Manila, The Philippines
March 24, 2008
By Melody M. Aguiba,
Manila Bulletin
Rice breeders are developing heat-resistant rice that can
withstand higher temperature arising from climate change and
still give a satisfactory yield of four to five metric tons (MT)
per hectare.
Department of Agriculture-attached
Philippine Rice Research
Institute (DA-Philrice) started since last year testing of
56 rice varieties identified to have heat tolerance. These
varieties originate from warmer climate in Pakistan, Iran, and
WARDA (West Africa Rice Development Association).
Norvie L. Manigbas, chief science research specialist at
Philrice's plant breeding and biotechnology division, said
breeders' objective is to find varieties that can grow well
beyond 35 degrees centigrade while the optimal temperature for
rice growing in the Philippines is between a much lower 20 to 35
degrees.
"We know work on this will push through because many countries
are predicted to become prone to the adverse effects of climate
change. With the funds coming in, I'm optimistic research can
prosper since climate change is a major issue in this century,"
said Manigbas in an interview.
The discovery of heat resistant-rice varieties will be crucial
specially as the Inter-governmental Panel on Climate Change
(IPCC) predicted that temperature will increase by 1.1 to 6.4
degrees during the next century, he noted.
And there can really be highly-potential heat resistant rice
from the varieties earlier selected by Dr. Yoshida of the
International Rice Research Institute (IRRI) including IR 36, IR
50, and IR 52. These are out of 157 varieties from IRRI's gene
bank.
The testings are being done in Nueva Ecija, Ilocos Norte, and
Los Banos. The varieties will be tested yearly until perhaps the
next six to seven years (using biotechnology techniques such as
marker-assisted breeding). A desired variety can be developed
normally over 10 years using traditional means.
Trials will be conducted only once a year—in the dry season.
The heat-resistant rice is one that does not become sterile from
extreme heat since reduction in yield comes from the inability
of the plant to pollinate as a result of pollen's stickiness due
to heat.
Without this resistance, reduction in yield could be at least 20
percent. At PHilrice's trial in Nueva Ecija, average temperature
was at 34.57 degrees, but temperature has been hitting a high of
37 degrees.
"We did staggered planting to ensure that all crops' (flowering)
will coincide with the highest temperature from mid-April to
mid-May," said Manigbas in an interview.
PHilrice is also obtaining data on varieties that are early
flowering and late flowering in order to time all the varieties'
flowering with the highest temperature. These are being
identified for breeding purposes. While the normal flowering
time for most rice varieties is at 10 to 12 a.m., the early
flowering blooms between 6 to 10 a.m.
Normal planting of rice for the dry season is done in
mid-December. But for this year's trial, the late flowering
variety was transplanted by breeders last Feb. 5 and the early
flowering, last Feb. 26.
"If a variety has a good yield under normal and heat stress
(conditions), it can be a donor parent," he said.
The agency needs a budget of P100,000 per month or P1 million
yearly for the trials for heat resistance.
With global warming, breeders are also finding the need to
conduct research and development on pest and disease since pests
can move from one place to another and also develop resistance
to existing varieties.
"It may happen in 20 to 30 years yet, but research has to be
done in advance," he said.
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