth rate in the progeny and produced indirect responses of lower density and higher tracheid length.

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