Rice is the primary food source for almost half of the world's population and is one of the most important food crops (GRiSP 2013). Currently, 90 percent of the world's rice is produced in Asia, but rice consumption has increased over the past few decades, especially in Africa, making rice a very important crop for global food security.

Climate change is expected to increasingly affect rice production through higher temperatures and reduced water availability. Unlike other crops, rice is a major contributor to greenhouse gas emissions due to methane release from paddy fields. Therefore, the development of rice varieties and cultivation systems that can enable adaptation to climate change and contribute to its mitigation is a critical issue for global food security. More specifically, it is necessary to (1) breed rice that is resilient to climate change, and at the same time, (2) breed rice in line with the development of cultivation technologies that reduce methane emissions from rice paddies.

On July 3, 2021, JIRCAS Senior Researcher, Dr. Matthias Wissuwa, together with researchers from the International Rice Research Institute (IRRI) in the Philippines, and the Forschungszentrum Jülich (FZJ) in Germany, published an article Breeding rice for a changing climate by improving adaptations to water saving technologies in Theoretical and Applied Genetics, an international journal of plant genetics and breeding.

The article focuses on two water-saving technologies that can shorten the period of time that rice is grown under fully flooded conditions, thereby improving water use efficiency and reducing methane emissions. Rice cultivation over the past few decades has largely focused on the development of high-yielding rice varieties adapted to continuously flooded conditions, where seedlings are grown in nurseries and transplanted into a puddled flooded soil. The shift in cultivation to direct-seeded rice (DSR) or the introduction of non-flooded periods such as alternate wetting and drying (AWD) poses new challenges that need to be addressed in rice cultivation. New adaptive traits such as rapid and uniform germination even under anaerobic (airless) conditions, seedling vigor, weed competitiveness, root plasticity, and moderate drought tolerance need to be incorporated into current elite rice cultivars. The article reviews the discovery of genes involved in these traits and the extent to which the selection of good rice lines and improvement of rice populations using DNA markers for these genes are being addressed.

JIRCAS, in collaboration with domestic and overseas research institutes, is working on the development of resilient rice, including the improvement of these traits.

References

• GRiSP (Global Rice Science Partnership). (2013). Rice almanac, 4th edition. Los Baños (Philippines): International Rice Research Institute. 283 p.
• Maria Cristina Heredia, Josefine Kant, M. Asaduzzaman Prodhan, Shalabh Dixit & Matthias Wissuwa (2021) Breeding rice for a changing climate by improving adaptations to water saving technologies. Theoretical and Applied Genetics　https://link.springer.com/article/10.1007/s00122-021-03899-8
• Technology development towards building a new food system with improved productivity, sustainability and resilience　https://www.jircas.go.jp/en/program/prob

Contributors: NAKASHIMA Kazuo (Director, Food Program), WISSUWA Mathias (Crop, Livestock and Environment Division)