The Philippines
January 25, 2008
By Hanah Hazel Mavi M. Biag,
PhilRice
“Teach
rice how to swim and it will survive the floods,” rice experts
say, which is the same idea behind the development of IR64 Sub1,
a submergence-tolerant rice line.
Rice can withstand flooding, but not for long. The pursuit for a
more resilient plant has paved the way for the discovery of a
“submergence gene” that enables rice to survive complete
submersion.
Usually, rice thrives in standing water, but complete
submergence for more than a few days can be highly damaging
resulting in yield losses, says Dr. Norvie L. Manigbas, a
research fellow from
PhilRice.
Containing the submergence tolerance (sub 1) gene IRRI line
IR40931 came out after IRRI and the University of
California-Davis discovered the gene in an Indian variety FR13A.
The gene was then introduced to IR64, the most popular rice
variety in the Philippines—hence, IR64 Sub1.
Dr. Manigbas said IR64 Sub1 is a non-genetically engineered rice
plant that can survive, grow, and develop even after 10 days of
complete submergence to murky and cloudy water.
The new rice line is not totally different from the original
IR64 variety in terms of morphological characteristics as plant
height, tillering, and yield performance.
As explained by Dr. Nenita Desamero of the PhilRice Plant
Breeding and Biotechnology Division, with or without the
submergence gene and planted under favorable condition, IR64
will have the same yield performance. However, when both are
submerged under water for 7 to 10 days, IR64 Sub1 will survive
and recover.
Normally, rice (without the sub1 gene) at tillering stage can
survive for one week under submergence condition while seedlings
can only last for three to five days.
As part of an IRRI’s project on the dissemination of its
submergence tolerant rice variety, PhilRice now leads the
national on-farm testing of IR64 Sub1 starting this year until
2009 with Dr. Desamero as the team leader and Dr. Manigbas as
the lead scientist. The target sites are rainfed and/or
irrigated areas prone to flash flooding for one to two weeks.
In July, pilot-testing in Bgy. Papaya, San Antonio, Nueva Ecija
failed as the crop was not submerged during the evaluation
period. Nonetheless, IR64, with and without sub1 gene, performed
comparably with wet season yield of 4.5 tons per hectare. Under
muddy irrigation water, crops recovered up to five to eight days
of submergence, on-station results showed. The second on-station
testing started in October 2007 while on-farm experiments began
this January still in Bgy. Papaya.
“On-farm tests may provide hope for farmers who took the risk of
planting rice during the rainy months, and whose fields are
submergence-prone during the wet season,” Dr. Manigbas said. |
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