Exploring the interaction between light intensity and rootzone water deficit stress as a means of improving berry phytonutrient content and Class 1 strawberry


Supervisors: Dr Mark Else (NIAB at East Malling); Prof Paul Hadley, Dr Carrie Twitchen (University of Reading)

This student will be registered with the University of Reading. Beginning in October 2022, the successful candidate should have (or expect to have) an Honours Degree (or equivalent) with a minimum of 2.1 in Plant Science, Biology, or other related science subjects.


Total environment-controlled agriculture (TCEA) systems offer great potential for a consistent supply of high quality and phytonutritious strawberries, provided that initial plant quality is high and growing conditions are fully optimised. However, this is often not the case. Although diurnal temperatures, photoperiods, light intensities, and wavelengths can all be controlled precisely, the optimum growing conditions for proprietary strawberry varieties are not known, and so Class 1 yields are significantly lower than anticipated in many TCEA systems. High relative humidifies often arise due to the constant high evaporative demand and imprecise irrigation scheduling, and so the energy costs associated with maintaining RH in the optimum range are often high.

Our previous work at East Malling showed that regulated deficit and transient deficit irrigation techniques could be used to improve resource use efficiency (light, water, fertiliser) and improve berry phytonutrient content whilst maintaining good commercial yields. The effect of a deficit-induced burst of ethylene production on antioxidant accumulation in non-climacteric strawberry fruit was also explored, and the work suggested that an interaction between light intensity and rootzone water deficits was more likely to raise berry phytonutrient content than either treatment alone.

Objectives and approaches

This PhD programme will investigate the role of hydraulic and chemical signals in the regulation of strawberry responses to targeted rootzone water deficits, and this knowledge will be used to inform, develop, and test new growing protocols for TCEA systems that incorporate beneficial stresses to improve resource use efficiency, marketable yields, and berry quality.   The lighting environment (intensity, wavelength, photoperiod) will be manipulated to maximise photosynthesis throughout the light period in TCEA systems, and to accommodate the diurnal decline in photosynthetic efficiency measured in strawberry. Sensor technologies will be deployed to monitor and control the growing environment, and to measure root, leaf, and fruit responses to applied treatments in real-time. Outputs from this plant environmental science-based CTP PhD study will include innovative growing protocols for proprietary strawberry varieties, and the resulting blueprints will help to inform commercial strawberry production in TCEA systems.


The successful candidate will gain a wide range of experience in plant physiology, agronomy and crop production as well as experimental design and statistical analysis.


Anyone interested should fill the online application form before the deadline of 17th June 2022. If need further help or clarification, please contact recruitmentctp@niab.com.

Contact Dr Mark Else for an informal discussion on research contents.