Hayes and Garber - Cucurbit Breeding

CHAPTER XII
FLAX AND TOBACCO
FLAX
Flax has been reported to have been grown by the Lake
Dwellers of Switzerland as early as 4,000 to 2,000 years
B.C. (Chapter I). Although the Egyptians and Hebrews used
flax to make clothing in very ancient times, little is known of the
origin of our present cultivated varieties.
Species Crosses.
Tammes (1911, 1915, 1916) has made some
interesting genetic studies of flax species crosses. Reciprocal
crosses were made between cultivated varieties of Linum usitatissimum
and the wild species L. perenne, austriacum, narbonnenese,
grandifiorum, and angustifolium. No seeds capable of germinating
were obtained except in the angustifolium cross. This was
considered a good cause for believing thatL. angustifolium has the
best right of any of the wild species to be considered the ancestral
form of cultivated flax. This wild species differs from the common
cultivated varieties in that the seeds and capsules are smaller, the
edges of the partition walls of the capsule are hairy, and the capsules
open at maturity. In general, crosses between hairy and glabrous
races showed dominance of the hairy condition in FI and a segregation
of 3 hairy to 1 glabrous in F The 2 open type of capsule
.
was imperfectly dominant in FI, i.e., the capsules did not open
as widely as in the open parent. Segregation occurred in F z
.
Parental types, i.e., homozygous open and homozygous closed
lines, were produced in later generations. Three or four factors
were necessary to explain results.
Interrelation of Factors for Flower and Seed-Colors.
Careful
studies have been made of the interrelation in inheritance
of various flax characters (Tammes 1911, 1914, 1915, 1916).
The results were carefully analyzed. Three factors called A, B,
and C, were shown to be necessary for the production of dark
blue flowers. B and C together produce light blue flowers, and
A is an intensification factor which in the presence of B and C
produces dark blue flowers. When C is
homozygous in the presence
of B,
the petal.
the veins of the petal are darker than the rest of
The veins are the same color as the rest of the petal
when C is heterozygous in the presence of B, B and A give the
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