Geoscience Reference
In-Depth Information
table 8.2
Symptoms of heat stress in rice
Growth stage
Symptoms
Vegetative
White leaf tip, chlorotic bands and
blotches, white bands and specks, reduced
tillering, reduced height
Reproductive anthesis
Reduce spikelet number, sterility
Ripening
Reduced grain-filling
Source: From Yoshida, S. 1981. Fundamentals of Rice Crop Science .
Los Baños, Philippines, IRRI. 269 pp.
rice is a more sustainable approach than altering well-estab-
lished cropping patterns, which will inevitably lead to yield
penalties (Nagarajan et al., 2010). The current temperatures are
already approaching critical levels during the susceptible stages
of the rice plant, namely, Pakistan/North India (October), South
India (April, August), East India/Bangladesh (March-June),
Myanmar/Thailand/Laos/Cambodia (March-June), Vietnam
(April/August), Philippines (April/June), Indonesia (August)
and China (July/August) (Wassmann et al., 2009b).
8.4 Land and water resources for rice
The increase in temperature will create more land and water
for growing rice in areas outside the tropical region (Darwin
et al., 2005). The areas of coastal regions in the United States
(Florida, much of Louisiana), the Nile Delta and Bangladesh
will become unsuitable for rice with the rise of sea level by
88 cm (Kluger and Lemonick, 2001).
During the last two decades, night temperatures have
increased at a much faster rate than day temperatures and global
climate models predict a further increase in its frequency and
intensity. The rice crop is affected both at the vegetative and
reproductive stage due to a rise in temperature and, hence, pro-
ductivity is also affected. The temperatures required at different
crop growth phases are given in Table 8.1. High temperatures
may result in various possible injuries to rice crops (Table 8.2).
High temperatures for 1-2 h at anthesis may result in sterility
of the rice crop. Mohandrass et al. (1995) predicted a decline
in yield by 14.5% in summer rice in India by 2005 based on
experiments at multi-locations. In the Philippines too, yields
of dry-season rice declined by 10% for every 1°C increase in
growing-season minimum temperatures, whereas the effect of
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