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Spring wheat is grown in regions with a very cold winter, or in Mediterranean
and subtropical zones. Spring wheat may also have a short vernalisation require-
ment. On areas with a mild winter and relatively high temperatures (6–10 °C), ver-
nalisation is protracted, so cultivars with a vernalisation requirement and those that
are photoperiod-sensitive can be sown in autumn without any danger of the plants
shooting before spring arrives, in which case ears in the booting stage could be dam-
aged by the cold or become sterile. Spring wheat also develops a deep root system
when sown in autumn, so it has better yield potential and yield stability than when
sown in the spring.
Durum wheat ( Triticum durum Desf.) has better drought and heat tolerance than
common wheat ( Triticum aestivum L.) , so it is more suitable for cultivation in a hot
climate than common wheat. The wider cultivation of the winter type is inhibited by
the fact that its winter hardiness is poorer than that of common wheat. Durum wheat
is cultivated on approx. 6 % of the total wheat-growing area, i.e., on 12–14 million
ha (USDA 2010 ). Countries with the largest areas sown to durum are the EU,
Canada, the USA, Turkey and North African countries with a Mediterranean
climate.
Spelt wheat ( Triticum spelta L.) is the cereal grown in cool, hilly regions of
Europe, but it is also grown as an alternative crop in the USA and Australia. Its total
sowing area is only a fraction of the durum area.
Wheat yields have tripled over the last 50 years, as demonstrated in Fig. 3.1. The
yield increase can be attributed chiefl y to the rise in average yields per hectare,
Fig. 3.1 World wheat production
Z. Bedő and L. Láng