ReLaunch: The next five years of variety trials

The Recommended Lists (RL) is hardwired into the fabric of cereals and oilseeds production – adding the finishing touches to years of plant-breeding investment. Paul Gosling, who leads the work at AHDB, looks at the latest phase of the variety-trialling project.

Variety development is about survival of the fittest – with each potential commercial variety facing a myriad of hurdles in breeders’ tests. Those that make the grade go on to feature in National Lists (NL) trials. Only the ones that emerge from this obtain permission to be marketed in the UK. It is this special pool of varieties that acts as the foundation for recommendation.

Despite the RL’s continuous nature, the project requires cycles of significant review and investment by industry. This year, we began the latest (five-year) instalment of the work. As usual, it involves a staggering number and diversity of trials.

The trials help tease apart varietal differences and reveal genetic potential. In addition to fungicide treated and untreated yield trials, the RL also includes naturally infected and artificially inoculated (with selected pathogen isolates) plots to deliver robust disease information.

Established over many years, the RL’s reputation is built on its independence and robustness. However, while these core elements are vital, it is essential to evolve the project.

In recent years, in response to user feedback, we launched new and improved digital resources – such as the RL app and variety selection tools. We also put more resources into higher priority areas, such as untreated trials.

In response to rapidly evolving pathogen populations, especially wheat rusts, we adapted our analysis of disease data to better account for the emergence and spread of resistance-busting strains. This included the introduction of the wheat yellow rust ‘watch list’ earlier this year, delivering a way to flag varieties that performed out of line with their published disease resistance rating at some sites.

In late spring, the disease story took an unexpected twist. In the last few years, yellow rust resistance has grabbed the headlines. This year, however, septoria tritici stole the show. Based on multi-gene resistance, septoria ratings are far less likely to fall dramatically, compared to the rust equivalents. Still, some genes play a bigger role than others and, if one of them is unpicked by the pathogen, this can result in unexpected disease levels. In-season observations, in trials and commercial crops, pointed to varieties with Cougar in their parentages, with several Group 3 and some soft Group 4 varieties suffering a decline in resistance. With the picture complex, the full implications of this septoria turbulence will be revealed in the RL 2022/23 (due at the end of November).

At present, we are reassessing lodging resistance too (wheat, barley and oats). This system needs to change. For example, although the performance of winter barley varieties varies in the field, such variations do not translate into sufficiently different lodging ratings. Our proposed approach will help pull apart these differences and deliver a wider range of ratings.

Other improvement areas include the potential to develop verticillium stem stripe (oilseed rape) and net blotch (spring barley) resistance ratings. We are also assessing oilseed rape’s resilience against cabbage stem flea beetle larvae.

At the end of each year, the RL is released. It represents the culmination of countless decisions – from the moment a promising line is identified by a breeder to its eventual recommendation. How varieties are trialled and assessed are ultimately the responsibility of the RL Project Board and its three supporting Crop Committees. These groups also help triage the numerous demands to deliver more through the RL by setting priorities and managing budgets.

This team involves the expertise of numerous stakeholders – from breeders and pathologists to farmers and end-users. As members serve on fixed terms, every year opportunities open up for passionate people to join and get behind the beating heart of variety recommendation.

There is a unique opportunity for a grower to join the RL Barley and Oats Crop Committee. The application deadline is 26 July 2021.

For complete information on the RL, including Board and Committee opportunities, visit ahdb.org.uk/rl