Agriculture Reference
In-Depth Information
or frequency, or both. The published reports on the subject predict higher
maximum temperatures and a greater number of hot days, higher mini-
mum temperatures and fewer cold days, reduced diurnal temperature rang-
es, more intense precipitation events, increased risk of drought in summer
periods, increases in peak wind intensities of cyclones, and increases in
mean and peak precipitation intensities of tropical cyclones. On top of
that, sea level is predicted to increase by 0.09-0.20 m.
1.3 CONSEQUENCES
The major changes in the earth's atmosphere are the concentrations of
CO
2
, which have increased by about 25% since the beginning of the indus-
trial revolution. The CO
2
concentration has increased from preindustrial
level of about 280 ppm to 393 ppm in 2010. Carbon dioxide enhances
photosynthesis and depresses plant respiration; these effects are expect-
ed to increase plant growth as well as affecting various other processes.
However, a number ofplants physiological processes are also affected by
changes in temperature, ozone, ultraviolet radiation, nutrients and water,
all of which are variable factors often associated with climatic change.
Weather is the most important cause of year-to-year variability in crop
production, even in high-yield and high technology environments. There
has been considerable concern in recent years about possibility of climatic
changes and their impact on the crop productivity. Today the entire world
is suffering from global warming and its consequent climate change. Its
impact on productivity and quality of crops has been documented fairly
well. Since a crop could be defined as a biological system tailored to give
certain products, the product output and quality is bound to vary with
change in the growing environment.
Crop productivity will not only be affected by changes in climatically
related abiotic stresses (i.e., increasing temperatures, decreasing water
availability, increasing salinity and inundation) and biotic stresses (such
as increases in pests and diseases), but also changes in the atmospheric
concentration of carbon dioxide, acid deposition and ground level ozone.
Hence, a key challenge is to assess how crops will respond to simultane-
ous changes to the full range of biotic and abiotic stresses. Responding to
these challenges will require advances in crop research and the adoption
of appropriate technologies.
