192 – II.3. BRASSICA CROPS (BRASSICA SPP.)
B. juncea varieties well suited to mechanical harvesting. Today there is essentially
no commercial production of B. nigra and it has become a weed of waste places in many
regions. It is an introduced species to the Americas and Australia. It has never become
established on the Canadian prairies although it is present throughout much of the
United States.
B. rapa
B. rapa is generally believed to have originated in the mountainous areas near the
Mediterranean sea rather than the coastal areas (Tsunoda, 1980). As with B. nigra,
B. rapa had a wide distribution before recorded history. Indian Sanskrit literature first
mentions the plant about 1599 B.C. as “Siddharth” (Prakash, 1961). Burkill (1930)
proposed that the leafy vegetable forms were developed in China from the oilseed form
about 2 000 years ago. Seeds of both B. rapa and B. juncea were found in excavations of
the ancient village of Banpo, Xian, Shanxi Province, China that existed in Neolithic times
6 000-7 000 years ago (Liu, 1985). Turnip seeds were also found in pottery jars from the
5th century B.C. at the Yang-shao agrological site in Shensi Province (Chang, 1970).
Cultivation of B. rapa is also mentioned in the oldest collection of Chinese poetry,
Shi Jing (the book of Odes), written during the Chunqui period about 535 A.D. (Liu,
1985; Chapman and Wang, 2002). In Scandinavia, B. rapa seeds were being consumed as
early as 350 B.C. as indicated by their presence in the stomach of the Tollund man
(Renfrew, 1973).
Figure 3.32. Evolutionary geography of B. juncea, B. carinata and Sinapis alba
Source: Greatly modified from Hemingway (1995).
Sinskaia (1928) proposed two main centres of origin, with the Mediterranean area as
the primary centre for the European form, and Afghanistan with the adjoining portion of
Pakistan as the other primary centre. Asia Minor, the Transcaucasus and Iran were
considered secondary centres. Alam (1945) concluded that the Sarson and Toria types of
B. rapa, now grown as oil crops in India and Pakistan, evolved in the Afghan-Persian
area and migrated south to India and further east. McNaughton (1995a) concluded that
multiple domestication of the wild forms for oilseed occurred from the Mediterranean to
India about 2000 B.C. with later selection for short stature and leafiness in the Far East
(China) resulting in the numerous B. rapa vegetable forms. Tsunoda and Nishi (1968)
proposed that, with selection for increased leaf number, subsp. chinensis, and japonica
