Research shows that inefficient storage is the main cause of staple commodity losses in the country. Despite producing 27 million tons of wheat annually worth $7.4 billion, there is less than 6 million tons of storage capacity available; around 10% of the surplus wheat is lost at a value of $740 million due to the use of unregulated conditions.
With the ability to store their commodity for an extra two or three months, farmers can increase their income by between 20 to 40 percent. Preserving the crops that have already been produced will also pass on a saving of between 15 to 20 percent to end consumers.
Hermetic technology developed by the International Maize and Wheat Improvement Center (CIMMYT), the International Rice Research Institute (IRRI) and the University of Hohenheim offers a potential storage solution by protecting the commodity from the ambient environment.
The planting of maize hybrid Wengkhar Hybrid Maize 1 (WHM-1) has helped farmers in the Mongar district of Bhutan double their maize yield.
WHM-1 was developed in partnership with the International Maize and Wheat Improvement Center (CIMMYT) and became the first maize hybrid to be released in Bhutan to combat the negative effect of increasing temperature or extreme heat events on maize.
The hybrid was designed with characteristics of heat and drought tolerance, as well as a resistance to stem and root lodging. It also had additional stay-green traits after cob maturity and produced a high yield.
The success of the implementation in Bhutan is leading to an increased production of WHM-1, which will aim to meet national demand and work towards country’s self-sufficiency.
Dechen Yangden is one of the smallholder beneficiaries in Tsakaling, a sub-district in Mongar in the east of the country, who have boosted their maize yield by planting WHM-1. “My attempt to grow WHM-1 has doubled my maize production compared to last season where I cultivated some other maize varieties (2.5 metric tons (mt) in one hectare (ha)),” she said.
Farmer holds up a maize cob of WHM-1 in Waichur hamlet, Mongor, Bhutan. (Photo: ARDC)
Farmers’ experiences of WHM-1
Since its official release in 2020, the national maize program based at Agriculture Research & Development Center (ARDC) started producing hybrid seeds and maintaining parental lines. To test the success of the ARDC’s work, planting was carried out in the Tsakaling and Waichur hamlets in Mongar districts, covering an area of six acres.
Maize farmers in Tsakaling shared that although the crop was affected by the insect fall armyworm during the early vegetative stage, the productivity of the crop was not affected, as it recovered at later stage.
Meanwhile, ARDSC Khangma carried out yield monitoring during the harvest, where WHM-1 yielded 5.8 mt ha-1, which is noticeable rise on the national average of 3.7 mt ha-1.
Following the conclusion of their harvest, farmers in the two localities shared their views on the newly released maize in order to review the effect of the implementation of WHM-1. Both sets of growers reported an improved performance from the use of WHM-1 and noted that, unlike other maize varieties, the hybrid has shorter and uniform plant height along with a higher resistance to lodging, which is an essential trait given the conditions it is grown in. Furthermore, the stay-green trait of the hybrid after maturity of cobs gave farmers an added advantage of green fodder, which can be used for feeding their cattle.
In Waichur, the growers found that this hybrid had a tight husk and fully filled kernels. They shared similar views to growers in Tsakaling, reporting positive lodging resistance in the hybrid.
Both communities expressed their interest in continuing to use WHM-1, given the availability and accessibility of the seeds. As a response, the National Maize Program at ARDC Wengkhar, is looking to deploy the newly released hybrid on a larger scale, which will ultimately contribute towards enhancing maize self-sufficiency in the country.
WHM-1 was developed through partnership of the National Maize Program at Wengkhar and CIMMYT under the Heat Stress Tolerant Maize for Asia (HTMA) project for germplasm and technical assistance and the Commercial Agriculture and Resilient Livelihoods Enhancement Program (CARLEP-IFAD/MoAF) for on-farm research and intensification.
Feasibility mapping for WHM-1 showed that its adaption stretches along the southern foothills and some parts of eastern district. The National Maize Program, sister research centers, and farmers are currently working on upscaling the seed production for intensification of national maize production to meet the domestic demands.
Cover photo: Women farmers tagging their first choice of maize crop, WHM-1, in Tsakaling hamlet, Mongor, Bhutan. (Photo: ARDC)
Harvest of hybrid WHM-1 maize. (Photo: ARDC)
This story is written by P.H. Zaidi of CIMMYT and Passang Wangmo and Tsheltrim Gyeltshen of the National Maize Program, ARDC Wengkhar, Bhutan.
In an article for Mexico Business News, Bram Govaerts, Director General of the International Maize and Wheat Improvement Center (CIMMYT), provides context for the organization’s seed systems strategy in relation to current challenges in agriculture.
Despite producing roughly 27 million tons of white maize used each year, Mexico imports approximately 18 million tons of yellow maize for fodder and raw material. To reduce reliance on imports, productivity of staple crops needs to be increased, during a time when climate change, conflict, COVID-19 and cost of living are all causing additional pressures.
Developing seeds with high yields and resilience to the impacts of climate change is required to close yield gaps in a sustainable way. However, the needs of smallholders differ from those of commercial farming, so inclusivity in seed systems is essential.
Elufe Chipande (left), a farmer at Songani in Zomba District, Malawi, is rotating maize (background) and pigeonpea (foreground) under conservation agriculture practices to improve soil fertility and capture and retain more water. Christian Thierfelder (center), a cropping systems agronomist working out of the Zimbabwe office of CIMMYT, advises and supports southern African farmers and researchers to refine and spread diverse yield-enhancing, resource-conserving crop management practices. Photo: Mphatso Gama/CIMMYTSRUC
An international team of scientists has found that eco-friendly practices such as growing a range of crops, including legumes such as beans or pigeonpea, and adding plant residues or manure to soils can raise food crop yields in places such as rural Africa, where small-scale farmers cannot apply much nitrogen fertilizer.
Published in the science journal Nature Sustainability and examining data from 30 long-running field experiments involving staple crops (wheat, maize, oats, barley, sugar beet, or potato) in Europe and Africa, this major study is the first to compare farm practices that work with nature to increase yields and explore how they interact with fertilizer use and tillage.
“Agriculture is a leading cause of global environmental change but is also very vulnerable to that change,” said Chloe MacLaren, a plant ecologist at Rothamsted Research, UK, and lead author of the paper. “Using cutting-edge statistical methods to distill robust conclusions from divergent field experiment data, we found combinations of farming methods that boost harvests while reducing synthetic fertilizer overuse and other environmentally damaging practices.”
Recognizing that humanity must intensify production on current arable land to feed its rising numbers, the paper advances the concept of “ecological intensification,” meaning farming methods that enhance ecosystem services and complement or substitute for human-made inputs, like chemical fertilizer, to maintain or increase yields.
Boosting crop yields and food security for far-flung smallholders
The dataset included results from six long-term field experiments in southern Africa led by the International Maize and Wheat Improvement Center (CIMMYT). Africa’s farming systems receive on average only 17 kilograms of fertilizer per hectare, compared to more than 180 kilograms per hectare in Europe or close to 600 in China, according to Christian Thierfelder, a CIMMYT cropping systems agronomist and study co-author.
“In places where farmers’ access to fertilizer is limited, such as sub-Saharan Africa or the Central American Highlands, ecological intensification can complement scarce fertilizer resources to increase crop yields, boosting households’ incomes and food security,” Thierfelder explained. “We believe these practices act to increase the supply of nitrogen to crops, which explains their value in low-input agriculture.”
The CIMMYT long-term experiments were carried out under “climate-smart” conservation agriculture practices, which include reduced or no tillage, keeping some crop residues on the soil, and (again) growing a range of crops.
“These maize-based cropping systems showed considerable resilience against climate effects that increasingly threaten smallholders in the Global South,” Thierfelder added.
Benefits beyond yield
Besides boosting crop yields, ecological intensification can cut the environmental and economic costs of productive farming, according to MacLaren.
“Diversifying cropping with legumes can increase profits and decrease nitrogen pollution by reducing the fertilizer requirements of an entire crop rotation, while providing additional high-value food, such as beans,” MacLaren explained. “Crop diversity can also confer resilience to weather variability, increase biodiversity, and suppress weeds, crop pests and pathogens; it’s essential, if farmers are to improve maize production in places like Africa.”
Thierfelder cautioned that widespread adoption of ecological intensification will require strong support from policymakers and society, including establishing functional markets for legume seed and for marketing farmers’ produce, among other policy improvements.
“Dire and worsening global challenges — climate change, soil degradation and fertility declines, and scarcening fresh water — threaten the very survival of humanity,” said Thierfelder. “It is of utmost importance to renovate farming systems and bring us back into a safe operating space.”
Click here to read the paper, Long-term evidence for ecological intensification as a pathway to sustainable agriculture.
A generalized wiring diagram for wheat, as proposed by the authors. The diagram depicts the traits most commonly associated with the source (left) and sink (right) strengths and others that impact both the sink and source, largely dependent on growth stage (middle). TGW, thousand grain weight.
As crop yields are pushed closer to biophysical limits, achieving yield gains becomes increasingly challenging. Traditionally, scientists have worked on the premise that crop yield is a function of photosynthesis (source), the investment of assimilates into reproductive organs (sinks) and the underlying processes that enable and connect the expression of both. Although the original source-and-sink model remains valid, it must embrace more complexity, as scientific understanding improves.
A group of international researchers are proposing a new wiring diagram to show the interrelationships of the physiological traits that impact wheat yield potential, published on Nature Food. By illustrating these linkages, it shows connections among traits that may not have been apparent, which could serve as a decision support tool for crop scientists. The wiring diagram can inform new research hypotheses and breeding decisions, as well as research investment areas.
The diagram can also serve as a platform onto which new empirical data are routinely mapped and new concepts added, thereby creating an ever-richer common point of reference for refining models in the future.
“If routinely updated, the wiring diagram could lead to a paradigm change in the way we approach breeding for yield and targeting translational research,” said Matthew Reynolds, Distinguished Scientist and Head of Wheat Physiology at the International Maize and Wheat Improvement Center (CIMMYT) and lead author of the study. “While focused on yield potential, the tool can be readily adapted to address climate resilience in a range of crops besides wheat.”
Breeding milestone
The new wiring diagram represents a milestone in deterministic plant breeding. It dovetails simpler models with crop simulation models.
This diagram can be used to illustrate the relative importance of specific connections among traits in their appropriate phenological context and to highlight major gaps in knowledge. This graphical representation can also serve as a roadmap to prioritize research at other levels of integration, such as metabolomic or gene expression studies. The wiring diagram can be deployed to identify ways for improving elite breeding material and to explore untapped genetic resources for unique traits and alleles.
Yield for climate resilience
The wheat scientific community is hard at work seeking new ways to get higher yields more quickly to help the world cope with population growth, climate change, wars and stable supplies of calories and protein.
“To ensure food and nutritional security in the future, raising yields must be an integral component of making crops more climate-resilient. This new tool can serve as a roadmap to design the necessary strategies to achieve these goals,” said Jeff Gwyn, Program Director of the International Wheat Yield Partnership (IWYP).
Matthew Reynolds – Distinguished Scientist and Head of Wheat Physiology at the International Maize and Wheat Improvement Center (CIMMYT)
Gustavo Ariel Slafer – Research Professor at the Catalonian Institution for Research and Advanced Studies (ICREA) and Associate Professor of the University of Lleida
For more information or to arrange interviews, please contact the CIMMYT media team:
The study is an international collaboration of scientists from the International Maize and Wheat Improvement Center (CIMMYT), the Catalonian Institution for Research and Advanced Studies (ICREA), the Center for Research in Agrotechnology (AGROTECNIO), the University of Lleida, the University of Nottingham, the John Innes Centre, Lancaster University, Technische Universität München, CSIRO Agriculture & Food, and the International Wheat Yield Partnership (IWYP).
ABOUT CIMMYT:
The International Maize and Wheat Improvement Center (CIMMYT) is an international organization focused on non-profit agricultural research and training that empowers farmers through science and innovation to nourish the world in the midst of a climate crisis.
Applying high-quality science and strong partnerships, CIMMYT works to achieve a world with healthier and more prosperous people, free from global food crises and with more resilient agri-food systems. CIMMYT’s research brings enhanced productivity and better profits to farmers, mitigates the effects of the climate crisis, and reduces the environmental impact of agriculture.
CIMMYT is a member of CGIAR, a global research partnership for a food-secure future dedicated to reducing poverty, enhancing food and nutrition security, and improving natural resources.
The International Wheat Yield Partnership (IWYP) represents a long-term global endeavor that utilizes a collaborative approach to bring together funding from public and private research organizations from a large number of countries. Over the first five years, the growing list of partners aims to invest up to US$100 million.
At the same time, climate change has likely slowed breeding progress for high-yielding, broadly adapted wheat, according to the new study, published recently in Nature Plants.
“Breeders are usually optimistic, overlooking many climate change factors when selecting,” said Matthew Reynolds, wheat physiologist at the International Maize and Wheat Improvement Center (CIMMYT) and co-author of the publication. “Our findings undermine this optimism and show that the amplified interaction of wheat lines with the environment due to climate change has made it harder for breeders to identify outstanding, broadly adapted lines.”
What do 10 million data points tell scientists?
Each year for nearly half a century, wheat breeders taking part in the CIMMYT-led International Wheat Improvement Network (IWIN) have tested approximately 1,000 new, experimental wheat lines and varieties at some 700 field sites in over 90 countries.
Promising lines are taken up by wheat breeding programs worldwide, while data from the trials is used to guide global breeding and other critical wheat research, explained Wei Xiong, CIMMYT crop modeler/physiologist based in China and lead author of the new paper.
“To date, this global testing network has collected over 10 million data points, while delivering wheat germplasm estimated to be worth several billion dollars annually in extra productivity to hundreds of millions of farmers in less developed countries,” Xiong said.
Xiong and his colleagues analyzed “crossover interactions” — changes in the relative rankings of pairs of wheat lines — in 38 years of data from four kinds of wheat breeding trials, looking for the extent to which climate change or breeding progress have flipped those rankings. Two of the trials whose data they examined focused on yield in bread wheat and durum wheat, while the other two assessed wheat lines’ performance under high temperatures and in semi-arid environments, respectively.
In addition to raising yields, wheat breeders are endowing the crop with added resilience for rising temperatures.
“We found that warmer and more erratic climates since the 1980s have increased ranking changes in global wheat breeding by as much as 15 percent,” Xiong said. “This has made it harder for breeders to identify superior, broadly adapted lines and even led to scientists discarding potentially useful lines.”
Conversely, wheat cultivars emerging from breeding for tolerance to environmental stresses, particularly heat, are showing substantially more stable yields across a range of environments and fostering wheat’s adaptation to current, warmer climates, while opening opportunities for larger and faster genetic gains in the future, according to the study.
“Among other things, our findings argue for more targeted wheat breeding and testing to address rapidly shifting and unpredictable farming conditions,” Reynolds added.
Gyanendra Pratap Singh (center), Director of ICAR-IIWBR, presents at the 60th All India Wheat and Barley Research Workers’ Meet. (Photo: Courtesy of ICAR-IIWBR)
The International Maize and Wheat Improvement Center’s (CIMMYT) legacy of work with the Indian Centre for Agricultural Research (ICAR) has once again produced more successful collaborations this year. This solid partnership resulted in the release of new varieties poised to bring new, superior yielding, disease-resistant, high-quality wheat varieties suitable for different production environments to Indian farms.
The National Variety Release Committee announced the release of nine new varieties at the 60th All India Wheat and Barley Research Workers’ Virtual Meet on August 23–24, 2021, hosted by the Indian Institute of Wheat and Barley Research (IIWBR) of ICAR. Of the nine new varieties identified, five were selected by national partners from CIMMYT international trials and nurseries.
At the event, ICAR-IIWBR director Gyanendra Pratap (GP) Singh highlighted the impressive growth trajectory of India’s wheat production, estimated at 109.52 million tons of wheat harvested in 2021, a figure which was 86.53 million tons in 2015 and less than 60 million tons in 1991. Singh highlighted that this success is dependent upon the deployment of superior wheat varieties, bridging yield and information gaps, strengthened seed value chain, supportive government policies and, of course, farmer support to adopt new varieties and technologies.
The CIMMYT-derived varieties announced at the meeting include DBW296, DBW327, DBW332, HUW296 and JKW261. A few days earlier, variety PBW869 was released by the Punjab Agricultural University for growing in Punjab State under conservation agriculture practices.
“An innovative and powerful feature of ICAR-CIMMYT collaboration has been the introduction of long-term (10-month) rotational involvement of Indian young scientists in CIMMYTs breeding program at Mexico as well as in wheat blast screening in Bolivia,” said Arun Joshi, CIMMYT Regional Representative for Asia and Managing Director, Borlaug Institute for South Asia (BISA). “In this way, the breeding program of CIMMYT is an excellent example of joint breeding program with national institutions.”
At the 60th All India Wheat and Barley Research Workers’ Meet, participants highlighted new varieties, production growth and strengthened collaboration. (Photo: CIMMYT)
Beyond expectations
In addition to these important new wheat varieties, some CIMMYT-derived wheat varieties that were released in recent years have now been deemed suitable for regions beyond their initial region of cultivation, showing wide adaptation and yield stability.
Wheat variety DBW222, released in 2020 for the northwestern plain zone, has now been deemed suitable for cultivation in the northeastern plain zone. Similarly, DBW187, which was initially released for the northeastern plain zone, and then for northwestern plain zone as well for early sowing, is now also extended for sowing in the central zone, together representing 25 million hectares of the 31 million hectares of wheat grown in India.
“Farmers prefer these types of varieties that give them flexibility during sowing time, and have high, stable yields, and disease resistance,” GP Singh said at the meeting.
A major achievement discussed at this year’s event was that three of the new varieties — DBW187, DBW303 and DBW222 — achieved record-high demand in Breeders Seed Indent, with first, second and seventh ranks, respectively. This is a reflection and indirect measure of popularity and demand for a variety. IIWBR’s innovative strategy to implement pre-release seed multiplication and create demand for seeds from new varieties has led to a faster turnover of improved varieties.
According to Ravi Singh, Distinguished Scientist and Head of Global Wheat Improvement at CIMMYT, the collaborators are “further expanding our partnership through the support from the Accelerating Genetic Gains in Maize and Wheat (AGG) and zinc-mainstreaming projects, to expand testing of larger sets of elite lines in targeted populations of environments of the four South Asian countries where various IIBWR-affiliated institutions shall expand testing in the 2021–22 crop season.” CIMMYT looks forward to continuing ongoing and new collaborations with the ICAR-IIWBR programs to deliver even faster genetic gain for yield and grain zinc levels in new varieties, he explained.
Speaking during the meeting Alison Bentley, Director of CIMMYT’s Global Wheat Program, highlighted the collaborative efforts underway as part of the AGG project to accelerate breeding progress. “Innovations and discoveries in breeding approaches are being rapidly made — with further investment needed — to quickly and equitably accumulate and deploy them to farmers,” she said.
More than 11,000 scientists signed on to a recent report showing that planet Earth is facing a climate emergency and the United Nations warned that the world is on course for a 3.2 degree spike by 2100, even if 2015 Paris Agreement commitments are met.
Agriculture, forestry, and land-use change are implicated in roughly a quarter of global greenhouse gas emissions.
Agriculture also offers opportunities to mitigate climate change and to help farmers — particularly smallholders in developing and emerging economies who have been hardest hit by hot weather and reduced, more erratic rainfall.
Most of CIMMYT’s work relates to climate change, helping farmers adapt to shocks while meeting the rising demand for food and, where possible, reducing emissions.
Family farmer Geofrey Kurgat (center) with his mother Elice Tole (left) and his nephew Ronny Kiprotich in their 1-acre field of Korongo wheat near Belbur, Nukuru, Kenya. (Photo: Peter Lowe/CIMMYT)
Climate-resilient crops and farming practices
53 million people are benefiting from drought-tolerant maize. Drought-tolerant maize varieties developed using conventional breeding provide at least 25% more grain than other varieties in dry conditions in sub-Saharan Africa — this represents as much as 1 ton per hectare more grain on average. These varieties are now grown on nearly 2.5 million hectares, benefiting an estimated 6 million households or 53 million people in the continent. One study shows that drought-tolerant maize can provide farming families in Zimbabwe an extra 9 months of food at no additional cost. The greatest productivity results when these varieties are used with reduced or zero tillage and keeping crop residues on the soil, as was demonstrated in southern Africa during the 2015-16 El Niño drought. Finally, tolerance in maize to high temperatures in combination with drought tolerance has a benefit at least twice that of either trait alone.
Wheat yields rise in difficult environments. Nearly two decades of data from 740 locations in more than 60 countries shows that CIMMYT breeding is pushing up wheat yields by almost 2% each year — that’s some 38 kilograms per hectare more annually over almost 20 years — under dry or otherwise challenging conditions. This is partly through use of drought-tolerant lines and crosses with wild grasses that boost wheat’s resilience. An international consortium is applying cutting-edge science to develop climate-resilient wheat. Three widely-adopted heat and drought-tolerant wheat lines from this work are helping farmers in Pakistan, a wheat powerhouse facing rising temperatures and drier conditions; the most popular was grown on an estimated 40,000 hectares in 2018.
Climate-smart soil and fertilizer management. Rice-wheat rotations are the predominant farming system on more than 13 million hectares in the Indo-Gangetic Plains of South Asia, providing food and livelihoods for hundreds of millions. If farmers in India alone fine-tuned crop fertilizer dosages using available technologies such as cellphones and photosynthesis sensors, each year they could produce nearly 14 million tons more grain, save 1.4 million tons of fertilizer, and cut CO2-equivalent greenhouse gas emissions by 5.3 million tons. Scientists have been studying and widely promoting such practices, as well as the use of direct seeding without tillage and keeping crop residues on the soil, farming methods that help capture and hold carbon and can save up to a ton of CO2 emissions per hectare, each crop cycle. Informed by CIMMYT researchers, India state officials seeking to reduce seasonal pollution in New Delhi and other cities have implemented policy measures to curb the burning of rice straw in northern India through widespread use of zero tillage.
Farmers going home for breakfast in Motoko district, Zimbabwe. (Photo: Peter Lowe/CIMMYT)
Measuring climate change impacts and savings
In a landmark study involving CIMMYT wheat physiologists and underlining nutritional impacts of climate change, it was found that increased atmospheric CO2 reduces wheat grain protein content. Given wheat’s role as a key source of protein in the diets of millions of the poor, the results show the need for breeding and other measures to address this effect.
CIMMYT scientists are devising approaches to gauge organic carbon stocks in soils. The stored carbon improves soil resilience and fertility and reduces its emissions of greenhouse gases. Their research also provides the basis for a new global soil information system and to assess the effectiveness of resource-conserving crop management practices.
CIMMYT scientist Francisco Pinto operates a drone over wheat plots at CIMMYT’s experimental station in Ciudad Obregon, Mexico. (Photo: Alfonso Cortés/CIMMYT)
Managing pests and diseases
Rising temperatures and shifting precipitation are causing the emergence and spread of deadly new crop diseases and insect pests. Research partners worldwide are helping farmers to gain an upper hand by monitoring and sharing information about pathogen and pest movements, by spreading control measures and fostering timely access to fungicides and pesticides, and by developing maize and wheat varieties that feature genetic resistance to these organisms.
Viruses and moth larvae assail maize. Rapid and coordinated action among public and private institutions across sub-Saharan Africa has averted a food security disaster by containing the spread of maize lethal necrosis, a viral disease which appeared in Kenya in 2011 and quickly moved to maize fields regionwide. Measures have included capacity development with seed companies, extension workers, and farmers the development of new disease-resilient maize hybrids.
The insect known as fall armyworm hit Africa in 2016, quickly ranged across nearly all the continent’s maize lands and is now spreading in Asia. Regional and international consortia are combating the pest with guidance on integrated pest management, organized trainings and videos to support smallholder farmers, and breeding maize varieties that can at least partly resist fall armyworm.
New fungal diseases threaten world wheat harvests. The Ug99 race of wheat stem rust emerged in eastern Africa in the late 1990s and spawned 13 new strains that eventually appeared in 13 countries of Africa and beyond. Adding to wheat’s adversity, a devastating malady from the Americas known as “wheat blast” suddenly appeared in Bangladesh in 2016, causing wheat crop losses as high as 30% on a large area and threatening to move quickly throughout South Asia’s vast wheat lands.
A community volunteer of an agricultural cooperative (left) uses the Plantix smartphone app to help a farmer diagnose pests in his maize field in Bardiya district, Nepal. (Photo: Bandana Pradhan/CIMMYT)
Partners and funders of CIMMYT’s climate research
A global leader in publicly-funded maize and wheat research and related farming systems, CIMMYT is a member of CGIAR and leads the South Asia Regional Program of the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS).
CIMMYT receives support for research relating to climate change from national governments, foundations, development banks and other public and private agencies. Top funders include CGIAR Research Programs and Platforms, the Bill & Melinda Gates Foundation, Mexico’s Secretary of Agriculture and Rural Development (SADER), the United States Agency for International Development (USAID), the UK Department for International Development (DFID), the Australian Centre for International Agricultural Research (ACIAR), Cornell University, the German aid agency GIZ, the UK Biotechnology and Biological Sciences Research Council (BBSRC), and CGIAR Trust Fund Contributors to Window 1 &2.
General view of the experimental field in Lempira, Honduras. (Photo: Nele Verhulst/CIMMYT)
Populations in Central America are rising rapidly, but staple crop production seems unable to keep up with increasing food demands.
Maize yields are particularly low compared to other regions. Cumulatively, farmers in El Salvador, Guatemala, Honduras and Nicaragua produce maize on nearly 2.5 million hectares, with a large proportion of these maize systems also including beans, either through relay cropping or intercropping. Though potential yields are estimated to be as high as 10 metric tons per hectare, average production remains low at around 2.28.
There is clearly immense opportunity for improvement, but it is not always obvious which issues need tackling.
Yield gap analysis — which measures the difference between potential and actual yield — is a useful starting point for addressing the issue and identifying intensification prospects. It is not a new concept in applied agronomy, but it has not been adequately applied in many regions. For example, Analyses of Central America tend to be grouped with the rest of Latin America, making it difficult to provide recommendations tailored to local contexts.
I see a more comprehensive understanding of the region’s specific crop production limitations as the first step towards improving food security.
Along with fellow researchers from the International Maize and Wheat Improvement Center (CIMMYT) and other institutions, we set out to identify the main factors limiting production in these areas. We established field trials in six maize and bean producing regions in El Salvador, Guatemala and Honduras, which represent about three-quarters of the maize producing area. We assessed factors such as water stress, nutrient deficiency, pressure from pests and diseases, and inter-plant competition, hypothesizing that optimized fertilization and supplementary irrigation would have the greatest effects on yields.
A maize cob in La Libertad, El Salvador, shows kernels affected by tar spot complex which have not filled completely (Photo: Nele Verhulst/CIMMYT)
We found that while improved fertilization improved maize yields by 11% on average, it did not have a significant effect on bean production. Irrigation had no effect, though this was mainly due to good rainfall distribution throughout the growing season in the study year. On average, optimized planting arrangements increased maize yields by 18%, making it the most promising factor we evaluated.
It was interesting though perhaps unsurprising to note that the contribution of each limiting factor to yield gaps carried across all sites and no single treatment effectively increased yields consistently across all sites. The trial results confirmed that production constraints are highly dependent on local management practices and agroecological location.
With this in mind, we recommend that development actors aiming to increase crop production begin by conducting multi-year, participatory experiments to understand the primary causes of yield gaps and identify the limitations specific to the areas in question, as this will allow for more effective research and policy efforts.
Guillermo Garcia Barrios, a co-author of the study and student at Colegio de Postgraduados in Montecillo, Mexico, with a PHERAstar machine used to validate genetic markers. (Photo: Marcia MacNeil/CIMMYT)
To meet the demand for wheat from a rising and quickly urbanizing population, wheat yields in farmers’ fields must increase by an estimated 1.5% each year through 2030.
Of all the factors that influence yield, grain weight is the trait that is most stable and heritable for use in breeding improved wheat varieties. Breeders measure this by thousand grain weight (TGW).
Over the years, molecular scientists have made efforts to identify genes related to increased TGW, in order to speed up breeding through marker-assisted selection (MAS). Using MAS, breeders can select parents that contain genes related to the traits they are looking for, increasing the likelihood they will be passed on and incorporated in a new variety.
There have been some limited successes in these efforts: in the past years, a few genes related to increased TGW have been cloned, and a set of genetic markers have been determined to be used for MAS. However, the effects of most of these candidate genes have not yet been validated in diverse sets of wheat germplasm throughout the world that represent the full range of global wheat growing environments.
A group of wheat geneticists and molecular breeders from the International Maize and Wheat Improvement Center (CIMMYT) has recently conducted a thorough study to confirm the effects of the favorable alleles reported for these genes on TGW in CIMMYT wheat, and to identify new genetic determinants of this desired trait.
They found some good news and some bad news.
First, the good news: focusing on more than 4,000 lines of CIMMYT wheat germplasm they found 15 haplotype blocks significantly associated with TGW. Four haplotype blocks associated with TGW were also associated with grain yield — a grand prize for breeders, because in general the positive association of grain yield with TGW is less profound and sometimes even negative. However, of the 14 genes that had been previously reported to increase TGW, only one in CIMMYT’s 2015-2016 Elite Yield Trial and two in Wheat Associative Mapping Initiative panel were shown to have significant TGW associations.
Wheat grains prepared for placement in a Thousand Grain Weight machine. (Photo: Marcia MacNeil/CIMMYT)
The scientists also found that the alleles — pairs of genes on a chromosome that determine heredity — that were supposedly favorable to TGW actually decreased it. These candidate genes also appear to vary in their TGW effects with genetic background and/or environment.
Thus, these findings also provide a foundation for more detailed investigations, opening the door for more studies on the genetic background dependence and environment sensitivity of the known candidate genes for TGW.
“Our findings indicate that it will be challenging to use MAS based on these existing markers across individual breeding programs,” said Deepmala Sehgal, CIMMYT wheat geneticist and the primary author of the study.
However, efforts to identify new genetic determinants of TGW were promising. The authors’ study of CIMMYT germplasm found one locus on chromosome 6A that showed increases of up to 2.60 grams in TGW and up to 258 kilograms per hectare in grain yield.
Thousand Grain Weight is measured in this machine at CIMMYT’s global headquarters in Texcoco, Mexico. (Photo: Marcia MacNeil/CIMMYT)
This discovery expands opportunities for developing diagnostic markers to assist in multi-gene pyramiding — a process that can derive new and complementary allele combinations for enhanced wheat TGW and grain yield.
Most of all, the study highlights the strong need for better and more validation of the genes related to this and other traits, so that breeders can be sure they are using material that is confirmed to increase wheat grain weight and genetic yield.
“Our findings are very promising for future efforts to efficiently develop more productive wheat in both grain weight and grain yield,” said Sehgal. “This ultimately means more bread on household tables throughout the world.”
“Validation of Candidate Gene-Based Markers and Identification of Novel Loci for Thousand-Grain Weight in Spring Bread Wheat” in Frontiers in Plant Science by Deepmala Sehgal, Suchismita Mondal, Carlos Guzman, Guillermo Garcia Barrios, Carolina Franco, Ravi Singh and Susanne Dreisigacker was supported by funding from the CGIAR Research Program on Wheat (WHEAT), the Delivering Genetic Gain in Wheat (DGGW) project funded by the Bill & Melinda Gates Foundation and the UK Department for International Development (DFID), and the US Agency for International Development (USAID) Feed the Future Innovation Lab for Applied Wheat Genomics.
