Water Deficit Response in Plant Populations

The experiment was conducted in a greenhouse of the Botanic Garden of the University of Coimbra in 2018, from January 24^th to May 15^th. Thirty seedlings from each of the nine selected populations from different mother lineages were individually transplanted into 1L plastic pots (8.6 × 8.6 wide and 21.5 cm deep) filled with a mixture of commercial soil and sand (1:1), resulting in a total of 270 pots. The pots were randomly assigned to a position in the greenhouse bench at the beginning of the experiment and rotated 1-2 times a week throughout the experimental time to account for microclimatic differences at different locations in the bench. Plants were kept at over 80% soil humidity until the beginning of the treatment application. Fifteen pots from each population were randomly assigned to the water deficit treatment, and the remaining 15 were used as control. Plants under the water deficit treatment were kept at 50-40%, and control plants were kept over 80% of field capacity. Soil water content was maintained by weighing the pots every two days and rewetting them to the required water levels. Plants were fertilized twice before the beginning of the water deficit treatment.