Sugar Beet, Energy Beet, and Industrial Beet - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 83

Humans have used beet as early as the late Mesolithic, and it was probably first
domesticated for their leaves for food and medicinal uses [ 14 ]. Selection
transformed the annual habit into the more or less biennial habit characteristic of
current crop types. The origin of the swollen root is not clear, but by the eighteenth
century, large swollen roots were widely used for food and fodder. The sugar beet
was selected from fodder beets from the late 1700s, and the first dedicated sugar
beet varieties were available by the 1860s [ 15 ]. Sucrose production from sugar
beets is an industrial process and requires dedicated factories for processing roots
and refining sucrose. Improvements in processing have been continuous over the
past 150 years, and breeding over this time has increased sucrose content of early
varieties from 15 % [ 16 ].

Beet morphological variation is impressive. In table, fodder, and sugar beets, the
shape and morphology of the enlarged and (ideally) unbranched taproot is
completely different from wild types, whose roots are thin and highly branched.
In leaf beet, only the foliar apparatus has been modified in size and shape, often
with thick, wide, and long petioles in a wide array of appealing colors. Color in beet
is taxonomically diagnostic, consisting of the alkaloid betalain pigments that
replace anthocyanins but serve similar functions as anthocyanins in most angio-
sperms [ 17 , 18 ].
Common beet pathogens do not discriminate between crop types, so breeding for
disease resistance is a common feature of all beet improvement programs. Often,
resistances identified in sugar beet have been transferred to other crop types, and
vice versa, although breeding efforts for vegetable (e.g., leaf and table beets) and
fodder beets are not as extensive as for sugar beet. Wild beets will continue to be
used as a resource to improve the current cultivated germplasm [ 14 , 15 ].

10 % (fresh weight) to a US industry average

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Areas of Production

Sugar beet is grown on every continent except Antarctica but yields best in
temperate climates, with major areas of production found across Northern Europe
and North America. Total production of sugar beet is relatively stable worldwide.
Yield of sugar beet per unit area has doubled since the early 1960s, and thus the
total area of beets in cultivation has decreased worldwide (Figs. 5.1 and 5.2 ). In
drier climates, irrigation is necessary. In warmer climates, sugar beet is often grown
as a winter crop, notably in North Africa and the Imperial Valley of California
(USA). Some of the excess factory production capacity caused by EU regulation
changes in Northern Europe was diverted to energy production, particularly in
France, Germany, and Scandinavia, and the short-term trend for beets as an energy
crop, for both bioethanol and biogas (methane), will likely continue to develop in
the North Atlantic and Baltic areas [ 19 - 21 ]. Beets grown strictly as an energy crop
are not currently planted in the USA or UK, although a factory is being built in
Mendota California for year-round beet ethanol production [ 113 ] and energy beets
are being considered as cool season crops in the Mid-Atlantic and Mid-South
regions of the USA [ 22 ] where it is anticipated that sweet sorghum and other