Rice researchers from the Philippines and Thailand have identified breeding lines that can tolerate both prolonged flooding and high salinity, traits that could help develop climate-resilient rice varieties for farms increasingly exposed to extreme weather and saltwater intrusion.
The study, conducted by the Philippine Rice Research Institute (PhilRice) in collaboration with Khon Kaen University in Thailand, found four rice breeding lines, SSal3, SSal15, SSal24, and SSal36, that showed tolerance to both submergence and salinity.
Submergence happens when rice plants are underwater for an extended period, while salinity refers to excessive salt in soil or irrigation water. Both conditions can weaken or kill rice plants and reduce farmers’ harvests.
The study, titled “Seeds of Survival: Unraveling Rice Breeding Lines for Dual Tolerance to Submergence and Salinity,” evaluated breeding lines for their ability to withstand these two stresses. Researchers also examined how the plants responded at the physiological and molecular levels to identify traits linked to tolerance.
Field evaluations during the 2024 wet season identified four elite breeding lines with tolerance to prolonged flooding and 33 breeding lines with tolerance to salinity. Among these, SSal3, SSal15, SSal24, and SSal36 showed tolerance to both conditions.
Molecular analysis also confirmed the presence of the Sub1 gene, which is associated with flood tolerance, and the Saltol quantitative trait locus, a genetic region linked to salinity tolerance. These genetic markers help breeders identify rice lines that may be useful in developing future varieties with combined tolerance to flooding and salinity.
Lead researcher Christopher C. Cabusora said the findings respond to field conditions that are becoming more common in rice-growing areas.
“There are already areas experiencing these combined stresses, and that is where many of our current varieties fall short,” Cabusora said.
He said the goal is to develop climate-resilient technologies that can help farmers avoid crop failure and economic losses as environmental stresses become more severe.
Developing the breeding lines required repeated screening and evaluation of thousands of breeding materials using conventional breeding methods.
“Our main limitations are human resource, breeding capacity, and resources. Much of our work relies on traditional, labor-intensive methods, requiring us to screen thousands of breeding materials and repeat evaluations for reliability,” Cabusora said.
The next phase of the research will test the identified breeding lines under actual field conditions in areas affected by both flooding and salinity before they can be recommended for wider use.
“For farmers, seeing is believing. That’s why we conduct field demonstrations in as many locations as possible,” Cabusora said.
The study also highlights continuing collaboration between PhilRice and Khon Kaen University, which includes joint research and internship opportunities. One Thai student intern who participated in the project later received the Best Research Problem Award at Khon Kaen University after presenting the study in Thailand.
The research was conducted by Cabusora, Sukritta Somthong, R.J.D. Buluran, Gelyn D. Valida, Hannah Filicia B. Mataia, Josielyn C. Bagarra, and Nenita V. Desamero.
The study received the first Best Poster Award in the Plant Breeding, Genetics, and Biotechnology Category during the 56th Crop Science Society of the Philippines Scientific Conference.
