Fig. 3. The vernalization responses of 12 winter wheat cultivars from 19 trials, and the f(V) predicted by the Morgan–Mercer–Flodin function (Eq. [2]). The sources of the observed data are in Table 1, and each point represents the fraction of full vernalization: 0 = unvernalized plants and 1 = fully vernalized plants. LN is the leaf number of plants at the onset of the vernalization treatment for cultivar Pioneer 2548. • = Pioneer 2548 - LN = 1, = Pioneer 2548 - LN = 2, = Pioneer 2548 - LN = 3, = Pioneer 2548 - LN = 4, = Pioneer 2548 - LN = 5, = Pioneer 2548 - LN = 6, = Arapahoe, = Karl 92, x = Osprey (T = 3°C), * = Osprey (T = 5°C), • = Hume, = Norstar, = Augusta, = Bezostaja, = Frederick, = Cheyenne, = Winalta, = Cappelle (Fowler et al., 1996), x = Cappelle (Brooking, 1996). VD, effective vernalization days.