3.3. Soluble sugars
D-Glucose and D-fructose were the two most abundant soluble
sugars in kale leaves (Table 4). Photoperiod conditions affected
the content of both D-glucose and D-fructose in leaves harvested
prior to cold acclimatisation (Table 4). A 24 h photoperiod led to
63% and 88% higher content at 21/15 C of D-glucose and D-fructose,
respectively, whilst this effect was not detected at the lower
growth temperatures. High growth temperature combined with
12 h day length however, reduced the content of both D-glucose
and D-fructose.
The results showed that without exception levels of soluble
sugar in the leaf tissue increased in response to cold acclimatisation
(Table 4). The average content before and after cold acclimatisation
increased with a factor of 1.3, 2.1 and 3.2 for D-glucose, Dfructose
and sucrose, respectively. After cold acclimatisation, no
difference in the content of the soluble sugars between growth
treatments was detected (Table 4).