2.1. Plant material and cultivation
Three experiments were carried out with the single-cropping
(June-bearing) strawberry cultivars ‘Korona’ and ‘Elsanta’
(Fragaria ananassa Duch). For Experiment 1 runner plants
were lifted in the field on July 7 and rooted directly in 10 cm
plastic pots in a glasshouse with 24-h LD and a minimum
temperature of 21 8C. On August 10 the plants were transferred
to the A ° s phytotron and exposed to 10-h SD for 5 weeks at
15 8C for floral induction. The plants received natural daylight
in daylight compartment for 10-h per day (8:00–18:00 h) and
were moved into darkness for the rest of the day in an adjacent
growth room. Following this 5-week SD induction period the
plants were exposed to varying degrees of chilling at 2 8C in
darkness (0, 2, 4 and 6 weeks) before the plants were
transplanted into 1.5 l plastic pots and set to forcing in two
growth rooms maintained at 18 8C with SD (10-h) and LD (24-
h) conditions. During the forcing period all plants received a
daily 10-h basic illumination with Philips HPI-T 400-W lamps
(270 mmol quanta m2 s1 PAR). Day length extension to 24-h
was provided by low-intensity light from 75 W incandescent
lamps (about 10 mmol quanta m2 s1), while the SD treatments
were in darkness for this period.