increasedCO 2 concentrations can also cause serious changes to
plant biochemistry, including an increase in carbon:nitrogen
ratios due to a reduction in nitrogen in the foliage and an
increase in carbon produced by higher photosynthetic rates.
Reduced nitrogen levels in plants and grains are a serious
concern, as nitrogen is a crucial building block of amino acids.
Hence lower nitrogen levels will reduce the protein concen-
tration in the grain, decreasing the nutritional value, baking
quality and other important characteristics oflour.
Under future climate conditions in the semi-arid wheat-
growing regions of southern Australia, the net simulated effect
of increasing atmosphericCO 2 andhotter and drier spring
conditions are expected to reduce the average yield by 3–13%.
While many studies have explained the effects of climate
change on plant physiology, we still don’t fully understand how
future climate will impact plant pathogens. For example, there
are knowledge gaps concerning the biology of barley yellow
dwarf virus and its aphid vectors, and it’s essential to ill in
these gaps if we are to mitigate the negative effects of this disease
in wheat crops under future climate conditions.
We have been attempting to redress this by investigating
the effects of increasedCO 2 on plantsinfected with barley
yellow dwarf virus. We grew virus-infected plants in a controlled
laboratory setting under current and elevatedCO 2 levels, and
used molecular techniques to determine the amount of virus
within the plant tissue.
We found that plants grown under elevatedCO 2 levels had
signiicantly higher viral loads.Thereason behind this 35%
increase in virus concentration is not well understood, but
cannot be explained by the plants’ stimulated growth rate. Our
unique study has been published inGlobalChange Biology
(http://tinyurl.com/hv5hk9q).
As aphids are responsible for spreading the virus to and
within a food crop, it’s also important to understand how
elevatedCO 2 levels will affect the insect.Therefore we are
conducting further research on the interactions between the
insect, wheat and virus under future climate conditions to
understand possible mechanisms across different wheat culti-
vars that can inhibit or eliminate the spread of the disease.
Aphids use their stylet to pierce plant tissue and feed on the
plant’s sap. Since this process is fully contained within the plant,
we are implementing different methods to understand how
aphids feed and how eicient the virus transmission can be in
plants grown under future climate conditions.
Since the global human population will continue to rise,
there will be even greater pressure on our agriculture and avail-
able land to grow crops. It’s extremely important to under-
stand how future climate and an increase in CO 2 concentration
in the atmosphere will affect our food production and agri-
cultural pests and diseases. We need to know how future climate
conditions will affect plant growth and yield, and how we can
prevent crop loss if the severity of pests and diseases increases.
Understanding how this climate will affect interactions
between pests and diseases will provides scientists with a great
opportunity to also ind solutions to sustain or even improve
current food production levels.
Piotr Trebicki is a Research Scientist for the Victorian Department of Economic
Development, Jobs, Transport and Resources in Horsham, Victoria.MAY 2016|| 37How Will Rising CO 2 Levels
Affect Agriculture?
Because carbon dioxide has the ability to trap
heat and is also important for plant growth, any
changes in the concentration of carbon dioxide
and temperature will have a huge effect on food
production.
Australia’s ancient soils and limited rainfall
and water supply mean that the margin is
already very narrow for the continent’s
agriculture. Uncertainties associated with future
climate and predictions of increased average
temperature and severe weather events need to
be better understood, especially in already
challenging food production regions.
Carbon dioxide is fundamental to plant
growth and development. Over the past 150
years its concentration in the atmosphere has
risen by 30% from 290 parts per million in 1860
to 405 ppm in 2016.
Models indicate that CO 2 concentrations will
rise even faster over the next 35 years, reaching
550 ppm. This surge in the atmospheric CO 2
concentration is the key factor that is increasing
the temperature of our planet at an accelerated
rate, altering many biological functions in both
plants and animals.
As this unfolds, the human population
continues to grow, and is estimated to exceed
nine billion by 2050. Global crop demand is
forecast to more than double 2005 levels by
2050.
Because of these factors, understanding how
elevated carbon dioxide and other aspects of
climate change affect agriculture is crucial if we
are to sustain or improve our current food
production capability.Left: an aphid is tethered by a gold wire to a penetration
electrode to measure feeding behaviour and virus transmission.