Agriculture Reference
In-Depth Information
26% had increased grain length. Similar results were obtained in the
cross Oryzica 3/
Oryza ru
pogon
. In this population, microsatellite
(simple sequence repeat (SSR)) markers RM13 and RM242 located on
chromosomes 5 and 9, respectively, were associated with alleles derived
from
Oryza Ru
pogon,
affecting grain yield positively. Out of 69 QTLs
identi
pogon
, 18 (26%) were trait-
improving alleles derived from
Oryza ru
ed in the cross Bg 90-2/
Oryza ru
pogon
, which showed no
detectable negative effect on any measured trait, and these alleles can
be used for breeding purposes. Based on analysis of 125 simple sequence
length polymorphism (SSLP) and restriction fragment length polymor-
phism (RFLP) markers scored on 274 BC
2
F
2
families from the Caiapo/
Oryza ru
pogon
cross, Moncada et al. (2001) detected 2 putative
O.
ru
pogon
-derived QTLs for grain yield, 13 for yield components, 4 for
maturity duration, and 6 for plant height. In addition, different Oryza
chromosome segment substitution line (CSSL) populations have been
developed and characterized molecularly at CIAT using wild rice spe-
cies including
Oryza ru
pogon
,
Oryza glaberrima
,
Oryza barthii
,
O.
glumaepatula
, and
Oryza meridionalis
(refer to Section IV).
2. Strong and Regionally Relevant Rice Improvement Program
Through Productive Partnerships.
From 1975 to 1995, 250 rice culti-
vars were released in the region;
70% of them were introduced to
different countries through the Red Internacional para la Evaluación
Genética del Arroz en América Latina y el Caribe (INGER-LAC, its
English acronym) (GRiSP 2013), with most of them (90%) targeted to
∼
flooded environments. Of the new cultivars, 40% came from crosses
made at CIAT and several of the others have parentage from CIAT or
IRRI progenitors (Sanint 2004). Additionally, 152 cultivars were released
from 1996 to 2012 (GRiSP 2013). Modern semidwarf cultivars (MSVs)
now account for 93% of all
flooded rice production, representing
>
80%
of the total rice production in LAC. Furthermore, CIAT
s rice working
collection has served as the breeding platform for the development of
43 cultivars released since 2003 by the members of the Latin American
Fund for Irrigated Rice (FLAR) (Zorrilla et al. 2013).
These new semidwarf cultivars were rapidly adopted and grown by
farmers not only in Colombia but also throughout the region, thus
positively affecting rice production in LAC. Average yield in Colombia
went from 1.5 t ha
1
in 1965 to 4.4 t ha
1
in 1975 (Scobie and Posada
1977). Rubinstein (1985) reported a 20% increase in yields in LAC due
to the new cultivars, which spread initially to the tropical region of LAC
and later to the southern temperate region, once some tolerance of cold
temperature was found by IRGA
'
'
'
s and INIA
s breeders in segregating
