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Requirements for inputs, particularly nitrogen, are relatively low. Barley
should be grown under moderate nitrogen fertility conditions because high
fertility will reduce kernel plumpness and increase lodging. The grain
protein target for malting barley is 11.5% to 13%, which must also be
considered in determining appropriate N fertilizer levels.
As a C3 plant, barley favors cool production conditions (15-30 °C)
and moderate precipitation (500 - 1000 mm annually). Cultivars that are
photoperiod sensitive require long days to flower. Both winter and spring
habit types exist. For winter barley, a vernalization period of two to
ten weeks below 50 °F is necessary. In general, winter barley genotypes
are not as cold hardy as winter wheat. Highest commercial yields tend
to come from central and northern Europe, where yields of 10 t/ha can
be obtained under intensive management.
No barley variety is adapted to all environments and, in fact, very
different gene pools have evolved in the major barley production areas
of the world. The gene pools may be defined by essential physiological
parameters that determine adaptation to a production environment - such
as vernalization and/or photoperiod response - or they may be defined
by evolutionary bottlenecks and the accidents of history, such as regional
preferences for two-rowed or six-rowed varieties.
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