APRIL has established the world’s first clonal plantation of Acacia crassicarpa trees in commercial forestry, a scientific milestone that represents the culmination of two decades of work. This development allows for far greater genetic consistency and significant increases in productivity.
With an increasing proportion of the company’s plantation concession areas planted with trees from the clonal programme, APRIL expects a further boost in the volume of fibre harvested per hectare. This will enable the production of more consumer products like paper, paperboard packaging and textile from the same plantation footprint on a sustainable basis.
The method, known as “clonal plantations”, relies on the most used plant propagation technique of growing new plants from cuttings. It also involves matching the right trees to the right sites, involving a deep understanding of genetic x environmental interaction of Acacia crassicarpa, while combining state-of-the-art tissue culture techniques and modern methods of plant breeding, such as genomic selection.
What is a cloned plant?
Unlike a seed, which results from the pollen grain germinating on the stigma and fertilising the ovary of a flower, a clone is a genetically identical copy of a plant, produced through asexual reproduction methods like cuttings, grafting, or tissue culture.
Both forms of propagation, seed and cuttings, have their advantages. Sexual reproduction mixes up the genes present in each parent to create new genetic combinations that could have desirable traits, such as resistance to a new fungal pest or better wood properties.
Clonal propagation from cuttings provides genetic uniformity, preserves desirable traits, ensuring uniformity and consistency in growth, yield, and quality across multiple plants, said Muhammad Yuliarto, Deputy Program Leader of APRIL’s Acacia Tree Improvement Program, which means a more uniform plantation and eventual product. “They react in a similar way to pests; have similar stem form; similar growth rates and wood properties,” he added.
The uniformity in a clonal plantation offers a considerable advantage, as raising plants of a single genotype in the nursery, along with managing and harvesting uniform forests, is likely easier. Making use of this uniformity, the harvested logs are of consistent length and thickness, therefore transportation can be more efficient too, allowing optimised truck loads to the mill.
APRIL’s research teams use plant breeding techniques to combine the best genetic traits from mother and father plants and can then fix those desirable genetic combinations by establishing a clonal line. None of these improvements requires genetic modification, a technology that APRIL does not deploy at any of its labs.
Field testing of the clones began in 2017 in the Clonal Field Test (CFT) trial-series for the first screening of the clonal development pipeline. Selections from the CFTs are propagated and planted in Clonal Site Interaction (CSI) trial-series on different sites around APRIL’s estates. These growing sites that differ in characteristics like peat type, elevation and propensity for high water table or flooding, wind exposure and salinity, act as environmental screening to test the adaptability of the clones to various growing zones.
Optimal growth
After three to four years, the researchers develop assessments and identify which clones grew best in which sites. The clones continue the development pipeline to intensive pre-deployment trial-series at different representative sites with several hectares each. At each site, they apply varied growing practices, such as how to space the seedlings between and in the rows, and how much fertiliser to apply.
The aim is to optimise the silviculture practices for each clone for best possible growth. Plant failures are inherent all the way through the process, with not well adapted trees removed in favor of the most productive clones. Tree breeders monitor the selection intensity, often starting in 10,000 initial selected trees, but ultimately resulting in only one or two successfully commercialised clone.
The role of APRIL’s Tissue Culture Lab for Acacia crassicarpa is to produce plantlets that will be used in the central nursery as mother plants (MPs). The MPs are trained in the nursery for shoot production, which are then harvested to produce plants for operational planting.
APRIL has established a state-of-the-art Tissue Culture Lab to fulfill the plant requirement from its operations. This 3,800 m2 Tissue Culture laboratory has dozens of white-coated scientists working in an ultra-clean environment free of pathogens that could infect the plants. Here, many new plantlets can be produced from clonal lines in each bottle. With optimization and continuous improvement, the lab’s capacity will reach 50 million plantlets per year, meaning that once a clone is selected for commercialisation, it can be rapidly scaled up for planting in the field or estates.
In 2023, APRIL planted Acacia crassicarpa clones on 250 hectares. This year it will be increased to 1,800 hectares, and the ambition is to scale this up so that clones make up the vast majority of the 60,000 hectares the company plant each year.
Future gazing
Creating the most resilient plants with the best genetic makeup to handle conditions out in the field is a major preoccupation for the 270-person Fiber Research and Development team at APRIL, which counts 9 PhDs and 21 colleagues with Masters-level qualifications. Furthermore, it enables them to tailor the plantations for likely future environmental scenarios, such as climate change.
Yuliarto says the company is selecting clones for planting now that are more tolerant of potential flooding and higher wind speeds.
The work of APRIL’s scientific teams is paving the way for the company to continue growing while keeping to its no deforestation commitment.
