Observing and modelling the response of crops to high temperatures (HTCrops)

Predicting the effects of climate change on agriculture remains highly uncertain due to limited understanding of crop responses to high temperature extremes. There are two major photosynthetic pathways in crops (and plants in general): C3 (e.g. wheat, rice) and C4 (e.g. maize, millet), and they have different responses to heat and water stress. C4 plants are well known for having high water use efficiency and are better equipped to resist high temperatures. Typically, modelled crop yield responses to climate do not represent heat stress well. To capture the process that is causing the productivity downturn we need high frequency observations of the water and energy fluxes. This project aims to understand, quantify and model the photosynthetic response of different crop-types to high temperature and humidity deficits in India.

India is chosen for this project as it is a place where heatwaves are frequent and crop-production is key to livelihoods (India is expected to lose >5% of its yield of maize, potatoes, rice and wheat by 2050) but also due the availability of key observational networks needed for this project. Specifically, the project will focus on plant physiological mechanisms that affect the photosynthesis of the different crop types.

The project involves the use of novel observations with thermal cameras, combined with conventional local and EO observations. This novel data will allow to infer crop-choice strategies for economic resilience to heatwaves in the future. Specifically, hand-held far-infrared cameras clipped onto iPhones will be used to observe crop temperatures. Methods to observe the relative temperature will be explored: e.g. spraying some leaves with water (no water stress) and smearing some with petroleum jelly (no transpiration) (Fig. 1). Additioanlly, the methodology includes using hand-held IRGAs, Photochemical Reflectance Index (PRI) and chlorophyll fluorescence sensors to measure crop stomatal conductance and photosynthesis. Existing CEH-supported flux-stations in India will measure sensible/latent heat and crop net CO2 exchanges at larger scales. Large scale soil moisture observations will be available through the existing COSMOS project. Data will be used to validate and improve the Joing UK Land environment Simulator (JULES), the land surface model of the UK earth system model.

This PhD project will parallel a grant application on a closely related topic ‘CropEX’, which focuses on ozone rather than heat stress.

Applicants for a studentship must have obtained, or be about to obtain, a 2.1 degree or higher. If you have a 2.2 degree, but have also obtained a masters qualification, you are also eligible. Substantial relevant post-graduate experience may also be sufficient, please contact the supervisors for more information.

To apply please send your CV and a covering letter stating your suitability for the project to the project supervisor Dr E. Blythe ([Email Address Removed]).