Agriculture Reference
In-Depth Information
have good F
1
seed production and sales at a reasonable price (Walton
2003). During seed production, special care must be taken to control
volunteer rice and red rice, thus requiring new
fields or very good crop
rotation practices.
Grain quality standards are very high in LAC and this creates addi-
tional challenges for hybrid rice breeding. In this region of the world,
people prefer long slender grain with low chalk, no aroma, high amylose
content, and intermediate to low gelatinization temperature. At the
same time, high head rice recovery (
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requirements. The use of Asian parents with different grain quality traits
increases problems with grain quality.
60%) is needed to meet millers
∼
B. Germplasm and Breeding Methods
Rice germplasm used in hybrid rice breeding in LAC has been restricted
to a few sources related to Chinese germplasm or germplasm from
IRRI. Early efforts in Colombia began in 1984 and were based on the
Chinese lines Zhenzhang 97A and V20A or IR lines such as IR58025A
crossed with elite lines and commercial cultivars from LAC (Holguin
et al. 1998). Hybrid rice research began in Brazil in 1984 with the
aim to combine male sterile cytoplasm with high outcrossing capacity
and produce adapted female parents using as basic germplasm lines
from China, Korea, and IRRI. As a result of these efforts, an elite male
sterile line (#046IA) was produced that combined allogamic traits from
Oryza longistaminata
and male sterile cytoplasm from Zhenzhang 97A
(Guimarães et al. 1996). To increase heterosis, a cornerstone of this
program has been the use of reciprocal recurrent selection methods
based on recessive male sterility (Guimarães et al. 1996). There are two
populations: the R population that provides the restorers and the B
population that provides the A/B lines. Both populations are improved
using a testcrossing scheme that uses the best A line (R population) and
the best R line (A/B population) as testers. Autocrossing capacity is also
considered in the improvement of the A/B population by measuring
seed production in male sterile plants in the S
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generation (Taillebois
et al. 2009). This collaborative program between Embrapa and CIRAD
released in 2010 a commercial hybrid, BRS CIRAD 302, for southern
Brazil with a yield advantage of 9
16% and premium grain quality
and more hybrids are under commercial testing in Colombia. The most
successful hybrid breeding program in the Americas is conducted by
Rice Tec Inc. with commercial products in the United States, Brazil,
Uruguay, and Argentina. The early A lines belonging to WA cytoplasm
were obtained from China
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s National Hybrid Rice Research Center
