Posts Tagged ‘Drought tolerance’

In new hostile climate, drought-tolerant crops, systems needed on unprecedented scale

This op-ed by Martin Kropff, Director General of the International Maize and Wheat Improvement Center, was originally published by SciDevNet.

Last year, droughts devastated staple food crops across the developing world, cutting production by about half in some countries. A stream of reports from Central America, Eastern and Southern Africa as well as the Asia-Pacific region painted a grim picture of suffering and upheaval.

Poor harvests subjected tens of millions to chronic hunger, prompting various governments to declare states of emergency. In Central America, survey results, including some from the US government, cited climate-induced food shortages as the main reason for emigration from drought-hit areas.

Extreme weather, with its appalling consequences, demands an extraordinary response. Redoubled efforts must focus on building resilience into the developing world´s major food systems.

Fortunately, agricultural science has already provided a wide range of solutions and continues to generate more.

Conservation agriculture and drought-tolerant crops

New technologies from the International Maize and Wheat Improvement Center (CIMMYT) suggest how developing countries can work toward a better future.

Drought-tolerant cereals show promise for helping stabilise maize and wheat production. Through many years of conventional plant breeding, researchers have developed more than 160 maize varieties for sub-Saharan Africa that yield 25-30 percent more than farmers’ standard varieties under drought, while performing at least equal to these under normal rainfall.

According to a study in Zimbabwe, farmers growing the drought-tolerant maize harvested up to 600 kilograms more grain per hectare in drought years – enough to feed a family of six for nine months. The improved varieties are already grown on 2.5 million hectares, benefitting around 54 million people. Researchers are also poised to develop wheat lines with tolerance to drought and heat, having identified genes for these traits though cutting-edge collaborative science.

“Extreme weather, with its appalling consequences, demands an extraordinary response. Fortunately, agricultural science has already provided a wide range of solutions and continues to generate more.”

Martin Kropff, director general, International Maize and Wheat Improvement Center

To provide maximum benefits, drought-tolerant crop varieties need to form part of smart farming systems that capture and conserve moisture. One such system – conservation agriculture – combines diverse crops with reduced or no ploughing, and the practice of leaving stalks and other crop residues on the ground after harvest. Already widely applied in South America´s Southern Cone, this system has also made inroads in the predominant rice-wheat system of South Asia´s Indo-Gangetic Plain, a major breadbasket for the region. Conservation agriculture is being widely promoted in parts of sub-Saharan Africa, Mexico and elsewhere.

Globally, around 80 per cent of food production depends on increasingly erratic rainfall. To ensure better water supplies, many farmers have purchased their own small pumps for irrigation, often using water from aquifers underground.  One drawback to this practice is that it can lead to groundwater depletion, which is already a serious problem in Northwest India, for example. In searching for solutions, researchers there have recently shown how farmers can grow just as much rice and wheat using only about half the water normally needed, through conservation agriculture combined with the use of a drip irrigation system that delivers just the right amount of water, plus fertiliser to crop roots through underground pipes.

Scaling-up drought solutions

The challenge now is to mainstream the growing portfolio of drought solutions – a task demanding not only technical acumen, but institutional vision.
Partnerships between private seed companies and public crop breeding programs, for example, played a vital role in getting drought-tolerant maize into farmers’ fields. But the people benefitting from this innovation today still constitute only a fraction of the 300 million Africans whose diets depend on maize. Clearly, such partnerships must be expanded.

Innovation platforms are rapidly becoming the tool of choice for refining and scaling out more complicated innovations, such as conservation agriculture. Transitioning to new production practices can be a daunting experience for farmers, especially smallholders. By bringing together networks of farmers, extension specialists, researchers, private companies and policymakers, innovation platforms offer the knowledge, services and products needed for change.

In order for improved technologies to have the desired effect, government and partner organisations must get their policies and decisions right. Recent research in Bangladesh, for example, has identified new policy measures for enhancing the efficiency of irrigation services. In addition, organisations must base their decisions and planning before and during droughts on information from new systems that use remote sensing and climate data analysis for drought monitoring and early warning.

Science-based climate projections tell us that drought will become even worse in the decades ahead. Only by implementing drought solutions on an unprecedented scale, will countries be able to avoid a future that leaves millions of people at the mercy of a hostile climate.

Wheat to beat the heat

Adapted from a blog by Jacques Wery, ICARDA Deputy Director General – Research, originally posted on the International Center for Agriculture in the Dry Areas (ICARDA) website.

Land temperature on June 26, 2019. Map generated using information from the Copernicus Sentinel-3’s Sea and Land Surface Temperature Radiometer

Western Europe is in the midst of an intense heat wave that started at the end of June. The southern French commune of Villevieille recorded a temperature of 45.1 °C, breaking the country’s all-time record. The heat also set new temperature records in Germany and the Czech Republic. Other countries like Italy, Spain and Portugal are also gripped with temperatures much higher than normal.

Scientists have attributed the soaring temperatures to the combination of a storm over the Atlantic Ocean and high pressure over central Europe, which is importing hot air from the Sahara. Though heat waves are not uncommon in Europe, this one was unusually early. Experts say climate change is making heat waves more common (Global warming of 1.5 °C IPCC Special Report).

Apart from human health, the heat wave is already causing significant damage in agriculture. Major wheat growers experienced temperatures of 40 °C and higher. This is of great concern, as the heat wave occurred during the crop’s critical growth stages. Wheat is a cool season crop with an optimal daytime growing temperature of 15 °C during the critical reproductive stage. Wheat plants exposed to high temperatures around the period of flowering lose fertility due to pollen dehydration, resulting in less grain formed. It is calculated that for every degree above the optimum 15 °C, wheat experiences a yield reduction of three to four percent.

If a heat wave like such as this one had occurred one month earlier, at the end of May, when Northern European wheat is in full bloom, it could have caused up to 50 percent yield loses, a devastating blow to the European agriculture and food sectors costing billions of Euros.

The response of scientists

Breeding heat tolerant wheat varieties remains one of the most strategic approaches to cope with the risk of unseasonal heat waves. The International Center for Agricultural research in Dry Areas (ICARDA) started in 2012 to use field stations that experience continuous heat-stress to select new wheat cultivars better primed to tolerate this stress.

In Sudan, the experimental farm of Wad Medani was developed together with the Agricultural Research Corporation (ARC) and CIMMYT (International Center for Maize and Wheat Improvement), to test thousands of wheat candidate varieties each year. This station experiences average maximum daily temperatures above 30 °C throughout the growing season, which is less than 100 days long, from planting to harvest. This test was used to identify critical genes controlling heat-tolerant in common wheat, and to release new cultivars of bread wheat and durum wheat capable of withstanding severe heat.

The ICARDA-ISRA durum variety Haby
Senegalese female cooperative growing the ICARDA-ISRA durum variety Haby at above 32 C throughout the season.

Similarly, two heat-stress experimental farms were developed in West Africa to test durum wheat germplasm. In collaboration with Prof Rodomiro Ortiz  of the Swedish University of Agricultural Sciences (SLU) Department of Plant Breeding, the stations of Kaédi in Mauritania and Fanaye in Senegal were upgraded in partnership with the Centre National de Recherche Agronomique et de Développement Agricole (CNRADA) and the Institut Sénégalais de Recherche Agricole (ISRA).

Field testing conducted at these stations – with daily temperatures above 32 °C throughout the cycle and a season of only 90 days – have revealed four new durum wheat cultivars perfectly adapted to tolerate intense heat. The work conducted in West Africa has even resulted in the awarding of the prestigious OLAM Prize for Innovation in Food Security to the team of researchers involved.

To convert this success into cultivars that could be grown, heat tolerance must be combined with the ability to cope with drought stress. An experiment was devised at the Marchouch station in Morocco, where plastic tunnels were placed on the wheat plants at the time of flowering to raise temperatures to above 40 °C and simultaneously prevent any rainfall from reaching the plants.

Plastic tunnels at the ICARDA Marchouch station in Morocco
Plastic tunnels were placed on the wheat plants at the time of flowering at the ICARDA Marchouch station in Morocco

When all other tested varieties lost more than 50 percent yield to the two combined stresses, the ICARDA-INRA (Institut Nationale de la Recherche Agronomique in Morocco) cultivar Faraj lost only 25 percent, a major positive result considering the severity of the stresses tested. Along the same principles, more than 60 wheat varieties of ICARDA origin have been released by national breeding programs in Central and West Asia and North Africa regions and sub- Saharan Africa regions in the last five years alone, thanks to the ability of the germplasm to adapt to some of the most severe wheat stresses occurring around the world.

Can Europe take advantage of success stories?

In the USA and Canada, farmers grow mostly wheat varieties developed and commercialized by public wheat breeding programs. These cultivars have been very popular and public sector wheat-breeding activities are vital to the industry.

In Australia, wheat breeding is conducted by the private sector. However, public researchers are spending the same amount of money on pre-breeding as they did 10 years ago on breeding and variety development together. To take advantage of some of the success stories of ICARDA and CIMMYT, the Australian wheat breeding programs established 10 years ago the CIMMYT-Australia-ICARDA Germplasm Evaluation project (CAIGE). Each year, Australian breeders visit the trials of ICARDA in Morocco and CIMMYT in Mexico. They select the top high yielding wheat genotypes that combine drought and heat tolerance, with other useful traits. These are then imported and tested across Australian sites to confirm the best one for commercialization or use in hybridization programs.

Dr Allan Rattey
Allan Rattey, national early generation wheat breeder with Intergrain/Australia, toured Morocco in April 2019 to witness the performances of ICARDA germplasm in a season that received less than 200 mm of total moisture, equivalent to what most regions of Northern Europe receive in the month of December alone, and with temperatures during flowering regularly exceeding 26 °C.  Dr. Rattey had a chance to select a range of novel genetic material in the form of promising ICARDA lines tested next to popular Australian varieties. 

In Europe, the situation is more like Australia, and public researchers do not work directly on the commercialization and development of varieties, which is left to the private companies. Instead, public research focuses on pre-breeding to develop new breeding techniques and on high-risk, longer-term targets, thereby supporting the private sector and farmers with high-tech innovations.

CGIAR centers such as ICARDA and CIMMYT have worked in close collaboration with European universities and advanced research institutions for a long time to develop and adapt the most novel technologies for pre-breeding. It might also be advantageous for European private sector companies to start taking advantage of CGIAR stress-tolerant wheat varieties and develop a system similar to CAIGE used by Australian breeders. By taking advantage of similar environments in Morocco and  Mediterranean environments in Europe, European breeders can select promising germplasm of tomorrow and provide the continent’s agricultural sector with a practical defense against future heat waves.