Only the best varieties get tested in RL trials

Only a fraction of new cereals and oilseeds varieties get sown in AHDB Recommended Lists (RL) trials. Paul Gosling explains how a data-driven process helps sort the wheat from the chaff.

Although the number of varieties on the RL is sometimes the subject of discussion, most (about 80%) farmer respondents to the latest RL review felt that the number of varieties was about right.

Only a relatively small proportion of new varieties that could be grown get listed in the RL. Most fall long before the final recommendation step.

In fact, the variety selection pipeline has many discrete steps: from breeders sifting through thousands of potential plant lines to the farmer picking the right one for their situation.

The selection done as part of the RL process sits between these two extremes.

As part of the winter wheat on trial initiative, we want to highlight how decisions are made that result in a new variety being added to the RL.

This blog examines how we select new varieties to drill in our trials.

On 7 October 2024, we drilled one of 31 winter wheat fungicide-treated yield trials for harvest 2025.

The focus trial in Norfolk features 50 unique varieties: 35 recommended and 15 candidate varieties, but many more potential candidates were rejected and not drilled.

To understand why, we first need to consider the Variety Lists (VL) trials.

The GB and NI Variety Lists (VL) are one of the most influential filtering steps in the variety selection pipeline.

Managed by the Animal & Plant Health Agency (APHA), only varieties on the VL can be legally sold and marketed in the UK (and have their yield and agronomic data released as part of the RL).

To secure VL listing status, a variety needs to pass two tests that take two to three years to complete. These tests help protect intellectual property (of the breeders and the farmer) and make sure the variety delivers value to users.

DUS tests assess if a variety is:

• Distinct (clearly distinguishable from other varieties)
• Uniform (no variation in the expression of its characteristics from one plant to another)
• Stable (from one generation to the next)

VCU tests assess if a variety:

• Offers value for cultivation and use

VCU tests consider key characteristics, including yield, crop responses (such as lodging), disease resistance and some quality traits.

Each year, many varieties pass the VL tests, including about 50 new winter wheat varieties.

Most of the new varieties that pass the VL tests will not offer any additional benefit over varieties already on the RL.

It is the role of three RL crop committees to decide which varieties to include in RL trials (like the one in Norfolk):

• Wheat crop committee
• Barley, oats and other cereals crop committee
• Oilseeds crop committee

The committee members, who represent the whole supply chain – from farmers and agronomists to millers and maltsters – meet in late summer (after harvest) to anonymously vote on whether a variety goes into trial or not.

Their decisions are based on evidence, which includes reviewing VL data, which is provided by breeders as a significant in-kind contribution to the RL project.

The decision-making process is like the one used to make final recommendations, although the data is more limited at this stage and some of the benchmarks are lower, particularly around end-use quality. 

Specifically, VL varieties are compared against specially selected comparator varieties (which are already on the RL). Although yield is important, other agronomic and quality characters are also considered.

We want to make sure that any new variety has a better balance of features than the comparator varieties.

For milling wheat and malting barley varieties, the committees also review initial end-user assessments of quality characteristics.

Breeders are also invited to deliver a presentation (in support of their varieties).

The committee members use the evidence to determine which varieties are most likely to provide a consistent economic benefit to industry (and ultimately secure recommendation).

Varieties entered into the RL trial system as a candidate are grown alongside varieties already on the RL.

There are no limits on the number of varieties that can be trialled as candidates.

Usually, a variety will be grown in all UK trials for the relevant crop, although sometimes it may only be grown in a specific region if a committee feels it is not suitable for the whole of the UK. This could be due to low yields in some areas or susceptibility to a regionally important disease.

A list of all varieties (including the 15 winter wheat candidates) in the Norfolk fungicide-treated trial for harvest 2025 is available on the winter wheat on trial web page.

Later this year, information on all varieties in the RL trials will be available on the harvest results web pages.