Variation in adaptation and growth among Corymbia citriodora natural-stand and landrace seed sources in southern China

ABSTRACT

Corymbia citriodora subsp. citriodora has a long history of cultivation as a multipurpose tree in China and many other countries in Southeast and South Asia. Despite this history and longstanding interest in the species, published studies examining genetic variation among and/or within provenances/seed sources are scarce. Recognising this and to initiate an improvement program for this species, a field trial was established in southern coastal China in 2015 with 171 open-pollinated single mother-tree family seedlots representing five natural-stand seed sources in Australia and six planted seed sources in China. Large significant variation was found among seed sources for pest and disease resistance, survival, growth and stem form up to age 81 months. Australian seed sources were generally superior to Chinese ones for most traits. Phenotypic correlations among traits, at both the individual tree and seed-source mean levels, were favourable, with the strongest individual tree correlations found between disease susceptibility at 10 months and various tree growth traits. Overall, the variation observed in this field trial indicates the potential gains in this species from seed-source selection and ongoing breeding.

KEYWORDS:

• provenance variation
• selection
• pest and disease resistance

Acknowledgement

We are also grateful to an anonymous reviewer and this journal’s editors for their useful, critical comments that helped significantly improve this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors thank the Chinese Academy of Forestry’s Research Institute of Fast-growing Trees (formerly called the China Eucalypt Research Centre) for supporting the long-term Corymbia citriodora tree improvement program. Financial support for part of this improvement was also provided by the Science and Technology Innovation Program of the Forestry Administration of Guangdong Province [Grant No. 2021KJCX019]; the National Key R&D Program of China for the 14th Five-year Plan [2022YFD2200203]; and a key research project from Zhanjiang University of Science and Technology [CJKY201902].