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Development Heterotic Groups Based Combining Ability Inter specific Hybrids Performance Yield Fiber Quality Traits
35
Center [CIMMYT] and five major commercial lines
from China). According to SCA_PY method, they
classified CML171, CML161, CML166 into one
heterotic group; Chang 631/o2, Zhongxi 096/o2 into
another heterotic group; and Qi 205 into a third
heterotic group.
Huang and Li (2001) evaluated 45 maize inbred lines
from China, U.S. Corn Belt, and tropical regions by
using 44 restriction fragment length polymorphism
(RFLP) markers equally distributed across the 10
maize chromosomes. The 45 inbred lines were
grouped into six heterotic groups: Mo17 was assigned
to group II; Tangsipinttou (TSPT) and Huangzao 4
(HZ4) were assigned to group IV and Dan 340 was
assigned to group VI.
Menkir et al. (2004) used two testers representing the
two heterotic patterns to test 38 tropical maize inbred
lines. The two testers successfully classified 23 of the
38 tested inbred lines into two heterotic groups based
on the SCA_PY method.
Fischer et al. (2010) identified two heterotic groups in
triticale by employing principle coordinate analysis
and an enumeration algorithm for maximizing F
1
performance, mid parent heterosis, and σ2 GCA/ σ2
SCA ratio for grain yield. Twenty one inbred lines and
their 210 diallel crosses were evaluated for grain
yield at five agroecologically diverse locations in
Germany.
Realizing the need for developing potential
interspecific (
G. hirsutum x G. barbadense
) hybrids, a
detailed study was initiated at UAS Dharwad to
identify hirsutum and barbadense genotypes capable
of giving potential interspecific hybrids. Based on this
study done during earlier years in 2009-2010 two
barbadense DB 533 and DB 534 and four hirsutum
DH 98-27 (T
1
),
ZCH 8 (T
2
), 178-24 (T
3
) and DH
18-31 (T
4
) lines giving best hybrids (H x B)
combinations between them were selected. After
identifying this heterotic box, these barbadense lines
DB 533 and DB 534 were crossed in 2007-2008 and
the material was advanced during succeeding years.
To confirm the potentiality of heterotic group, the
detailed evaluation of interspecific hybrids involving
these lines along with other crosses was taken up
during 2010-2011. The main objectives of this study
are 1) development of hirsutum
vs
barbadense
heterotic groups 2) To determine combining ability
effects (
gca
and
sca
), variances (GCA and SCA),
combining ability patterns of these barbadense and
hirsutum lines. 3) Comparison of hybrids based on
heterotic box with checks and other interspecific
hybrids.
1 Results
Brbadense lines were crossed to hirsutum testers in
Line x Tester fashion to determine whether the
heterotic groups (2 barbadense and 4 hirsutum lines)
formed is potential. This Line x Tester study is
denoted as YHB trial fast to distinguish it from other
studies. After determining potential of the heterotic
box, the 8 interspecific crosses were compared with
commercial checks and many other potential
interspecific crosses developed by the centre. This
study distinguished as best HB trial and the results are
presented below.
1.1 Line x Tester for confirmation of interspecific
heterotic groups
1.1.1 Analysis of variance for combining ability
Analysis of variance for combining ability done with
respect to hybrids are summarized in Table 1 for eight
characters. Among the lines (males), the mean sum of
squares (MSS) were not significant for all characters
except mean boll weight and seed cotton yield which
showed highly significant. Testers (females) exhibited
significant difference for four characters seed index,
ginning outturn, lint index and seed cotton yield which
showed highly significant. Whereas, line x tester
interactions were highly significant for all characters
except plant height and number of sympodia per plant
which recorded not significant differences.
The estimates of variance due to general combining
ability (GCA), variance due to specific combining
ability (SCA), the magnitude of SCA variance were
greater than GCA variance for all 8 characters and
the variance ratio was less than half in these traits
(Table 2).
Cotton Genomics and Genetics