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

水稻是低收入和中低收入国家人民最重要的主食作物。据估计，亚洲有超过35亿人依靠大米为生。大米是撒哈拉以南非洲地区增长最快的主食，也是拉丁美洲增长最快的主食之一。水稻是水的主要使用者；大约24-30%的淡水和34-43%的灌溉用水用于水稻种植。政府间气候变化专门委员会估计，到2020年，约有12亿人将面临淡水短缺，到2050年，农作物产量可能下降30%。水稻的需水量是其他谷物的两到三倍。在大多数水稻种植区，特别是在低收入和中等收入国家，它是在水坑移植条件下种植的，这是高度劳动和水密集型的。对大量日益稀缺的水、劳动力和能源的需求使稻米生产的利润下降。此外，城市化程度的提高使劳动力从农村转移到城市地区。在南亚和东南亚的许多地区，农民正在转向种植直接播种水稻（DSR），作为一种更可持续的替代方案。要想利用DSR获得好收成，种子必须在土壤中迅速发芽，幼苗必须茁壮成长。然而，由于育种家们把重点放在开发传统栽培的水田移栽水稻品种上，很少或根本没有对DSR所需的种子活力和相关幼苗性状进行选择。在水资源和资源有限的条件下，缺乏适合DSR系统的稳产和干直接播种品种是实现最大产量潜力的主要限制因素。该项目小组通过最近的研究，成功地确定了适合DSR的水稻品系。通过对大量水稻品种进行平行实验室和田间表型分析，我们已经确定了迄今为止“未知”的品种，它们的种子性状更适合DSR。下一步，我们希望利用这些品系与现有的高产抗病水稻品种结合，培育出新的高产“适应DSR”的水稻品种。一旦我们开发出这些新品种，我们就会在多个地点评估它们在田间的表现。最后，在向农民发布这些品种之前，最有希望的育种品系将被提名进行国家级和国家级的田间试验。最后一步超出了这个项目的时间表；然而，我们有一个明确的愿景，以交付与我们的合作伙伴。国际水稻研究所在水稻育种方面有着悠久的历史，我们的合作伙伴在过去20年里开发了50多个新品种。随着气候条件的变化和劳动力-水资源供应的减少，“适应DSR”的水稻品种和适应DSR的栽培系统对发展可持续的以水稻为基础的农业粮食系统的潜在贡献从未如此重要。

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.