PhilRice develops flood-tolerant variety

A rice variety that could withstand complete submergence for at least two weeks has been developed by the Philippine Rice Research Institute (PhilRice).

PhilRice executive director Dr. Leocadio S. Sebastian said the new line, developed by a young plant breeder at the PhilRice Midsayap branch station in North Cotabato, can withstand continuous submergence up to 28 days. Tagged as PR33395-27-1-B-B-B, this rainfed elite line is a cross of Malay 1 and Matatag 1. Malay 1 is an advance upland breeding line, while Matatag 1 is a tungro resistant and irrigated lowland variety.

This line may very well be one of PhilRice’s answers to the adverse effects that would be brought about by climate change, which is expected to lead to greater rainfall variability, resulting in increased frequency of extreme events like flashfloods in some places. 

Even at present, the Philippines already suffers from frequent typhoons from July to December, which bring in strong winds and excess water, resulting in continuous flooding. During this period, 10 to 40 percent of the rice area is damaged by flashfloods, most especially in Nueva Ecija, Isabela, Cagayan, Pangasinan, Bulacan, Pampanga, Camarines Sur, Mindoro Occidental, Tarlac, and Nueva Vizcaya. 

Almost all of the popular varieties cannot survive prolonged submergence of more than three days, resulting in huge losses. Nationwide, production losses due to flashfloods are valued at an average P2 million every year. 

PhilRice’s submergence tolerant line has been named Raeline 10, which stands for rainfed advance elite line. 

Jonathan M. Nones, the plant breeder, said Raeline 10 is tungro resistant, has intermediate resistance to bacterial leaf blight, early maturing [105 days], moderate to shatter ability, and its eating quality is comparable to IR64.

In screen house tests in cemented ponds in 2006 and 2007, Raeline 10 had a 100 percent plant survival in 21 days of submergence. In contrast, the IRRI line IR64-Sub 1 had only 75 percent survival, while Swarna-Sub 1, which was found earlier to survive complete submergence in northern Bangladesh, did not survive extended submergence.

The screen house tests also showed that the original IR 64 had 50.5 percent survival at 21 days of submergence, while IR 36 and IR 45 had 75 percent like IR64-Sub 1. PSB Rc68 also had 75 percent survival, while PSB Rc18 had 50 percent.

In a field adaptation trial in Brgy. Bulucaon, Pigcawayan, North Cotabato, a large percentage of the Raeline 10 plants survived 28 days of continuous submergence under water, while IR64-Sub 1 was almost wiped out.  — Sosimo Ma. Pablico