Greenhouse experiment
One season later (Nov 2013 – May 2014), we raised these 320 genotypes
under conditions as above, yet under five water levels. One pot (10 × 10
× 10 cm) per genotype was included in each water level (1600 pots in
total). Per pot, 15 seeds of one genotype were sown in a 1:1 mixture of
nutrient-poor potting soil and sand, enriched with 0.1 g Osmocote® slow
release fertilizer (14-14-14 NPK; Scotts GmbH, Germany). On the first
and third day of the experiment, all pots were watered equally to
saturation to ensure seed germination. After germination was completed,
seedlings were randomly thinned to one per pot and five watering levels
were initiated (90 ml, 50 ml, 30 ml, 20 ml, and 15 ml per pot and
watering event, respectively). Watering was applied manually with
dispensers approx. every 2-3 days, i.e. when most plants in the lowest
water level showed strong signs of drought stress. Pots were randomized
across the greenhouse and re-randomized every three weeks.