Geoscience Reference
In-Depth Information
table 15.2
Grain yields, components of yield and harvest index of rice grown at
different CO
2
levels and temperature regimes
CO
2
concentration
(ppmv)
Mean air
temperature
(°C)
Grain
yield
mg/ha
Number of
panicles/
plant
Number of
filled grains/
panicle
Harvest
index
(%)
330 24.2 7.9 5.1 34.5 47
25.1 8.0 5.6 47.5 43
31.0 4.3 5.4 19.0 26
34.1 3.2 5.2 15.2 24
660 24.2 8.4 5.0 37.7 46
25.1 10.1 6.2 54.2 47
31.0 6.4 6.0 24.6 29
34.1 3.4 5.6 12.9 18
Source:
Cline, R. W. 1999.
Global Warming and Agriculture: Impact Estimation by Country
.
Center for Global Development and the Peterson Institute for International Economics,
Washington, DC.
table 15.3
Seed yield, components of yield and harvest index of soya bean
grown at two CO
2
concentrations and three temperatures
Day/night
temperature
(°C)
Grain
yield
(g/plant)
Seed
number/
plant
Harvest
index
(%)
CO
2
concentration
Seed mass
(mg/seed)
330 26/9 9.0 44.7 202 53
31/24 10.1 52.1 195 51
36/29 10.1 58.9 172 45
660 26/19 13.1 58.8 223 49
31/24 12.5 63.2 198 45
36/29 11.6 70.1 165 44
Source:
Aggarwal, P. K. 2000.
Climate Change and Agriculture: Information Needs and
Research Priorities
. Indian Agricultural Research Institute, New Delhi.
what it is today under cool climates (Mann et al., 1999). Mixed
yield results were obtained from different models and it is quite
difficult to summarise them and come to a conclusion. In cool
temperature and cold regions, the yield is expected to rise, pro-
vided the soil moisture is optimum. But global warming causes
soil moisture depletion and this has a serious effect on crop
yields. A study predicts that the maize yield will reduce by 20%,
even if the crop is irrigated due to severe depletion of soil mois-
ture and an increase in temperature (ICAR, 2005) (Table 15.4).
In another study, it is revealed that an increase in rainfall may be
beneficial to yields of crops. It is assumed that with an increase
