PhilRice comes up with submergence tolerant line

By Sosimo Ma. Pablico

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

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 typhoons in July to December, which bring in strong winds and excess water, resulting in continuous flooding of rice fields. 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 under prolonged submergence of more than three days, resulting in huge losses for the farmers.  At the national level, production losses are estimated at an average P2.0 million every year. 

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

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

Nones 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 same 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.  In like manner, PSB Rc68 also had 75 percent survival, while PSB Rc18 had 50 percent.

In a field adaptation trial in Brgy. Bulucaon, Pigcawayan, North Cotabato to demonstrate the PhilRice and IRRI lines, a large percentage of the Raeline 10 plants survived 28 days of continuous submergence under water, while IR64-Sub 1 was almost wiped out.

Under irrigated lowland conditions at PhilRice Midsayap, Raeline 10 yielded 4.38 t/ha, a little lower than three other Raelines – Raeline 4 [4.67 t/ha], Raeline 3 [4.58 t/ha], and Raeline 9 [4.40 t/ha].  Incidentally, Raeline 3 is drought tolerant. 

Scientists at the PhilRice Central Experiment Station in Nueva Ecija are also evaluating nine IRRI elite lines and six lines derived from anther culture are also being evaluated for submergence tolerance. Dr. Norvie Manigbas said the plants were submerged for 12 days at 30 days after transplanting with murky and cloudy water from irrigation canals and nearby fields.

None of the entries survived 12 days of submergence in the first trial.  In the second screening, the IRRI lines IR64-Sub 1, FR13A, Swarna-Sub 1, Samba Mahsuri survived 10 days of continuous flooding. The PhilRice lines derived from anther culture also showed tolerance to submergence.

(Readers may reach columnist at spablico@yahoo.com. For past columns, click http://sundaypunch.prepys.com/archives/category/opinion/harvest-time/ For reactions to this column, click “Send MESSAGES, OPINIONS, COMMENTS” on default page.)

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