Rice, rocks and the parasitic weed Striga: Increasing sustainable cereal production and protection in sub-Saharan Africa

Grantham Scholar David Rapley’s project looks at how to increase cereal crop yields sustainably with a focus on rice, silicon and Striga.

The project

Silicon enhances the resistance of plants to biotic stresses, such as from fungal and bacterial pathogens, insect pests and nematodes. Very recently, one study has shown that silicon increases the resistance of plants a parasitic weed, although the mechanisms underlying this effect were not explored. Whilst the precise mechanisms underlying the effects of silicon on biotic stresses are not fully understood, there is increasing evidence that silicon enhances physical, biochemical and molecular defences in plants, including physical reinforcement of the cell wall, biochemical activation of defence-related enzymes and molecular upregulation of complex defence signalling pathways.

The parasitic weed Striga is major constraint to crop production in sub-Saharan Africa, which acts by infecting the roots of its hosts to steal nutrients and water. Applying silicon in the form of basalt rock dust or silicon fertilizers could provide a relatively low-cost means of enhancing resistance to these devastating parasites.

My PhD will determine whether enhanced uptake and accumulation of silicon by crop plants such as rice can increase its resistance to Striga. Following this, my research will determine the physical, biochemical and molecular mechanisms by which silicon may enhance defence against this parasite at different stages of its life cycle of infection.

My PhD is linked with the Leverhulme Centre for Climate Change Mitigation (LC3M). Check out their website here.

David Rapley’s outreach and engagement

In 2021, David became a Postgraduate Fellow at UK Parliamentary Office of Science and Technology (POST). As part of this he produced a report on genome-edited crops. Read: David Rapley research fellowship in Parliament.

In 2020, David and 6 other Grantham Scholars went to COP26 as official observers for the University of Sheffield. You can find interviews with David and the other Scholars about GOP26 here.


Parliamentary Office of Science and Technology (POST), Genome-Edited Food Crops, Post Note 663, 24 January 2022.




Dr Mathias Lorieux

International Center for Tropical Agriculture