Successful growth, both vegetative and reproductive, are the final goals for plants. In the case of erops, knowing how plants make use of the available resourees to convert them into biomass, and espeeially, what is the main limiting factor for growth, is of paramount importanee. Although much effort has been dedieated to study how different agronomieal practices affect crop water relations and leaf gas exchange, we still lack the knowledge on the precise conditions that favour or limit plant growth. The classieal view, shared among most seientists, is that earbon limit plant growth. This coneeption makes sense sinee photoassimilates are the brieks to build the biomass. However, other proeesses are as important as C02 uptake. In particular, the maintenance of turgor is as critical for growing as photosynthesis. This misconception on the key limiting factor for growth, giving a major role to the souree aetivity instead of the sink aetivity, has emerged from the limitation and availability ofteehnical methods to evaluate both. In our researeh group we have developed novel methods to overcome these limitations, and we have made them suitable for their use under fieId conditions and long period of time during the growing season. Our results confirrn some opinions found in the literature and support, now with empirical evidence, that photosynlhesis, in most cases, is not lhe main limiting factor for growth but turgor. The new coneept "hours of turgor" emerges and will help us understand the perfonnanee of a speeies under a given environment and the funetional physiological traits thal make the difference in growth among species.

Presentación de la conferencia invitada en el BP2021: XXIV Reunión de la Sociedad Española de Biología de Plantas y XVII Congreso Hispano-Luso de Biología de Plantas, 7 y 8 de julio de 2021. online

This research was supported by Spanish Ministry of Scienee, Innovation and Universities (research project AGL2015-71585-R). A.P-A was the recipient of a contract from FPI-CSIC program (Spain).

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