Agriculture Reference
In-Depth Information
number is 32 and the plants are thought to be autotetraploids (Toyama and
Wakamiya, 1990). In growth the plants resemble chives, but the leaves and
flower stalks are distinctive (see Fig. 1.1).
The leaves are slender and 30-60 cm long. The crop develops rather
elongated bulbs in the spring and early summer and then becomes summer
dormant, the foliage withering and dying back from mid-summer until the
autumn. It is therefore grown as an autumn-planted crop to produce an early
summer bulb harvest. The bulbs are grey-white or purple, have a thin trans-
parent skin and are rather oval in shape. Inflorescences, bearing an umbel of
six to 30 reddish-purple flowers on a stalk 40-60 cm long, may develop in the
autumn, after summer dormancy. If an inflorescence forms, the swollen leaf
bases of the shoot axis where it terminates wither, and further shoot and bulb
development occurs to the side of the inflorescence stalk. As a consequence,
unlike the other allium crops, the inflorescence is to the side of the main
growing shoot, not emerging from its centre.
There are many local strains of rakkyo in China and Japan, most of them
not fully characterized, but within Japan the three cultivars 'Tama Rakkyo'
(meaning ball-type rakkyo), 'Rakuda' and 'Yatsufusa' are distinct (Toyama and
Wakamiya, 1990). Cv. 'Tama Rakkyo' has short, thin leaves and each plant
produces ten to 25 small (1.5-3.0 g), white bulbs that are suitable for high-
quality pickles. Cv. 'Rakuda' forms taller, more robust plants which typically
produce six to nine rather elongated bulbs weighing 4-10 g. Cv. 'Yatsufusa'
produces smaller bulbs with a narrow, firm neck and are favoured for pickling.
It matures earlier and is lower yielding than cv. 'Rakuda'.
Chives, Allium schoenoprasum L.
This is the most widely distributed allium species. It grows wild in Eurasia and
America and, being very cold hardy during its winter dormancy, it grows in arctic
regions at latitudes as high as 70°N. At low latitudes it grows in mountainous
areas - for example, in northern India. It is a plant of moist soils in damp meadows.
Chives have been grown for their green, onion-flavoured leaves as a crop in Europe
since the 16th century (Poulsen, 1990). In the wild, many ecotypes and biotypes
differing in size exist, but these have been shown to be interfertile, and therefore all
of the same species. The wild species is also very variable in its chromosome
number. Diploids, with 16 chromosomes and tetraploids, with 32 occur, as do
irregular chromosome numbers that are not multiples of 8.
The plants form dense clumps of low-growing, narrow, hollow leaves (see
Plate 1, Fig. 1.1 and Table 1.2). An axillary bud develops and forms a side shoot
after every two or three leaves has formed, and thereby the plants develop into
a cluster of shoots. The shoots remain attached to each other on a short
rhizome, and the plants do not produce bulbs. The plants become dormant in
short day-lengths (see Chapter 4).
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