The growing global demand for rice means that this staple food will have to be produced more intensively in Asia, Africa, Latin America and the Caribbean. Asian urban centers hold the majority of the world’s urban poor and, within the next 25 years, nearly 55% of the population of Asia will be located in these areas. Both the urban and rural poor require food at affordable prices and this must come from increased productivity in intensive rice systems, which account for 75% of total rice production.
Similarly, Africa’s intensive irrigation schemes and expansion are expected to contribute greatly in enhancing rice production in Africa. Varieties that do well in Asian irrigation schemes are expected to also perform well in Africa. For example, the well-known Sahel108 variety selected by AfricaRice and now widely grown in the Senegal River Valley is originally an IRRI variety.
In Latin America and the Caribbean (LAC), rice is the leading food. Demand for it is growing. From 1990 to 2004, rice yield in these regions expanded annually at 3.5%. LAC has unique pests and diseases, as well as distinct grain types and cropping systems. Eco-efficient rice production systems, with high productivity and low impact on the environment, are critical for the future. However, considerable opportunities to increase rice production exist given LAC’s abundant land and water resources.
In this light, IRRI develops elite inbred rice lines with higher yield potential, multiple resistance to insects and diseases, and superior grain quality. We also explore the higher yield potential of newer varieties released for irrigated systems.
We develop rice types that can better adapt to aerobic conditions, given the increasing water scarcity threatening agriculture and livelihoods, which will be pronounced in many areas. Similarly, we develop varieties specifically suited to mechanized direct seeding (due to labor shortage) as well as varieties for evolving conservation agriculture systems.
New generation of elite inbreds with increased yield potential
We develop higher-yielding varieties by focusing on key physiological plant traits and genes expected to increase yield potential. We also do this by a more systematic selection for yield in early generations and in multi-environment yield trials. We seek to have a better understanding of the genetic basis and physiological mechanisms of yield potential, from which we develop elite inbred rice lines with about 10% higher yield potential and possess other important traits. Improvements in yield potential of inbreds will also contribute to increasing the yield potential of hybrids.
High-yielding varieties for irrigated systems in Asia
Conventional transplanted systems in Asia represent the largest areas of rice cultivation. Although high-yielding varieties are grown in these areas, continual progress is necessary to incorporate disease and insect resistance and improved grain quality into rice varieties. Farmers in these areas are expected to rapidly adopt new varieties that are superior to the older varieties being planted. We use new approaches for increasing yield potential, such as marker-assisted breeding to develop the next generation of rice varieties suited for irrigated environments in Asia.
High-yielding varieties for irrigated systems in Africa
Irrigated rice represents about 15% of the total area under rice in Africa. But this percentage is expected to increase rapidly. Irrigated rice yields in Africa are often comparable to yields obtained in Asia, but there is a need for improved, high-yielding varieties, resistant to major environmental stresses, pests and diseases. We employ the same breeding approaches and methods as those in Asia, to develop new generations of high-yielding varieties suited to irrigated areas in Africa. New irrigated rice varieties are also expected to do well in the more favorable rainfed lowland areas.
Rice varieties for dry seeding in aerobic rice and conservation agriculture systems
Water shortage is becoming an increasing problem in traditionally irrigated areas because of depleting groundwater resources and competing uses from other sectors. Likewise, particularly in systems such as rice-wheat, rice-maize, or rice-pulses, frequent tillage and removal of residues may lead to a decline in soil fertility and unsustainable production.
Resource-conserving technologies, particularly water-saving irrigation, reduced or no tillage, and retention of residues, are required to re-vitalize yield growth, improve production efficiency, and reduce the negative impact on natural resources.
However, cultivating rice under such conditions requires new genotypes adapted to dry direct seeding; that is, varieties that have early vegetative vigor, are competitive with weeds, have strong root systems, and are also resistant to lodging, root pathogens, and nematodes. Herbicide resistance may also be a useful characteristic.
Genetic diversity exists for these traits, and the best donors are crossed with high-yielding varieties to develop improved varieties for these systems. A key strategy is to select for the new traits required from early stages in the breeding cycle and under the target environments particularly in South Asia and some areas in Latin America.
Improved rice varieties for temperate rice environments
Japonica varieties are typically grown in the temperate regions of Asia, Africa and Latin America. While yields are generally high in these areas, the rice types must be further improved for yield potential and resistance to insects and diseases as well as for environmental stress tolerance, especially cold. High grain quality is a crucial requirement.
Indica, including aus type and tropical japonica rice varieties, are good donors for many desirable traits. However, resulting progeny often suffer from spikelet sterility, poor quality and other undesirable characteristics. We employ new strategies to eliminate linkage drag and incorporate desirable traits into temperate japonica cultivars.