Geoscience Reference
In-Depth Information
the evaluation uncertainties, but also validates the adapting
or avoiding studies of heat stress or negative influence on rice
under projected climate change. The biomass production in rice
will be more, which may or may not increase the grain yield.
The higher temperatures can result in sterility in flowers, which
will then adversely affect yields. The higher respiration losses
due to a rise in temperature will also make rice less productive.
IRRI research indicated that a rise in nighttime temperature by
1°C may result in losses in rice yields by about 10%.
8.5
Salinity, flooding and rice
Rice is highly sensitive to salinity. Salinity often coincides
with other stresses in rice production, namely drought in inland
areas or submergence in coastal areas. Submergent tolerance
of rice plants has substantially been improved by introgressing
the Sub1 gene into popular rice cultivars in many rice-growing
areas in Asia. The rice crop has many unique features in terms
of susceptibility and adaptation to climate change impacts due
to its semi-aquatic phylogenetic origin. The bulk of global rice
supply originates from irrigated systems, which are to some
extent shielded from immediate drought effects. The buffer
effect of irrigation against climate change impacts, however,
will depend on the nature and state of the respective irrigation
system (Wassmann et al., 2009b). Although rice can grow in
water fields, submerged crops under water for long periods of
time are not tolerated by rice plants. Flooding due to sea level
rises in coastal areas and tropical storms will hinder rice pro-
duction. At present, about 20 million hectares of the world's
rice-growing area is at risk of occasionally being flooded to
submergence level in India and Bangladesh. Wassmann et al.
(2009b) in his review paper mentioned that the mega-deltas in
Vietnam, Myanmar and Bangladesh are the backbone of the
rice economy in the respective country and will experience
specific climate change impacts due to sea level rise. Significant
improvements of the rice production systems, that is, higher
resilience to flooding and salinity, are crucial for maintaining
or even increasing yield levels in these very productive del-
taic regions. The other 'hotspot' with especially high climate
change risks in Asia is the Indo-Gangetic Plains (IGP), which
will be affected by the melting of the Himalayan glaciers.
The dominant land use type in the IGP is rice-wheat rotation.
The geo-spatial vulnerability assessments may become cru-
cial for planning targeted adaptation programmes, but policy
