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Productivity, natural pest control, and arable plants in population wheat. What are the tradeoffs compared with single varieties?

Primary Supervisor: Dr Nicola Randall, Crop & Environmental Sciences

Secondary supervisor: Dr Ed Dickin

PhD project title: Productivity, natural pest control, and arable plants in population wheat. What are the tradeoffs compared with single varieties?

University of Registration: Harper Adams University

One way to help achieve sustainable intensification of agriculture is to improve resilience of crops to biotic and abotic stresses such as pest outbreaks and weather extremes. Monocultures can be particularly vulnerable to extreme shocks as all individuals are at similar risk.

Crop diversification is one way to build resilience in agricultural systems (Lin, 2011). Growing mixtures of varieties of one crop can also reduce disease pressure and the need for fungicides. Taking diversity further, using composite cross populations formed by bulking the F2s of many crosses in place of growing single varieties, was first investigated by Harlan in the 1920s. The Wakelyns YQ population is being successfully grown on organic and low input regenerative farms in the UK, and has a following among artisan bakers for its depth of flavour. The Oak farm population developed at Harper Adams University from crosses of landrace, 20th Century and modern wheat varieties, has a very wide genetic base due to the landraces, which do not feature in the pedigree of any UK varieties since the early 1900s.

These wheat populations may offer improved resilience to different stresses, impacting on yield variations and on wider environmental impacts. For example, research at Harper Adams University has found differences between wheat varieties in aphid feeding preference. The diversity in a wheat population could potentially prevent aphid epidemics while supporting a sufficient aphid population for predators. Additionally, the diversity of resistance genes means the need for fungicide is reduced or eliminated, which may have impacts on wider invertebrate biodiversity as several groups of fungicide may be implicated in sub-lethal effects on invertebrates. Farm trials of Wakelyns YQ show a greater suppression of weeds, a possible result of the natural selection within the population, which favours more competitive, ‘fitter’ individuals. Therefore, potentially more weeds could also be tolerated without significant yield loss, with concomitant benefits to invertebrate biodiversity. Populations are also likely to be more resilient to abiotic stresses such as drought or waterlogging due to their diversity. To date little research has been carried out combining yield and ecosystem impacts of growing populations as opposed to single varieties under different environmental scenarios, but the use of these populations may support reduced input farming.

The aim of this research is to assess whether there are trade-offs in ecosystem service provision (yield, natural pest control and weed suppression) in the population wheat compared with single varieties. Weed cover, natural enemies, pest species and overall yields will all be assessed under a combination of conditions.

The student will be expected to carry out the following pieces of research:

  • A structured evidence review (eg see: Collaboration for Environmental Evidence, 2018; James et al. 2016) to create a database (and associated meta-analysis if appropriate) of traits (potential yield, pest resistance, drought resistance, preferred soil type etc) of different wheat varieties and populations.
  • Glasshouse studies of wheat populations (some of which may be developed by the student in response to the evidence review) and of single varieties to assess their respective development, biomass and yield responses to environmental conditions (eg water stress, waterlogging).
  • Field studies of wheat populations and of single varieties to investigate arable plant communities, pest and beneficial invertebrates and crop biomass and yield.

The results of the research studies will be used to inform policymakers and practitioners on the use of population wheat within their own systems.


  1. Collaboration for Environmental Evidence. 2018. Guidelines and Standards for Evidence synthesis in Environmental Management. Version 5.0 (AS Pullin, GK Frampton, B Livoreil & G Petrokofsky, Eds)
  2. James, K.L., Randall, N.P. and Haddaway, N.R., 2016. A methodology for systematic mapping in environmental sciences. Environmental evidence, 5(1), p.7.
  3. Lin, B.B., 2011. Resilience in agriculture through crop diversification: adaptive management for environmental change. BioScience, 61(3), pp.183-193.

BBSRC Strategic Research Priority: Sustainable Agriculture and Food: Plant and Crop Science

Contact: Dr Nicola Randall, Harper Adams University