II.3. BRASSICA CROPS (BRASSICA SPP.) – 197
B. carinata
B. carinata, commonly called Abyssinian or Ethiopian mustard or simply “carinata”,
is an amphidiploid species derived from and containing the full genomic complement of
the putative parental species, B. nigra (black mustard) as the female and B. oleracea as
the male (Uchimiya and Wildman, 1978; Palmer et al., 1983; Song, Osborn and Williams,
1988b; Erickson, Straus and Beversdorf, 1983). The plant is cultivated on a small scale on
the Ethiopian plateau. B. carinata may have originated from a hybrid between kale,
which is grown on the plateau, and wild B. nigra, which is also present. However, this
species, as with others in this group, almost certainly originated in the Mediterranean
basin where the two putative parental species were growing in close proximity. It is
believed that the cross occurred many eons ago when the climate on the African side of
the Mediterranean was moist and lush. However, as the climate of this region became
dryer and hotter, B. carinata, together with the plant community of the region that
included castor oil plant and coffee, moved to the south and became isolated in the
Ethiopian highlands. Thus, Ethiopia in effect preserved the environment of the centre of
origin of B. carinata (Figure 3.32). Farmers of northeast Africa grow the plant both for its
leaves, which are plucked, boiled and eaten, and for the edible oil in the seed. The local
common name for the crop is gomenzer. The interspecific cross that created this species
does not appear to have occurred elsewhere in nature or, if it did, the progeny did not
survive. There is no commercial production of this species, other than in Ethiopia and
neighbouring countries where the crop is grown on small holdings or in kitchen gardens.
However, the species is being investigated and bred for potential commercial production
in Australia, Canada, India and Spain.Sinapis alba
Sinapis alba has its centre of origin in the eastern Mediterranean region (Figure 3.32)
and wild forms are present around most of the Mediterranean littoral (Hemingway, 1995).
In China, S. alba appears to have been cultivated by the middle of the first
millennium A.D. (Hemingway, 1995).Reproductive biology
Generation time and duration under natural and managed conditions
Generation and flowering times are discussed in the above sections dealing with
cultivation and management.ReproductionFloral biology^4
The basic floral characteristics of all the Brassica species included in this chapter are
essentially the same, differing only in flower size. The floral arrangement in Brassica
species is typically a corymbiform raceme. Flowering is indeterminate beginning at the
lowest part of the main raceme and auxiliary branches, and continuing upward.
The inflorescence may attain a length of 1-2 m. The buds begin opening under the
pressure of the rapidly growing petals. The process of flower opening begins in the
afternoon and is all but complete very early the following morning. The stigma is
receptive from three days before to three days after the flower opens (Mohammad, 1935).
Day length can play a critical role in initiating bolting of the flowing stem. Species such