Agriculture Reference
In-Depth Information
4. Advances in Grain Quality.
All of IRGA
s semidwarf cultivars have
long and slender milled grains, with high amylose content and low
gelatinization temperature. After cooking, the grains are soft and non-
sticky, remaining the same way after cooling and reheating. Old cultivars
such as BR-IRGA 409 and IRGA 417 are still considered quality stan-
dards for the Brazilian market and farmers get a 10% premium price.
The release of new cultivars IRGA 425, IRGA 426, IRGA 427, IRGA 429,
and IRGA 430 marked very signi
'
cant progress in this trait, and today it is
fair to state that thesenewalternatives have highyieldpotential associated
with high industrial and cooking grain quality. Thus, IRGA is delivering
more competitive products to the market and catering to the growing
demand of consumers.
5. Advances Related to Blast Resistance.
Breeding for genetic resist-
ance to blast is the main objective of IRGA
is rice breeding program. This
biotic stress is caused by
P. oryzae
and
Magnaporthe oryzae
(the perfect
form), and it is the most important disease in southern Brazil, where
damage can reach 100% depending on the degree of cultivar suscepti-
bility, sowing date, andweather conditions. The use of genetic resistance
is considered the most economical and environment friendly strategy
to minimize losses caused by blast. Thus, IRGA receives an important
contribution from CIAT and FLAR, with the introduction of sources of
blast resistance and their use in the crossing program.
Annually,
'
800 genotypes are introduced fromCIATandFLAR, includ-
ing nurseries of breeding lines showing durable resistance to blast. These
breeding lines are phenotypically evaluated at Rice Experiment Stations
in Cachoeirinha and Santa Vitória do Palmar, and also in the blast nursery
(
∼
field information, the best lines are
selected for crosses in the next crop season. To illustrate the progress
made in improving blast resistance at IRGA, Funck and Kempf (2011)
found 36% and 56% of blast-resistant breeding populations out of a total
of 842 and 746 F
3
and F
5
generation materials, respectively. These crosses
involved CIAT and FLAR germplasm as gene donors for this trait.
“
hot spot
”
) in Torres. Based on this
6. Future Perspectives.
The main challenge of IRGA
s rice breeding
program in the near future is to maintain the progress in combining high
yield potential with excellent grain quality, as shown by cultivars IRGA
417 and IRGA 424. The second most important need is the replacement
of early- to medium-maturity herbicide-resistant cultivars by cultivars
with higher yield potential. These requirements are being ful
'
lled with
the delivery of IRGA 424RI, IRGA 429, and IRGA 430, which will be
available to commercial areas in the 2014
-
2015 crop season.
