New varieties of direct seeded rice for farmers in Lower Middle Income Countries

Rice is the most important staple crop for people in low and lower-middle-income countries. It has been estimated that over 3.5 billion people in Asia rely on rice to live. Rice is the fastest growing food staple in sub-Saharan Africa, and one of the fastest in Latin America. Rice is a major user of water; approximately 24-30% of total fresh water and around 34-43% of total irrigation water is used in rice cultivation. The Intergovernmental Panel on Climate Change estimates that about 1.2 billion people could face freshwater shortages by 2020 and crop yields could drop by 30% by 2050. Water requirement for rice is two-three times that of other cereals. In the majority of the rice growing areas especially in lower and middle-income countries, it is cultivated in puddled transplanted conditions which is highly labour and water intensive. The requirement of large amounts of increasingly scarce water, labour and energy resources is making rice production less profitable. In addition, increased urbanisation has shifted labour from rural to urban areas. In many parts of South and Southeast Asia, farmers are switching to direct seeded rice (DSR) as a more sustainable alternative. To obtain a good crop using DSR it is imperative that the seeds germinate quickly in the soil and that the seedlings grow vigorously. However, because breeders have focused on developing traditionally cultivated varieties for puddled transplanted rice, there has been little or no selection for seed vigour and associated seedling traits desirable for DSR. The lack of stable yielding and dry direct seeded adapted varieties for DSR system is a major limitation in achieving the maximum yield potential under water and resource limited conditions. This project team has been successful in identifying rice lines suitable for DSR through their recent research. Using a parallel laboratory and field phenotyping programme on a large set of rice varieties, we have identified hitherto 'unknown' varieties more suitable to DSR in terms of their seed traits. As a next step, we want to use these lines to combine with current good yielding and disease resistant rice cultivars to generate new high-yielding "DSR adapted" rice varieties. Once we develop these new varieties, we would then evaluate their performance in the field at multiple locations. Finally, the most promising breeding lines will be nominated for state level and national level field trails before release of these varieties to farmers. This last step is beyond the timeline of this project; however, we have a clear vision for delivery in accordance with our partners. IRRI has a long track record in rice breeding, our partner having developed more than 50 new varieties over the last 20 years. With the changing climatic conditions and reducing labour-water availability, the potential contribution of "DSR adapted" rice varieties and DSR adapted cultivation system to develop a sustainable rice based agri-food system has never been more vital.

The main impact beneficiaries of this project will be rice farmers in Lower Middle Income Countries on the DAC list. Rice is the most important staple crop for more than half the world's population, where it has been estimated that over 3.5 billion people rely on it to provide in excess of 20% of their daily calories. Climate change presents a significant challenge to the sustained production of rice, which is already coping with the growing food demand driven by population growth in developing countries. Drought is the most important limiting factor for rice production and is becoming an increasingly severe problem. The dominant method of rice cultivation is puddled transplanted rice (PTR), which accounts for about 55% of global crop area and around 75% of world production. Rice plants use between 1500-2500 litres of water to produce one kilogram of seed. The availability of water for agriculture in general (and rice cultivation in particular) is decreasing due to a shift in rainfall patterns, with less rain at the beginning of the season making irrigation for PTR less reliable. Furthermore, increased industrialisation has led to increased agricultural labour shortages. Mechanised dry direct seeded rice (DSR) is becoming a more attractive alternative to PTR. Many farmers are transitioning to dry DSR owing to this combination of environmental, social and economic factors. In South Asia this transition is occurring fastest in India, Nepal and Bangladesh, and in Cambodia, Philippines, Vietnam, Laos and Myanmar in Southeast Asia. However, DSR has yet to be adopted in many countries and regions because suitable rice varieties are not yet available. In Southeast Asia this issue is of particular relevance owing to the importance of rice to the national food security, economy and livelihoods, and also because of the intensity of the impacts of climate change in the region. Adaptation in rice production systems has an important role to play. Farmers will need to have access to a genetically diverse range of improved DSR adapted rice varieties suited to a variety of ecosystem, farming practices and consumer taste.
The proposed project led by Rothamsted Research is in collaboration with the International Rice Research Institute (IRRI) and Punjab Agricultural University (PAU). More than half the area of rice grown in Asia is planted to IRRI-bred varieties or their progenies. This project will directly generate better varieties for dry direct seeded conditions which will be released after evaluation using established IRRI delivery pipelines. DSR varieties require improved seed vigour so that they can germinate and emerge rapidly from deeper soil depth, where more moisture is available. This is currently a weakness of elite rice varieties, which have been bred for the PTR system where seed vigour is much less important. In addition, it has been estimated by researchers at IRRI that PTR contributes up to 20% of all methane emission hence the continued transition to DSR will have a major environmental benefit in combating global warming. DSR could increase rice yields by ~0.5 t/ha, reduce the need for irrigation by ~40 cm of water/ha, allow labour savings of ~25 person-days/ha, make energy savings of ~1,500 Mj/ha, reduce greenhouse gas emissions by ~1,500 kg of CO2 equivalent/ha and increased net economic returns by USD 50/ha in most of the rice growing countries in Asia.