Home' Partners : Partners February 2010 Contents PA RTNERS NOVEMBER 2009 FEBRUARY 2010
On the land management front, Dr Peng
described three core strategies:
nImprove dryland production, especially by
applying conservation farming techniques,
recycling field run-off and making more water-
efficient crops available---a strategy currently
seeing sorghum heavily promoted to farmers
by the Chinese Ministry of Agriculture.
nLimit the amount of water used in irrigated
fields in ways that maximise yields. This
approach is seeing drip irrigation, deficit
irrigation (DI) and partial root drying (PRD)
optimised for use in grain and horticultural
production systems across China.
nConsideration for the needs of natural
systems where competition between
agriculture and natural ecosystems is leading
to encroaching desertification.
Australia is already well advanced in many
of these techniques and, through ACIAR, is
helping their wider adoption in developing
countries where there is growing momentum
to adopt water-conserving farming techniques.
Collaborative research projects are helping to
adapt existing techniques such as zero-tillage
and stubble retention, drip irrigation, DI and PRD
for use in China, India, Bangladesh, Syria and Iraq.
On the breeding front there are major
pushes to identify plant traits that improve
water-use efficiency (WUE), especially in cereals.
Promising levels of genetic gain have been
achieved, especially in maize, rice, pearl millet
and wheat, with researchers from the centres
of the Consultative Group on International
Agricultural Research (CGIAR) playing leading
roles. Once again, Australia is involved in a
number of ways: through funds provided by
ACIAR to the centres, through the involvement
of Australian scientists, and in collaborative
CGIAR's International Maize and Wheat
Improvement Center (CIMMYT ) has achieved
impressive results in maize using a selection
technique called managed stress screening
(MSS). The project, which has been running for
12 years, targets farmers in Africa and is headed
by Dr Gary Atlin and Dr Marianne Bänziger.
The value of CIMMYT's protocol was formally
tested in 2001--02 when its MSS-selected
varieties were compared with those produced
by other seed producers, including Monsanto.
"These were large experiments and the
CIMMY T maize showed a 12--18% yield
advantage over other varieties when tested in
low-yielding environments," Dr Atlin said. "The
yield differences were smaller but persisted in
higher-yielding conditions. It seems unlikely that
molecular markers or transgenics delivered the
same gains for the time and money invested. So
this breeding protocol works very well."
An agreement is now in place that will see
CIMMYT's maize germplasm combined with
Monsanto's drought-tolerance gene technology
and field tested in Africa. The deal will see
technology fees on any resulting varieties
waived for African farmers.
Furthermore, the protocol has been adopted
by the CGIAR's International Rice Research
Institute (IRRI) to develop drought-tolerant rice
varieties using field sites where water stress
can be managed by draining and irrigating as
needed. About 900 rice lines have been tested
and IRRI has identified germplasm that yields
50--100% higher under drought stress.
"The CIMMYT and IRRI breeding programs
have demonstrated that gains in drought
tolerance from MSS are subsequently expressed
in the target farming environment," Dr Atlin said.
"Generally, MSS in maize and rice has proven
adequately repeatable as a breeding strategy
on a single-site basis."
Molecular breeding technology is also being
applied. For drought, this primarily involves
mapping regions of the genome associated
with improved WUE, followed by either the
development of molecular markers to facilitate
selective breeding or gene discovery to
develop GM varieties.
At Huazhong Agricultural University,
Dr Zhang's team is using two genes identified
by IRRI to change the performance of Chinese
rice to common water stresses. These are the
Sub1 gene, which provides rice plants with
tolerance to submergence underwater during
flooding, and the Saltol gene, which provides
a measure of tolerance to saline water. Projects
are also underway to locate genes associated
with drought tolerance and a dozen such genes
are currently undergoing testing in an extensive
At the International Crop Research Institute
for the Semi-Arid Tropics (ICRISAT), impressive
gains have been made using the most
drought-tolerant cereal crop---pearl millet---in
collaboration with India's Central Soil Salinity
Research Institute, the All India Coordinated
Pearl Millet Improvement Project and the
Institute of Biological, Environmental and Rural
Sciences in the UK.
Pearl millet is the staple cereal and fodder
crop grown in the hottest, driest regions of Sub-
Saharan Africa and the Indian subcontinent,
but Dr Rattan Yadav said that post-flowering
drought stress consistently and drastically
reduces yields and yield stability. However, a
single discrete site in the pearl millet genome
has now been identified that can account for
32% of yield variation seen between varieties
during terminal drought.
"This site is associated with maintaining yield,
biomass and harvest index under drought and
in delaying leaf rolling," Dr Yadav said. "It also
provides an added advantage under salt stress."
Similar mapping approaches are underway
in wheat, durum, barley, sorghum, peanuts,
cotton, chickpeas and common bean. Australia
is involved in some of these efforts, with
projects at the Australian Centre for Plant
Functional Genomics, CSIRO Plant Industry and
Queensland Primary Industries and Fisheries.
Most of the advances have come from
measuring root and leaf characteristics long
known to be associated with drought tolerance,
Dr Blum said. However, he added that relatively
few new drought-tolerance traits have been
identified since the 1970s. The most valuable
is carbon isotope discrimination---a technique
developed in Australia and used by Dr Richard
Richards and Dr Greg Rebetzke's CSIRO Plant
Industry teams to develop more water-efficient
Addressing delegates in Shanghai,
Dr Rebetzke presented the next generation of
wheat WUE traits under development at CSIRO.
These include early shoot vigour, reduced tiller
numbers, and the replacement of dwarfing
genes that are more compatible with WUE.
"We sought an alternative dwarfing gene
and found one (Rht) that reduces height
without reducing seedling growth," Dr Rebetzke
said. In adapted backgrounds, the early vigour
trait is now associating with yield increases of
7--16%, reaching as high as 38% under some
The Shanghai conference was the third time
in 12 years that scientists have met under the
Interdrought banner, with prior meetings in
Montpellier, France, in 2001 and Rome in 2005.
Because of the growing urgency surrounding
drought and a drying climate, the period between
conferences is being reduced to three years, with
Interdrought-IV scheduled for Perth in 2012. n
Six hundred agricultural scientists at the conference rated drought as the biggest
threat to food production in developing and developed countries.
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