when winters are mild or rapidly get milder as we have seen in the recent past. These
effects are well understood in so-called winter and spring cereals. ‘Winter varieties’
will not set ears unless they experienced a cold winter as it naturally occurs in their
steppe-type original habitats. ‘Spring cereals’, cultivars sown in spring, have very
little or no chilling requirement for initiating the reproductive phase.Awinter variety
sown in a climate with a warm winter will thus fail to produce a harvestable crop,
but remain trapped in the vegetative life phase (a green meadow, Colour Plate 5).