The canephora species of coffee is very
different from the arabica; it is as robust in taste as it is in its
resistance to diseases and pests; unfortunately, in this case strong is
not the best, and its flavor is not as desirable as that of arabica.
Consequently, robusta accounts for less than 30 percent of world coffee
production, in spite of being cheaper in price. Robusta's commercial use
is primarily in blends, where its full body is appreciated, and in
soluble, or instant coffee, where the processing reduces its more
obtrusive flavor. Although robusta trees must be pollinated or grown
from cuttings, they are far easier to grow, and when many arabica
plantations were destroyed by rust disease in the second half of the
19th century, many estates were replanted with robusta trees. It is now
grown throughout the tropical zone, but most of the world's robusta
comes from the West and Central Africa, South-East Asia, and Brazil,
where it grows in altitudes from sea-level up to 700 meters.
Robusta can withstand heavier tropical
rainfalls of 300 cm or more, although, as with all coffee, the trees
should never stand in water. Conversely, the shallow roots of robusta
enable it to live successfully where rainfall is unpredictable or even
scanty. Similarly, it survives when equatorial temperatures sour,
although its happiest at an average temperature somewhere between 24-30oC.
Robusta trees flower rather
irregularly, and take 10-11 months to go from blossom to mature cherry.
The ripe cherries are generally picked by hand, except in Brazil where
the flat terrain and vast spaces allow machine harvesting. Robusta is
processed mostly by the "unwashed", or dry method, and the beans are
smaller and more hump-backed than those of arabica; they are also often
distinguished by small points at either end of the central "crack" on
Robusta trees produce a slightly higher
yield per hectare than do arabica trees. The most common varieties of
robusta are conilon from Brazil, the Java-Ineac, Nana,
Kouilou and congensis.