The relationship between plant growth and water consumption : A history from Greek philosophers to early 20th century scientists. Oliver Brendel Université de Lorraine, AgroParisTech, INRA, UMR SILVA Nancy, France email :
[email protected] Tel : 00 33 383394100 postal address: Oliver Brendel, INRAE, UMR Silva, F-54280 CHAMPENOUX, France Abstract The relationship between plant growth and water consumption has for a long time occupied the minds of philosophers and natural scientists. The ratio between biomass accumulation and water consumption is known as water use efficiency and is widely relevant today in fields as diverse as crop improvement, forest ecology and climate change. Defined at scales varying from single leaf physiology to whole plants, it shows how botanical investigations changed through time, generally in tandem with developing disciplines and improving methods. The history started as a purely philosophical question by Greek philosophers of how plants grow, progressed through thought and actual experiments, towards an interest in plant functioning and their relationship to the environment. This article retraces this history by elucidating the progression of scientific questions posed through the centuries, presents the main methodological and conceptual developments. Keywords Transpiration efficiency; water use efficiency; plant physiology; botany Introduction The ratio of biomass accumulation per unit water consumption is known today as water use efficiency (WUE) and is widely relevant to agriculture ( e.g. Vadez et al.2014; Tallec et al.; Blum 2009), to forest ecology (e.g. Linares and Camarero 2012; Lévesque et al. 2014), and in the context of global climate change (e.g., Cernusak et al. 2019). This ratio can be defined at various levels, from the physiological functioning of a leaf to the whole plant and at the ecosystem level.