climate change on canola cropping in victoria

8/7/2019 Climate Change on Canola Cropping in Victoria

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Impacts of Climate Change on Canola Cropping in Victoria

Babu Ram Pandey, Student ID. 318294

INTRODUCTION

The climate change is going to be a major challenge of food production in future. The global

warming caused by higher atmospheric CO2 levels due to human activities will have several

impacts on existing crops. Several effects of elevated CO2 on climatic parameter have already

been experienced worldwide and in Australia. The main effects are rising temperatures,

changing rainfall pattern, reducing frost incidence, increased evaporation etc. The existing

crop plants are going to be affected by these changes in climatic parameters.

Australia grows more than a million hectares of oilseed Brassicas each year mainly canola

(Brassica napus) with a small amount of juncea canola (B. juncea). Australia exports the

second largest quantity of canola exceeding 1 million tonnes every year and it is the third

largest broad acre crop after wheat and barley (AOF, 2010). Besides export income, canola isan important crop to improve the yield and sustainability of wheat and legumes in cropping

rotations. Norton (2003) reported beneficial effects of canola on wheat yields as part of a

rotation, for the winter cropping belt of southern Australia. Several researchers in Australia

have demonstrated that wheat following canola has a 20% yield benefit over wheat following

wheat by reducing weeds and minimizing cereal root diseases like take-all (Edward and

Haagensen, 2010). Recently released Australian canola cultivars have a reputation for

improved oil and protein content compared to those released in past decades (Mailer, 1999).

In Victoria 221 kilo tones of canola was produced on 196 kilo hectares in 2008, which was

the second largest canola production after WA (ABS Agricultural Commodities, Australia,

cat no. 7121.0).

LIKELY PROJECTED CHANGES

Canola is a winter crop sown in May/June and harvested in November/December. Canola

growth and yield attributes are mainly affected by climatic parameters during winter and

spring. Therefore, changes in temperature, rainfall, relative humidity and evapotranspiration

during these periods are discussed in this report. This report uses medium emissions scenario

and 50th percentile estimates to discuss the changes in climatic variables in Victoria in 2050.

The projections were developed using a model developed by CSIRO available at

www.climatechangeinaustrali.com.au.

Temperature

Temperature change projections relative to 1990 baseline are variable depending on emission

scenarios during both the seasons (Figure 1). There will be smaller changes (1-1.5 0C) in

winter than in spring (1-20C) under medium emission scenarios. The changes during winter

are shown to be uniform while coastal areas will receive smaller changes in spring than the

inner parts of the state. Similar projections were reported by Suppiah et al. (2004).

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Figure 3. Victoria Relative humidity change in 2050 (50th Percentile). The first, the second

and the third columns present low, medium and high emissions scenarios, respectively.

Potential Evapotranspiration

The potential evapotranspiration (PET) accounts for all the water evaporated from soil and

transpired from plant canopy when water availability is not a limitation. It indicates the

ability of the environmental conditions to remove water away from the plant and soil. The

overall projected PET tends to increase over the state; however, it will vary depending on

emission scenarios and the regions in the state. PET will increase more in winter than in

spring. Winter PET is projected to go up by 8 to >16% while spring RH will go up only by 2

to 8%.

Figure 4. Victoria potential evapotranspiration change in 2050 (50th Percentile). The first, the

second and the third columns present low, medium and high emissions scenarios,

respectively.

CLMATE CHANGE IMPACTS

Rising CO2 concentrations alone has been shown to have positive impacts on plant growthand development. There were complex interactions between aspects of climate change on

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crop systems in Western Australia (Ludwig and Asseng, 2006). The effects of higher

temperatures, elevated CO2 and changed rainfall differ significantly with soil types and

locations. Higher temperatures combined with the lower rainfalls can affect several plant

physiological processes. The expected changes in temperature and rainfall, particularly in

spring, can result in shorter filling periods, small seeds, reduced number of pods and seeds.

Heat stress

Canola is susceptible to heat stress. High temperatures can cause sterility of both male and

female floral parts. Pollen viability under field conditions in Australia is short because of

high temperatures and low RH during flowering time (Salisbury, 2006). Further increase in

temperatures and reductions in RH in spring might reduce the pollen viability drastically

resulting in poor seed setting. Higher temperatures not only reduces yield but also reduces oil

content (Potter et al., 1999). Though plants are less sensitive to heat stress at pod set than at

flowering, heat stress has been demonstrated at lower temperatures when there is drought

(Canola Council of Canada, 2006). The combination of heat and drought stress can result in

sterile and deformed pods.

Moisture stress

Canola growth and seed yield depends on water availability to the crop. Water availability is

an important limitation in Australia, at least during seed maturation. Canola is grown in areas

with 325 to 700 mm annual rainfall. North West of Victoria is too dry to successfully grow

canola while eastern part generally is too wet (see Figure 5). Middle parts of the state have

favourable rainfall for canola growth. The projected decline particularly in spring (10-20%,

Figure 2) is likely to make the dry margins unfavourable for canola production. The areas

including Horsham, Charlton and Echuca might not support successful canola production by

2030 due to insufficient spring rains. In contrast, canola cropping could be expanded towards

wet margins due to decline in rainfall. Lower yields were highly correlated with the higher

temperatures and the lower precipitations in Saskatchewan, Canada (Kutcher et al., 2010).

Water and heat stresses can be worsened by lower relative humidity (Figure 3) and higher

potential evapotranspiration (Figure 4) during the growing season. Under these

circumstances, water loss from plant and soil can be rapid resulting in intense abiotic stresses.

Elevated CO2 concentration can attenuate the effects of drought but it is highly uncertain tosay whether there will be beneficial effect of elevated CO2 under such multiple stress

conditions.

Nutrient stress

Canola has higher requirements for N, P and S than cereals and other crops (Colton and

Sykes, 1992). Higher photosynthetic efficiency of plants under elevated CO2 concentrations

is likely to increase N demand of the crop plants. Poor N nutrition of canola means poor yield

and protein in the seed.

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Figure 5. Rainfall map of Victoria.

Insects, Pests and Weeds

Under altered environmental conditions, it is likely to arise some new insect, disease and

weeds species or some existing species become severe problems. Biology of insects and

pathogens are directly affected by changes in temperatures, rainfalls and relative humidity.

Higher temperatures may favour more number of generations of insects.

The overall effect of climate change is going to be low yield and productivity of cropping

systems. However, the impact of climate change will vary depending upon scale of climate

change and the area where it happens. Eastern parts of the state are likely to be benefitted

while western parts will be harmed.

The impacts of climate change on canola cropping in Victoria will be reflected in every levels

of our social structure from community to national level. Every farmer will be hit by the

lower productivity of the system. Lower farm profitability will influence not only life of anindividual but also the whole community attached with the canola cropping. Related

industrial sectors will be affected. Victoria being the second largest producer of canola after

WA, it will influence the national export of canola.

ADAPTATION OPTIONS/STRATEGIES

Adaptation strategies are undertaken in order to effectively manage potential risks over

coming decades as the climate changes (Howden et al., 2007). The adaptation technologies

and benefits will vary depending on the severity of climate change impacts in the region. The

projected changes in rainfall, temperature, RH and evapo-transpiration will require different

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levels of adaptation actions from eastern to the western part of the state. Reduction in rainfall

is likely to benefit the eastern regions where current rainfalls are too high for cropping.

There are several strategies available. One or combination of them can be employed

depending upon climate change severity in the region. Climate information can be

successfully used to manage risk. Studies in Queensland indicate that by using seasonal

forecasts in combination with system analyses, farmers can reduce the impact of various

climate risks (Crimp et al., 2006). Farmers can take actions accordingly if they know what the

season is likely to be.

Application of biotechnology or breeding is another sustainable approach to adapt the climate

change. Heat and drought stress would be most important challenges of canola in Victoria.

Higher temperatures could cancel out the benefits derived from elevated CO2. It was

estimated that, in absence of adaptive measures, a 1.5-2oC increase in mean temperature

would cancel out the grain yield increase in wheat deriving from a CO2 doubling (Howden,

2002). Because the impact of climate change differs with the varieties (genotypes), selection

of varieties best suited for the specific regions can offset the climate change impacts. New

varieties with shorter maturity and better tolerance to heat and water stress can be bred. Some

companies like ‘Evogene’ and ‘Viterra’ have taken initiative to develop such stress tolerant

canola cultivars. Trangenic cultivars are potential option because transfer of drought and heat

stress tolerance has been successful in Arabidopsis.

Current crop management practices should be modified to suit the changing climate.

Temperature would be hotter during the whole growing season but it would be too hot during

filling and maturation stages. Sowing earlier than the current sowing time would protect thecrops from heat stress at the maturation. Changes in other management practices like tillage,

irrigation, fertilizer application and others should be considered.

The crop management changes would not work when the climate change impacts are worse.

Variations in cropping or land use systems might be necessary in such a case. Alternative

crops or farming systems might be appropriate rather than continuing with canola. For

example, rainfalls in Beulah, Kerang and Ouyen might be limiting for a successful cropping

of canola. New crop called juncea canola is an option for the dry environments. The juncea

canola is more vigorous and tolerant to heat and drought stress than canola ( Burton et al.,

1999). A few juncea canola varieties (e.g. Dune, Oasis CL and Sahara CL) have beenreleased and are popular in dry regions. Some even drier regions could be unfit for cropping

and modified to pasture or forestry. Canola cropping could also be moved to wet margins

which would become appropriate for canola as a result of climate change. The areas around

Mansfield, Albury and Beechworth are such potential areas.

Climate change adaptations must be linked to the policy levels. The adaptation strategies

cannot be implemented without relevant policies. Current policies might not support the

adaptation plans to implement. Appropriate policies are necessary to reduce barriers and

prevent mal-adaption. The stake holders should get appropriate financial and policy supports

if the adaptation is going incur some costs. Government supports are required in educating

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farmers about climate change and adaptation technology, infrastructure modification if

needed, efficient agricultural systems, crop insurance etc.

BARRIERS/LIMITS

Climate change adaptation is a social phenomenon. It is not only about the physical climatescience and adaptation technologies. Adaptation incorporates adaptive capacity which

consists of regionally specific socioeconomic and other factors (Barlow et al. Unpublished).

There are certain barriers that must be addressed to make the adaptations timely and

effective.

Social barriers are obvious as the adaptation is going to happen in society. The society may

not be ready to adopt the adaptation techniques. Farmers must be trained about the climate

change, its impact on their cropping and possible benefits from adaptations.

Cost incurred with the adaptation is very important in decision making. The farmers mayneed financial support from the government for equipments like zero till planters and

infrastructures like irrigation and drainage. Similar sort of supports might be necessary for

those who have to alter their cropping or land use systems.

Institutional barriers may appear because many organizations are involved in the adaptation.

The organizations include research institutes, extension agencies, policy formulation bodies,

financial organizations etc. Limitations might arise from all the organizations. For example,

research organizations have challenge of precise climate change information and adaptation

techniques. Extension agencies require trained manpower to extend the technologies to the

farming community. Similarly, financial institutions might have challenges to invest tosupport the adaptations.

Some barriers in relation to appropriate policy to implement the adaptation plans are

expected. If policy makers failed to make proper policies to address the future climate

change, it would be probably the biggest hurdle to a successful adaptation.

CONCLUSION

A climate model developed by CSIRO was used to project climate variables in Victoria in

2050. Temperature, rainfall, relative humidity (RH) and evapo-transpiration in winter and

spring were projected using medium emission scenarios and 50th percentile estimates.

Temperature has been projected to increase throughout Victoria while the rainfall has been

projected to be lower in the state in 2050 relative to 1990. Slightly low relative humidity and

higher evapo-transpiration are expected. All the changes were shown to be more intense in

spring than in winter. In spring, maximum increase in temperature and decline in rainfall

were 2oC and 20%, respectively.

Combined effects of these changes together with higher evapo-transpiration can severely

affect physiological processes of canola. Heat and drought stress are most likely at the

maturation stage of the crop. Premature ripening (short growing period), few number of podsand seeds, small seeds, deformed pods are most probable effects. There are beneficial effects

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of elevated CO2 in terms of improved photosynthetic efficiency of plants but the heat stress

might counteract them. Nitrogen demand of crop will rise because of improved

photosynthetic efficiency. This might affect the quality in terms of protein and oil content.

Canola yields will decline in western areas of the state (dry margins). Some areas in wet

margins might be suitable for canola production. Less productive systems would impactnegatively from individual farmer to national level.

There are adaptation options available to minimize climate change impacts or to even get

benefitted from the changes in some areas. Climate information beforehand can be used to let

farmers act according to the probable changes. There are crop management techniques like

residue and fertilizer management, tillage and change in sowing time, cultural and

intercultural practices etc which can potentially improve adaptive capacity and even mitigate

emissions. High rainfall areas (500-700 mm annual rainfall) in the middle of the state are

most likely to benefit from these management changes. The areas in dry margins will have to

adopt drought and heat tolerant cultivars together with these changes. Juncea canola andtransgenic cultivars tolerant to such abiotic stresses are the best options in the dry

environments. Shifting to pasture or forestry can be the only option in the areas like western

part of the state where rainfall becomes too low to support canola growth.

All the stake holders from research organizations to extension agencies and farming

community need appropriate policy support to plan and implement adaptation strategies.

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References

ABS Agricultural Commodities, Australia. 2009. http://www.abs.gov.au/AUSSTATS.

Australian Oilseeds Federation (AOF), 2010. Australian Oilseeds Industry.

www.australianoilseeds.com.

Burton, W.A., Pymer, S.J., Salisbury, P.A., Kirk, J.T.O. and Oram, R.N. 1999. Performance

of Australian canola quality Indian mustard breeding lines. Proc. 10th Int. Rapeseed

Congress, Canberra, Australia.

http://www.regional.org.au/au/gcirc/4/51.htm#TopOfPage

Canola Council of Canada. 2006. Missing pods or blanks on the main stem! What could be

the cause? Canolafact, September 2006.

Colton R.T. and J.D Sykes. 1992. Canola (Agfact p 5.2.1). NSW Agriculture Pp: 1-50.

Edward E. and A. Haagensen. 2010. Wheat in farming systems. In: The Wheat Book,Anderson W.K., J.R. Garlinge (eds.), P:112-130. Dept. of Agri, WA.

Howden S.M. 2002. Potential global change impacts on Australia’s wheat cropping systems.

In: Effects of climate change and variability on agricultural production systems (Eds.

OC Doering, J.C. Randolph, J. Southworth, R.A. Pfeifer) pp. 219-247. Springer, the

Netherlands.

Howden S.M., J.F. Soussana, F.N. Tubeillo, N. Chhetri, M. Dunlop and H. Meinke. 2007.

Adapting agriculture to climate change. PNAS 104: 19691-19696.

Kutcher H.R, J.S. Warland and S.A. Brandt. 2010. Temperature and precipitation effects on

canola yields in Saskatchewan, Canada. Agriculture and Forest Meteorology,

150:161-165.

Ludwig F. and S. Asseng. 2010. Potential benefits of early vigor and changes in phonology in

wheat to adapt to warmer and drier climates. Agricultural systems 103: 127-136.

Mailer R. 1999. Quality of canola in Australia. In: Salisbury P.A., T.D. Potter, G. McDonald

and A.G. Green (eds.), Canola in Australia: the first thirty years.

Norton R. 2003. Conservation farming systems and canola. Avcare, The University of

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Salisbury P. 2006. Biology of Brassica juncea and potential gene flow from B. juncea to

Brassicaceae species in Australia. Miscellaneous report PAS 2006/1.,University of

Melbourne.

Suppiah R., P.H. Wheltton and I.G. Watterson. 2004. Climate change in Victoria. Department

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http://www.abs.gov.au/AUSSTATS

http://www.australianoilseeds.com/


http://www.abs.gov.au/AUSSTATS

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