Refining drought stress measurement methods for banana – leaf temperature and δ¹³C of leaf and phloem sap

The COVID-19 pandemic has affected all of us, as well as hampered ongoing research. This was also the case for the PUI (Peaceful Uses Initiative) project on Enhancing climate change adaptation and disease resilience in bananacoffee cropping systems in East Africa (started in 2019). Planned research activities in Tanzania had to be called off. Fortunately though, KU Leuven (Belgium), partner in this research, allowed us to initiate last-minute research activities in Belgium, turning this drawback into an opportunity. KU Leuven hosts the world's largest banana gene bank and has proven experience and knowhow on assessing drought stress in banana. Against this background, an experiment was set up in an open-ground greenhouse, in cooperation with MSc student. The purpose was to (1) evaluate different stress parameters and measurement methods under progressing drought conditions and (2) improve our understanding of the δ¹³C signal as a proxy for water use efficiency in banana. An optimal and a deficit irrigation treatment were applied to nine mature banana plants (cv. Cavendish). Treatments were initiated at the end of June 2020. The soil moisture availability was followed up with TDR sensors for every individual plant and the micro-environment (air temperature (°C), relative humidity (%) and light intensity (μmol (m²s)^-1) was monitored with strategically placed sensors.