2. Material and methods
2.1. Plant material and growth conditions
Block-rooted cuttings (8
±
1 leaves per plant) of chrysanthemum
(Chrysanthemum morifolium) ‘Zembla’ (Deliflor, The
Netherlands) were planted in plastic pots (diameter, 14 cm)
containing a peat-based commercial potting compost (Lentse potground
nr. 4; 85% peat, 15% clay) and acclimated under artificial
LD conditions (15 h photoperiod, 100
±
5 mol m−2 s−1 LED irradiance
of combined 80% red and 20% blue light [mixed RB light]) in
a climate chamber (Unifarm of Wageningen UR, The Netherlands).
After 5 days, the 30 plants were grown under individual light treatments
for 42 days. To avoid light interference among each light
treatment, we used customized fabric tents. The tents were continuously
ventilated to ensure no variation in growth conditions.
The day and night temperature was 22
±
0.2 ◦C, relative humidity
was 65
±
2%, and the CO2 concentration was ambient. Water
was supplied daily via overhead irrigation, and nutrient solution
(Hoagland, pH = 5.9
±
0.2, EC = 1.2 mS cm−1) was provided every 4
days. The plants were rearranged every 4 days to minimize edge or
position effects in the climate tents.