SRC willow varieties

Article

SRC willow varieties

Commercial willow breeding programmes were set up in Sweden in 1987 and the UK in 1996. The main aims of breeding were to increase biomass yields and create tall, straight and disease and pest resistant cultivars.

You can read all about willow breeding in this article: Breeding willows for biomass

A variety guide was published in 2012 by Teagasc and AFBI. This publication will be updated by Envirocrops.

Swedish Willow Breeding Programmes

The Swedish willow breeding programme was set up by Svalöf-Weibull in 1987. Crosses generally involved accessions of the osier (Salix viminalis) and other closely related species such as S. dasyclados and S. schwerinii. As frost tolerance was a main issue for the Swedish programme many new accessions were sourced from expeditions to Russia and Siberia in the early 1990s.

Initial varieties mainly involved S. viminalis strains. These were given old Nordic names such as Orm, Ulv, Jorr, Jorunn and Rapp. A major breakthrough came from the cross between S. viminalis and a Russian S. schwerinii clone L79069. This led to what became the industry standard varieties Tora (a female variety) and Bjorn (a male variety). Tora has been an exceptional variety for over 20 years and remains near the top of the table for yield and is disease free.

The success in trials of Tora and Bjorn meant they were used extensively as parental stock in new crosses and because of this selection bias, the vast majority of varieties produced in Sweden have some relationship to this original cross (See table 1).

In 2011 the rights to the SW varieties were sold to a new company called Salix Energi Europa.

Currently available varieties are listed below. All but Dimitrios have been tested in the UK although only the ones in bold have been extensively tested in many different trials and locations. Ones that have an * have some relationship to Tora and Bjorn:

Dimitrios*
SW Inger
Karin*
Klara*
Linnéa
Lisa*
Olof*
Petra
Stina*
Sven*
Tora *
Tordis*
Torhild*

These varieties are available from Energy Crops Consultancy Ltd.

Also in 2011, the former SW willow breeder Stig Larsson set up his own company called European Willow Breeding (EWB). The latter company has also created a number of varieties with similar pedigrees. None of these have been extensively tested in the UK.

Birgit*
Erik*
Estelle*
Esther
Wilhelm*
Winter*

European Willow Breeding Partnership (EWBP)

In 1996, a partnership was created between Long Ashton Research Station (LARS based in Bristol, UK), Murray Carter (a willow producer based in Yorkshire, UK) and Svalöf-Weibull. The aim of this breeding programme was to harness greater diversity in crosses from the National Willow Collection (NWC) that was held at LARS. This included over 100 species and hybrid forms from all over the world totalling over 1,500 accessions.

As the climate in the UK and the Island of Ireland are much more maritime than Sweden, a key focus of this programme was to create varieties that were resistant to the fungal pathogen willow rust (Melampsora sp). From the beginning, the crossing programme at LARS was much more widely focussed than in Sweden. Although S. viminalis, S. schwerinii and S. dasyclados were all used extensively, many novel crosses were made with exotic equivalents of these species from China, Japan and North America. Species that were used included S. redheriana, S. miyabeana, S. sachalensis, S. caprea, S. discolor, S. aegyptiaca and S. glaucophyloides.

Material produced from the crossing programme was tested in yield trials in several sites in England, Northern Ireland, Wales and Ireland. Results of these trials can be found in these papers:

The crosses performed between 1996-2002 led to a number of very interesting varieties that have performed well in yield trials. Varieties were named after ships of discovery and exploration such as Endurance, Resolution, Terra Nova, Endeavour and Beagle.

The UK Government took the decision to close LARS in 2001 and in 2003 the EWBP was dissolved. After several years of negotiations Murray Carter became the sole rights’ holder for these varieties.

The breeding material generated from this programme was extensive. As a result many diverse and high yielding breeding lines have not yet reached the market place. Currently available varieties are lised below. All have been thoroughly tested in multiple trials and locations across the UK and Ireland. The varieties are less dependent on the ancestry of Tora and Bjorn.

Advance*
Beagle
Endurance
Endeavour
Meteor
Paramore
Resolution*
Terra Nova

The varieties Endurance and Resolution have been very consistent performers and frequently top the yield trial rankings. More information is available here.

These varieties are available from Crops for Energy Ltd.

Multiplication plantation of the SRC willow variety Endurance (1 year old)

Rothamsted Breeding Programme

Following the aftermath of the demise of LARS, the NWC was relocated and breeding work continued at Rothamsted Research (based in Hertfordshire, UK). This was more scientific and less commercial in its rationale with crosses being used to provide information for genetic mapping and to develop marker assisted breeding.

This was the only breeding programme to receive 100% Government funding. Because of the very focussed nature of the work it was important to use crossing material for which there was a great deal of existing knowledge, understanding and data. Hence, the earliest selections from this programme also are dominated by crosses involving S. viminalis and S. schwerinii and many have ancestry similar to those produced in Sweden and to a lesser extent at LARS.

Varieties are named after mountains and hill ranges in the UK and have a prefix Roth to show that they were bred at Rothamsted. All the varieties have been extensively trialled in the UK and Ireland but all have some relatedness to Tora and Bjorn. Released varieties are listed below.