Assessing crop physiology traits for their competitiveness against weeds in low-input and organic farming systems

Background

A strong demand for more variety data was identified during the 2022/23 review of the Recommended Lists for cereals and oilseeds (RL). The survey of RL users identified an appetite for crop physiology information, especially to assist with variety selection under lower inputs.

In particular, information on variety competitiveness against grass weeds was found to be of importance, as it would help growers exploit crop genetics more fully, as part of an integrated pest management (IPM) approach. The need for this information is underpinned by a lack of herbicide chemistry and increasing herbicide resistance issues.

Many studies have investigated cereal traits associated with varietal competitiveness with weeds, including early growth habit, tillering and height. However, there is relatively little information in a practical format that can be trusted and used by farmers.

Currently, weed competition or suppression is not assessed in RL trials. However, competitive crops could play a much bigger role in integrated weed management. For example, research estimates suggest that up to 25% control of black-grass can be achieved – with some crop species more competitive than others (e.g. barley is more competitive than wheat).

In addition to crops, there is a growing body of evidence to support use of competitive varieties. For instance, an ongoing AHDB-funded PhD studentship project has shown that the strong rooting habits of some winter wheat varieties improve competition against black-grass during the autumn.

However, many aspects of competition remain poorly understood. Additionally, management choices also influence a crop’s ability to compete with weeds (e.g. seed rates, row spacing and seedbed quality), which add further complexity to the variety-assessment process.

Initial work

In 2017, the Organic Research Centre developed a network (comprising farmers and researchers) to establish and evaluate field-scale winter wheat variety trials.

Initially focused on commercial organic farms, the network was supported through the LiveSeed and LiveWheat projects and included an emphasis on weed abundance/composition, as well as key agronomic, yield and quality traits.

The network provided a proof of concept for variety evaluation in a wide range of farming systems, including organic, reduced-tillage and lower-input systems, and identified three main traits responsible for weed competitiveness:

1. Early crop vigour
2. Early crop ground cover
3. Good crop canopy cover at flowering

The speed of growth, rate of development, overall biomass production (ground cover and height) all help keep crops ahead of weeds.

This project

This project will build upon the initial work and has four main objectives:

1. Co-organise a workshop with other researchers and stakeholders to steer the direction of the project, including focus traits, trial protocols and data-collection approaches
2. Manage a UK wheat-variety-testing network focused on low-input systems
3. Work with the RL wheat crop committee and plant breeders to develop recommendations for measurable crop physiology traits associated with weed competition
4. Disseminate results and consult with stakeholders

This project will contribute to a robust multi-year, on-farm trial data set based on traits that correlate with weed competitiveness in organic and low-input farming systems. The results will be made available for exploitation alongside or as part of crop physiology assessments within RL trials. Ultimately, the project will give farmers additional information on the weed competitiveness of varieties.

The project has three collaborating organisations: Cope Seeds (UK) Limited*, Organic Research Centre (ORC)* and UK Grain Lab.

*These organisations are also funding partners, each contributing £5,000 in-kind to the project, which includes the provision of data from additional farms to strengthen the overall data set.

Get involved

We are looking for commercial farms to host on-farm strip trials to identify wheat varieties that compete better against weeds.

Complete our form if you're interested in taking part

Watch a video on the use of competitive cultivars for weed management (published by Oper8)

Providing answers to your questions

This research project was funded via a levy-payer-led commissioning process.

It was developed following an AHDB research call at the start of 2025.