Proceedings of the Fifth Asian Regional Maize Workshop - Search ...

and reverse inbreeding process. Advanced sublines originating from a common early generation
line, (say S3) can be recombined to develop an early generation 'FRIP' line. several hybrids
gave outstanding performance outyielding commercial hybrids and OPVs as check entries (Srinivasan
et a7. 1992).
Table 6.
Top performing non-conventional hybrids.
Hybrid type
Superiority (~
over check)
Intervarietal hybrids
Family hybrid
Double topcross
Topcross
15-18 ~
20-30 ~
25-30 ~
33-40 ~
Table 7.
Top performing conventional hybrids.
Hybrid type
Superiority (~
over best EVs)
Double cross
Three-way cross
Single cross
20-26 %
26-33 ~
40-53 ~
So far, CIMMYT has restrained from distributing international hybrid trials. It seems
that there is demand for such trials which would greatly benefit certain national programs who
have little or no effort on hybrid development. The small seed companies will equally benefit
from such trials in absence of enough resources that could be devoted to hybrid research.
Beginning in 1994, CIMMYT will be distributing international hybrid trials from lowland tropical,
subtropical, and highland programs.
e. Announcement of CI~ i nbrads
In the past 3 years, CIMMYT maize program has made three announcements/releases of maize
inbred lines. CIMMYT lines are designated as 'CML' referring to CIMMYT maize lines. The first
announcement consisted of 74 tropical (CML 1-74) and 65 subtropical (CML 75-139) lines developed
at CIMMYT headquarters in Mexico. The second announcement was made in 1992 and it consisted of
99 CML lines (CML 140-238). The lines represented 33 tropical QPM (CML 140-172), 22 subtropical
QPM (CML 173-194), 22 mid-altitude (CML 175-216), and 22 lowland tropical (CML 217-238). CML
lines 140-194 were developed in Mexico and the rest (CML 195-238) were developed at Harare,
Zimbabwe with special emphasis on resistance to maize streak virus. The third announcement was
made in 1993 and it comprised 8 highland lines (CML 239-246).
The announced lines are freely available to everyone on request. Lines are being tried in
hybrid combinations both by public and private company breeders. More information on the use of
these lines will become available in the near future. These lines will be useful to all institutions
concerned but will be particularly helpful to breeders of small companies and national
programs with insufficient resources for hybrid work. It may be pointed out that in some
populations enough lines have been announced. Lines from the same population which adapt well in
a spec;fic location could be recycled to generate new lines. The good performing CIMMYT lines
could also be recycled with locally adapted lines. At least 50 more tropical lines are expected
to be announced in the near future. The announcement of new and diverse lines will continue
periodically to accelerate hybrid maize breeding programs in the developing world.
199