Findings from a recent study conducted in Pakistan and Egypt by researchers from the Imperial College, London, suggest that a secondary pollutant, surface ozone, may well be responsible for substantial reduction in the yields of major crops
SURFACE ozone is produced as a result of
chemical reactions in the atmosphere,
driven by the action of ultra-violet (UV)
radiation in the sunlight, involving both
nitrogen oxides (NOX) and volatile
organic compounds (VOCs). While both
Nox and VOCs are emitted in large
amounts by motor vehicles, other
important sources of VOCs include solvents used in industrial and chemical
processes.
The British team comprising J N B
Bell, M R Ashmore and R Maggs, of the
department of biology, Imperial
College, London, in collaboration with
A Wahid and S R A Shamsi, of the
department of botany, University of
Punjab, Lahore, studied the impact of
ambient air pollution on wheat and rice
yields in the vicinity of Lahore.
Their study demonstrated reductions of 42 per cent and 37 per cent in
the case of grain yields of two cultivars
of rice (Oriza sativa L) and 46.7 per cent
and 34.8 per cent in the grain yields of
two cultivars of winter wheat (Triticum
aestivum L). Says Bell, "The very large
yield reductions found in this study and
the fact that surface ozone - a secondary pollutant that can spread in high
concentrations over rural areas may be a
major contributor to the observed
effects - suggests the potential impact
of air pollution". The British team made
similar observations while studying the
impact of surface ozone on Egyptian
varieties of vegetables in Alexandria.
"A comprehensive scientific study
on crop losses due to air pollution, particularly the impact of surface ozone in
developing countries, is most urgently
required. This will help in a generic
analysis of the issue, which is essential
for assessing the scale of the problem at
national and global levels, as also for
providing an environmentally sound
basis for agricultural policies," argued
Bell while addressing a workshop on the
effects of air pollution on crop yields in
India, organised by the School of
Environmental Sciences, Jawaharlal
Nehru University, New Delhi.
The British team's visit to India was
aimed at soliciting the assistance of
Indian scientists on a project that would
seek to examine the relation between air
pollution and agricultural production
within the country. India was selected
for the proposed study because the
problems of air pollution and its impact
on the country's vegetation has been a
subject of interest for the past several
years. Also, a number of research groups
are already working in this field. But -
according to Ashmore - little has been
done by way of establishing the effects of
surface ozone on crop physiology and
growth in the rural areas.
The ambitious proposals put forth
by the Imperial College team , during
the course of the two-day seminar,
generated considerable interest among
Indian scientists. The propositions
included a plan to collate data on air
pollution levels in India and extend
measurements of surface ozone and
nitrogen oxides to more rural sites. Six
research centres were to be established
throughout the country to conduct
experiments in rural locations to assess
the impact of surface ozone on crop
growth, apart from identifying local cultivars; of major crops which may be sensitive or resistant to air pollution,
among others.
But the enthusiasm diminished
towards the end of the second day of
the conference because the British team
ultimately announced that they
could offer a grant of just Rs 600,000
through the Overseas Development
Administration (ODA) for the research
to be conducted over a period of
two years. The limited funding
substantially scaled down the objectives
of the Indian case study to a mere
reviewing and synthesising of the
existing data available on the subject,
The results of the case study would be
used to evolve a project proposal for
soliciting additional external funding at
a later stage.
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