Results after 19 years of testing in a Pinus strobus x P. wallichiana F1 hybrid population

• Main Authors: I. Blada, F. Popescu
• Format: Article
• Language: English
• Published: ‘Marin Drăcea’ National Research-Development Institute in Forestry 2013-12-01
• Series: Annals of Forest Research
• Subjects: pinus strobus, p. wallichiana, hybrid, cronartium ribicola, heterosis, additive variance, heritability, genetic correlation, genetic gain
• Online Access: https://www.afrjournal.org/index.php/afr/article/view/161
• ISSN: 1844-8135; 2065-2445

<p>Full-sib families were generated from a factorial design between seven female trees of P. strobus and four male trees of P. wallichiana to combine the rapid growth of former species with high resistance to blisterrust (Cronartium ribicola) of the latter one. At age two the hybrid families were artificially inoculated with blister-rust and at age six they<br />were field planted. Total height growth, diameter at 1.3 m, basal area, stem volume, stem straightness and tree survival were measured<br />at age 19 after planting. Significant (p&lt;0.05) and highly significant (p&lt;0.01; p&lt;0.001) differences among female effects were found for all tested traits including survival suggesting that nuclear additive genes<br />controlled these traits. Male effects were significant only for stem straightness. In all but one trait the σ2GCA: σ2SCA and σ2GCA-F : σ2GCA-M ratios were in favour of additive variance suggesting<br />that this variance should be used in the breeding strategy. Narrow-sense heritability at family level was 0.778 for volume growth rate<br />and 0.861 for survival; such high values indicate that the breeding programme, has good chances of success. Two of the 11 tested parents<br />exhibited significant positive g.c.a. effects for survival after heavy blister-rust inoculation. One parent exhibited highly significant<br />positive g.c.a. effects for volume growth rate. The three good general combiners should be taken into account in the breeding programme.<br />Estimate of the high-parent heterosis was negative for the volume but positive for survival. For volume, the hybrid mean was 5.9% lower<br />than the mean of the eastern white pine but 85.4% greater than blue pine bulk lot for survival. Estimate of low-parent heterosis for survival<br />was also positive; i. e. the hybrid population mean was 537.5% greater than eastern white pine. If the hybrids will be used in operational<br />planting programs, a variable genetic gain between 6.0 and 10.5% for volume and between 6.8 and 9.6% for survival could be<br />achieved.</p>