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

大米是低收入和中低收入国家人民最重要的粮食作物。据估计，亚洲有超过35亿人以大米为生。大米是撒哈拉以南非洲增长最快的主食，也是拉丁美洲增长最快的主食之一。水稻是用水的大户，大约24%-30%的淡水和34%-43%的灌溉水用于水稻种植。政府间气候变化专门委员会估计，到2020年，大约12亿人可能面临淡水短缺，到2050年，农作物产量可能会下降30%。水稻的需水量是其他谷物的2-3倍。在大多数水稻种植区，特别是在低收入和中等收入国家，它是在高度劳力和水密集型的水坑移栽条件下种植的。对日益稀缺的大量水、劳动力和能源的需求正在降低水稻生产的利润。此外，日益加剧的城市化已将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，农民正在转向直播水稻(DSR)，作为一种更可持续的替代选择。为了利用DSR获得好的作物，种子必须在土壤中迅速发芽，幼苗必须茁壮成长。然而，由于育种者一直专注于开发传统的水坑移栽水稻品种，因此很少或根本没有对种子活力和相关的苗木性状进行选择，这是DSR所希望的。在水分和资源有限的条件下，缺乏适合DSR系统的稳产、旱作直播适应性品种是发挥最大产量潜力的主要限制因素。这个项目团队通过他们最近的研究，已经成功地识别出适合DSR的水稻品系。通过对一大批水稻品种进行平行的实验室和田间表型鉴定程序，我们已经确定了迄今为止更适合DSR的未知品种的种子特性。作为下一步，我们希望利用这些品系与目前高产和抗病的水稻品种相结合，创造出新的高产“DSR适应”水稻品种。一旦我们开发了这些新品种，我们就会在多个地点评估它们在田间的表现。最后，最有希望的育种品系将在向农民发布这些品种之前被提名为国家级和国家级田间试验。这最后一步超出了这个项目的时间表；然而，我们根据我们的合作伙伴对交付有一个明确的愿景。国际水稻研究所在水稻育种方面有着长期的记录，在过去的20年里，我们的合作伙伴已经开发了50多个新品种。随着气候条件的变化和劳动力-水可获得性的减少，“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.