Mighty oaks from little acorns grow - unless of course you decide to propagate using faster treecloning methods. Researchers at Dublin City University are looking at new propagation methods aimed at improving Ireland's forestry stocks.
Researchers from Coillte, Teagasc and UCD are also involved, Dr Michael Parkinson, a lecturer in DCU's School of Biotechnology, said. The goal was to be able to see into the future, to identify superior trees before planting them, to maximise yields from Irish forests.
This isn't only about getting the largest yield of timber per hectare. The quality of the tree stock is also important - and in the case of hardwoods it can be central. It may take decades, however, before a forester can see whether a given tree will deliver what is wanted.
It takes 30 years for oaks to mature, Dr Parkinson explained. "It makes breeding programmes very slow indeed."
Scientists are trying to improve the odds of getting a good tree by introducing new propagation methods. It is not sufficient to find a superior tree in a plantation and then harvest its seeds, hoping to grow hundreds of duplicates. As with any siblings, there can be great variety between individuals in a family and having a strong, tall brother does not mean that you will end up that way too.
Vegetative propagation or cloning provides a much better chance of achieving a tree of comparable quality. It is difficult to clone from an old tree however. "The problem with trees is that they show their superiority when they are quite old, when they are too old to propagate." Young trees are easier to clone but it is too soon to know whether they will produce a superior tree.
Buds can be taken from mature branches for example, but when cloned and propagated they tend to produce branching plants and not trees. Planting these would produce a forest of branches, he said, with no substantial trunks.
One research approach involves attempting to "rejuvenate" mature trees so that they can be propagated vegetatively. It involves grafting a bud from a sapling onto a mature branch sustained in culture. This young graft causes nearby buds on old wood to act like young plant material.
"Whatever chemicals are involved . . . will be transmitted across the union between new and old," he said. The more often this is done the more the old wood is rejuvenated and the easier it becomes to clone.
Another promising technique is known as somatic embryogenesis, which produces large numbers of duplicates that deliver a plant complete with root and shoot in one step.
Most of the volume of a seed is made up of food to supply the small collection of cells which have the potential to develop into a viable plant. Somatic embryogenesis involves taking out the seed embryo and culturing it in nutrients and plant hormones.
The embryo, about 1 mm 3in size, begins to divide indefinitely, producing duplicates of itself. The hormone mix is then changed, which encourages these now plentiful cloned embryos to mature, as they would had they grown in complete seeds. The final step is to take the matured embryos and "plant" them in yet another medium which encourages them to sprout like normal seed.
Forests could never be populated by clones alone, Dr Parkinson said, and any attempt to do so would be a serious mistake. Such tree stands would be susceptible to emergent diseases and there would be a loss of biodiversity.