Growing roots: the Living Ash Project
The Living Ash Project (LAP) aims to identify and ‘propagate’ ash dieback-tolerant trees. Propagation is the process of breeding new plants, from a parent plant. Funded by Defra, this project is a collaboration between the Future Trees Trust, Fera, Forest Research and Kew.
Kew’s contribution to the LAP consists of a series of trials to improve ash propagation techniques using cuttings. A cutting is made by taking a section of a plant (in this case a portion of a branch) and encouraging it to form new roots in soil. This generates a genetically identical clone of the mother plant. If successful, the best methods found in our trials may be used to propagate tolerant trees for seed orchards or woodlands where ash has been lost.
Kew’s ash propagation trials
We have set up two trials in the Wakehurst nursery so far: one involved semi-ripe cuttings taken last July, the other focussed on hardwood cuttings taken in mid-February. For each trial, the arboriculture team (who are responsible for the cultivation and care of trees) helped us cut down some branches for cuttings from local trees. We also collected cuttings from trees growing in the nearby National Trust estate at Nymans and from seedlings found around Wakehurst, since younger cuttings are expected to root more easily. The horticulture team (that takes care of the Wakehurst nursery and gardens) came together to help with preparing and setting up the cuttings in trays in the nursery: a great example of how science is all about collaboration between people at Kew and beyond.
LAP trial of semi-ripe cuttings (July 2021): Isabel Negri/ RBG Kew
LAP trial of hardwood cuttings (February 2022): Isabel Negri/ RBG Kew
When preparing for the LAP trials, it became obvious that a huge number of factors can influence the rooting of cuttings. We decided to test the effects of different soil types, specifically peat-based versus more sustainable peat-alternative compost. We are currently experimenting with different concentrations of rooting hormones too, as well as the use of mycorrhizal fungi (fungi that grows and lives symbiotically with plant roots). Soil inoculated with such fungi has already been found to enhance the rooting of cuttings in several other tree species.
Some roots are already visible, peeking out from the bottom of the trays of our first trial. Let’s hope to see lots more when we begin to collect results.
Ash roots, LAP trial (summer 2021): Isabel Negri/RBG Kew