Agriculture Reference
In-Depth Information
(HRRC) and the male parents were
indica
cultivars from southern China
that are traced to IRRI materials (Walton 2003). The standard pedigree
method is followed for most breeding efforts that are directed to meeting
requirements for yield advantage, grain quality, and outcrossing capac-
ity (Tsuchiya et al. 2003). The efforts in the Southern Cone began in 1992
for testing hybrids in a winter nursery and by 2003 the
first hybrid
(AVAXI) was launched. Since then, several hybrids, including those
with IMI herbicide tolerance (Clear
eld System
), have been released
(Ritter et al. 2009). This trait has shown its importance for raising
productivity under the direct-seeding system by improving red rice
control. Another hybrid breeding program began in Brazil in 2003
-
2004 among IRGA, Ana Paula Farm, and the Hunnan Rice Research
Institute. Similarly, this program has been using Chinese germplasm as
raw material and, by 2010, it had released its
first commercial hybrid,
named QM 1010.
Despite all the efforts, years after the
first launching, the area under
hybrid rice in Latin America is very low. Commercial hybrids are being
planted on
70,000 ha in Brazil, Uruguay, and Argentina in the South-
ern Cone and commercial testing is being done in several countries in the
tropics. Three problems lie behind this slow adoption: low grain quality
(high gelatinization temperature, low amylose, high chalkiness, and low
whole-grain yield), low yield advantage compared with inbred cultivars,
especially in high-yielding environments, and high seed price.
∼
C. The CIAT Rice Program on Hybrid Rice
Hybrid rice technology is an approach to increasing rice productivity in
Latin America; however, it represents the challenge of producing hybrids
adapted to direct seeding with high grain quality standards and develop-
ing seed production systems under direct seeding. For this reason, CIAT
began a hybrid breeding program in 2009. The objectives are to (1) develop
experimental hybrids with high heterosis, disease resistance, and good
grain quality for the LAC market; (2) develop new cytoplasmic male
sterility (CMS) pairs using the WA system with good combining ability
and good adaptation; (3) develop new thermosensitive genetic male
sterility (TGMS) lines with good combining ability and adaptation;
(4) develop new restorers for the CMS system; and (5) establish pilot tests
of seed production using direct seeding. The initial testcrosses by CIAT
using IRRI females or FLAR restorers weremade in 2009. By 2011, the
rst
19 experimental hybrids were tested at several locations in LAC under
different seeding systems during the rainy season. In the 2012
-
2013
season, extensive testing was done in the Southern Cone and the tropics.
