Estimates of genetic parameters and genetic gains for growth traits of two Eucalyptus urophylla populations in Zululand, South Africa. Issue 3 (2nd July 2016)

• Record Type: Journal Article
• Authors: van den Berg, Gert J; Verryn, Steven D; Chirwa, Paxie W; van Deventer, Francois
• Is Part Of: Southern forests. Volume 78:Issue 3(2016)
• Page Start: 209
• Page End: 216
• Publication Date: 2016-07-02
• Subjects: Eucalyptus urophylla -- genetic correlations -- genetic gains -- genetic parameters; Forests and forestry -- Southern Hemisphere -- Periodicals; Forests and forestry -- Periodicals; 634.9091814
• DOI: 10.2989/20702620.2016.1162616
• Languages: English
• ISSNs: 2070-2620

Abstract

Abstract : In South Africa, Eucalyptus urophylla is an important species due to its disease tolerance to fungal diseases such as Crysoporthe austroafricana and the Coniothyrium sp. cankers. It is mainly planted as a parental species in a hybrid combination with E. grandis . Generally, the E. grandis × E. urophylla hybrid has better disease tolerance and higher wood density than pure E. grandis . The current strategy is to maintain large breeding populations of both parental species in order to provide improved elite selections for hybrid crosses on a regular basis. With this in mind, two E. urophylla populations, consisting of five provenance/progeny trials, were established in the subtropical region of Zululand. The aims of this study were, firstly, to determine the magnitude of genotype × environment interaction of E. urophylla in Zululand; secondly, to estimate genetic parameters and correlations for diameter at breast height (DBH), height and volume; and thirdly, to identify selections to advance the current breeding population as well as to hybridise with E. grandis . Results indicated that genotype × environment interaction effects would be practically negligible for growth in Zululand and therefore a single breeding population will be appropriate. In general, all growth traits were under low to moderate genetic control, with narrow-sense heritabilities ranging between 0.14 and 0.48 for volume. The genetic correlations between growth traits were high (0.98 and 0.99 for DBH– volume). This is an indication that DBH is a sufficient growth measure to use in E. urophylla breeding programmes. Best linear unbiased prediction estimates indicated that aa selection scenario of 200 individuals will generate genetic gains of 44.7% over the population mean. The estimated gains for the top 50 individuals that could potentially be used as hybrid parents to cross with E. grandis was 59.8% over the population mean.