(go to
KOMUGI Home) (go
to WIS List) (go to NO.79
Contents)
3. Objectives and results
of barley (Hordeum vulgare L.) breeding
The main objectives of barley breeding in Japan are as follows:
early maturity, cold resistance including tolerance to deep snow,
short strong culm, high-yielding ability, disease resistance (barley
yellow mosaic, barley yellow dwarf, powdery mildew, scab, etc.) and
improved grain quality.
1) Breeding for early maturity, cold resistance, short strong culm
and high-yielding ability: In Japan barley is sown in autumn, except
in Hokkaido. Barley is the second crop in a rotation with rice or
summer upland crops. Consequently, the interval between the
harvesting of barley and the transplanting or sowing of the
succeeding crops is very short. Double cropping is not possible in
the northern part of Japan. To prevent maturity falling in the rainy
season, early June to late July, it is essential to breed cultivars
that mature as early as possible.
In the case of 6-rowed hulled barley, tall and late maturing, normal
types of barley used to be grown, especially in Kanto district.
However, due to the increased application of chemical fertilizers,
improvement in lodging resistance of barley cultivars has become
necessary. In order to breed cultivars resistant to lodging, there
are two breeding strategies: 1) reduction of culm length, and 2)
increase of culm stiffness. In the first strategy, the uz gene
has been used for reducing the culm length. Tall and late maturing,
normal types have been replaced by the semi-dwarf "uzu" type of
cultivars which are early maturing and short, but retain a high
yielding potential. In the second strategy, the cultivar Haganemugi
has been used as a gene source for increasing culm stiffness.
Haganemugi has stronger culm as a result of a thicker culm wall and a
larger culm diameter (Oda et al. 1966). This results in a higher
resistance to culm breaking when compared with a representative "uzu"
type, Sekitorisai 1 (Table
2). Several
cultivars have been developed from crosses involving
Haganemugi.
2) Breeding for resistance
to barley yellow mosaic virus (BaYMV): Barley yellow mosaic caused by
BaYMV previously inflicted serious damage especially on two-rowed
malting barley. Gene sources and virus strains have been identified,
and effective resistant cultivars have been developed
(Table
3).
In Japan, three virus strains, I, II and III, have been identified
(Usugi et al. 1985; Kashiwazaki et al. 1989). Strain I shows the
widest distribution in the country followed by strain II, and strain
III now occurs in a limited small area in Ibaraki Prefecture (Usugi
et al. 1985; Kashiwazaki et al. 1989).
Five resistance genes, Ym, Ym2, ym3, ym4 and Ym5(t),
have been identified in Japan (Table
3). The variety
Mokusekko 3 has two resistant genes Ym and Ym5(t)
(Makino, personal communication). Ym is an incompletely
dominant gene and linked to the gene K conferring hooded lemma
with a recombination value of 29.4% on chromosome 4 (Takahashi et al.
1970). The resistance reaction of Ym to BaYMV strains I, II
and III is probably S (susceptible), R (resistant) and R,
respectively (Makino, personal communication). Ym5(t) is also
incompletely dominant gene and linked to the complex loci
(Est1-Est2-Est4) for the esterase isozymes with the
recombination values ranging from 1.26 to 5.01 % on chromosome 3
(Konishi et al. 1989). The resistance reaction of Ym5(t) to
BaYMV strains I, II and III is R, R and S, respectively (Makino,
personal communication).
The variety Mihorihadaka has the resistant gene Ym2
which is incompletely dominant and linked to the gene n conferring
naked caryopsis with a recombination value of 31.4% on chromosome 1
(Takahashi et al. 1970). The resistance reaction of Ym2 to BaYMV
strains I, II and III is R, S and R, respectively (lida et al.
1992).
<--Back | -->Next
(go to
KOMUGI Home) (go
to WIS List) (go to NO.79
Contents)