Insect resistance in plants is needed now more than ever. The UN, which has named 2020 as the International Year of Plant Health, estimates that almost 40% of food crops are lost annually due to plant pests and diseases.
Earlier this month, a group of wheat breeders and entomologists came together for the 24th Biannual International Plant Resistance to Insects (IPRI) Workshop, held at the International Maize and Wheat Improvement Center (CIMMYT).
We caught up with Mustapha El-Bouhssini, principal scientist at the International Center for Agricultural Research in the Dry Areas (ICARDA) to discuss insect pests and climate change. He explains how pests such as the Hessian fly â a destructive wheat pest which resembles a mosquito â and the chickpea pod borer are extending their geographical ranges in response to rising temperatures.
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 â 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 â which are not often made using intact grains â 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 âwholeâ when each of the three original parts â the bran, germ and endosperm â 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 â where both the bran and germ are removed â 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 â or fortified â 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 â such as copper and magnesium â 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 ânixtamalized.â 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 diïŹerent 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 âfiber,â âmultigrainâ and even âwholegrainâ are often used on packaging for products which are not 100% wholegrain. The easiest way to check a productâs 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.
In crop research fields, it is now a common sight to see drones or other high-tech sensing tools collecting high-resolution data on a wide range of traits â from simple measurement of canopy temperature to complex 3D reconstruction of photosynthetic canopies.
This technological approach to collecting precise plant trait information, known as phenotyping, is becoming ubiquitous, but according to experts at the International Maize and Wheat Improvement Center (CIMMYT) and other research institutions, breeders can profit much more from these tools, when used judiciously.
In a new article in the journal Plant Science, CIMMYT researchers outline the different ways in which phenotyping can assist breeding â from large-scale screening to detailed physiological characterization of key traits â and why this methodology is crucial for crop improvement.
âWhile having been the subject of debate in the past, extra investment for phenotyping is becoming more accepted to capitalize on recent developments in crop genomics and prediction models,â explain the authors.
Their review considers different contexts for phenotyping, including breeding, exploration of genetic resources, parent building and translations research to deliver other new breeding resources, and how these different categories of phenotyping apply to each. Some of the same tools and rules of thumb apply equally well to phenotyping for genetic analysis of complex traits and gene discovery.
The authors make the case for breeders to invest in phenotyping, particularly in light of the imperative to breed crops for warmer and harsher climates. However, wide scale adoption of sophisticated phenotyping methods will only occur if new techniques add efficiency and effectiveness.
In this sense, âbreeder-friendlyâ phenotyping should complement existing breeding approaches by cost-effectively increasing throughput during segregant selection and adding new sources of validated complex traits to crossing blocks. With this in mind, stringent criteria need to be applied before new traits or phenotyping protocols are incorporated into mainstream breeding pipelines.
A farmer checks the drip irrigation system at his rice field in India. (Photo: Hamish John Appleby/IWMI)
In 2009, state governments in Northwest India implemented a policy designed to reduce groundwater extraction by prohibiting the usual practice of planting rice in May and moving it to June, nearer the start of monsoon rains.
Although the policy did succeed in alleviating pressure on groundwater, it also had the unexpected effect of worsening already severe air pollution. The reason for this, according to a recent study published in Nature Sustainability, is that the delay in rice planting narrowed the window between rice harvest and sowing of the subsequent crop â mainly wheat â leaving farmers little time to remove rice straw from the field and compelling them to burn it instead.
Even though burning crop residues is prohibited in India, uncertainty about the implementation of government policy and a perceived lack of alternatives have perpetuated the practice in Haryana and Punjab states, near the nationâs capital, New Delhi, where air pollution poses a major health threat.
Land preparation on a rice field with a two-wheel tractor. (Photo: Vedachalam Dakshinamurthy/CIMMYT)
A farmer uses a tractor fitted with a Happy Seeder. (Photo: Vedachalam Dakshinamurthy/CIMMYT)
A farmer checks the drip irrigation system at his rice field in India. (Photo: Hamish John Appleby/IWMI)
Wheat crop in conservation agriculture. (Photo: Vedachalam Dakshinamurthy/CIMMYT)
A farmer ploughs a rice field with a water buffalo. (Photo: Licensed from Digitalpress – Dreamstime.com; Image 11205929)
Decades of research for development have enabled researchers at the International Maize and Wheat Improvement Center (CIMMYT), the Indian Council of Agricultural Research (ICAR) and other partners to identify potential solutions to this problem.
One particularly viable option focuses on the practice of zero tillage, in which wheat seed is sown immediately after rice harvest through the rice straw directly into untilled soil with a single tractor pass.
In a new blog published as part of the Chicago Council on Global Affairsâ Field Notes series, CIMMYT scientists Hans Braun and Bruno Gerard discuss the combination of agronomic and breeding conditions required to make zero tillage work, and propose a fundamental shift away from current incentives to maximize the regionÂŽs cereal production.
Reduced water availability for irrigation and increasing temperatures are of great concern. These two factors can considerably affect wheat production and reduce grain yields.
Watch CIMMYT Wheat Breeder Suchismita Mondal explain â in just one minute â how breeders are developing wheat varieties that have stable grain yield under low water availability and high temperatures.
In crop research fields, drones and other high-tech sensing tools are now a common sight. They collect high-resolution data on a wide range of traits â from simple measurement of canopy temperature to complex 3D reconstruction of photosynthetic canopies.
This technological approach to collecting precise plant trait information, known as phenotyping, is becoming ubiquitous. According to experts at the International Maize and Wheat Improvement Center (CIMMYT) and other research institutions, breeders can profit much more from these tools, when used judiciously.
Examples of different classes and applications of breeder friendly phenotyping. (Image: M. Reynolds et al.)
In a new article in the journal Plant Science, CIMMYT Wheat Physiologist Matthew Reynolds and colleagues explain the different ways that phenotyping can assist breeding â from simple to use, âhandyâ approaches for large scale screening, to detailed physiological characterization of key traits to identify new parental sources â and why this methodology is crucial for crop improvement. The authors make the case for breeders to invest in phenotyping, particularly in light of the imperative to breed crops for warmer and harsher climates.
A second âGreen Revolutionâ is needed to increase global wheat production by sixty per cent by 2050 when the world population is predicted to be 9.3 billion, global wheat research organisation, âWheat Initiativeâ said in a report.
Wheat spikes against the sky. (Photo: H. Hernandez Lira/CIMMYT)
New research by an international team of scientists, including International Maize and Wheat Improvement Center (CIMMYT) agricultural systems and climate change scientist Tek Sapkota, has identified the optimum rates of nitrogen fertilizer application for rice and wheat crops in the Indo-Gangetic Plains of India.
By measuring crop yield and nitrous oxide (N2O) fluxes over two years, Sapkota and his colleagues reported that the optimum rate of N fertilizer for rice is between 120 and 200 kg per hectare, and between 50 and 185 kg per hectare for wheat. The results of the study have the potential to save farmerâs money and minimize dangerous greenhouse gas emissions while maintaining crop productivity.
Nitrous oxide, one of the most important greenhouse gases in the earthâs atmosphere, is responsible for ozone depletion and global climate change, and has a global warming potential 265 times that of carbon dioxide (CO2).
Research has shown that agricultural soils account for around 60% of global nitrous oxide emissions. These emissions are directly related to the application of nitrogen fertilizers to croplands. While these fertilizers help crop yields, studies show that only about one third of the applied nitrogen is actually used by crops. The rest is released as nitrous oxide or seeps into waterways, causing harmful algal blooms.
In India, the total consumption of nitrogen fertilizer is about 17 million tons â expected to rise to 24 million tons by 2030 to feed a growing population. Nitrous oxide emissions will rise along with it if farmers do not minimize their fertilizer use and manage application more efficiently. Whatâs more, farmers receive a higher subsidy for nitrogen fertilizer â a policy that leads farmers to apply more fertilizer than the recommended dose.
Measured methods
The study, led by Sapkota, estimated the rate of nitrogen fertilizer application with the most economically optimum yield and minimum environmental footprint. Applying more fertilizer than this would be a waste of farmerâs money and cause unnecessary harm to the environment.
Researchers measured crop yield and nitrous oxide fluxes for two wheat seasons and one rice season from 2014 to 2016. Â The scientists found that nitrogen fertilization rate clearly influenced daily and cumulative soil nitrous oxide emissions in wheat and rice for both years. Nitrous oxide emissions were higher in both wheat and rice in the nitrogen-fertilized plots than in the control plots.
Using statistical methods, the researchers were able to measure the relationship between crop productivity, nitrogen rate and emissions intensity, in both rice and wheat. This gave them the optimum rate of nitrogen fertilizer application.
This work was carried out by International Maize and Wheat Improvement Center (CIMMYT) and implemented as part of the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), with support from the CGIAR Trust Fund and through bilateral funding agreements.
Understanding tropical maize (Zea mays L.): the major monocot in modernization and sustainability of agriculture in sub-Saharan Africa. 2019. Awata, L.A.O., Tongoona, P., Danquah, E., Ifie, B.E., Mahabaleswara, S.L., Jumbo, M.B., Marchelo-Dâragga, P.W., Sitonik, C. In: International Journal of Advance Agricultural Research v. 7, no. 2, p. 32-77.
CGIAR Operations under the Plant Treaty Framework. 2019. Lopez-Noriega, I., Halewood, M., Abberton, M., Amri, A., Angarawai, I.I., Anglin, N., Blummel, M., Bouman, B., Campos, H., Costich, D.E., Ellis, D., Pooran M. Gaur., Guarino, L., Hanson, J., Kommerell, V., Kumar, P.L., Lusty, C., Ndjiondjop, M.N., Payne, T.S., Peters, M., Popova, E.,Prakash, G., Sackville-Hamilton, R., Tabo, R., Upadhyaya, H., Yazbek, M., Wenzl, P. In: Crop Science v. 59, no. 3, p. 819-832.
Wheat provides, on average, 20% of the calories and protein for more than 4.5 billion people in 94 developing countries. To feed a growing population, we need both better agronomic practices and to grow wheat varieties that can withstand the effects of climate change and resist various pests and diseases.
Watch CIMMYT Wheat Physiologist Carolina Rivera discuss â in just one minute â choosing and breeding desirable wheat traits with higher tolerance to stresses.
CIMMYT and JAAS representatives signed the agreement to establish a screening facility for Fusarium head blight in Nanjing, China.
The CGIAR Research Program on Wheat (WHEAT), led by the International Maize and Wheat Improvement Center (CIMMYT) and the International Center for Agriculture in the Dry Areas (ICARDA), recently announced a partnership with the Jiangsu Academy of Agricultural Sciences (JAAS) in China to open a new screening facility for the deadly and fast-spreading fungal wheat disease Fusarium head blight, or FHB.
The new facility, based near the JAAS headquarters in Nanjing, aims to capitalize on CIMMYTâs world-class collection of disease-resistant wheat materials and the diversity of the more than 150,000 wheat germplasm in its Wheat Germplasm Bank to identify and characterize genetics of sources of resistance to FHB and, ultimately, develop new FHB-resistant wheat varieties that can be sown in vulnerable areas around the world.
âThe participation of JAAS in the global FHB breeding network will significantly contribute to the development of elite germplasm with good FHB resistance,â said Pawan Singh, head of wheat pathology for CIMMYT.
âWe expect that in 5 to 7 years, promising lines with FHB resistance will be available for deployment by both CIMMYT and China to vulnerable farmers, thanks to this new station.â
Fusarium head blight is one of the most dangerous wheat diseases. It can cause up to 50% yield loss and produce severe mycotoxin contamination in food and feed, which affects farmers in the form of increased health care and veterinary care costs, and reduced livestock production.
Even consuming low to moderate amounts of Fusarium mycotoxins may impair intestinal health, immune function and fitness. Deoxynivalenol (DON), a mycotoxin the fungus inducing FHB produces, has been linked to symptoms including nausea, vomiting, and diarrhea. In livestock, Fusarium mycotoxin consumption exacerbates infections with parasites, bacteria and viruses â such as occidiosis in poultry, salmonellosis in pigs and mice, colibacillosis in pigs, necrotic enteritis in poultry and swine respiratory disease.
In China, the worldâs largest wheat producer, Fusarium head blight is the most important biotic constraint to production.
The disease is extending quickly beyond its traditionally vulnerable wheat growing areas in East Asia, North America, the southern cone of South America, Europe and South Africa â partly as a result of global warming, and partly due to otherwise beneficial, soil-conserving farming practices such as wheat-maize rotation and reduced tillage.
âThrough CIMMYTâs connections with national agricultural research systems in developing countries, we can create a global impact for JAAS research, reaching the countries that are expected to be affected the expansion of FHB epidemic area,â said Xu Zhang, head of Triticeae crops research group at the Institute of Food Crops of the Jiangsu Academy of Agricultural Sciences.
The new collaborative effort will target Fusarium head blight research but could potentially expand to research on other wheat diseases as well. Wheat blast, for example, is a devastating disease that spread from South America to Bangladesh in 2016. Considering the geographical closeness of Bangladesh and China, a collaboration with CIMMYT, as one of the leading institutes working on wheat blast, could have a strong impact.
Although the platform is new, the two institutions have a longstanding relationship. The bilateral collaboration between JAAS and CIMMYT began in early 1980s with a shuttle breeding program between China and Mexico to speed up breeding for Fusarium head blight resistance. The two institutions also conducted extensive germplasm exchanges in the 1980s and 1990s, which helped CIMMYT improve resistance to Fusarium head blight, and helped JAAS improve wheat rust resistance.
Currently, JAAS and CIMMYT are working on Fusarium head blight under a project funded by the National Natural Science Foundation of China called âElite and Durable Resistance to Wheat Fusarium Head Blightâ that aims to deploy resistance genes/QTL in Chinese and CIMMYT germplasm and for use in wheat breeding.
The International Maize and Wheat Improvement Center (CIMMYT) is the global leader in publicly-funded maize and wheat research and related farming systems. Headquartered near Mexico City, CIMMYT works with hundreds of partners throughout the developing world to sustainably increase the productivity of maize and wheat cropping systems, thus improving global food security and reducing poverty. CIMMYT is a member of the CGIAR System and leads the CGIAR Research Programs on Maize and Wheat and the Excellence in Breeding Platform. The Center receives support from national governments, foundations, development banks and other public and private agencies. For more information, visit staging.cimmyt.org.
ABOUT JAAS:
Jiangsu Academy of Agricultural Sciences (JAAS), a comprehensive agricultural research institution since 1931, strives to make agriculture more productive and sustainable through technology innovation. JAAS endeavors to carry out the Plan for Rural Vitalization Strategy and our innovation serves agriculture, farmers and the rural areas. JAAS provide more than 80% of new varieties, products and techniques in Jiangsu Province, teach farmers not only to increase yield and quality, but also to challenge conventional practices in pursuit of original ideas in agro-environment protection. For more information, visit home.jaas.ac.cn/.
With new pathogens of crop diseases continuously emerging and threatening food production and security, wheat breeder and wheat rust pathologist Mandeep Randhawa and his colleagues at the International Maize and Wheat Improvement Center (CIMMYT) and the Kenya Agricultural and Research Organization (KALRO) are working tirelessly to identify new sources of rust resistance through gene mapping tools and rigorous field testing.
With wheat accounting for around 20% of the worldâs calories and protein, outbreaks of disease can pose a major threat to global food security and farmer livelihoods. The most common and prevalent diseases are wheat rusts â fungal diseases that can be dispersed by wind over long distances, which can quickly cause devastating epidemics and dramatically reduce wheat yields.
To tackle the problem, Randhawa and his colleagues work on developing improved wheat varieties by combining disease-resistant traits with high yielding ones, to ensure that farmers can get the best wheat yields possible while evading diseases.
Screening for disease
A native of the Punjab state of India, Randhawa joined CIMMYT as a Post-doctoral Fellow in Wheat Rust Resistance Genetics in 2015. He now works as a CIMMYT scientist and manages the Stem Rust Screening Platform in Njoro, Kenya, which supports screening against stem rust of up to 50,000 wheat lines per year from as many as 20 countries. Over the last 10 years about 650,000 wheat lines have been evaluated for stem rust resistance at the facility.
âThe platformâs main focus is on evaluation of wheat lines against the stem rust race Ug99 and its derivative races prevalent in Eastern to Southern Africa, the Middle East and Iran,â explains Randhawa. Ug99 is a highly virulent race of stem rust, first discovered two decades ago in Uganda. The race caused major epidemics in Kenya in 2002 and 2004.
âEast African highlands are also a hotspot for stripe wheat rust so, at the same time, we evaluate wheat lines for this disease,â adds Randhawa.
The facility supports a shuttle breeding scheme between CIMMYT Mexico and Kenya, which allows breeders to plant at two locations, select for stem rust (Ug99) resistance and speed up the development of disease-resistant wheat lines.
âWheat rusts in general are very fast evolving and new strains are continuously emerging. Previously developed rust-resistant wheat varieties can succumb to new virulent strains, making the varieties susceptible. If the farmers grow susceptible varieties, rust will take on those varieties, resulting in huge yield losses if no control measures are adopted,â explains Randhawa.
Helping and sharing
For Randhawa, helping farmers is the main goal. âOur focus is on resource-poor farmers from developing countries. They donât have enough resources to buy the fungicide. Using chemicals to control diseases is expensive and harmful to the environment. So in that case we provide them solutions in the form of wheat varieties which are high yielding but they have long-lasting resistance to different diseases as well.â
Under the Borlaug Global Rust Initiative, Randhawa and his team collaborate with KALRO to facilitate the transfer of promising wheat lines with high yield potential and rust resistance to a national pipeline for soon-to-be-released wheat varieties.
When he is not screening for wheat rusts diseases, Randhawa  also organizes annual trainings on stem rust diagnosis and germplasm evaluation for young wheat breeders and pathologists from developing countries. More than 220 wheat researchers have been trained over the last decade.
Mandeep Randhawa (left) talks to the participants of the 11th annual training on stem rust notetaking and germplasm evaluation. (Photo: Jerome Bossuet/CIMMYT)
A farmer at heart
Randhawa always had an interest in agricultural science. âInitially, my parents wanted me to be a medical doctor, but I was more interested in teaching science to school students,â he says. âSince my childhood, I used to hear of wheat and diseases affecting wheat crops, especially yellow rust â which is called peeli kungi in my local language.â This childhood interest led him to study wheat genetics at Punjab Agricultural University in Ludhiana, India.
His mentors encouraged him to pursue a doctorate from the Plant Breeding Institute (PBI) Cobbitty at the University of Sydney in Australia, which Randhawa describes as âthe mecca of wheat rust research.â He characterized two new stripe rust resistance genes formally named as Yr51 and Yr57 from a wheat landrace. He also contributed to the mapping of a new adult plant stem rust resistance gene Sr56.
Coming from India, his move to Australia was a pivotal moment for him in his career and his identity â he now considers himself Indian-Australian.
If he had not become a scientist, Randhawa would be a farmer, he says. âFarming is my passion, as I like to grow crops and to have rich harvest using my scientific knowledge and modern technologies.â
At CIMMYT, Randhawa has a constant stream of work identifying and characterizing new sources of rust resistance. âDealing with different types of challenges in the wheat field is what keeps me on my toes. New races of diseases are continuously emerging. As pests and pathogens have no boundaries, we must work hand-in-hand to develop tools and technologies to fight fast evolving pests and pathogens,â says Randhawa.
He credits his mentor Ravi Singh, Scientist and Head of Global Wheat Improvement at CIMMYT, for motivating him to continue his work. âTireless efforts and energetic thoughts of my professional guru Dr. Ravi Singh inspire and drive me to achieve research objectives.â
CIMMYT’s multi-crop, multi-use zero-tillage seeder at work on a long-term conservation agriculture trial plot at the center’s global headquarters in Mexico. Maize crop residues are visible in the foreground. (Photo: CIMMYT)
New research published in Field Crops Research by scientists at the International Maize and Wheat Improvement Center (CIMMYT) responds to the question of whether wheat varieties need to be adapted to zero tillage conditions.
With 33% of global soils already degraded, agricultural techniques like zero tillage â growing crops without disturbing the soil with activities like plowing â in combination with crop residue retention, are being considered to help protect soils and prevent further degradation. Research has shown that zero tillage with crop residue retention can reduce soil erosion and improve soil structure and water retention, leading to increased water use efficiency of the system. Zero tillage has also been shown to be the most environmentally friendly among different tillage techniques.
While CIMMYT promotes conservation agriculture, of which zero tillage is a component, many farmers who use CIMMYT wheat varieties still use some form of tillage. As farmers adopt conservation agriculture principles in their production systems, we need to be sure that the improved varieties breeders develop and release to farmers can perform equally well in zero tillage as in conventional tillage environments.
The aim of the study was to find out whether breeding wheat lines in a conservation agriculture environment had an effect on their adaptability to one tillage system or another, and whether separate breading streams would be required for each tillage system.
The scientists conducted parallel early generation selection in sixteen populations from the breeding program. The best plants were selected in parallel under conventional and zero-till conditions, until 234 and 250 fixed lines were obtained. They then grew all 484 wheat lines over the course of three seasons near Ciudad Obregon, Sonora, Mexico, under three different environments â zero tillage, conventional tillage, and conventional tillage with reduced irrigation â and tested them for yield and growth traits.
The authors found that yields were better under zero tillage than conventional tillage for all wheat lines, regardless of how they had been bred and selected, as this condition provided longer water availability between irrigations and mitigated inter-irrigation water stress.
The main result was that selection environment, zero-till versus conventional till, did not produce lines with specific adaptation to either conditions, nor did it negatively impact the results of the breeding program for traits such as plant height, tolerance to lodging and earliness.
One trait which was slightly affected by selection under zero-till was early vigor â the speed at which crops grow during the earliest stage of growth. Early vigor is a useful adaptive trait in conservation agriculture because it allows the crop to cope with high crop residue loads â materials left on the ground such as leaves, stems and seed pods â and can improve yield through rapid development of maximum leaf area in dry environments. Results showed that varieties selected under zero tillage showed slightly increased early vigor which means that selection under zero tillage may drive a breeding program towards the generalization of this useful attribute.
The findings demonstrate that CIMMYTâs durum wheat lines, traditionally bred for wide adaptation, can be grown, bred, and selected under either tillage conditions without negatively affecting yield performance. This is yet another clear demonstration that breeding for wide adaptation, a decades-long tradition within CIMMYTâs wheat improvement effort, is a suitable strategy to produce varieties that are competitive in a wide range of production systems. The findings represent a major result for wheat breeders at CIMMYT and beyond, with the authors concluding that it is not necessary to have separate breeding programs to address the varietal needs of either tillage systems.
This work was implemented by CIMMYT as part of the CGIAR Research Program on Wheat (WHEAT).
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 15,000âhectares 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 â 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 (VetenskapsrĂ„det). Some of the partners who collaborate include the Bangladesh Wheat and Maize Research Institute (BWMRI), Boliviaâs Instituto Nacional de InnovaciĂłn Agropecuaria y Forestal (INIAF), Kansas State University and the Agricultural Research Service of the US (USDA-ARS).
This month, the worldâs eyes are upon global leaders gathered in Madrid for COP25 to negotiate collective action to slow the devastating impacts of climate change.
According to the UN, the world is heading for a 3.2 degrees Celsius global temperature rise over pre-industrial levels, leading to a host of destructive climate impacts, including hotter and drier environments and more extreme weather events. Under these conditions, the worldâs staple food crops are under threat.
A new video highlights the work of the Heat and Drought Wheat Improvement Network (HeDWIC), a global research and capacity development network under the Wheat Initiative, that harnesses the latest technologies in crop physiology, genetics and breeding to help create new climate-resilient wheat varieties. With the help of collaborators and supporters from around the world, HeDWIC takes wheat research from the theoretical to the practical by incorporating the best science into real-life breeding scenarios.
