Schonhof, Kläring, Krumbein,
Claußen, and Schreiner (2007) reported that low temperatures
increased the content of aliphatic glucosinolates in broccoli, whilst
high temperatures increased the levels of indolic glucosinolates.
Kale is highly tolerant to frost and it is not unusual that these
plants remain unharvested in the field late in the growth season,