Agriculture Reference
In-Depth Information
way, where the relative effects of these variables on crop growth and yield
can be studied in particular combinations on regional basis. Early simula-
tion studies on impacts of climate change gave prime importance to the
expected increase in carbon dioxide levels only, while off late researchers
have suggested, from their studies, that agricultural production gets af-
fected not only by CO 2 alone, but also by weather variables (Curtis and
Wang, 1998).
Most crops grown under enriched carbon dioxide environment showed
increased growth and yield (Allen et al., 1997; Parry et al., 2004). En-
hanced CO 2 effects the growth and physiology of crops, enhancing pho-
tosynthesis as well as water use efficiency (De Costa et al., 2003; Ewert,
2004; Widodo et al., 2003). Elevated CO 2 besides affecting the crop af-
fects the environment, which in turn may have either beneficial or damag-
ing effect on agricultural production. Mall and Singh, 2000 reported that
small changes in growing season temperature over the years appeared to
be key aspect of weather affecting yearly wheat yield fluctuations. Pathak
et al. (2003) attributed the decline in potential yield of wheat and rice to
the negative trend in solar radiation and an increase in minimum tempera-
ture in the Indo-gangetic plains of India. FAO and IPCC have estimated
a drop in cereal production for India as much as by 125 mt and an overall
increase of 2°C in temperature may lead to almost 8% loss in farm level
net revenue and around 5% in GDP (Gahukar, 2009). C4 plants are pho-
tosynthetically more efficient than C3, especially when the level of CO 2 is
high (Ku et al., 1999). This chapter examines results of different studies,
which has special significance for Bihar.
21.2
IMPACTS OF CLIMATE CHANGE ON AGRICULTURE
21.2.1 DIRECT EFFECTS
Some of the direct effects reported by various studies are higher water de-
mand, increase in evaporation rate, reduction in crop growth period, crop
damage/failure, inability to cultivate on land due to increased salinization
/water logging (coastal areas), reduced net photosynthetic rate, extension/
shortening of growing season, lesser production and productivity in warm-
er regions, increased production in some rabi crops due to elevated CO 2
and temperature effects, etc.
 
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