2.2. Crop management
Young plants were potted five weeks after cutting in pots with a diameter of 10.5 cm, in a substrate composed of peat (50%), coir (40%) and perlite (10%). They were placed in a glass greenhouse Fig. 1. Rose plants on a sub-irrigation table with the experimental mechanical stimulation device; Rosa hybrida ‘Radrazz’, Knock-Out®. on a 2.1-m2 (2.1 m × 1.0 m) shelf equipped with a nutrient solution tank, at a density of 28 plants/m2 (Fig. 1). A tensiometer was used to determine when to trigger subsurface irrigation when the water potential value reached −10 kPa. Mineral nutrition was provided by fertigation, with a liquid fertiliser (3-2-6) with a pH of 6.5 and an average electrical conductivity of 1.2 mS cm−1. Minimum air temperature was maintained at 16 ◦C, with aeration at 20 ◦C. Relative hygrometry was maintained at 70% by a fine misting system. Plants were submitted to a photoperiod of 16 h, with a minimum light intensity of 90 E s−1m−2, provided by 400-W high-pressure sodium vapour lamps. Experiments were carried out from 1st March to 22nd April 2010 (Exp. 1) and from 6th May to 22nd June 2010 (Exp. 2). Sixty plants were used for each experiment, including 30 control plants and 30 plants subjected to MS.