Variety Testing

SASA has been involved in various aspects of variety work from its earliest days. Initially limited to important Scottish crops of the early 20th century such as turnips, swedes, fodder grasses, clover and of course potatoes, the enactment of the Plant Varieties and Seeds Act in 1964 encouraged the development of private sector plant breeding by introducing Plant Breeders Rights to the UK.  Accession to the EEC in 1972 saw a further increase in the need for variety testing with the predecessor of SASA becoming one of the UK test centres for potatoes, cereals, fodder crops and vegetables. Further rationalisation in the 1980s, aimed at removing duplication of effort within the UK, resulted in SASA being the sole UK test centre for vegetables.  (UK variety testing is co-ordinated by the Plant Variety Rights and Seeds Office (PVS), which is part of the Animal and Plant Health Agency (APHA) based in Cambridge).  SASA also tests a number of what are known as “Agricultural” crops, covered by different legislation than vegetables and in the case of potatoes, requiring further agronomic tests called Value for Cultivation and Use (VCU) trials. 

SASA Variety Testing also undertakes a programme of Agriculture and Horticulture Development Board (AHDB) funded Independent Variety Trials (IVT) for potatoes which provides “independent resistance data for pests, diseases and pathogens deemed to be of high importance/threat to our national potato crop”.

Sprouting potato tubers, cv. Asterix

As a result of its long involvement with DUS, VCU & IVT, SASA Variety Testing has built up a unique series of well-characterised reference collections of its test crops stretching back more than 40 years and constituting a very substantial genetic resource.  We also host the Scottish Landrace Protection Scheme which functions as a “safety-net” for locally adapted and traditional Scottish genetic resources by storing this material and making it available both to the original donors in case of harvest failure, as well as the wider research and breeding communities.


Distinctness, Uniformity and Stability (DUS) Testing

DUS testing is a way of determining whether a newly bred variety differs from existing varieties within the same species (the Distinctness part), whether the characteristics used to establish Distinctness are expressed uniformly (the Uniformity part) and that these characteristics do not change over subsequent generations (the Stability part).  DUS tests exist so that new varieties can legally gain access to their market via the UK National List and/or for the granting of Plant Breeders Rights, a form of intellectual property rights designed to safeguard the substantial economic investment involved in modern plant breeding.

A DUS test is usually conducted in the field or glasshouse over two successive growing seasons.  During this period a number of mainly morphological characteristics are recorded both on the new (or candidate) variety and on similar varieties in what is known as “Common Knowledge”.  Differences, if they exist, are established by observation and measurement using internationally agreed protocols.  SASA Variety Testing staff are closely involved in the design of these protocols by regularly meeting with colleagues from other countries within the International Union for the Protection of New Varieties of Plants (UPOV) based in Geneva and the Community Plant Variety Office, a European Union Agency based in Angers, France.

SASA is the UK DUS testing centre for vegetable species and offers DUS tests in the following:

Beetroot (including Leaf Beet & Chard)

Broccoli (including sprouting types)

Brussels Sprout



Vegetable Kales


Onion & Shallot




Radish (including Oriental types)

Runner Bean



Turnip Rape

See the related links box for more information about DUS



Value for Cultivation and Use (VCU) Testing of Potatoes

Potato plant - BlacklegIn addition to the DUS test, new varieties of some species of economically important plant species are also required to undergo Value for Cultivation and Use (VCU) Testing before inclusion on the UK National List. Variety Testing at SASA, in conjunction with colleagues at NIAB in Cambridge, conduct VCU tests on potato candidates. Whereas DUS characteristics focus on morphological characteristics, VCU concentrates on agronomic characters - with an emphasis on resistance to diseases and defects important in potato production in the UK. 

VCU tests fall into four categories:

  • Yield
  • Factors in the physical environment – e.g. susceptibility to damage
  • Resistance to harmful organisms – e.g. Blackleg (see image), Common Scab or Leafroll
  • Quality – e.g. crisping / French-fry  quality

See Disease Testing and New Varieties pages or related links box for more information.

Independent Variety Trials (IVT)

Blight trialsIn addition to DUS and VCU trials, SASA Variety Testing, in collaboration with its partners Biomathematics and Statistics Scotland (BioSS), James Hutton Limited (JHL) and SAC Consulting Ltd., undertake Independent Variety Trials (IVT) on behalf of the Agriculture and Horticulture Development Board (AHDB). The potato Industry considers it very desirable to compile a comprehensive, independent data set of varietal ratings for diseases considered to be of most importance for UK potato production.  To this end, AHDB Potatoes fund a set of tests for some diseases not covered by the official National List programme but nevertheless fully integrated with the statutory testing system.  A full list of the disease resistances tested can be found on the potato disease testing page.  


Agents/breeders of varieties entering the second year of UK National List are invited to enter their varieties for IVT testing.  In addition, agents/breeders of varieties found on the European Union Common Catalogue intended for production in GB are also invited to enter their varieties. The results of all tests are published on the AHDB Potatoes' Potato Variety Database hosted by SASA.


Disease Testing


Dry Rot (NL test): (Fusarium coeruleum and F. sulphureum, separate test conducted for each pathogen):  tubers are wounded and inoculated with a suspension of spores and incubated at 12-15oC. The degree of internal rotting is assessed.

Foliage Late Blight (NL test): greenhouse-grown plants at or near flowering are sprayed with a known R-gene complex isolate(s) of Phytophthora infestans.  Leaf area blighted is scored after 7 days incubation.

Foliage Field Late Blight (IVT test):  test plants grown in small field plots are exposed to spores of known R-gene complex isolate(s) from adjacent infected plants of a susceptible variety.  Leaf area blighted is assessed on at least 3 ocassions.

Tuber Late Blight (NL test):  the rose-end of field-grown tubers is sprayed with a known R-gene complex isolate(s) of Phytophthora infestans.  The number of blighted tubers is counted after 10-14 days incubation.

Common Scab (NL test):   tubers are planted in pots containing artificially infested compost and kept dry during tuber initiation. Severity of common scab is assessed on daughter tubers.

Powdery Scab (NL test):  tubers are planted in pots in compost infested with scab peelings and kept wet during tuber initiation.  Severity of powdery scab is assessed on daughter tubers.

Blackleg (NL test):   tubers are inoculated at heel end with Pectobacterium atrosepticum and planted in an irrigated field trial. The incidence of blackleg is assessed at least 3 times during the growing season.

Black Dot (IVT test):  tubers are planted in a greenhouse in pots filled with a compost infested with mycelia and spores of Colletotrichum coccodes.  The severity of black dot is assessed on daughter tubers after 6 weeks incubation.

Black Scurf (IVT test):  tubers are planted in a greenhouse in pots filled with a compost infested with mycelia of at least 3 isolates of Rhizoctonia solani.  The severity of black scurf is assessed on daughter tubers.

Silver Scurf (IVT test):  tubers are planted in artificially infested compost of Helminthosporium solani and planted in a polytunnel.  The severity of silver scurf is assessed on daughter tubers after 4-5 months incubation at 12-15oC.

Skin Spot (IVT test):  tubers are dipped in a suspension of spores and mycelia of Polyscytalum pustulans and planted outdoors in compost in pots.  The  severity of skin spot is assessed on daughter tubers after 5-6 months incubation at 5-8oC.


Potato Cyst Nematode (Globodera spp.) (NL test, Separate tests are conducted for G.rostochiensis pathotype Ro1 and G.pallida pathotypes 2/3 and 1):  tubers are planted in pots in  compost infested with a standard concentration of PCN eggs.  Cyst multiplication on roots is assessed. View


Damage, external (splitting) and internal (bruising) (NL test):  a standard force is applied to the heel end of field grown tubers.  Tubers for ‘splitting’ test are stored at 4-6oC and the incidence of splitting at the point of impact is recorded. Tubers for ‘bruising’ test are stored at 9-11oC and the depth of damage at point of impact measured.

Tuber Quality

External tuber defects:  The weight of tubers >35 mm and < 35 mm is recorded in kg, unmarketable tubers are divided into 10 categories: growth cracks, greens, mis-shapes,mechanical damage, cutworms, common scab >25% surface area covered, late blight, wet rots and other faults. The weight of each category is recorded in kg.

Internal tuber defects:  The number of tubers with hollow heart, internal blemishes or other defects is recorded by cutting, initially, 25 tubers. If any faults are found in this sample, a further 25 tubers are cut.

View the official Value for Cultivation and Use (VCU) protocols and procedures documents on the website.

New Varieties

Disease, pest and damage susceptibility ratings obtained during National List Trials for new varieties are available on the AHDB Potatoes' Potato Variety Database together with results from Independent Variety Trial tests. Additional information on these varieties may also be found on the European Cultivated Potato Database.

Varieties added to the UK National List in 2015

Golden Beauty
Golden Sun 

Varieties added to the UK National List in 2016

Mayan Rose

Varieties added to the UK National List in 2017


Variety Collections

Seed storage in the Deep Freeze Seed StoreIn order to satisfactorily perform DUS trials which, it will be recalled, are essentially a series of comparisons; a substantial collection of reference varieties must be assembled and held viable and ready to be incorporated into plots in the field.  Over the forty-plus years of variety testing at SASA and its antecedents, very substantial collections have been amassed and maintained here.  Stored in conditions of low temperature and humidity and regularly monitored for viability, these reference collections, as well as providing the foundation for DUS trials, also represent a very significant crop genetic resource relevant to the UK’s commitment to international treaties such as the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) and the Convention on Biological Diversity (CBD). 

As well as the crops DUS tested at SASA, we also hold small collections of other vegetable species including tomato, parsley, spinach and cauliflower.  However it is in our main test species that our collections are notable for their range, the top five (as of early 2017) are:

Pea:  4261 accessions
Cabbage:  2664 accessions
Carrot: 1527 accessions
Potatoes:  1187 varieties (maintained as tubers)
Onion:  1047 accessions
Radish:  759  accessions

Scottish Landraces

A landrace is a locally adapted variety of a domesticated species of plant (or animal) which over time has become well adapted to its local environmental conditions.  Although landraces have a distinct identity, they are genetically more diverse than commercial cultivars as they have not been produced by breeding (deliberate crossing of specific characteristics), but are maintained by continual regeneration of seed by local farmers. Populations of the same landrace grown in different localities will often have slightly different identities due to a variation in the balance of individual plants within a population.

Landrace seed may or may not be sold commercially and the harvested product may have multiple uses such as food or forage. Landraces may be cultivated using traditional or modern methods and are often grown as mixtures.

Where are landraces grown in Scotland?

Landraces are almost entirely grown outwith the Scottish mainland.  In the Outer Hebrides, substantial areas of small oat (or Corce Beag in the gaelic), rye and bere barley landraces can be seen, often grown together in mixtures. In the Northern Isles you can find Shetland cabbage, Shetland oats and bere barley - on Orkney as well as Shetland. 

Bere barley, small oat and Shetland cabbage are probably the oldest surviving agricultural plants in Scotland, the cereal landraces having been considered the main crop for the Hebrides in the seventeenth and eighteenth centuries and Shetland cabbage (or kale) known on Shetland since the time of Cromwell.

Why do we want to conserve landraces?

  1. The Scottish Government has a commitment to conserve its plant genetic resources as a signatory to international treaties such as the Convention on Biological Diversity (CBD) 1992 and the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) 2004.
  2. Landraces have become very rare, and like rare animal breeds, represent genetic resources of unknown diversity.  In mainland Scotland landraces were replaced, firstly by traditional or primitive varieties in the late 19th and early 20th centuries, and more recently by modern varieties produced by plant breeders in the latter half of the 20th century. There is therefore a need to collect landrace seed, record their morphological and molecular characteristics and make the germplasm available to the plant breeding community. 
  3. As landraces are variable locally adapted populations, they may have a role to play in producing varieties adapted to climate change.
  4. Continued growing and regeneration of landraces plays an important role in maintaining sensitive habitats such as the machair of the Western Isles.
  5. As part of Scotland’s agricultural heritage landraces obviously have cultural value. 

The survival of landraces is dependent on a continual cycle of regeneration and sowing; if seed harvest fails, the landrace will be lost unless a sample of the population has been conserved in ex situ storage.  For this reason the Scottish Landrace Protection Scheme was set up at SASA in 2006


Camacho Villa, C.T., Maxted, N., Scholten, M., and Ford-Lloyd, B. (2006) "Defining and identifying crop landraces", Plant Genetic Resources, 3(3), 373-384, available from:


Scottish Landrace Protection Scheme (SLPS)

The Scottish Landrace Protection Scheme was launched by SASA in August 2006 to provide a safety net for the continued use of Scottish landraces by safely storing seed produced by each grower ex-situ in SASA’s freezers. In the event of poor harvest, a grower can request some of his or her seed already stored at SASA. With the consent of the donor, the stored seed can also be made available for research, breeding and education.

As landrace populations may be selected over many years for growing in a specific locality, they are not always suitable for growing in other places, Bere Barley from Orkney, for example, does not grow particularly well in South Uist. One of the aims of the SLPS is to prevent the loss of locally adapted landraces by removing the need for growers to source seed from other areas.

The SLPS holds collections for six Scottish landraces:

  1. Bere Barley (Hordeum vulgare)
  2. Small Oat (Avena strigosa)
  3. Hebridean Rye (Secale cereale)
  4. Shetland Cabbage (Brassica oleracea)
  5. Wheat (Triticum aestivum L.)
  6. Potato (Solanum tuberosum L.)

On receipt at SASA, each collected or donated seed sample is registered, examined for seed health and tested for germination. The growers are informed of the results and consent is sought for general distribution of seed. Seed is then cleaned, dried and stored at 22oC and a sub-sample is removed for safety duplication.

A minimum seed quantity is required for participation in the SLPS in order for it to fulfill all the functions of the scheme: emergency regeneration, re-supplying the donor, general distribution for bona fide research, breeding and education reasons, morphological and molecular characterisation and monitoring the germination and vigour in store.

Bere Barley

Bere Barley (Hordeum vulgare L.)

The six-rowed spring barley called 'bere' has been dated back to the 8th century and is likely to have been introduced by the Norse (Jarman, 1996). It has been used both as food (bread) and beverages (beer, ale, whisky) as well as feed. Historically associated with Scotland, there was no evidence of any cultivation on mainland Scotland at the time of the compilation of the National Inventory (Scholten et al. 2004). On the Outer Hebrides, bere barley was rarely grown for human consumption and its cultivation had decreased to an estimated six to twelve crofters. In 2006 however it was observed here in several fields mixed in with oat and rye. Very few crofters grew it as single stand.

On the Northern Islands, Shetland cereal cultivation has seen a steep decline as sheep production increased, with the consequence that both bere and Shetland oat (Avena strigosa Schreb.) cultivation almost ceased a few years ago on both island groups, but for a couple of farmers. A project was initiated to encourage and increase the cultivation of heritage crops such as bere and small oat. The project, run by the Shetland Organic Growers Group, was targeting 15 farmers to grow 4 hectares of cereals in 2004.

Orkney is the only location where bere barley is still grown for human consumption; i.e. for bere meal production, used for making traditional biscuit (bannock) for tourists. Meal is ground at the Barony Mills in Birsay.

Some farmers also grew bere for animal feed. Bere's nutritional value has recently been investigated by the Agronomy Institute at Orkney College UHI (Theobald et al 2006) as part of a wider project into its marketing potential. The two traditional beverages associated with bere; beer and whisky, have both been reintroduced successfully in 2006: ale by an Orkney brewery, beer by a Shetland brewery and whisky from a distillery on Islay. In 2012 a limited edition Arran Malt was produced in conjunction with the Agronomy Institute at Orkney College UHI, using Orkney bere. For more information see the Agronomy Institute website.

Results from a recent PhD project (Southworth 2007) indicated that there were three significantly different and isolated sub-populations of bere being grown Scotland: the Shetland islands, the Orkney islands and the Western Isles (outer Hebrides).

The greatest proportion of genetic diversity was found within populations, probably resulting from geographically isolated founding populations diverging over a long time. However, exchange of seed between growers may also have contributed to high variation within populations. The greatest diversity was found in the Western Isles.

There is a clear need for in situ and ex situ conservation both within each of the sub-populations and of individual populations in each island group.


Jarman, R.J. (1996) "Bere barley: a living link with the 8th century", Plant Varieties and Seeds, 9(3), 191-196.

Southworth, C. (2007) The use of microsatellite markers to differentiate UK barley (Hordeum vulgare) varieties and in population genetic analysis of bere barley from the Scottish islands, PhD thesis Heriot Watt University, Edinburgh.

Theobald, H.E., Wishart, J.E., Martin, P.J., Buttriss, J.L., and French, J.H. (2006) "The nutritional properties of flours derived from Orkney grown bere barley (Hordeum vulgare L.)", Nutrition Bulletin, 31(1), 8-14, available from:

PDF icon Bere barley accessions35.34 KB

Small Oat/Shetland Oat & Common Oat

Small Oat or Shetland Oat (Avena strigosa Schreb.)

Small, black or bristle oat (Avena strigosa) is a historical crop of marginal soils that has largely disappeared from Northern Europe (Weibull et al. 2001). Formerly widely grown on the poorer soils in the UK, and included in plant breeding programmes in Wales, cultivation of the small oat has now almost ceased (Chater 1993, Scholten et al 2004).

The major remaining area of cultivation in the UK are on the Uists and Benbecula in the Outer Hebrides where over 300 hectares are planted every year with mixtures of small oat, rye and bere barley. Smaller areas of cultivation are scattered over Lewis and Harris, Tiree and Islay. The use of mixtures is an ancient agricultural strategy to safeguard crop yields in a highly risky growing environment.

On the Hebrides A. strigosa it is known as small oat, black oat or, in Gaelic, Corce beag, in contrast to Avena sativa (common oat) which is called big, mainland or white oat.

Its cultivation on the Hebrides is for the production of winter feed for animals and is restricted to very light, highly alkaline machair soils. The alkalinity and nutrient deficiencies, such as manganese, make it difficult to grow common oat without additional nutrients. In contrast, the small oat yields well under these conditions without the need for additional nutrient. The small oat has survived thanks to its adaptation to very marginal growing conditions.

Cultivation of low input local cereal varieties (landraces) make an important contribution to biodiversity conservation of the machair, a man-made habitat unique to the British Isles. A large part of the machair is protected with a Western Isles Local Biodiversity Action Plan (LBAP) which advocates support for the local cereal varieties.

On the Northern Isles A. strigosa is called Shetland oat or aets. On both islands groups it is used as winter feed. However, in Shetland, the oat straw is primarily used for making traditional straw baskets called 'kishies', thatching and for the backs of traditional Orkney chairs. The Shetland Organic Producers Group included it in their heritage cereals program and it can also be seen on the Burland Croft Trail, among other Shetland local varieties and rare breeds.

On Orkney its occurrence is associated with the traditional Orkney chairs for which the black oats provide strong straw of a beautiful color.


Chater, A.O. (1993) "Avena strigosa Schreb., Bristle Oat and other cereals as crops and casuals in Cardiganshire, V.C. 46", Welsh Bulletin of the Botanical Society of the British Isles (BSBI), no 55, 7-14.

Scholten, M., Maxted, N., Ford-Lloyd, B. (2004) UK Inventory of Plant Genetic Resources for Food and Agriculture, University of Birmingham available from:

Scholten, M. (2007) "Uist cereals attract research interest. Part 1: Small oat", Am Pàipear, March.

Scholten, M., Maxted, N., Ford-Lloyd, B., and Green, N. (2008) "Hebridean and Shetland Oat (Avena strigosa Schreb.), and Shetland cabbage (Brassica oleracea L.) landraces: occurrence and conservation issues", BIOVERSITY/FAO PGR Newsletter, 154, 1-5, available from:

Weibull, J., Johansen Bojensen, L.L., Rasomavicius, V. (2001) "Avena strigosa Schreb. in Denmark and Lithuania", BIOVERSITY/FAO PGR Newsletter, 131, 1-4, available from:

PDF icon Small oat & common oat accessions29.25 KB

Hebridean Rye

Hebridean Rye (Secale cereale L.)

Rye has never been an important crop in the UK compared to other cereals. Perceval (1946) observed that "no well-marked races of rye are met with and the number of constant varieties is small". The Hebridean rye is the least known of the Scottish landraces, although historical references document rye cultivation on the islands. However, it's origin is unknown.

The rye is grown in a mixture with oat, in order to safeguard a harvest in dry years. The ratio oat to rye was usually given as 40 to 60 but also as 30 to 70 on the lighter soils in South Uist. No common or local names were encountered for the local rye.

The first two accessions of rye in the SASA landrace collection have been collected as a mixture with Small Oat (Avena strigosa Schreb.) whereas the final two accessions are pure.


Percival, J. (1946) Agricultural botany : theoretical and practical, 8th ed., London: Duckworth.


PDF icon Rye accessions6.69 KB

Shetland Cabbage

Shetland Cabbage / Kale: the oldest Scottish local vegetable variety?

Shetland cabbage or Shetland kale, a landrace of unknown origin, has been grown on the Shetland Islands since at least the 17th century (Fenton 2007). First used as a vegetable, it was then widely grown as winter feed for cattle and sheep. The last 30 years however, has seen a steep decline in the use of this landrace

Seed of Shetland cabbage is not sold commercially and the survival of this and other landraces is entirely dependent on saved seed from growers. Community Action plans, such as that for Yell have advocated support for Shetland cabbage.

The life cycle has been well documented (Fenton 1978, Anderson 2001). Traditionally a plantie crub or crö, a small circular stone-walled enclosure, was used for raising cabbage seedlings (Anderson 2001), which were then transplanted into larger kale yards, also often with protective stone walls. These structures can be seen all over the islands though many have now been abandoned or are used for other purposes.

Shetland cabbage seed was collected in the 1980s and deposited at the vegetable genebank at Warwick HRI in Wellesbourne where some accessions were found to show Clubroot (Plasmodiophora brassicae) resistance.

Then in the mid-2000s as the Scottish Landrace Protection Scheme was being set up, further material was obtained and conserved at SASA which now holds around 50 accessions from a wide range of locations in Shetland and Foula.

Characterisation of accessions, collected on the Shetland mainland and the neighbouring islands shows wide morphological variation within and between accessions for traits such as foliage colour, head formation, head density and powdery mildew resistance.

Here’s a reference to the kale and the crö in the first verse* of “Probably still the most famous poem in the Shetland dialect”, "Auld Maunsie's Crö " by Basil R. Anderson:

Oot-ower apon a weel-kent hill,
Whase watters rise ta grinnd a mill,
Auld Maunsie biggit him a crö,
Ta growe him kale for mutton brö –
Fir Maunsie never tocht him hale,
Withoot sheeps’ shanks an cogs o kale.

* View the full 12 entertaining verses along with some translation.



Anderson, L. F. (2001) The Bressay Plantie Crubs, Bressay: Bressay Local History Group.

Crute, I.R. and Pink, D.A.C. (1989) "The characteristics and inheritance of resistance to clubroot in Brassica oleracea", Aspects of applied biology, 23, 57-60.

Fenton, A. (1978) The Northern isles: Orkney and Shetland, Edinburgh: John Donald.

Fenton, A. (2007) The food of the Scots : Scottish Life and Society : a compendium of Scottish ethnology, Edinburgh: John Donald.

Lever, L. A. (2006) A survey of Landraces on the Sheland Islands, MSc. thesis School of Biosciences,University of Birmingham.

Scholten, M., Maxted, N., Ford-Lloyd, B., and Green, N. (2008) "Hebridean and Shetland Oat(Avena strigosa Schreb.), and Shetland cabbage (Brassica oleracea L.) landraces: occurrence and conservation issues", BIOVERSITY/FAO PGR Newsletter, 154, 1-5, available from:

PDF icon Shetland cabbage accessions108.57 KB


There are no wheat landraces currently grown in Scotland. An old traditional variety 'Red Standard' obtained in 1950 is currently maintained in the SASA genetic resource collection

PDF icon wheat accessions9.74 KB


For further information please see The European Cultivated Potato Database - a resource for potato breeders, scientists and farmers.

PDF icon potato accessions9.1 KB

Requests for further information and seed


Genetic Resources, SASA, Roddinglaw Road, Edinburgh, EH12 9FJ, UK



Seed of Landraces is limited and will only be supplied for bona fide research, plant breeding or educational purposes. A standard Material Transfer Agreement must be signed by the recipient in advance of seed being supplied.