GE Xin

Ph student
in Plant Ecophysiology and Bioclimatology

Équipe MAGE:

I am a PhD candidate in crop physiology and modelling, jointly trained at Nanjing Agricultural University and INRAE LEPSE. My research focuses on quantifying the effects of combined heat and drought on wheat physiological processes and on improving the representation of these processes in crop models under current and future climate conditions.

Start of the PhD: 01.01.2023

Subject: Process-based modelling of wheat growth, physiological regulation, and yield formation under combined post-anthesis heat and drought stress

Abstract
The objective of my PhD research is to understand how combined heat and drought stress modify key physiological processes in wheat and how these changes affect crop performance and yield. The study focuses on stomatal conductance, photosynthesis, transpiration and organ temperature, because these processes determine carbon assimilation, water use and the thermal environment of the plant.
The experimental component includes multi-year field observations and controlled-environment studies designed to monitor high-frequency changes in gas exchange, transpiration and the temperatures of leaves and spikes during natural and induced stress events. These datasets reveal marked differences between organs, clear diurnal patterns in stress sensitivity and frequent divergence between organ temperature and air temperature under combined stress.
Based on these physiological observations, I develop a unified gs-ET-Tc model that combines stomatal regulation, Penman-Monteith energy balance and radiation absorption by different plant organs. The model explicitly simulates leaf and spike temperatures, which allows a detailed quantification of how heat drought interaction constrains water loss, and how these limitations influence crop performance.
In the final stage of the work, the improved model is applied across a range of environmental conditions and future climate scenarios to evaluate their consequences for transpiration patterns, thermal stress and yield. By linking empirical measurements with a mechanistic modelling approach, this research advances the understanding of heat drought interaction in wheat and improves the capacity of crop models to assess climate impacts and support adaptation strategies.

Key words: Crop model, Energy balance, Evapotranspiration, Gas exchange, Heat drought interaction, Wheat.

Supervisors
Nanjing Agricultural University: Yan Zhu (PhD supervisor), Bing Liu (co-supervisor)
UMR LEPSE, MAGE team: Pierre Martre (co-supervisor)