Impacts of Climate Change on Agriculture - Climate Resilient Agriculture for Ensuring Food Security - page 58

Fig. 4.6 Modeled
responses of total dry
matter production and
grain yield of winter
wheat. A , curves modeled
from the 1981 climatic
conditions at Brooms Barn,
Bury St. Edmunds (UK);
B , simulates the effect of a
doubling of CO 2 concen-
tration, and C , the effect of
both a doubled CO 2
concentration and a rise in
mean temperature of 3 °C
(Squire and Unsworth
1988 )

Belt of North America, the European lowlands,
and the Soviet Ukraine, increases in temperature
would probably lead to decreased cereal yield
due to a shortened period of crop development
(Smith and Tirpak 1990 ). In eastern England, for
example, a 3 °C rise in mean annual temperature
is estimated to reduce winter-wheat yield by
about 10 %, although the direct effect of a dou-
bling of ambient atmospheric CO 2 might more
than compensate for this (Fig. 4.6 ).
In other mid-latitude regions, much would
depend on possible changes in rainfall. For exam-
ple, in the Volgograd region, just east of the
Ukraine, spring wheat yields are estimated to fall
only a small amount with a 1 °C increase in mean
temperature during the growing season, though
they could increase or decrease substantially if
the temperature change was accompanied by an
increase or decrease of rainfall (Table 4.7 ).
Every 1 °C increase in temperature reduces
wheat production by 4-5 million tons. Loss shall
be only 1-2 million tons if farmers could plant in
time (Fig. 4.7 ).
Yields of root crops such as sugar beet and
potatoes, with an indeterminate growth habit, can
be expected to see an increase in yield with
increasing temperatures, provided these do not
exceed temperatures optimal for crop develop-
ment (Squire and Unsworth 1988 ).

Table 4.7 Response of spring wheat yield (as % of the
long-term mean) to variations in air temperature and
precipitation during the growing season (Pallasovka,
Volgograd region) (Ni konov et al. 1988 )

Air temperature (°C)
−1.0

Precipitation (mm) −0.5 0 +0.5 +1.0

−40 79 79 76 76 76

−20 92 92 89 89 89

0 104 103 100 100 99

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A temperature gradient tunnel (TGT) installed
at Indian Agricultural Research Institute Farm,
New Delhi, India, was used to assess the impact
of high temperature on crop growth and yield
during rabi season of 2008-2009. It was found
that TGTs were able to maintain the temperature
gradient in wheat and chickpea crops. The study
revealed that high temperature reduced the dura-
tion of crop growth in both wheat and chickpea.
The period for 50 % fl owering in wheat and
chickpea crops was decreased by 5 days with
2.9 °C and by 6 days with 3.1 °C rise in
temperature. Rise in temperature inside the
TGTs also led to reduction in biomass and grain
yield of both wheat and chickpea crop
(Table 4.8 ).