Eucalyptus Tree Improvement Empowers Small And Medium-Scale Growers

“To respond to changes in market- and climatic conditions… relies on strong, well-managed tree improvement programmes with clear goals and objectives”

THE OWNERSHIP of forest plantations in South Africa (SA) is diverse, ranging from large corporates to small- and medium-scale growers managing anywhere from a single hectare to hundreds of hectares. Small- and medium-scale growers collectively manage approximately 20% of SA’s forestry land (Godsmark and Oberholzer 2019) and their share is expected to grow as the country continues to redress past inequalities. With a significant area managed, small- and medium-scale growers are undoubtedly vital contributors to the Forestry Industry’s role as a supplier of renewable raw material, an employer and driver of rural development.

To respond to changes in marketand climatic conditions, the emergence of new pests and diseases and to remain globally competitive as a sector, there is a need to plant genetic material that is adaptable, versatile (can serve multiple markets), tolerant to pests and pathogens and capable of producing maximum volumes of high-quality timber. Achieving this relies on strong, well-managed tree improvement programmes with clear goals and objectives. However, tree improvement requires substantial financial investment and technical expertise, resources that small- and medium-scale growers often lack access to or cannot afford.

THE HYBRID CLONE CONSORTIUM (HCC)

The Hybrid Clone Consortium (HCC), in collaboration with the Institute for Commercial Forestry Research (ICFR), develops and deploys improved genetic material primarily to benefit small- and medium-scale growers. HCC is a non-profit organization funded by NCT Forestry Agricultural CoOperative Limited (NCT), TWK Agri and private commercial nurseries including Sunshine Seedlings, Ezigro Seedlings, CPS Seedlings and Sutherland Seedlings. The ICFR manages the base tree breeding programme. They are responsible for controlled pollination, the development of hybrid seed and the establishment of progeny trials.

From the ICFR progeny trials, top-performing hybrids – selected based on tree volume, form and pest and disease tolerance – are taken as cuttings for further evaluation in a hybrid clonal programme managed by HCC. Clonal forestry allows the genetics of these high-performing individuals to be multiplied and tested across multiple sites to confirm their performance and adaptability. The development, testing and deployment of hybrid clones offer numerous benefits, such as the opportunity to capture the superior traits of both parent species. For example, E. grandis × E. smithii combines the excellent wood properties of E. smithii with the Phytophthora tolerance of E. grandis.

The hybrid clones are first tested in line trials planted across variable site conditions to assess and rank their  performance (Figure 1). Line trials enable the testing of a large number of individuals within a single trial. Tree growth, wood properties, stem form and pest and disease tolerance are assessed periodically. At four years, data from all sites are combined and statistically analysed to identify individuals whose performance matches or exceeds that of the current commercial hybrid clones and seedlings.

The selected individuals (from line trials) are then planted in block trials (Figure 2), which more accurately represent commercial plantations where each clone competes with trees of the same genetics. Small- and medium-scale growers often collaborate with HCC during this stage by hosting block trials on their land and managing the  trials until rotation-end (in terms of the execution of silvicultural treatments and fire protection). Tree performance is periodically evaluated as in the line trials. At a predetermined age, a combined-site statistical analysis of the block trial data is conducted to identify clones that significantly outperform the current commercial material. Clones with superior growth, desirable wood properties and tolerance to pests and diseases, are then approved for commercial release. Propagation rights for these elite clones are granted to private commercial nurseries within the HCC, ensuring that the improved material is accessible not only to small- and medium-scale growers but to the broader SA forestry industry.

This collaboration and programme has already led to numerous successes, such as the development of various clones of E. grandis x E. urophylla, e.g. GU 400 and GU 412 which were both some of the few clones tolerant to Leptocybe invasa at the height of severe Leptocybe infestations, the deployment of GN 2107, the most widely planted E. grandis x E. nitens clone by the SA Forestry Industry, deployment of SU 107 (a E. saligna x E. urophylla clone with exceptional wood properties accepted in sawtimber, pole and pulpwood markets) and recently the deployment of three new E. grandis x E. nitens clones (GN 311, GN 350 and GN 389) which will improve yields in E. grandis x E. nitens plantings and offer diverse genetics and GS 211 (new E. grandis x E. smithii clonal hybrid).

THE E. SMITHII TREE IMPROVEMENT PROGRAMME

NCT also collaborates with Sappi in an E. smithii tree improvement programme, focusing on selecting high-yielding families for establishment in seed orchards, reducing self- pollination/selffertilisation in E. smithii orchards to improve seed quality and identifying genetic sources tolerant to Phytophthora spp. The improved seed sources that are developed in this programme are then propagated by Sunshine Seedlings, Ezigro Seedlings, Sutherland Seedlings and CPS Seedlings and made available to small- and medium-scale growers.

“This collaboration and programme has already led to numerous successes”

CONCLUSION
Collaboration in tree improvement bridges the gap for small- and medium-scale growers, giving them access to superior genetic material that enhances yields, sustains profitability and keeps forestry a viable livelihood. These partnerships not only strengthen the growers’ businesses but also contribute to the growth of rural economies and the communities that depend on them.

“These partnerships not only strengthen the growers’ businesses but also contribute to the growth of rural economies and the communities that depend on them”

Written By: Dr Noxolo Ndlovu (NCT Forestry Agricultural Co-Operative Limited)

Source: Tip-Mag

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