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“IMPACT OF CLIMATE CHANGE ON PLANT DISEASES”

OUTLINE OF SEMINAR

Climate change

Causes of climate change

Forms of climate change

Plant diseases and climate change

Impact climate change factors on plant

Impact on plant disease management

Response to climate change

Conclusion

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The Earth is surrounded by a thick layer of gases which keeps the planet warm and allows plants, animals and microbes to live. These gases work like a blanket.

Without this blanket the Earth would be much colder and less suitable for life.

Weather is the day-to-day conditions of a particular place.

The climate is the common, average weather conditions at a particular place over a long period of time.

What is climate change?

Change in climate over time, either due to natural variability or as a result of human activity

IPCC-2007

FORMS OF CLIMATE CHANGE

Indian drought -2014 due to El nino effect

Forest fire in russia-2010

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SOURCE: www.ipcc-data.org SOURCE: www.ipcc-data.org

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• International Agencies working to curb climate change

• IPCC Intergovernmental Panel on Climate change

• UNFCC United Nations Framework Convention on Climate Change

• WMO World Meteorological Organization

• UNEP United Nations Environment Programme

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Causes of climate change

1.High CO2 in the atmosphere

2. Increase in Temperature Maximum and minimum temperature

3.Variation in rainfall patternNo. of rainy days/ shift in seasonAmount and distribution

4.Solar radiation Day length5.Drought6.Floods

Major Parameters of Climate change

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When sunlight reaches Earth's surface some is absorbed and warms the

earth and most of the rest is radiated back to the atmosphere at a longer

wavelength than the sun light. Some of these longer wavelengths are

absorbed by greenhouse gases in the atmosphere before they are lost to

space. The absorption of this long wave radiant energy warms the

atmosphere. These greenhouse gases act like a mirror and reflect back to

the Earth some of the heat energy which would otherwise be lost to

space. The reflecting back of heat energy by the atmosphere is called the

"Greenhouse Effect".

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Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-twentieth century, and its projected continuation..

IPCC, (2007)

GLOBAL WARMINGGLOBAL WARMING

Global temperature

rises

Effects

Temperature rise in 1˚C Thousand of home flooded

Temperature rise in 2˚C Glacier disappear

Temperature rise in 3˚C Amazon drains out ,snowcaps on alps disappears.

Temperature rise in 4˚C Ocean rises flooding populated area of Bangladesh washed away.

Temperature rise in 5˚C Desertification river dry up climate refugee conflict over water, food and space

Temperature:

Each pathogen has an optimum temperature for growth. In

addition, different growth stages of the fungus, such as the

production of spores, their germination, and the growth of the

mycelium, may have slightly different optimum temperatures.

Relative humidity :

Relative humidity is very critical in fungal spore germination

and the development of storage rots.

Environmental factors affecting disease development

High humidity favours development of the great majority of

leaf and fruit diseases caused by fungi and bacteria.

Soil moisture:

High or low soil moisture may be a limiting factor in the

development of certain root rot diseases.

High soil-moisture levels favour development of destructive

water mold fungi, such as species of Aphanomyces, Pythium,

and Phytophthora.

Effect of increased CO2 concentration on pathogens

An increase in CO2 levels may encourage the production of plant

biomass.

Concentration of carbohydrates in the host tissue promotes the

development of biotrophic fungi such as rust.

Chakraborty et al. (2002)

Altered the expression of three soybean diseases, namely downy mildew

(Peronospora manshurica), brown spots (Septoria glycines) and sudden death

syndrome (Fusarium virguliforme) .

Higher CO2 can increase the fertility of fungi, which may produce more

spores,

At the same time, plants grown in high carbon dioxide environments also

close their stomata, pores in the leaves that allow the plant to take in carbon

dioxide and release oxygen, more often. Because plant pathogens often

enter the plant through the stomata, the more frequent closing of the

stomata may help prevent some pathogens from getting into the plant.

Changes brought by high CO2 concentration like reduced stomatal

density .

The reduction in stomatal opening can inhibit stomata-invading

pathogens, such as rusts, downy mildews.

Manning & Tiedemann (1995)

Effect of increase in temperature

Changes in temperature and precipitation alter the growth stage,

development rate and pathogenicity of infectious agents,

Chakraborty, S. et al.,(1998)

Climate change is also reported to cause a shift in the geographical

distribution of host pathogens.

Mboup, M et al, (2012).

A change in temperature affect the physiology and resistance of the

host plant.

Higher risk of dry root rot has been reported in Fusarium wilt

chickpea-resistant varieties in those years when the temperature

exceed 33 0 C .

Bacterial diseases such as Ralstonia solanacearum, Acidovorax

avenae and Burkholderia glumea.

Drought stress has been found to affect the incidence and

severity of viruses such as Maize dwarf mosaic virus and Beet

yellows virus.

Clover, et al (1999)

Early outbreak or increases in the intensity of potato late

blight (Phytophthora infestans) under climate change in central

Europe.

Kocmánková et al (2009)

IMPACT ON DISEASE MANAGEMENT

HOST RESISTANCE

Cultivar resistance to pathogens may become less effective because of

increased static and dynamic defences from changes in physiology,

nutritional status, and water availability .

Durability of resistance may be threatened, however, if the number of

infection cycles within a growing season increases because of one or more of

the following factors: increased fecundity, more pathogen generations per

season, or a more suitable microclimate for disease development. This may

lead to more rapid evolution of aggressive pathogen races.

CHEMICAL CONTROL Climate change could affect the efficacy of crop protection

chemicals.

Changes in temperature and precipitation may alter the

dynamics of fungicide residues on the crop foliage. Globally,

climate change models project an increase in the frequency of

intense rainfall events which could result in increased fungicide

wash-off and reduced control.

Response to climate changeResponse to climate change

Better understanding of gene expression in plants and

pathogens in response to climatic factors.

Integrated studies of host and pathogen responses, as well

as communities of soil and plant associated microbes.

Multifactor studies of climate change effects.

Long-term, large-scale records of pathogen and host

distributions.

Conclusions :  Plant disease has a major impact on agricultural and natural

systems.

Current strategies for management need to be maintained and

improved, even if the climate did not change.

Climate change will increase some disease risks and decrease

others.

Systems may change more rapidly than in the past, requiring more

research and policy attention.

  

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