The Importance of Rice
Over the last 70 years, the region’s per capita consumption of rice has increased
threefold, rising from 10 kilograms in the 1920s to 30 kilograms in the 1990s. Rice has
become particularly important in the diets of the poor, who constitute about 40 percent of
Latin America's total population.
The displacement by rice of traditional staples, such as cassava and plantains, which
are bulkier and more perishable, has its roots in rapid urbanization throughout the
region. Because of its convenience, rice has found sizable markets in recent decades in
the cities, where nearly three-quarters of all Latin Americans currently reside. Rice has
many other dietary virtues as well, being rich in vitamins and minerals, low in fat and
salt, and free of cholesterol.
Rice is a versatile crop, with varieties adapted to a wide range of climates, soils,
and moisture conditions. In Latin America about 55 percent of the crop (3.7 million
hectares) is concentrated in wetlands, and roughly two-thirds of that area is irrigated.
The other 45 percent (3.0 million hectares), referred to as "upland" rice, is
grown under rainfed conditions.
Most upland rice in Latin America is mechanized; about a third is cultivated manually.
Upland rice has served as a pioneer crop during this century, with mechanized production
spreading into Latin America's vast tropical savannas and manual cultivation penetrating
the margins of its tropical forests.
Irrigation provides the best conditions for rice production, so naturally irrigated
areas have registered the most gains in recent decades. Irrigated rice is grown mainly on
a commercial basis in Latin America, involving almost universal adoption of modern
varieties and widespread use of agrochemicals for fertilization and pest control.
Research for Development
Challenge
Given continued rapid growth of Latin America's metropolitan areas, and of its
population generally, more efficient rice production is a matter of considerable urgency.
Unless marked progress is achieved in the lowland and upland areas already under rice
cultivation, production will undoubtedly spread further into the tropical savannas and
forests, increasing the pressure on natural resources in these fragile agroecosystems.
One of the major obstacles to rice improvement in Latin America and other regions is
that the crop's yield potential has reached a plateau, which conventional breeding has
been unable to surpass. Other barriers to higher, more stable yields include several major
diseases and pests in both lowland and upland environments and the prevalence of infertile
acid soils in the latter. Disease and pest problems often prompt farmers to use excessive
applications of agrochemicals, which pose a threat to human health and the environment.
To help overcome these problems, rice scientists at CIAT are engaged in a well-focused
program of research that integrates advanced techniques with conventional plant breeding
and related research. A central aim of this work is to broaden the genetic base of rice
production, providing genes for useful traits that have not previously been available to
the region's rice growers.
Though most of the gains in Latin America's rice production so far have been registered
in irrigated lowlands, rice in the rainfed uplands—especially the vast savannas of
Brazil, Colombia, Venezuela, and Bolivia—continues to occupy an important place in
the region’s agriculture. A central challenge of research for this environment is to
make rice production more competitive and profitable by providing technology that
increases productivity and reduces costs.
In the sections that follow, we briefly describe the main lines of rice research at the
Center, with emphasis on recent outcomes.
Conventional Population Improvement
CIAT's current rice breeding strategy is focused on the development and improvement of
populations, or gene pools, through recurrent selection. Our aim is to offer national rice
programs diverse sources of potential parents for crossing, as opposed to finished lines
for release as varieties. Breeding populations of both lowland and upland rice are widely
distributed in Latin America for evaluation and selection.
In connection with this work, rice scientists at CIAT have identified various
characteristics of the "new plant type" developed at the International Rice
Research Institute (IRRI) in the
Philippines that could enhance rice germplasm in Latin America. Among the desirable traits
are heavier grains, a longer grain-filling period, and sturdier stems. To incorporate
these traits into rice gene pools for the region, selected IRRI lines are being crossed
with locally adapted genotypes.
Germplasm Development for the Uplands
In population improvement CIAT researchers work closely with numerous national programs
and with several international centers, as described below in "Partnerships."
Under an agreement with France's Center for International Cooperation in Agricultural
Research for Development (CIRAD), two
CIRAD rice breeders are based at CIAT headquarters, where they are engaged in improvement
of upland rice populations through recurrent selection.
These researchers are placing particular emphasis on tolerance to soil acidity,
resistance to pests and diseases, good grain quality, and early maturity. A large number
of lines have been selected for recombination and multilocation evaluation in several
countries, and new populations are being developed. Lines developed jointly by CIRAD and
CIAT are in high demand among national programs in Latin America and Asia.
During recent years CIRAD scientists have expanded their work for the uplands to
include germplasm development for the midaltitude hillsides of the Andean zone. This is in
response to the demand for new alternatives from coffee growers and other farmers who want
to diversify their agricultural production and create new sources of income. Lines derived
from recurrent selection at CIAT and introduced from Madagascar are currently being
evaluated in Colombian farmers' fields.
Exotic Genes for Rice Improvement
One of the brightest hopes for breaking the yield barrier in rice lies with some 20
wild Oryza species. Using techniques developed by colleagues at Cornell University in the USA, CIAT
researchers are exploring the potential of these species for improving rice yield and
other traits, with the aid of molecular markers.
While showing some undesirable characteristics, the wild species have much potential as
sources of genes for improved yield as well as better grain quality and stress resistance
in the cultivated crop. To introduce such genes into improved cultivars, Center scientists
have made crosses between wild species and improved varieties. In the resulting
populations, they have applied an advanced backcross QTL (quantitative trait loci) method,
featuring molecular marker-assisted selection. Families resulting from a cross between the
variety Bg 90-2 and O. rufipogon yield 5 to 25 percent more than the variety.
Families from a cross between the variety Lemont and O. barthii yield up to 30
percent more than Lemont. Several new interspecific populations are being developed and
evaluated, using O. glaberrima.
There is thus clear evidence that crossing improved cultivars with wild species can
produce offspring whose yields are superior to those of the cultivated parent. Moreover,
molecular markers can be used to locate the genes responsible for higher yield, with a
view to speeding germplasm improvement. Rice lines derived from interspecific crosses are
also being evaluated for traits other than yield, such as plant architecture, grain type,
and disease resistance.
Anther Culture to Speed the Breeding
Another technique that CIAT is applying and improving to quicken the pace and lower the
cost of rice improvement is anther culture. With this method homozygous, or true-breeding,
lines are developed from segregating populations by doubling the chromosomes of the
haploid pollen and regenerating double haploid plants, all in a single cycle of tissue
culture. In contrast, with the standard pedigree method, it normally takes six generations
of selfing to produce completely homozygous rice lines. By thus accelerating the
development of breeding populations, anther culture can cut several years off the
approximately 15-year process of developing and releasing a new commercial rice variety.
CIAT scientists are currently employing this technique in gene pool improvement, with
particular emphasis on identifying genes for cold tolerance and disease resistance. The
technique is also being used to fix enhanced traits in the backcrossed populations
resulting from crosses between cultivated rice and wild species. Anther culture should
prove useful as well for accelerating the introgression of QTLs for higher yield from wild
species into cultivated rice varieties.
In addition to using anther culture in its own rice improvement research, the Center
has transferred this technology to national programs throughout Latin America by means of
workshops, training, and instructional materials.
Durable Resistance to Rice Blast
In a further effort to make rice improvement more efficient, CIAT scientists have
integrated molecular marker techniques into pathology research and breeding aimed at
developing durable resistance to rice blast.
Blast is the most widespread and damaging disease of the crop worldwide. In Latin
America alone, it causes losses estimated at US$200 million annually. The disease attacks
the crop at all stages of development, prompting frequent fungicide applications, which
are expensive and pose an environmental hazard.
Developing durable blast resistance is complicated by extreme diversity among the large
number of races, or pathotypes, produced by the disease's fungal pathogen (Pyricularia
grisea). Most resistant varieties released so far have contained single resistance
genes, which are effective only against certain pathotypes. After 2 or 3 years, this
resistance breaks down as a result of shifts in the frequency of pathotypes or the
emergence of new ones through mutation or other mechanisms.
Thus, a key requirement for finding sources of durable resistance is to gain a better
understanding of the genetic structure and population dynamics of the blast pathogen.
Toward this end an interdisciplinary team of CIAT researchers has carried out virulence
diversity studies and characterized the genetic structure of the pathogen, with the aid of
DNA "fingerprinting." These studies have shown that a large and diverse
population of pathotypes can be grouped into a relatively small number of families, or
lineages.
This knowledge has better enabled scientists to identify combinations of genes with
resistance to various lineages. Under screen house and field evaluation, 15 rice lines
containing two resistance genes have held up against all the lineages that encompass the
highly diverse blast pathogen population in Colombia. These genes are now being
incorporated into commercially available cultivars in Latin America and the Caribbean.
In search of further resistance sources, CIAT scientists are using molecular markers to
identify genes in the cultivar Oryzica Llanos 5, which has shown stable blast
resistance since its release in Colombia during 1989. They are also starting to identify
resistance genes in the wild species O. rufipogum and O. glaberrima.
Novel Resistance to Rice "Hoja Blanca" Virus
Another major disease of rice, one that attacks the crop only in tropical America, is
caused by the rice hoja blanca virus (RHBV). Recurring epidemics of the disease
have taken place in the Andean zone, Central America, and Caribbean over the last 30
years, often causing severe damage. The virus is transmitted by a planthopper insect (Tagosodes
oryzicolus), referred to in Latin America as sogata, which can also cause
serious damage by feeding on rice. Control of the planthopper with pesticides is generally
self-defeating, because it eliminates the predators that help keep the pest in check.
Efforts to break the cycle of recurring epidemics date back to the 1950s, when the
Rockefeller Foundation created a rice improvement project in the Colombian Institute of
Agriculture (ICA), which was the
predecessor of CIAT’s rice program begun in 1967. Since then a series of
disease-resistant varieties has been developed, but these depend on a single source of
resistance, which offers protection only to plants that are more than 25 days old and also
tends to break down over time. CIAT scientists and their national partners continue the
search for lines resistant both to the disease and insect. In Colombia current control
strategies depend heavily on new varieties that are resistant to the insect and show an
intermediate reaction to the virus.
To further reduce the risk of disease epidemics, CIAT scientists have created an
entirely novel resistance source through genetic transformation of rice. This has involved
incorporating the nuclear protein gene of RHBV into CICA-8, a disease-susceptible rice
variety that is widely grown in Latin America. The nuclear protein protects the rice crop
by impeding replication of the virus in the plants. The results of crossing transgenic
plants with highly resistant, intermediate resistant, and susceptible rice lines suggest
that the transgene can be used effectively to complement natural disease resistance.
Partnerships
Partnerships between national and international as well as public and private
organizations are absolutely critical for the successful development and delivery of new
rice technology.
International Centers
Within the Consultative Group on International Agricultural Research (CGIAR), CIAT has a regional responsibility
for rice research in Latin America and the Caribbean. In fulfilling this role, the Center
works closely with IRRI in the
Philippines, which has a global mandate for the crop within the CG. The CG's West Africa
Rice Development Association (WARDA)
in Cote d'Ivoire is also a valued collaborator in rice research, serving as a source of
germplasm and of feedback on materials received from tropical America.
Over the years a key vehicle for cooperation in rice improvement has been the
International Network for Genetic Evaluation of Rice (INGER), which is
operated by IRRI and circulates new germplasm and evaluation results among national
programs worldwide. For Latin America and the Caribbean, the network is coordinated by the
Fund for Latin American Irrigated Rice (FLAR),
of which both CIAT and IRRI are members (see discussion below).
CIRAD, another international center
with a major commitment to rice research, has become an especially close partner in recent
years. As mentioned previously, CIRAD scientists have focused mainly on the development
and improvement of rice populations and on promoting this breeding approach in Latin
America and other regions through workshops, training, and information exchange.
Industrialized Country Universities
To further the integration of new techniques into conventional breeding, CIAT has
established partnerships with various advanced laboratories. For example, as mentioned
earlier, our work with rice wild relatives involves close collaboration with Cornell University in the USA. In our
research on the genetic structure and population dynamics of the blast pathogen, Purdue University in the USA has been a
key partner.
National and Regional Institutions
National institutions have been central partners in rice research at CIAT from its
inception. Just how much they value this collaboration has become especially evident in
the last 5 years.
Starting in 1995, public and private organizations in 13 countries have joined forces
with CIAT, CIRAD, and IRRI in support of an innovative model for financing and guiding
rice research. This is FLAR, a regional
consortium that has taken responsibility for ensuring that irrigated rice production in
the region continues to benefit from new technology, despite a decline in public-sector
support for international and national rice research during recent years. Each national
member of the consortium contributes a yearly quota, based on the country's annual rice
production. Members also define the agenda of the research they are financing.
By thus consolidating rice research for the region, FLAR reduces duplication of effort,
promotes sharing of knowledge and experience, and achieves economies of scale in key areas
of research, such as germplasm development and exchange and integrated crop management.
Impact
One of CIAT's initial objectives was to develop high-yielding semidwarf rice varieties
and production technologies that would largely replace Latin America’s low-yielding
traditional rices. In the late 1960s, the first high-yielding rice variety developed by
IRRI, IR8, was introduced in Latin America. IR8 received mixed reviews, primarily because
it was susceptible to local pests and diseases. Farmers needed high-yielding lines that
were better adapted to conditions in the region.
In response a joint breeding project was set up in Colombia involving CIAT and ICA. The
new rice varieties and production practices they developed spread quickly through the
efforts of the Colombian Rice Growers Federation (FEDEARROZ). This was the beginning of
Latin America’s Green Revolution in rice.
In the 1970s farmers throughout Latin America rapidly adopted new rice varieties
developed by CIAT, IRRI, and national programs. By 1981 annual production in the region
had reached 15.7 million tons, an increase of 50 percent from 1966. According to a major
study on the economic impact of rice varieties, carried out recently by CIAT and the
International Food Policy Research Institute (IFPRI), the new varieties made flooded and irrigated rice systems more
competitive. Higher yields resulted in lower costs to farmers and lower rice prices for
consumers.
Over the last three decades, national rice research programs across the region have
released, on average, a total of 10 new wetland rice varieties a year. Of the
approximately 300 improved rice varieties released to the region’s growers, about 90
percent have been targeted to flooded conditions. Today these varieties account for more
than 70 percent of the region’s total rice production.
Many of the improved rice varieties (242 released in 23 countries) were developed from
germplasm provided by CIAT. The rest have come from crosses made at IRRI or have been
derived from germplasm identified by national programs in Latin America, Africa, and Asia.
In general, each new variety represents significant improvement for at least one key
trait, on top of the gains already achieved.
The new varieties, along with new crop management techniques, increased the average
rice yield in wetland areas from 3.3 tons per hectare in the mid 1960s to 4.6 tons (5 tons
for irrigated rice) in 1995. As a result of these yield gains, total rice production
doubled during the 30-year period to 20.6 million tons, making Latin America about 90
percent self-sufficient in rice. The area planted to rice, meanwhile, rose modestly, from
5.8 million hectares in 1966 to 6.7 million in 1995.
Currently, more than 3.2 million hectares of the region's rice land is sown to
CIAT-related varieties. In many countries these account for a large percentage of the
total rice area: e.g., 94 percent in Brazil, 86 percent in Ecuador, and 84 percent in
Peru.
The large increase in rice output has brought down its price by about half over the
last three decades. According to the above-mentioned CIAT/IFPRI study, consumers have
saved US$518 million in rice purchases annually since 1966. Despite lower prices,
producers in irrigated areas have also captured large benefits, amounting to $437 million
per year.
More recent analysis carried out by CIAT economists estimated the cumulative value of
production increases made possible by Center-related varieties since 1970 at about $5.5
billion in 1990 dollars. The internal rate of return to rice improvement at CIAT was
estimated to be an impressive 57 percent.
Large gains in irrigated rice have been offset somewhat by losses in other production
environments. Mechanized upland rice, for example, registered net annual losses of $70
million between 1966 and 1995. The losses in manual upland rice amounted to $5 million
annually over the same period.
These were the result of falling rice prices—due to productivity gains in
irrigated rice—combined with the inability of manual and mechanized upland rice
growers to match the technical progress of their counterparts in irrigated environments.
In other words rice production in irrigated areas simply proved more competitive than that
in the uplands.
Bad news for upland rice producers meant good news for the environment. The
discouraging economics of upland rice reduced growers' financial incentive to spread
production further into the savannas and tropical forest margins. Irrigated rice thus
acted as a kind of safety valve, removing some of the pressure on these ecologically
fragile areas.
Were it not for the dramatic increase in yields of irrigated rice, Latin American
farmers would have had to at least double the area planted in order for production to
reach its current annual level of 20.6 million tons. Most of the area expansion would have
occurred in the savannas and forest margins, at a huge cost in terms of biodiversity loss,
deforestation, and contamination of water from overuse of agrochemicals.
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