Typically looking like a small caterpillar growing up to 5 cms in length, the fall armyworm (FAW, Spodoptera frugiperda) is usually green or brown in color with an inverted “Y” marking on the head and a series of black dots along the backs. Thriving in warm and humid conditions, it feeds on a wide range of crops including maize, posing a significant challenge to food security, if left unmanaged. The fall armyworm is an invasive crop pest that continues to wreak havoc in most farming communities across Africa.
A CIMMYT researcher surveys damaged maize plants while holding a fall armyworm, the culprit. (Photo: Jennifer Johnson/CIMMYT)
The first FAW attack in Zimbabwe was recorded around 2016. With a high preference for maize, yield losses for Zimbabwe smallholder farmers are estimated at US$32 million. It has triggered widespread concern among farmers and the global food system as it destroyed large tracts of land with maize crops, which is a key staple and source of farmer livelihood in southern Africa. The speed and extent of the infestation caught farmers and authorities unprepared, leading to significant crop losses and food insecurity.
Exploring the destructive FAW life cycle
It undergoes complete metamorphosis, progressing through four main stages including egg, larva, pupa, and adult. Reproducing rapidly in temperatures ranging from 20 to 38°C, moist soil conditions facilitate the egg-laying process, while mild winters enable its survival in some regions. The larval stage is the most destructive phase, feeding voraciously on plant leaves and can cause severe defoliation. They can migrate in large numbers, devouring entire fields within a short period if left unchecked.
Working towards effective FAW management
A farmer and CIMMYT researcher examine maize plants. (Photo: CIMMYT)
Efficient monitoring, early detection, and appropriate management strategies are crucial for mitigating the impact of FAW infestations and protecting agricultural crops. To combat the menace of this destructive pest, CIMMYT, with support from the United States Agency for International Development (USAID), has been implementing research and extension on cultural control practices in Zimbabwe. One such initiative is the “Evaluating Agro-ecological Management Options for Fall Armyworm in Zimbabwe”. Since 2018, this project strives to address research gaps on FAW management and cultural control within sustainable agriculture systems. The focus of the research has been to explore climate-adapted push-pull systems and low-cost control options for smallholder farmers in Zimbabwe who are unable to access and use expensive chemical products.
Environment friendly practices are proving effective to combat FAW risks
To reduce the devastating effects of FAW, the project in Zimbabwe is exploring the integration of legumes into maize-based strip cropping systems as a first line of defense in the Manicaland and Mashonaland east provinces. By planting maize with different, leguminous crops such as cowpea, lablab and mucuna, farmers can disrupt the pests’ feeding patterns and reduce its population. Legumes release volatile compounds that repel FAW, reducing the risk of infestation. Strip cropping also enhances biodiversity, improves soil health and contributes to sustainable agricultural practices. Overall results show that FAW can be effectively managed in such systems and implemented by smallholder farmers. Research results also discovered that natural enemies such as ants are attracted by the legumes further contributing to the biological control of FAW.
Spraying infested maize crop with Fawligen in Nyanyadzi. (Photo: CIMMYT)
Recently, the use of biopesticides such as Fawligen has gained traction as an alternative to fight against fall armyworm. Fawligen is a biocontrol agent that specifically targets the FAW larvae. Its application requires delicate attention – from proper storage to precise mixing and accurate application. Following recommended guidelines is essential to maximize its effectiveness and minimize potential risks to human health and the environment.
Impact in numbers
Since the inception of the project, close to 9,000 farmers participated in trainings and exposure activities and more than 4,007 farmers have adopted the practices on their own field with 1,453 hectares under improved management. Working along with extension officers from the Ministry of Lands, Agriculture, Water, Fisheries & Rural Resettlement, the project has established 15 farmer field schools as hubs of knowledge sharing, promoting several farming interventions including conservation agriculture practices (mulching, minimum tillage through ripping), timely planting, use of improved varieties, maintaining optimum plant population, and use of recommended fertilizers among others.
Addressing FAW requires a multi-faceted approach. The FAW project in Zimbabwe is proactive in tackling infestation by integrating intercropping trials with legumes, harnessing the application of biopesticides, and collaborative research. By adopting sustainable agricultural practices, sharing valuable knowledge, and providing farmers with effective tools and techniques, it is possible to mitigate the impact of FAW and protect agrifood systems.
Maize grain heavily damaged by the larger grain borer and maize weevil. (Photo: Jessica González/CIMMYT)
According to the World Health Organization (WHO), 10% of the global population suffers from food poisoning each year. Aflatoxins, the main contributor to food poisoning around the world, contaminate cereals and nuts and humans, especially vulnerable groups like the young, elderly, or immune-compromised, and animals are susceptible to their toxic and potentially carcinogenic effects.
Fungi contamination occurs all along the production cycle, during and after harvest, so the mitigation of the mycotoxins challenge requires the use of an integrated approach, including the selection of farmer-preferred tolerant varieties, implementing good agricultural practices such as crop rotation or nitrogen management, reducing crop stress, managing pests and diseases, biological control of mycotoxigenic strains, and good post-harvest practices.
Monitoring of mycotoxins in food crops is important to identify places and sources of infestations as well as implementing effective agricultural practices and other corrective measures that can prevent outbreaks.
A bug problem
Insects can directly or indirectly contribute to the spread of fungi and the subsequent production of mycotoxins. Many insects associated with maize plants before and after harvest act as a vector by carrying fungal spores from one location to another.
International collaboration is key to managing the risks associated with the spread of invasive pests and preventing crop damage caused by the newly introduced pests. CIMMYT, through CGIAR’s Plant Health initiative, partners with the Center for Grain and Animal Health Research of the US Department of Agriculture (USDA) and Kansas State University are investigating the microbes associated with the maize weevil and the larger grain borer.
The experiment consisted of trapping insects in three different habitats, a prairie near CIMMYT facilities in El Batán, Texcoco, Mexico, a maize field, and a maize store at CIMMYT’s experimental station at El Batán, using Lindgren funnel traps and pheromones lures.
Hanging of the Lindgren funnel traps in a prairie near El Bátan, Texcoco, Mexico. (Photo: Jessica González/CIMMYT)
Preliminary results of this study were presented by Hannah Quellhorst from the Department of Entomology at Kansas State University during an online seminar hosted by CIMMYT.
The collected insect samples were cultured in agar to identify the microbial community associated with them. Two invasive pests, the larger grain bore and the maize weevil, a potent carcinogenic mycotoxin was identified and associated with the larger grain borer and the maize weevil.
The larger grain borer is an invasive pest, which can cause extensive damage and even bore through packaging materials, including plastics. It is native to Mexico and Central America but was introduced in Africa and has spread to tropical and subtropical regions around the world. Together with the maize weevil, post-harvest losses of up to 60% have been recorded in Mexico from these pests.
“With climate change and global warming, there are risks of these pests shifting their habitats to areas where they are not currently present like sub-Saharan Africa and North Africa,” said Quelhorst. “However, the monitoring of the movement of these pests at an international level is lacking and the microbial communities moving with these post-harvest insects are not well investigated.”
Maize is a staple crop in Zimbabwe, playing a vital role in the country’s agricultural landscape as food for its own people and an export good. However, behind every successful maize harvest lies the quality of seed and resistance to diseases and stresses.
Amidst the multitude of diseases that threaten maize crops, one adversary is maize lethal necrosis (MLN). Though not native to Zimbabwe, it is crucial to remain prepared for its potential impact on food security.
What is maize lethal necrosis?
MLN is a viral disease, caused by a combination of two virus diseases. The disease emerged in Kenya in 2011 and quickly spread to other countries in eastern Africa. The introduction of MLN to Africa was likely affected by the movement of infected seed and insect vectors. MLN has had a severe impact on regional maize production, leading to yield losses of up to 90%.
Recognizing the need to equip seasoned practitioners with the knowledge and skills to effectively diagnose and manage MLN, CIMMYT organized a comprehensive training on MLN diagnosis and management, targeting 25 representatives from Zimbabwe’s Plant Quarantine Services.
From students to experienced technicians, pathologists and plant health inspectors, this was an opportunity to refresh their knowledge base or an introduction to the important work of MLN mitigation. “This training for both advanced level practitioners and students is crucial not only for building competence on MLN but also to refresh minds to keep abreast and be prepared with approaches to tackle the disease once it is identified in the country,” said Nhamo Mudada, head of Plant Quarantine Services.
Expectations were diverse, ranging from sharpening understanding of key signs and symptoms to learning from country case examples currently ridden with the disease. With CIMMYT’s guidance, practitioners learned how to identify MLN infected plants, make accurate diagnoses, and implement management strategies to minimize losses.
“For over 10 years, these trainings have been important to raise awareness, keep local based practitioners up to speed, help them diagnose MLN, and make sure that they practice proper steps to tackle this disease,” said L.M Suresh, CIMMYT maize pathologist and head of the MLN screening facility in Kenya.
Identifying the specific MLN causing viral disease affecting a maize plant is the first step in combating MLN. Determining whether it is a biotic or abiotic disease is critical in establishing its cause and subsequent diagnosis. By implementing proper diagnostic techniques and understanding the fundamentals of good diagnosis, practitioners can bring representative samples to the lab and accurately identify MLN.
Tackling MLN in Zimbabwe
Initiated in 2015 at Mazowe as a joint initiative between the Government of Zimbabwe and CIMMYT, a modern quarantine facility was built to safely import maize breeding materials from eastern Africa to southern Africa and enable local institutions to proactively breed for resistance against MLN.
The MLN quarantine facility at the Plant Quarantine Institute is run by the Department of Research and Specialist Services (DRSS) and is mandated to screen maize varieties imported under strict quarantine conditions to ensure that they are MLN-free.
Training participants pose outside of the MLN screening facilities. (Photo: CIMMYT)
To date, CIMMYT and partners have released 22 MLN resistant and tolerant hybrids in eastern Africa. CIMMYT’s research and efforts to combat MLN have focused on a multidimensional approach, including breeding for resistant varieties, promoting integrated pest management strategies, strengthening seed systems, and enhancing the capacity of farmers and stakeholders.
“Support extended through valuable partnerships between CIMMYT, and the collaborations have played a pivotal role from surveillance to diagnostics and building capacity,” said Mudada.
Feedback and insights
Chief Plant Health Inspector for Export and Imports Biosecurity, Monica Mabika, expressed gratitude for the training. “It is always an honor when we have expert pathologists come through and provide a valuable refresher experience, strengthening our understanding on issues around biosecurity and learning what other countries are doing to articulate MLN,” she said.
Students learn how to screen maize plants for MLN. (Photo: CIMMYT)
Among the students was Audrey Dohwera from the University of Zimbabwe, who acknowledged the importance of the training. “I have been attached for 2 months under the pathology department, and I was eager to learn about MLN, how to detect signs and symptoms on maize, how to address it and be able to share with fellow farmers in my rural community,” she said.
With the knowledge gained from this training, practitioners are well equipped to face the challenges that MLN may present, ultimately safeguarding the country’s maize production status.
For certified seed to reach a farmer’s field for cultivation, it passes through many hands – international and national breeding programs, government regulatory agencies, private seed companies, and retailers or agrodealers. These organizations each play an important role in the design, testing, production and distribution of improved maize and wheat varieties.
Together, these processes, actors, and the relationships between them form a seed system, which incorporates the production, conservation, exchange, and use of propagation materials for crops. As defined by the CGIAR Community of Excellence for Seed Systems Development (COE), seed systems are complex, involving arrangements between public and private sectors, layers of regulation, and years of research and development, and are specific to each crop, country, agroecological environment and market context.
The International Maize and Wheat Improvement Center (CIMMYT) has extensively researched and worked with the facets and actors of cereal seed systems in Latin America, Asia and Africa, specifically in relation to cereal crops, and with maize and wheat in particular.
The role of CIMMYT scientists in supply and demand
Breeding teams use traditional and advanced techniques to identify improved maize and wheat breeding lines according to the desired traits determined by farmers and consumer markets. In addition to higher grain yields, other preferred traits include more and larger grains or fruit, resistance to pests and diseases, tolerance to environment pressures (such as drought or poor soils), better nutritional quality, or flavor and ease of processing.
These lines are used for further breeding, testing, seed multiplication by public and private sector partners. Others engage in varietal testing on farmers’ fields and support seed companies in production.
To foster smallholder farmers’ access to these improved varieties, CIMMYT implements a seed systems strategy divided into supply side development, concerning breeding and seed production, and demand side development, covering issues related to variety distribution and uptake. On the supply side, CIMMYT scientists’ work is carried out in three phases:
Product development phase: Breeders advance through CIMMYT’s breeding funnel (pipeline) the most promising materials from one improvement stage to the next. The best candidates are first tested in field trials at research stations and then in farmers’ fields. Afterwards, CIMMYT organizes field days to showcase the best performing materials to public and private sector partners.
Product allocation phase: Local partners request new CIMMYT products and sign licensing agreements that protect the new seed from private ownership claims and help accelerate marketing and distribution in target regions at affordable prices.
Release and commercialization phase: Farmers can obtain and benefit from seed of improved maize and wheat once national authorities register and release varieties that excel in national performance trials and public and private sector partners begin seedproduction and marketing or distribution.
On the demand side, CIMMYT scientists work to support seed systems development though its work on:
Farmer preferences and demand for varieties: Scientists look to understand current and future preferences and needs for varieties. This involves the use of innovative tools, such as product concept testing, on-farm testing and ranking, and participatory varietal evaluation.
Seed industry development: Small and medium sized seed businesses, as well as agrodealers, play a critical role in the distribution of seed. Our work looks to understand entry points for support to the seed industry for advancing faster uptake of new varieties by farmers.
Consumer demand for grain: The preferences of consumers and agroindustry for grain and grain-based foods provide an important source of demand for new varieties. CIMMYT scientists engage with consumers and agroindustry for innovation in food product design and testing consumer acceptance. Insights gains are reported back to breeding and seed production teams for design of future cereal varieties.
Gender-sensitive seed systems
A team of social scientists at CIMMYT with expertise in economics, gender and marketing works to understand the needs and preferences of farmers, consumers, and the agroindustry for new varieties. They develop retail strategies, such as targeted marketing, in-store seed assessment support and price incentives, promote the adoption of better policies in support of seed companies and seed markets.
CIMMYT explores mechanisms to help seed companies adapt their products to women’s preferences. Research shows that beyond yield potential, women seek different characteristics in seeds than men. For example, women are more inclined to favor a variety with a longer grain shelf life. Similarly, when women engage in participatory variety selections, they tend to make more objective evaluations of varieties than men.
Our experts advance strategies to promote inclusive and effective delivery systems, helping both female and male farmers obtain the seed that works best for their specific needs. This ongoing model gives CIMMYT feedback from farmers and public and private sector partners, which informs subsequent breeding research.
Why are cereal seed systems important?
CIMMYT contributes to new improved seeds getting to farmers, consumers and agroindustry, which ultimately leads to lasting positive impacts in terms of food security and economic development.
Cereals such as maize and wheat play a critical role in global food security. Increasing their productivity in the Global South remains a key developmental priority. Smallholders face increasing pressure to sustain and increase their yields in the face of three main issues: climate change, which increases the frequency of severe drought, floods, and pest and disease outbreaks; rapidly rising costs of inputs, such as land, labor, fertilizer; and unfavorable marketing conditions for their grain.
As a critical entry point for improved agricultural technology, seed systems are in urgent need of improvement and modernization. Since the onset of the Green Revolution in the 1960s, the discovery, development, and delivery of improved seed for smallholder farmers has remained an essential part of global and local initiatives to increase smallholder productivity.
What does a sustainable, inclusive, and productive seed system look like?
For the future, there are serious challenges for expanding and deepening the impact from investments in breeding. Market intelligence systems are urgently needed to support breeding teams in future product design and evidence-based prioritization. Innovation is needed in terms of how actors within the systems inform and support farmers to experiment with new seeds.
CIMMYT is working with CGIAR partners to implement a new, 10-year strategy. Effective seed systems achieve the widespread adoption of varieties that capture the gains from crop improvement and connect actors along the value chain so that all can benefit from a productive crop, from seedbank to soil. In close collaboration with national agricultural research systems (NARS), CGIAR has had historic success introducing improved cultivars to smallholder producers of staple crops, with high return on investment. However, there is still some standing criticism that large, public breeding programs take a technologically-biased and supply-pushed approach to agricultural innovation.
Cereal crop breeding programs can become more demand-oriented by employing more market segmentation strategies – breaking down target client markets into smaller, more geographically and demographically specific groups – and developing a more accessible description and profile of its products. Using similar approaches, CGIAR is likely to expand demand-oriented programs in genetic innovation and seed systems development in the new phase of operations.
Cover photo: Staff members bag maize at the Demeter Seeds warehouse. (Photo: Emma Orchardson/CIMMYT)
Emerging in the last 120 years, science-based plant breeding begins by creating novel diversity from which useful new varieties can be identified or formed. The most common approach is making targeted crosses between parents with complementary, desirable traits. This is followed by selection among the resulting plants to obtain improved types that combine desired traits and performance. A less common approach is to expose plant tissues to chemicals or radiation that stimulate random mutations of the type that occur in nature, creating diversity and driving natural selection and evolution.
Determined by farmers and consumer markets, the target traits for plant breeding can include improved grain and fruit yield, resistance to major diseases and pests, better nutritional quality, ease of processing, and tolerance to environmental stresses such as drought, heat, acid soils, flooded fields and infertile soils. Most traits are genetically complex — that is, they are controlled by many genes and gene interactions — so breeders must intercross and select among hundreds of thousands of plants over generations to develop and choose the best.
Plant breeding over the last 100 years has fostered food and nutritional security for expanding populations, adapted crops to changing climates, and helped to alleviate poverty. Together with better farming practices, improved crop varieties can help to reduce environmental degradation and to mitigate climate change from agriculture.
Is plant breeding a modern technique?
Plant breeding began around 10,000 years ago, when humans undertook the domestication of ancestral food crop species. Over the ensuing millennia, farmers selected and re-sowed seed from the best grains, fruits or plants they harvested, genetically modifying the species for human use.
Modern, science-based plant breeding is a focused, systematic and swifter version of that process. It has been applied to all crops, among them maize, wheat, rice, potatoes, beans, cassava and horticulture crops, as well as to fruit trees, sugarcane, oil palm, cotton, farm animals and other species.
With modern breeding, specialists began collecting and preserving crop diversity, including farmer-selected heirloom varieties, improved varieties and the crops’ undomesticated relatives. Today hundreds of thousands of unique samples of diverse crop types, in the form of seeds and cuttings, are meticulously preserved as living catalogs in dozens of publicly-administered “banks.”
The International Maize and Wheat Improvement Center (CIMMYT) manages a germplasm bank containing more than 180,000 unique maize- and wheat-related seed samples, and the Svalbard Global Seed Vault on the Norwegian island of Spitsbergen preserves back-up copies of nearly a million collections from CIMMYT and other banks.
Through genetic analyses or growing seed samples, scientists comb such collections to find useful traits. Data and seed samples from publicly-funded initiatives of this type are shared among breeders and other researchers worldwide. The complete DNA sequences of several food crops, including rice, maize, and wheat, are now available and greatly assist scientists to identify novel, useful diversity.
Much crop breeding is international. From its own breeding programs, CIMMYT sends half a million seed packages each year to some 800 partners, including public research institutions and private companies in 100 countries, for breeding, genetic analyses and other research.
A field worker removes the male flower of a wheat spike, as part of controlled pollination in breeding. (Photo: Alfonso Cortés/CIMMYT)
A century of breeding innovations
Early in the 20th century, plant breeders began to apply the discoveries of Gregor Mendel, a 19th-century mathematician and biologist, regarding genetic variation and heredity. They also began to take advantage of heterosis, commonly known as hybrid vigor, whereby progeny of crosses between genetically different lines will turn out stronger or more productive than their parents.
Modern statistical methods to analyze experimental data have helped breeders to understand differences in the performance of breeding offspring; particularly, how to distinguish genetic variation, which is heritable, from environmental influences on how parental traits are expressed in successive generations of plants.
Since the 1990s, geneticists and breeders have used molecular (DNA-based) markers. These are specific regions of the plant’s genome that are linked to a gene influencing a desired trait. Markers can also be used to obtain a DNA “fingerprint” of a variety, to develop detailed genetic maps and to sequence crop plant genomes. Many applications of molecular markers are used in plant breeding to select progenies of breeding crosses featuring the greatest number of desired traits from their parents.
Plant breeders normally prefer to work with “elite” populations that have already undergone breeding and thus feature high concentrations of useful genes and fewer undesirable ones, but scientists also introduce non-elite diversity into breeding populations to boost their resilience and address threats such as new fungi or viruses that attack crops.
Transgenics are products of one genetic engineering technology, in which a gene from one species is inserted in another. A great advantage of the technology for crop breeding is that it introduces the desired gene alone, in contrast to conventional breeding crosses, where many undesired genes accompany the target gene and can reduce yield or other valuable traits. Transgenics have been used since the 1990s to implant traits such as pest resistance, herbicide tolerance, or improved nutritional value. Transgenic crop varieties are grown on more than 190 million hectares worldwide and have increased harvests, raised farmers’ income and reduced the use of pesticides. Complex regulatory requirements to manage their potential health or environmental risks, as well as consumer concerns about such risks and the fair sharing of benefits, make transgenic crop varieties difficult and expensive to deploy.
Genome editing or gene editing techniques allow precise modification of specific DNA sequences, making it possible to enhance, diminish or turn off the expression of genes and to convert them to more favorable versions. Gene editing is used primarily to produce non-transgenic plants like those that arise through natural mutations. The approach can be used to improve plant traits that are controlled by single or small numbers of genes, such as resistance to diseases and better grain quality or nutrition. Whether and how to regulate gene edited crops is still being defined in many countries.
The mobile seed shop of Victoria Seeds Company provides access to improved maize varieties for farmers in remote villages of Uganda. (Photo: Kipenz Films for CIMMYT)
Selected impacts of maize and wheat breeding
In the early 1990s, a CIMMYT methodology led to improved maize varieties that tolerate moderate drought conditions around flowering time in tropical, rainfed environments, besides featuring other valuable agronomic and resilience traits. By 2015, almost half the maize-producing area in 18 countries of sub-Saharan Africa — a region where the crop provides almost a third of human calories but where 65% of maize lands face at least occasional drought — was sown to varieties from this breeding research, in partnership with the International Institute of Tropical Agriculture (IITA). The estimated yearly benefits are as high as $1 billion.
Intensive breeding for resistance to Maize Lethal Necrosis (MLN), a viral disease that appeared in eastern Africa in 2011 and quickly spread to attack maize crops across the continent, allowed the release by 2017 of 18 MLN-resistant maize hybrids.
Improved wheat varieties developed using breeding lines from CIMMYT or the International Centre for Agricultural Research in the Dry Areas (ICARDA) cover more than 100 million hectares, nearly two-thirds of the area sown to improved wheat worldwide, with benefits in added grain that range from $2.8 to 3.8 billion each year.
Breeding for resistance to devastating crop diseases and pests has saved billions of dollars in crop losses and reduced the use of costly and potentially harmful pesticides. A 2004 study showed that investments since the early 1970s in breeding for resistance in wheat to the fungal disease leaf rust had provided benefits in added grain worth 5.36 billion 1990 US dollars. Global research to control wheat stem rust disease saves wheat farmers the equivalent of at least $1.12 billion each year.
Crosses of wheat with related crops (rye) or even wild grasses — the latter known as wide crosses — have greatly improved the hardiness and productivity of wheat. For example, an estimated one-fifth of the elite wheat breeding lines in CIMMYT international yield trials features genes from Aegilops tauschii, commonly known as “goat grass,” that boost their resilience and provide other valuable traits to protect yield.
Biofortification — breeding to develop nutritionally enriched crops — has resulted in more than 60 maize and wheat varieties whose grain offers improved protein quality or enhanced levels of micro-nutrients such as zinc and provitamin A. Biofortified maize and wheat varieties have benefited smallholder farm families and consumers in more than 20 countries across sub-Saharan Africa, Asia, and Latin America. Consumption of provitamin-A-enhanced maize or sweet potato has been shown to reduce chronic vitamin A deficiencies in children in eastern and southern Africa. In India, farmers have grown a high-yielding sorghum variety with enhanced grain levels of iron and zinc since 2018 and use of iron-biofortified pearl millet has improved nutrition among vulnerable communities.
Innovations in measuring plant responses include remote sensing systems, such as multispectral and thermal cameras flown over breeding fields. In this image of the CIMMYT experimental station in Obregón, Mexico, water-stressed plots are shown in green and red. (Photo: CIMMYT and the Instituto de Agricultura Sostenible)
Thefuture
Crop breeders have been laying the groundwork to pursue genomic selection. This approach takes advantage of low-cost, genome-wide molecular markers to analyze large populations and allow scientists to predict the value of particular breeding lines and crosses to speed gains, especially for improving genetically complex traits.
Speed breeding uses artificially-extended daylength, controlled temperatures, genomic selection, data science, artificial intelligence tools and advanced technology for recording plant information — also called phenotyping — to make breeding faster and more efficient. A CIMMYT speed breeding facility for wheat features a screenhouse with specialized lighting, controlled temperatures and other special fixings that will allow four crop cycles — or generations — to be grown per year, in place of only two cycles with normal field trials. Speed breeding facilities will accelerate the development of productive and robust varieties by crop research programs worldwide.
Data analysis and management. Growing and evaluating hundreds of thousands of plants in diverse trials across multiple sites each season generates enormous volumes of data that breeders must examine, integrate, and co-analyze to inform decisions, especially about which lines to cross and which populations to discard or move forward. New informatics tools such as the Enterprise Breeding System will help scientists to manage, analyze and apply big data from genomics, field and lab studies.
Following the leaders. Driven by competition and the quest for profits, private companies that market seed and other farm products are generally on the cutting edge of breeding innovations. The CGIAR’s Excellence in Breeding (EiB) initiative is helping crop breeding programs that serve farmers in low- and middle-income countries to adopt appropriate best practices from private companies, including molecular marker-based approaches, strategic mechanization, digitization and use of big data to drive decision making. Modern plant breeding begins by ensuring that the new varieties produced are in line with what farmers and consumers want and need.
Cover photo: CIMMYT experimental station in Toluca, Mexico. Located in a valley at 2,630 meters above sea level with a cool and humid climate, it is the ideal location for selecting wheat materials resistant to foliar diseases, such as wheat rust. Conventional plant breeding involves selection among hundreds of thousands of plants from crosses over many generations, and requires extensive and costly field, screenhouse and lab facilities. (Photo: Alfonso Cortés/CIMMYT)
For centuries, people across Mexico and Central America have been using a traditional method, known as nixtamalization, to process their maize.
Now carried out both at household and industrial levels, this technique offers a range of nutritional and processing benefits. It could easily be adopted by farmers and consumers in other parts of the world.
What is nixtamalization?
Nixtamalization is a traditional maize preparation process in which dried kernels are cooked and steeped in an alkaline solution, usually water and food-grade lime (calcium hydroxide).
After that, the maize is drained and rinsed to remove the outer kernel cover (pericarp) and milled to produce dough that forms the base of numerous food products, including tortillas and tamales.
How does it work?
Key steps of the traditional nixtamalization process. (Graphic: Nancy Valtierra/CIMMYT)
What happens when maize kernels are nixtamalized?
The cooking (heat treatment) and steeping in the alkaline solution induce changes in the kernel structure, chemical composition, functional properties and nutritional value.
For example, the removal of the pericarp leads to a reduction in soluble fiber, while the lime cooking process leads to an increase in calcium content. The process also leads to partial starch gelatinization, partial protein denaturation — in which proteins present in the kernel become insoluble — and a partial decrease in phytic acid.
What are the benefits of processing maize in this way?
In addition to altering the smell, flavor and color of maize products, nixtamalization provides several nutritional benefits including:
Increased bioavailability of vitamin B3 niacin, which reduces the risk of pellagra disease
Increased calcium intake, due to its absorption by the kernels during the steeping process
Increased resistant starch content in food products, which serves as a source of dietary fiber
Significantly reduced presence of mycotoxins such as fumonisins and aflatoxins
Increased bioavailability of iron, which decreases the risk of anemia
These nutritional and health benefits are especially important in areas where maize is the dietary staple and the risk of aflatoxins is high, as removal of the pericarp is thought to help reduce aflatoxin contamination levels in maize kernels by up to 60% when a load is not highly contaminated.
Additionally, nixtamalization helps to control microbiological activity and thus increases the shelf life of processed maize food products, which generates income and market opportunities for agricultural communities in non-industrialized areas.
Where did the practice originate?
The word itself comes from the Aztec language Nahuatl, in which the word nextli means ashes and tamali means unformed maize dough.
Populations in Mexico and Central America have used this traditional maize processing method for centuries. Although heat treatments and soaking periods may vary between communities, the overall process remains largely unchanged.
Today nixtamalized flour is also produced industrially and it is estimated that more than 300 food products commonly consumed in Mexico alone are derived from nixtamalized maize.
Can farmers and consumers in other regions benefit from nixtamalization?
Nixtamalization can certainly be adapted and adopted by all consumers of maize, bringing nutritional benefits particularly to those living in areas with low dietary diversity.
Additionally, the partial removal of the pericarp can contribute to reduced intake of mycotoxins. Aflatoxin contamination is a problem in maize producing regions across the world, with countries as diverse as China, Guatemala and Kenya all suffering heavy maize production losses as a result. While training farmers in grain drying and storage techniques has a significant impact on reducing post-harvest losses, nixtamalization technology could also have the potential to prevent toxin contamination and significantly increase food safety when used appropriately.
If adapted, modern nixtamalization technology could also help increase the diversity of uses for maize in food products that combine other food sources like vegetables.
Nitrogen is the most essential nutrient in crop production but also one of the most challenging to work with. The compound is central to global crop production — particularly for major cereals — but while many parts of the world do not have enough to achieve food and nutrition security, in others excess nitrogen from fertilizer leaks into the environment with damaging consequences.
What is nitrogen?
Around 78% of the Earth’s atmosphere is made up of nitrogen gas or N2 — a molecule made of two nitrogen atoms glued together by a stable, triple bond.
Though it makes up a large portion of the air we breathe, most living organisms can’t access it in this form. Atmospheric nitrogen must go through a natural process called nitrogen fixation to transform before it can be used for plant nutrition.
Why do plants need nitrogen?
In both plants and humans, nitrogen is used to make amino acids — which make the proteins that construct cells — and is one of the building blocks for DNA. It is also essential for plant growth because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (photosynthesis).
The nitrogen cycle
The nitrogen cycle is the process through which nitrogen moves from the atmosphere to earth, through soils and is released back into the atmosphere — converting in and out of its organic and inorganic forms.
It begins with biological nitrogen fixation, which occurs when nitrogen-fixing bacteria that live in the root nodules of legumes convert organic matter into ammonium and then nitrate. Plants are able to absorb nitrate from the soil and break it down into the nitrogen they need, while denitrifying bacteria convert excess nitrate back into inorganic nitrogen which is released back into the atmosphere.
The process can also begin with lightning, the heat from which ruptures the triple bonds of atmospheric nitrogen, freeing its atoms to combine with oxygen and create nitrous oxide gas, which dissolves in rain as nitric acid and is absorbed by the soil.
Excess nitrate or that lost through leaching — in which key nutrients are dissolved due to rain or irrigation — can seep into and pollute groundwater streams.
A diagram shows the process through which nitrogen moves from the atmosphere to earth, through soils and is released back into the atmosphere – converting in and out of its organic and inorganic forms. (Graphic: Nancy Valtierra/CIMMYT)
What about nitrogen fertilizer?
For thousands of years, humans didn’t need to worry about nitrogen, but by the turn of the Twentieth Century it was evident that intensive farming was depleting nitrate in the soil, which raised concerns about the world’s rising population and a possible food crisis.
In 1908, a German chemist named Fritz Haber devised a process for combining atmospheric nitrogen and hydrogen under extreme heat and pressure to create liquid ammonia — a synthetic nitrogen fertilizer. He later worked with chemist and engineer Carl Bosch to industrialize this process and make it commercially available for farmers.
Once production was industrialized, synthetic nitrogen fertilizer — used in combination with new, high-yielding seed varieties — helped drive the Green Revolution and significantly boost global agricultural production from the late 1960s onwards. During this time Mexico became self-sufficient in wheat production, as did India and Pakistan, which were on the brink of famine.
In today’s intensive agricultural systems, synthetic nitrogen fertilizer has become increasingly crucial. Worldwide, companies currently produce over 100 million metric tons of this product every year, and the Food and Agriculture Organization of the United Nations predicts that demand will continue to rise steadily, especially in Africa and South Asia.
Is it sustainable?
As demand continues to rise worldwide, the challenge of nitrogen management is to provide enough to meet global food security needs while minimizing the flow of unused nitrogen — which is 300 times more polluting than carbon dioxide — to the environment.
While many regions remain short of available nitrogen to achieve food and nutrition security, in others nearly half of the fertilizer nitrogen applied in agriculture is leaked into the environment, with negative consequences including increased environmental hazards, irreparable land degradation and the contamination of aquatic resources.
This challenge can be addressed by improving nitrogen use efficiency — a complex calculation which often involves a comparison between crop biomass (primarily economic yield) or nitrogen content/uptake (output) and the nitrogen applied (input) through any manure or synthetic fertilizer. Improving this ratio not only enhances crop productivity but also minimizes environmental losses through careful agronomic management and helps improve soil quality over time.
Currently, average global nitrogen use efficiency does not exceed 50%, which falls short of the estimated 67% needed to meet global food demand in 2050 while keeping surplus nitrogen within the limits for maintaining acceptable air and water qualities.
A woman in India uses a precision spreader to apply fertilizer on her farm. (Photo: Wasim Iftikar)
Blue-sky technology
Much progress has been made in developing technologies for an efficient nitrogen management, which along with good agronomy are proven to enhance crop nitrogen harvest and nitrogen use efficiency with lower surplus nitrogen.
Scientists are investigating the merits of biological nitrification inhibition, a process through which a plant excretes material which influences the nitrogen cycle in the soil. Where this process occurs naturally — in some grasses and wheat wild relatives — it helps to significantly reduce nitrogen emissions.
In 2007, scientists discovered biological nitrification traits in a wheat relative and in 2018 they succeeded in transferring them into a Chinese spring wheat variety. The initial result showed low productivity and remains in the very early stages of development, but researchers are keen to assess whether this process could be applied to commercial wheat varieties in the future. If so, this technology could be a game changer for meeting global nitrogen use efficiency goals.
By 2050, the world’s population could grow to 9.7 billion, food demand is expected to increase by 50% and global demand for grains such as maize, rice and wheat could increase by 70%. How can we meet the food and nutrition demands of a rising population, without negative environmental and social consequences?
Sustainable intensification is an approach using innovations to increase productivity on existing agricultural land with positive environmental and social impacts. Both words, “sustainable” and “intensification,” carry equal weight.
CIMMYT conducts research on sustainable intensification to identify ways farmers can increase production of crops per unit of land, conserve or enhance important ecosystem services and improve resilience to shocks and stresses, especially those due to climate change and climate variability.
For example, CIMMYT’s research on sustainable intensification in India has helped shape policies that increase farmer income while reducing pollution and land degradation.
What is the scope of sustainable intensification?
Sustainable intensification takes into consideration impact on overall farm productivity, profitability, stability, production and market risks, resilience, as well as the interests and capacity of individual farmers to adopt innovations. It is not limited to environmental concerns, but also includes social and economic criteria such as improving livelihoods, equity and social capital.
Certain methods and principles are needed to achieve the goals of sustainable intensification. In collaboration with farmers and other change actors, CIMMYT carries out research-for-development projects to test and scale a range of technologies and approaches that contribute to these results. The research focuses on combined resource use efficiencies of crop production inputs: land, plant nutrients, labor and water.
One example is conservation agriculture, the combination of crop diversification, minimal soil movement and permanent soil cover. International scientific analysis has found that conservation agriculture can, in many places with different characteristics, play a crucial role towards achieving the United Nations Sustainable Development Goals.
Crop and system modeling, geographic information systems, remote sensing, scale-appropriate mechanization and socioeconomic modeling are some of the approaches that contribute to the design and evaluation of sustainable intensification alternatives in current farming systems.
Figure: Multi-criteria sustainability assessment of alternative (sustainable intensification) and reference systems in the Western Highlands of Guatemala.
What are some more examples?
Several interventions by CIMMYT aim at safeguarding biodiversity and protecting — in some cases increasing — ecosystem services crucial for small-scale farmers’ livelihoods and the health of all. Others have studied the impact of landscapes on dietary diversity and nutrition. Yet others have developed appropriate small-scale machines, allowing farmers to save time, costs and labor associated with agriculture to increase yields, halt the expansion of the agricultural frontier and invest in new opportunities.
How is sustainable intensification different from ecological intensification, agroecological intensification or climate-smart agriculture?
Sustainable intensification, ecological intensification and agroecological intensification strive for the same general goal to feed an increasing population without negative environmental and social consequences, but they place emphasis on different aspects.
Ecological intensification focuses on ecological processes in the agroecosystem. Agroecological intensification emphasizes a systems approach and strongly considers social and cultural perspectives.
Climate-smart agriculture and sustainable intensification are complementary, but climate-smart agriculture focuses on climate stress, adaptation and mitigation.
Sustainable intensification can be achieved with a range of methods, including these concepts. It is one strategy among many for global food system transformation.
What is the history of CIMMYT’s research on sustainable intensification?
In the 1960s, the Green Revolution brought high-yielding crops to some regions of Latin America and South Asia, allegedly saving millions from starvation. Yet the Green Revolution had unintended environmental and social consequences. Critics of the Green Revolution argued these cropping techniques were highly dependent on external inputs, fossil fuels and agrochemicals, causing environmental damage through overuse of fertilizers and water, and contributing to soil degradation.
In the 1980s, CIMMYT scientists began placing stronger emphasis on environmental and social aspects — such as conserving soil and water, and ensuring social inclusion of marginalized groups — recognizing their importance to sustain the intensification of crops in South Asia. It was understood that sustainability includes improving the livelihoods of rural people who depend on these natural resources, in addition to better resource management. CIMMYT began to take these considerations to the core of its work.
Farmers Maliamu Joni and Ruth Andrea harvest cobs of drought-tolerant maize in Mbeya, Tanzania. (Photo: Peter Lowe/CIMMYT)
Are these practices successful?
Sustainable intensification can boost yields, increase farmers’ profits and reduce greenhouse gas emissions. The reduction of greenhouse gas emissions can be achieved by increasing nitrogen use efficiency, which also reduces groundwater pollution.
Research from CIMMYT’s SIMLESA project has shown that conservation agriculture-based sustainable intensification practices led to a 60-90% increase in water infiltration and a 10-50% increase in maize yields in Malawi. In Ethiopia, crop incomes nearly doubled with crop diversification, reduced tillage and improved varieties, compared to using only one of these practices.
According to research from Stanford University, agricultural intensification has avoided emissions of up to 161 gigatons of carbon from 1961 to 2005. CIMMYT research shows that India could cut nearly 18% of agricultural greenhouse gas emissions through sustainable intensification practices that reduce fertilizer consumption, improve water management and eliminate residue burning. Zero-tillage wheat can cut farm-related greenhouse gas emissions by more than 75% in India and is 10-20% more profitable on average than burning rice straw and sowing wheat using conventional tillage.
A CIMMYT study in Science shows that thousands of wheat farmers in northern India could increase their profits if they stop burning their rice straw residue and adopt no-till practices, which could also cut farm-related greenhouse gas emissions by as much as 78% and lower air pollution. This research and related work to promote no-till Happy Seeders led to a 2018 policy from the government of India to stop farmers from burning residue, including a $166 million subsidy to promote mechanization to manage crop residues within fields.
In light of this evidence, CIMMYT continues to work with stakeholders all along the value chain — from farmers to national agricultural research organizations and companies — to promote and scale the adoption of practices leading to sustainable intensification.
Cover photo: Irrigated fields under conservation agriculture at CIMMYT’s CENEB experiment station near Ciudad Obregón, Sonora, northern Mexico. (Photo: CIMMYT)
The most recent dietary guidelines provided by the World Health Organization and other international food and nutrition authorities recommend that half our daily intake of grains should come from whole grains. But what are whole grains, what are their health benefits, and where can they be found?
What are whole grains?
The grain or kernel of any cereal is made up of three edible parts: the bran, the germ and the endosperm.
Each part of the grain contains different types of nutrients.
The bran is the multi-layered outer skin of the edible kernel. It is fiber-rich and also supplies antioxidants, B vitamins, minerals like zinc, iron, magnesium, and phytochemicals — natural chemical compounds found in plants that have been linked to disease prevention.
The germ is the core of the seed where growth occurs. It is rich in lipids and contains vitamin E, as well as B vitamins, phytochemicals and antioxidants.
The largest portion of the kernel is the endosperm, an interior layer that holds carbohydrates, protein and smaller amounts of vitamins and minerals.
The grain or kernel of maize and wheat is made up of three edible parts: the bran, the germ and the endosperm. (Graphic: Nancy Valtierra/CIMMYT)
A whole grain is not necessarily an entire grain.
The concept is mainly associated with food products — which are not often made using intact grains — but there is no single, accepted definition of what constitutes a whole grain once parts of it have been removed.
Generally speaking, however, a processed grain is considered “whole” when each of the three original parts — the bran, germ and endosperm — are still present in the same proportions as when the original one. This definition applies to all cereals in the Poaceae family such as maize, wheat, barley and rice, and some pseudocereals including amaranth, buckwheat and quinoa.
Wholegrain vs. refined and enriched grain products
Refined grain products differ from whole grains in that some or all of the outer bran layers are removed by milling, pearling, polishing, or degerming processes and are missing one or more of their three key parts.
For example, white wheat flour is prepared with refined grains that have had their bran and germ removed, leaving only the endosperm. Similarly, if a maize kernel is degermed or decorticated — where both the bran and germ are removed — it becomes a refined grain.
The main purpose of removing the bran and germ is technological, to ensure finer textures in final food products and to improve their shelf life. The refining process removes the variety of nutrients that are found in the bran and germ, so many refined flours end up being enriched — or fortified — with additional, mostly synthetic, nutrients. However, some components such as phytochemicals cannot be replaced.
A hand holds grains of wheat. (Photo: Thomas Lumpkin/CIMMYT)
Are wholegrain products healthier than refined ones?
There is a growing body of research indicating that whole grains offer a number of health benefits which refined grains do not.
Bran and fiber slow the breakdown of starch into glucose, allowing the body to maintain a steady blood sugar level instead of causing sharp spikes. Fibers positively affect bowel movement and also help to reduce the incidence of cardiovascular diseases, the incidence of type 2 diabetes, the risk of stroke, and to maintain an overall better colorectal and digestive health. There is also some evidence to suggest that phytochemicals and essential minerals — such as copper and magnesium — found in the bran and germ may also help protect against some cancers.
Despite the purported benefits, consumption of some wholegrain foods may be limited by consumer perception of tastes and textures. The bran in particular contains intensely flavored compounds that reduce the softness of the final product and may be perceived to negatively affect overall taste and texture. However, these preferences vary greatly between regions. For example, while wheat noodles in China are made from refined flour, in South Asia most wheat is consumed wholegrain in the form of chapatis.
Popcorn is another example of a highly popular wholegrain food. It is a high-quality carbohydrate source that, consumed naturally, is not only low in calories and cholesterol, but also a good source of fiber and essential vitamins including folate, niacin, riboflavin, thiamin, pantothenic acid and vitamins B6, A, E and K. One serving of popcorn contains about 8% of the daily iron requirement, with lesser amounts of calcium, copper, magnesium, manganese, phosphorus, potassium and zinc.
Boiled and roasted maize commonly consumed in Africa, Asia and Latin America are other sources of wholegrain maize, as is maize which has been soaked in lime solution, or “nixtamalized.” Depending on the steeping time and method of washing the nixtamalized kernels, a portion of the grains used for milling could still be classed as whole.
Identifying wholegrain products
Whole grains are relatively easy to identify when dealing with unprocessed foods such as brown rice or oats. It becomes more complicated, however, when a product is made up of both whole and refined or enriched grains, especially as color is not an indicator. Whole wheat bread made using whole grains can appear white in color, for example, while multi-grain brown bread can be made primarily using refined flour.
In a bid to address this issue, US-based nonprofit consumer advocacy group the Whole Grains Council created a stamp designed to help consumers identify and select wholegrain products more easily. As of 2019, this stamp is used on over 13,000 products in 61 different countries.
However, whether a product is considered wholegrain or not varies widely between countries and individual agencies, with a lack of industry standardization meaning that products are labelled inconsistently. Words such as “fiber,” “multigrain” and even “wholegrain” are often used on packaging for products which are not 100% wholegrain. The easiest way to check a product’s wholegrain content is to look at the list of ingredients and see if the flours used are explicitly designated as wholegrain. These are ordered by weight, so the first items listed are those contained more heavily in the product.
As a next step, an ad-hoc committee led by the Whole Grain Initiative is due to propose specific whole grain quantity thresholds to help establish a set of common criteria for food labelling. These are likely to be applied worldwide in the event that national definitions and regulations are not standardized.
If not practiced sustainably, agriculture can have a toll on the environment, produce greenhouse gases and contribute to climate change. However, sustainable farming methods can do the opposite — increase resilience to climate change, protect biodiversity and sustainably use natural resources.
One of these methods is conservation agriculture.
Conservation agriculture conserves natural resources, biodiversity and labor. It increases available soil water, reduces heat and drought stress, and builds up soil health in the longer term.
What are the principles of conservation agriculture?
Conservation agriculture is based on the interrelated principles of minimal mechanical soil disturbance, permanent soil cover with living or dead plant material, and crop diversification through rotation or intercropping. It helps farmers to maintain and boost yields and increase profits, while reversing land degradation, protecting the environment and responding to growing challenges of climate change.
To reduce soil disturbance, farmers practice zero-tillage farming, which allows direct planting without plowing or preparing the soil. The farmer seeds directly through surface residues of the previous crop.
Zero tillage is combined with intercropping and crop rotation, which means either growing two or more crops at the same time on the same piece of land, or growing two different crops on the same land in a sequential manner. These are also core principles of sustainable intensification.
How is conservation agriculture different from sustainable intensification?
Sustainable intensification is a process to increase agriculture yields without adverse impacts on the environment, taking the whole ecosystem into consideration. It aims for the same goals as conservation agriculture.
Conservation agriculture practices lead to or enable sustainable intensification.
What are the benefits and challenges of conservation agriculture?
Zero-tillage farming with residue cover saves irrigation water, gradually increases soil organic matter and suppresses weeds, as well as reduces costs of machinery, fuel and time associated with tilling. Leaving the soil undisturbed increases water infiltration, holds soil moisture and helps to prevent topsoil erosion. Conservation agriculture enhances water intake that allows for more stable yields in the midst of weather extremes exacerbated by climate change.
While conservation agriculture provides many benefits for farmers and the environment, farmers can face constraints to adopt these practices. Wetlands or soils with poor drainage can make adoption challenging. When crop residues are limited, farmers tend to use them for fodder first, so there might not be enough residues for the soil cover. To initiate conservation agriculture, appropriate seeders are necessary, and these may not be available or affordable to all farmers. Conservation agriculture is also knowledge intensive and not all farmers may have access to the knowledge and training required on how to practice conservation agriculture. Finally, conservation agriculture increases yields over time but farmers may not see yield benefits immediately.
However, innovations, adapted research and new technologies are helping farmers to overcome these challenges and facilitate the adoption of conservation agriculture.
How did conservation agriculture originate?
Belita Maleko, a farmer in Nkhotakota, central Malawi, sowed cowpea as an intercrop in one of her maize plots, grown under conservation agriculture principles. (Photo: T. Samson/CIMMYT)
The term “conservation agriculture” was coined in the 1990s, but the idea to minimize soil disturbance has its origins in the 1930s, during the Dust Bowl in the United States of America.
CIMMYT pioneered no-till training programs and trials in the 1970s, in maize and wheat systems in Latin America. In the 1980s this technique was also used in agronomy projects in South Asia.
CIMMYT began work with conservation agriculture in Latin America and South Asia in the 1990s and in Africa in the early 2000s. Today, these efforts have been scaled up and conservation agriculture principles have been incorporated into projects such as CSISA, FACASI, MasAgro, SIMLESA, and SRFSI.
Farmers worldwide are increasingly adopting conservation agriculture. In the 2015/16 season, conservation agriculture was practiced on about 180 mega hectares of cropland globally, about 12.5% of the total global cropland — 69% more than in the 2008/2009 season.
Is conservation agriculture organic?
Conservation agriculture and organic farming both maintain a balance between agriculture and resources, use crop rotation, and protect the soil’s organic matter. However, the main difference between these two types of farming is that organic farmers use a plow or soil tillage, while farmers who practice conservation agriculture use natural principles and do not till the soil. Organic farmers apply tillage to remove weeds without using inorganic fertilizers.
Conservation agriculture farmers, on the other hand, use a permanent soil cover and plant seeds through this layer. They may initially use inorganic fertilizers to manage weeds, especially in soils with low fertility. Over time, the use of agrichemicals may be reduced or slowly phased out.
How does conservation agriculture differ from climate-smart agriculture?
While conservation agriculture and climate-smart agriculture are similar, their purposes are different. Conservation agriculture aims to sustainably intensify smallholder farming systems and have a positive effect on the environment using natural processes. It helps farmers to adapt to and increase profits in spite of climate risks.
Climate-smart agriculture aims to adapt to and mitigate the effects of climate change by sequestering soil carbon and reducing greenhouse gas emissions, and finally increase productivity and profitability of farming systems to ensure farmers’ livelihoods and food security in a changing climate. Conservation agriculture systems can be considered climate-smart as they deliver on the objectives of climate-smart agriculture.
Cover photo: Field worker Lain Ochoa Hernandez harvests a plot of maize grown with conservation agriculture techniques in Nuevo México, Chiapas, Mexico. (Photo: P. Lowe/CIMMYT)
Wheat blast is a fast-acting and devastating fungal disease that threatens food safety and security in tropical areas in South America and South Asia. Directly striking the wheat ear, wheat blast can shrivel and deform the grain in less than a week from the first symptoms, leaving farmers no time to act.
The disease, caused by the fungus Magnaporthe oryzae pathotype triticum (MoT), can spread through infected seeds and survives on crop residues, as well as by spores that can travel long distances in the air.
Magnaporthe oryzae can infect many grasses, including barley, lolium, rice, and wheat, but specific isolates of this pathogen generally infect limited species; that is, wheat isolates infect preferably wheat plants but can use several more cereal and grass species as alternate hosts. The Bangladesh wheat blast isolate is being studied to determine its host range. The Magnaporthe oryzae genome is well-studied but major gaps remain in knowledge about its epidemiology.
The pathogen can infect all aerial wheat plant parts, but maximum damage is done when it infects the wheat ear. It can shrivel and deform the grain in less than a week from first symptoms, leaving farmers no time to act.
Where is wheat blast found?
First officially identified in Brazil in 1985, the disease is widespread in South American wheat fields, affecting as much as 3 million hectares in the early 1990s. It continues to seriously threaten the potential for wheat cropping in the region.
In 2016, wheat blast spread to Bangladesh, which suffered a severe outbreak. It has impacted around 15,000 hectares of land in eight districts, reducing yield on average by as much as 51% in the affected fields.
Wheat-producing countries and presence of wheat blast.
How does blast infect a wheat crop?
Wheat blast spreads through infected seeds, crop residues as well as by spores that can travel long distances in the air.
Blast appears sporadically on wheat and grows well on numerous other plants and crops, so rotations do not control it. The irregular frequency of outbreaks also makes it hard to understand or predict the precise conditions for disease development, or to methodically select resistant wheat lines.
At present blast requires concurrent heat and humidity to develop and is confined to areas with those conditions. However, crop fungi are known to mutate and adapt to new conditions, which should be considered in management efforts.
How can farmers prevent and manage wheat blast?
There are no widely available resistant varieties, and fungicides are expensive and provide only a partial defense. They are also often hard to obtain or use in the regions where blast occurs, and must be applied well before any symptoms appear — a prohibitive expense for many farmers.
The Magnaporthe oryzae fungus is physiologically and genetically complex, so even after more than three decades, scientists do not fully understand how it interacts with wheat or which genes in wheat confer durable resistance.
Researchers from the International Maize and Wheat Improvement Center (CIMMYT) are partnering with national researchers and meteorological agencies on ways to work towards solutions to mitigate the threat of wheat blast and increase the resilience of smallholder farmers in the region. Through the USAID-supported Cereal Systems Initiative for South Asia (CSISA) and Climate Services for Resilient Development (CSRD) projects, CIMMYT and its partners are developing agronomic methods and early warning systems so farmers can prepare for and reduce the impact of wheat blast.
CIMMYT works in a global collaboration to mitigate the threat of wheat blast, funded by the Australian Centre for International Agricultural Research (ACIAR), the CGIAR Research Program on Wheat (WHEAT), the Indian Council of Agricultural Research (ICAR) and the Swedish Research Council (Vetenskapsrådet). Some of the partners who collaborate include the Bangladesh Wheat and Maize Research Institute (BWMRI), Bolivia’s Instituto Nacional de Innovación Agropecuaria y Forestal (INIAF), Kansas State University and the Agricultural Research Service of the US (USDA-ARS).
