Use of lightweight, 5-9-horsepower mini-tillers by smallholder farmers in Nepal’s mid-hills cut tillage costs and boosted maize yields by facilitating timely maize cultivation, thus enhancing food self-sufficiency and farm profits and reducing rural poverty, a new study by an international team of scientists shows.
Published in the Journal of Economics and Development, the study reports findings of an on-farm survey involving more than 1,000 representative households from 6 districts of the mid-hills, a region of steep and broken terrain where rainfed maize is a staple crop, outmigration of working-age inhabitants makes farm labor scarce and costly, and farmers on small, fragmented landholdings typically till plots by hand or using ox-drawn plows.
“Conventional two- or four-wheel tractors are difficult to operate in the mid-hills’ rugged topography,” said Gokul P. Paudel, researcher working together with the International Maize and Wheat Improvement Center (CIMMYT) and Leibniz University, Hannover, Germany, and lead author of the study. “Farms are small and the mini-tillers are a good fit. Very small farms — those comprising less than 0.4 hectares of land and normally not served by hired farm labor or larger machinery — benefited the most from mini-tiller adoption.”
The paper is the first to provide empirical linkages between small-scale farm mechanization and the UN Sustainable Development Goals, particularly No Poverty (SDG-1) and Zero Hunger (SDG-2).
“Given its rural poverty and the resulting outmigration from farm areas to cities and to other countries, Nepal has increasingly become a labor-exporting country,” explained Paudel, who partnered in this study with researchers from the Asian Development Bank Institute and Cornell University. “Our research can help guide investments by Nepal and other developing countries in scale-appropriate farm mechanization, supporting those who wish to remain on rural homesteads and make a go of it.”
Machine operators starting the mini-tiller in the Kavrepalanchok district in the mid-hills of Nepal. (Photo: CIMMYT)
The science team found that farm size, labor shortages, draft animal scarcity, and market proximity were major factors that facilitate the adoption of appropriate mechanization in Nepal, according to Tim Krupnik, CIMMYT systems agronomist and study co-author.
“Smallholder farms dominate more than two-thirds of agricultural systems globally,” Krupnik said. “Interest in scale-appropriate farm mechanization is growing rapidly, particularly among donors and governments, and practical empirical measures of its impact are crucial.” The findings of the latest study fill this knowledge gap and provide sufficient evidence to prioritize the spread of appropriate technologies among smallholder farmers.
Krupnik noted that, through its office in Nepal and strong shared research and capacity-building activities, CIMMYT has worked for almost four decades with Nepali scientists and development partners, including the Nepal Agricultural Research Council (NARC) and the Ministry of Agriculture and Livestock Development (MoALD), to raise the productivity and sustainability of the country’s maize- and wheat-based farming systems.
In addition to strong government partnerships, CIMMYT works closely in Nepal with a range of non-government organizations, and importantly, hand-in-hand with private farm machinery manufacturers, retailers, and mechanics.
The study described was supported by the Bill & Melinda Gates Foundation, the US Agency for International Development (USAID), the Academy for International Agricultural Research (ACINAR) commissioned by the German Federal Ministry for Economic Cooperation and Development (BMZ) and carried out by ATSAF e.V. on behalf of the Deutsche Gesellschaft fur Internationale Zusammenarbeit (GIZ) GmbH, the One CGIAR Regional Integrated Initiative Transforming Agrifood Systems in South Asia (TAFSSA), and generous funders who contribute to the CGIAR Trust Fund.
“To meet expected wheat demand for 2050, production will need to double, which means increasing harvests nearly 70 kilograms per hectare each year,” said Leonardo Crespo-Herrera, CIMMYT wheat scientist and 2022 Japan Award recipient. “Breeding will be a major contributor, but better agronomic practices and policies will also be critical.” (Photo: CIMMYT)
International science to save wheat — a crucial food grain for 2.5 billion of the world’s poor — from a rising tide of insect pests known as aphids was lauded on November 22 with the 2022 Japan International Award for Young Agricultural Researchers (the Japan Award).
The 2022 Japan Award recognized novel breeding approaches to identify and select for genetic resistance in wheat to two species of aphids that cause wheat grain losses reaching 20% and whose rapid spread is propelled by rising temperatures.
Aphid resistant wheat can contribute to more sustainable food production, protecting farmers’ harvests and profits, while reducing the need to use costly and harmful insecticides, said Leonardo Crespo-Herrera, bread wheat improvement specialist for the International Maize and Wheat Improvement Center (CIMMYT) and one of the three 2022 Japan Award recipients.
“In addition to genetic yield potential, CIMMYT wheat breeding focuses on yield stability, disease resistance, and nutritional and end-use quality,” Crespo-Herrera explained. “Adding another target trait — aphid resistance — makes wheat breeding much more challenging.”
Efficient and effective field testing to confirm the genetics
Crespo-Herrera and his CIMMYT colleagues managed to identify and characterize genome segments responsible for aphid resistance in wheat and its near relatives, as well as running innovative field tests for a set of elite wheat breeding lines that were predicted to carry that resistance.
“With the aphid species called the greenbug, its feeding causes yellowing and necrotic spots on wheat, so we could actually measure and score wheat plants in plots that we deliberately infested with the aphids, keeping the resistant lines and throwing out the susceptible ones,” said Crespo-Herrera.
For the other species, the bird cherry-oat aphid, the only visible feeding damage is when the plants become stunted and die, so Crespo-Herrera and colleagues instead measured biomass loss and reduced growth in 1,000 artificially infested wheat lines, identifying a number of lines that had low scores for those measurements. Given that the lines tested came from a set that had already shown resistance to the greenbug, some of the successful lines feature resistance to both aphid species.
For the bird cherry-oat aphid, in two years of additional field tests, Crespo-Herrera and his team found that aphid populations were lower in plots sown with resistant wheat lines. “The experiments included remote sensing measurements that identified certain spectral signatures correlated with aphid populations; this may help us to assess resistance in future field trials.”
The researchers also found that a cutting-edge approach known as “genomic prediction” provided good estimations regarding promising, aphid-resistant wheat breeding lines.
Motivating young researchers in research and development
Established in 2007, the Japan Award is an annual prize organized by the Agriculture, Forestry and Fisheries Research Council (AFFRC) of Japan’s Ministry of Agriculture, Forestry and Fisheries (MAFF) and supported by the Japan International Research Center for Agricultural Sciences (JIRCAS). Awardees receive a $5,000 cash prize.
In an excerpt of an official note regarding Crespo-Herrera’s research, those agencies said “…This study has been highly evaluated for developing (wheat) lines that have been distributed worldwide for use in wheat breeding, and the methods of this study have been applied to develop varieties with resistance mechanisms against various kinds of insects, not only aphids.”
Crespo-Herrera thanked JIRCAS and MAFF for the award. “I feel honored to have been selected.”
For the first time in Zambia, a special Ministry of Agriculture committee has endorsed innovative sustainable intensification practices to diversify maize-based farming systems and boost the food and nutritional security of millions of small farm households, while enriching depleted soils.
Zambia’s recently formed “National Advisory Committee for the Approval/Validation of Candidate Technologies or Agronomic Practices” approved in September the release to farmers of three new systems for better yields and soil maintenance: growing maize between “hedge-rows” of legume trees; or in rows side-by-side with grain legumes as strip crops; or on permanent, raised soil beds or ridges.
Legume trees and grain legumes enhance soil nitrogen and organic matter content, and legume grains themselves are a valuable, alternative food, rich in protein for rural households. Raised soil beds and ridges can keep soils oxygenated and productive when heavy rainfall floods the fields, as can often occur in northern and northwestern Zambia.
All three systems can be bundled with conservation agriculture approaches, which are based on the principles of minimum soil disturbance, keeping crop residues on the soil, and growing a more diverse selection of crops.
“The official clearing of these transformative cropping technologies is a huge milestone for the project and for Zambia’s resource-poor farmers,” said Christian Thierfelder, CIMMYT principal cropping systems agronomist based in southern Africa who, as part of SIFAZ, is testing and disseminating maize cropping practices that boost harvests, enrich soils, and capture and conserve moisture. “We’re working closely with Zambia’s MoA and the FAO, planning research trials, demonstrations and promotion to reach 20,000 farmers as a first step.”
An essential crop
Maize is the number-one food staple in sub-Saharan Africa, sown by some 300 million smallholder farmers using seasonal rains. A leading crop as well for Zambia’s small-scale, subsistence, and often impoverished farmers, maize grows poorly in extreme heat, infertile soils, and extended dry weather. Failed maize crops can bring hunger to smallholders and their families, for whom risks are high and formal safety nets are non-existent.
The EU recently announced that it will provide an additional EUR 20 million in funding for SIFAZ, now three years old and operating in five provinces and 27 districts of Zambia.
The cropping practices submitted to the National Advisory Committee by Thierfelder and his colleagues conform to a sustainable intensification assessment framework developed by the Feed the Future Innovation Lab for Collaborative Research on Sustainable Intensification of the US Agency for International Development (USAID) and Kansas State University.
“The framework provides a set of indicators for evaluating technologies according to their effects on productivity, economics, the environment, and social and human conditions — domains considered essential for sustainable agriculture systems,” Thierfelder explained. “The framework is well suited for smallholder farm settings, where agriculture is linked to development goals such as alleviating poverty, avoiding land degradation, increasing food and nutrition security, and supporting women’s empowerment.”
Cover photo: Jane Miti, a Zambia extension methodology officer, is testing intercropped strips of maize and soybean at Nyanje, Sinda District, to improve her soils and yields. (Photo: Christian Thierfelder/CIMMYT)
The International Maize and Wheat Improvement Center (CIMMYT) is a non-profit international organization focused on applied agricultural research and training. It empowers farmers through science and innovation to nourish the world in the midst of a climate crisis.
Established in 1974, the research partnership between the People’s Republic of China and CIMMYT is improving the lives of millions of people in China through science-driven, evidence-based solutions. CIMMYT has five offices and over 20 collaborators throughout China.
The CIMMYT–China collaboration over four decades has added some 10.7 million additional tons of wheat to China’s national wheat output. Since 2000, CIMMYT germplasm has been planted on more than one million hectares across the country.
We look forward to many more years of collaboration to improve the lives of millions of people in China and the world.
Cover photo: An agricultural landscape in Yunnan Province, China. (Photo: Michelle DeFreese/CIMMYT)
Data collector reading data from offline groundwater level logger – one of the three tested monitoring technologies. (Credit: Subash Adhikari/CIMMYT)
Based on a pilot study regarding the feasibility and cost effectiveness of several groundwater monitoring approaches for agriculture in Nepal’s Terai region, a water and food security specialist who led the research has recommended the use of phone-based systems.
Speaking to diverse experts at the recent World Water Week 2022 in Stockholm, Sweden, Anton Urfels, a systems agronomist at the International Maize and Wheat Improvement Center (CIMMYT), said that manual monitoring with phone-based data uploading is relatively low-cost and effective and could be scaled up across the Terai.
“One alternate monitoring approach studied — online data uploading — has substantially lower staff time requirements and technology costs and higher temporal resolution than phone-based monitoring, but does not provide real-time data and entails high technical skills, capital costs, and risks of theft and damage,” said Urfels in his presentation, ‘Upgrading Groundwater Monitoring Networks in Low-Income Countries’.
Urfels and partners also developed a prototype of an open-source groundwater monitoring dashboard to engage stakeholders, help translate raw data into actionable information, and detect water depletion trends.
Water has become a key part of food research and innovation, critical for sustainable and ecological intensification in agriculture, according to the scientist.
“Collecting groundwater data is difficult and the technology for monitoring is unreliable, which impairs effective modeling, decision-making, and learning,” Urfels explained. “Like other countries in the region, Nepal is increasing its agricultural groundwater consumption, particularly through private investment in irrigation wells and pumps that open irrigation to more farmers. This and climate change have altered groundwater recharge rates and availability, but national data on these trends are incomplete.”
An extensive lowland region bordering India and comprising one-fifth of the nation’s territory, the Terai is Nepal’s breadbasket.
Held yearly since 1991, World Water Week attracts a diverse mix of participants from many professions to develop solutions for water-related challenges including poverty, the climate crisis, and biodiversity loss. The 2022 theme was “Seeing the Unseen: The Value of Water”.
“I’d recommend more pilot studies on phone-based groundwater monitoring for other areas of Nepal, such as the Mid-hill districts,” Urfels said. “We also need to fine-tune and expand the system dashboard and build cross-sectoral coordination to recognize and take into account groundwater’s actual economic value.”
Urfels said the Nepal Ministry of Energy, Water Resources and Irrigation has requested the nationwide scale-out of a digital monitoring system, and CIMMYT and Nepal experts will support this, as well as improving the system, which would be freely available for use and development by researchers and agencies outside of Nepal.
Cutting-edge models for crops and crop diseases, boosted by high-resolution climate datasets, could propel the development of early warning systems for wheat blast in Asia, helping to safeguard farmers’ grain supplies and livelihoods from this deadly and mysterious crop disease, according to a recent study by scientists at the International Maize and Wheat Improvement Center (CIMMYT).
Originally from the Americas, wheat blast shocked farmers and experts in 2016 by striking 15,000 hectares of Bangladesh wheat fields, laying waste to a third of the crops. The complex interactions of wheat and the fungus, Magnaporthe oryzae pathotype Triticum (MoT), which causes blast, are not fully understood. Few current wheat varieties carry genetic resistance to it and fungicides only partly control it. Warm temperatures and high humidity favor MoT spore production and spores can fly far on winds and high-altitude currents.
Mean potential wheat blast disease infections (NPI) across Asia, based on disease and crop infection model simulations using air temperature and humidity data from 1980-2019. Black dots represent wheat growing areas with presumably unsuitable climates for wheat blast. The x and y axes indicate longitude and latitude.
“Using a wheat blast infection model with data for Asia air temperatures and humidity during 1980-2019, we found high potential for blast on wheat crops in Bangladesh, Myanmar, and areas of India, whereas the cooler and drier weather in countries such as Afghanistan and Pakistan appear to render their wheat crops as unlikely for MoT establishment,” said Carlo Montes, a CIMMYT agricultural climatologist and first author of the paper, published in the International Journal of Biometeorology. “Our findings and approach are directly relevant for work to strengthen monitoring and forecasting tools for wheat blast and other crop diseases, as well as building farmers’ and agronomists’ disease control capacity.”
Montes emphasized the urgency of those efforts, noting that some 13 million hectares in South Asia are sown to wheat in rotation with rice and nearly all the region’s wheat varieties are susceptible to wheat blast.
Published in Nature Scientific Reports, a new study describes an innovative method to assess the reach and impacts of knowledge and partnerships created as part of the work of research-for-development organizations.
It uses text mining and the analysis of social networks and hyperlinks to draw inferences from publicly available digital sources, including institutional repositories, scientific databases, and social media.
“The method can uncover narratives, dynamics, and relationships that are hidden from traditional bibliometric analyses,” said Tek Sapkota, a cropping systems and climate change specialist at the International Maize and Wheat improvement Center (CIMMYT) and co-author or the study, which also involved the University of Coimbra, Portugal, and the University of Molise, Italy.
“Nearly 90 percent of CIMMYT’s research is related to climate change and its impact on food systems and vice-versa, so we assessed that to illustrate our new, web-based analytical framework. This novel approach can help research-for-development organizations to leverage online data and measure their impact.”
Cover photo: Twitter mentions network for the International Maize and Wheat Improvement Center official account (@CIMMYT). (Credit: Nature Scientific Reports)
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.
For the first time ever, a biotechnology team has identified vegetative storage proteins (VSP) in maize and activated them in the leaves to stockpile nitrogen reserves for release when plants are hit by drought, which also causes nutrient stress, according to a recent report in Plant Biotechnology Journal. In two years of field testing, the maize hybrids overexpressing the VSP in leaf cells significantly out-yielded the control siblings under managed drought stress applied at the flowering time, according to Kanwarpal Dhugga, a principal scientist at the International Maize and Wheat Improvement Center (CIMMYT).
“One of the two most widely grown crops, maize increasingly suffers from erratic rainfall and scarcer groundwater for irrigation,” Dhugga said. “Under water stress, nitrogen availability to the plant is also attenuated. If excess nitrogen could be stored in the leaves during normal plant growth, it could help expedite the plant’s recovery from unpredictable drought episodes. In our experimental maize hybrids, this particular VSP accumulated to more than 4% in mesophyll cells, which is five times its normal levels, and offered an additional, dispensable source of nitrogen that buffered plants against water deficit stress.”
Dhugga noted as well that the study, whose authors include scientists from Corteva Agriscience, the Bill & Melinda Gates Foundation, and the US Department of Agriculture (USDA), provides experimental evidence for the link between drought tolerance and adequate nitrogen fertilization of crop plants. “This mechanism could also help farmers and consumers in sub-Saharan Africa, where maize is grown on nearly 40 million hectares, accounts for almost one-third of the region’s caloric intake, and frequently faces moderate to severe drought.”
Scientists multiply and power up vegetative storage proteins in maize leaves as nutrient stockpiles for drought-stressed maize crops. Graphic adapted from: Pooja Gupta, Society for Experimental Biology (SEB).
A climate change hotspot region that features both small-scale and intensive farming, South Asia epitomizes the crushing pressure on land and water resources from global agriculture to feed a populous, warming world. Continuous irrigated rice and wheat cropping across northern India, for example, is depleting and degrading soils, draining a major aquifer, and producing a steady draft of greenhouse gases.
Through decades-long Asian and global partnerships, the International Maize and Wheat Improvement Center (CIMMYT) has helped to study and promote resource-conserving, climate-smart solutions for South Asian agriculture. Innovations include more precise and efficient use of water and fertilizer, as well as conservation agriculture, which blends reduced or zero-tillage, use of crop residues or mulches as soil covers, and more diverse intercrops and rotations. Partners are recently exploring regenerative agriculture approaches — a suite of integrated farming and grazing practices to rebuild the organic matter and biodiversity of soils.
Along with their environmental benefits, these practices can significantly reduce farm expenses and maintain or boost crop yields. Their widespread adoption depends in part on enlightened policies and dedicated promotion and testing that directly involves farmers. We highlight below promising findings and policy directions from a collection of recent scientific studies by CIMMYT and partners.
Getting down in the dirt
A recent scientific review examines the potential of a suite of improved practices — reduced or zero-tillage with residue management, use of organic manure, the balanced and integrated application of plant nutrients, land levelling, and precise water and pest control — to capture and hold carbon in soils on smallholder farms in South Asia. Results show a potential 36% increase in organic carbon in upper soil layers, amounting to some 18 tons of carbon per hectare of land and, across crops and environments, potentially cutting methane emissions by 12%. Policies and programs are needed to encourage farmers to adopt such practices.
Another study on soil quality in India’s extensive breadbasket region found that conservation agriculture practices raised per-hectare wheat yields by nearly half a ton and soil quality indexes nearly a third, over those for conventional practices, as well as reducing greenhouse gas emissions by more than 60%.
Ten years of research in the Indo-Gangetic Plains involving rice-wheat-mungbean or maize-wheat-mungbean rotations with flooded versus subsoil drip irrigation showed an absence of earthworms — major contributors to soil health — in soils under farmers’ typical practices. However, large earthworm populations were present and active under climate-smart practices, leading to improved soil carbon sequestration, soil quality, and the availability of nutrients for plants.
The field of farmer Ram Shubagh Chaudhary, Pokhar Binda village, Maharajganj district, Uttar Pradesh, India, who has been testing zero tillage to sow wheat directly into the unplowed paddies and leaving crop residues, after rice harvest. Chaudhary is one of many farmer-partners in the Cereal Systems Initiative for South Asia (CSISA), led by CIMMYT. (Photo: P. Kosina/CIMMYT)
Rebooting marginal farms by design
Using the FarmDESIGN model to assess the realities of small-scale, marginal farmers in northwestern India (about 67% of the population) and redesign their current practices to boost farm profits, soil organic matter, and nutritional yields while reducing pesticide use, an international team of agricultural scientists demonstrated that integrating innovative cropping systems could help to improve farm performance and household livelihoods.
More than 19 gigatons of groundwater is extracted each year in northern India, much of this to flood the region’s puddled, transplanted rice crops. A recent experiment calibrated and validated the HYDRUS-2D model to simulate water dynamics for puddled rice and for rice sown in non-flooded soil using zero-tillage and watered with sub-surface drip irrigation. It was found that the yield of rice grown using the conservation agriculture practices and sub-surface drip irrigation was comparable to that of puddled, transplanted rice but required only half the irrigation water. Sub-surface drip irrigation also curtailed water losses from evapotranspiration and deep drainage, meaning this innovation coupled with conservation agriculture offers an ecologically viable alternative for sustainable rice production.
Given that yield gains through use of conservation agriculture in northern India are widespread but generally low, a nine-year study of rice-wheat cropping in the eastern Indo-Gangetic Plains applying the Environmental Policy Climate (EPIC) model, in this case combining data from long-term experiments with regionally gridded crop modeling, documented the need to tailor conservation agriculture flexibly to local circumstances, while building farmers’ capacity to test and adapt suitable conservation agriculture practices. The study found that rice-wheat productivity could increase as much as 38% under conservation agriculture, with optimal management.
Key partner organizations in this research include the following: Indian Council of Agricultural Research (ICAR); Central Soil Salinity Research Institute (CSSRI), Indian Agricultural Research Institute (IARI), Indian Institute of Farming Systems Research (IIFSR), Agriculture University, Kota; CCS Haryana Agricultural University, Hisar; Punjab Agricultural University, Ludhiana; Sri Karan Narendra Agriculture University, Jobner, Rajasthan; the Borlaug Institute for South Asia (BISA); the Trust for Advancement of Agricultural Sciences, Cornell University; Damanhour University, Damanhour, Egypt; UM6P, Ben Guerir, Morocco; the University of Aberdeen; the University of California, Davis; Wageningen University & Research; and IFDC.
Generous funding for the work cited comes from the Bill & Melinda Gates Foundation, The CGIAR Research Programs on Wheat Agri-Food Systems (WHEAT) and Climate Change, Agriculture and Food Security (CCAFS), supported by CGIAR Fund Donors and through bilateral funding agreements), The Indian Council of Agricultural Research (ICAR), and USAID.
Cover photo: A shortage of farm workers is driving the serious consideration by farmers and policymakers to replace traditional, labor-intensive puddled rice cropping (shown here), which leads to sizable methane emissions and profligate use of irrigation water, with the practice of growing rice in non-flooded soils, using conservation agriculture and drip irrigation practices. (Photo: P. Wall/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)
India has conferred posthumously upon Sanjaya Rajaram, 2014 World Food Prize laureate and former wheat breeder and Director of the Wheat Program at the International Maize and Wheat Improvement Center (CIMMYT), its prestigious 2022 Padma Bhushan Award in “Science and Engineering” in recognition of “distinguished service of high order.”
Among the most successful crop breeders in history, Rajaram, who passed away in 2021, personally oversaw the development of nearly 500 high-yielding and disease-resistant wheat varieties that were grown on at least 58 million hectares in over 50 countries, increasing global wheat production by more than 200 million tons and especially benefiting hundreds of millions of the resource-poor whose diets and livelihoods depend on this critical crop. In India and the neighboring South Asian nations of Bangladesh, Nepal, and Pakistan, inhabitants consume more than 120 million tons of wheat and wheat-based foods each year.
“Dr. Rajaram was a true titan of wheat breeding and an inspiration for young researchers, training and mentoring more than 700 scientists from developing countries worldwide,” said Bram Govaerts, CIMMYT director general. “He was also a complete gentleman, comporting himself with modesty and grace despite his many honors and accomplishments; his first priority was helping and crediting others. Rajaram is an example today for all of us to keep working with the final stakeholder — the farmer — in mind.”
The rise from rural beginnings
Born on a small farm in District Varanasi, Uttar Pradesh, India, in 1943, Rajaram studied genetics and plant breeding at the Indian Agricultural Research Institute in New Delhi. After receiving his Ph.D. from the University of Sydney, he joined CIMMYT in 1969, working as a wheat breeder alongside Nobel Prize Laureate and CIMMYT scientist Norman Borlaug in Mexico. Recognizing his talent and initiative, Borlaug appointed Rajaram as head of CIMMYT’s wheat breeding program at just 29 years of age.
The Padma Bhushan Award was announced by President Ram Nath Kovind of India on the country’s Republic Day, January 26. In 2015, Rajaram received the Pravasi Bharatiya Samman award, the highest honor conferred on Indians overseas. In 2001 he accepted the Padma Shri award from the government of India and, in 1998, the Friendship Award from the government of China.
Sanjaya Rajaram (Photo: Xochil Fonseca/CIMMYT)
Though a plant breeder and scientist by profession, Rajaram used the platform of his 2014 World Food Prize to promote an expansive, integrated vision for agricultural development. “If we want to make a change, research won’t do it alone; we need to work directly with farmers and to train young agronomists, ensuring they have a broad vision to address the problems in farmers’ fields,” Rajaram said at a news conference in Mexico City in 2014.
Rajaram also served as Director of the Integrated Gene Management Program at the International Center for Agricultural Research in the Dry Areas (ICARDA) before formally retiring in 2008. In his retirement, he continued as a special scientific advisor to CIMMYT and ICARDA.
Longstanding partners pushing forward for farmers
“India’s agricultural research community is proud of the distinguished achievements of Dr. Rajaram,” said Trilochan Mohapatra, Director General of the Indian Council of Agricultural Research (ICAR) and Secretary of the Department of Agricultural Research and Education (DARE), of India’s Ministry of Agriculture and Farmers’ Welfare. “ICAR greatly appreciates its valuable collaborations with CIMMYT to help farmers grow better crops and conserve resources under increasingly challenging conditions.”
The partnership of India with CIMMYT harks back to the 1960s-70s, when Indian farmers tripled national wheat yields in a few years by growing Borlaug’s high-yield wheat varieties and adopting improved farming practices.
In 2011, India and CIMMYT jointly launched the Borlaug Institute for South Asia (BISA) to improve cropping systems and food security, helping farmers to confront climate change and natural resource scarcities, among other challenges.
S. Ayyappan, former ICAR Director General who signed the joint declaration of intent for BISA’s establishment in India, has been honored with the 2022 Padma Shri Award.
CIMMYT is a non-profit international agricultural research and training organization focusing on two of the world’s most important cereal grains, maize and wheat, and related cropping systems and livelihoods. Wheat varieties derived from CIMMYT and ICARDA research cover more than 100 million hectares — nearly two-thirds of the area sown to improved wheat worldwide — and bring benefits in added grain worth as much as $3.8 billion each year.
Genomic selection identifies individual plants based on the information from molecular markers, DNA signposts for genes of interest, that are distributed densely throughout the wheat genome. For wheat blast, the results can help predict which wheat lines hold promise as providers of blast resistance for future crosses and those that can be advanced to the next generation after selection.
In this study, scientists from the International Maize and Wheat Improvement Center (CIMMYT) and partners evaluated genomic selection by combining genotypic data with extensive and precise field data on wheat blast responses for three sets of genetically diverse wheat lines and varieties, more than 700 in all, grown by partners at locations in Bangladesh and Bolivia over several crop cycles.
The study also compared the use of a small number of molecular markers linked to the 2NS translocation, a chromosome segment from the grass species Aegilops ventricosa that was introduced into wheat in the 1980s and is a strong and stable source of blast resistance, with predictions using thousands of genome-wide markers. The outcome confirms that, in environments where wheat blast resistance is determined by the 2NS translocation, genotyping using one-to-few markers tagging the translocation is enough to predict the blast response of wheat lines.
Finally, the authors found that selection based on a few wheat blast-associated molecular markers retained 89% of lines that were also selected using field performance data, and discarded 92% of those that were discarded based on field performance data. Thus, both marker-assisted selection and genomic selection offer viable alternatives to the slower and more expensive field screening of many thousands of wheat lines in hot-spot locations for the disease, particularly at early stages of breeding, and can speed the development of blast-resistant wheat varieties.
The research was conducted by scientists from the International Maize and Wheat Improvement Center (CIMMYT), the Bangladesh Wheat and Maize Research Institute (BWMRI), the Instituto Nacional de Innovación Agropecuaria y Forestal (INIAF) of Bolivia, the Borlaug Institute for South Asia (BISA) and the Indian Council of Agricultural Research (ICAR) in India, the Swedish University of Agricultural Sciences (Alnarp), and Kansas State University in the USA. Funding for the study was provided by the Bill & Melinda Gates Foundation, the Foreign and Commonwealth Development Office of the United Kingdom, the U.S. Agency for International Development (USAID), the CGIAR Research Program on Wheat (WHEAT), the Indian Council of Agricultural Research (ICAR), the Swedish Research Council, and the Australian Centre for International Agricultural Research (ACIAR).
Cover photo: A researcher from Bangladesh shows blast infected wheat spikes and explains how the disease directly attacks the grain. (Photo: Chris Knight/Cornell University)
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.
A maize ear harvested from a “milpa,” the maize-based intercrop that is a critical source of food and nutritional security for smallholder farming communities in remote areas such as the Western Highlands of Guatemala. (Photo: Cristian Reyna)
The traditional milpa intercrop — in which maize is grown together with beans, squash, or other vegetable crops — can furnish a vital supply of food and nutrients for marginalized, resource-poor communities in the Americas, according to a study published today in Nature Scientific Reports.
One hectare of a milpa comprising maize, common beans, and potatoes can provide the annual carbohydrate needs of more than 13 adults, enough protein for nearly 10 adults, and adequate supplies of many vitamins and minerals, according to the study. The research was based on data from nearly 1,000 households across 59 villages of the Western Highlands of Guatemala and is the first to relate milpa intercropping diversity with nutritional capacity, using multiple plots and crop combinations.
“The milpa was the backbone of pre-Columbian agriculture in North America, Mexico, and Central America,” said Santiago López-Ridaura, specialist in agricultural systems and climate change adaptation at the International Maize and Wheat Improvement Center (CIMMYT) and lead author of the article.
“Milpa production anchored around locally-adapted maize is still an essential food and nutritional lifeline for isolated, often indigenous communities throughout Mexico and Central America, and can be tailored to improve their food and nutritional security, along with that of small-scale farmers in similar settings,” he added.
Maize for feed or food and nutrition?
In modern times, some 1 billion tons of maize are harvested yearly from about 200 million hectares worldwide. Much of this output results from intensive monocropping of hybrids that yield an average 10 tons per hectare, in places like the U.S.
This massive world harvest goes chiefly for animal feed, corn starch, corn syrup, ethanol, and myriad industrial products, but in sub-Saharan Africa, Latin America, and parts of Asia, maize remains a critical food staple, often grown by smallholder farmers with yields averaging around 1.5 tons per hectare.
The Western Highlands of Guatemala is among the world’s poorest regions — a mountainous area ill-served by markets and where communities battered by food insecurity and malnutrition sow crops at altitudes of up to 3,200 meters, according to Cristian A. Reyna-Ramírez, a co-author of the study from the Universidad Autónoma Metropolitana-Xochimilco, Mexico.
“Fully two-thirds of farmers in this region grow milpas based on maize but varying the intercrops with potatoes, faba bean, and even fruit trees,” Reyna-Ramírez said. “Our study showed that combinations such as maize-common bean-faba bean, maize-potatoes, and maize-common bean-potatoes provided the most carbohydrates, proteins, zinc, iron, calcium, potassium, folate, thiamin, riboflavin, vitamin B6, niacin and vitamin C.”
The classic “milpa” intercrop comprises maize, beans, and squash. The bean plant climbs the maize stalk to reach sunlight and its roots add nitrogen to the soil; the squash leaves shade the soil, conserving moisture and inhibiting weed growth. Milpa systems are often grown on steep hillsides at a wide range of altitudes. (Photo: Cristian Reyna)
Better diets and routes out of poverty?
With typical landholdings of less than a quarter hectare and households averaging six members, Guatemala’s Western Highlands inhabitants cannot depend on the milpa alone to satisfy their needs, López-Ridaura cautioned.
“As with many smallholder farm communities, lack of land and general marginalization traps them in a vicious circle of poverty and malnutrition, forcing them to experiment with risky cash crops or for working-age members to undertake dangerous and heartbreaking migrations to find work and send back remittances,” he explains.
According to López-Ridaura, this study points the way for tailoring milpa systems to help communities that still rely on that intercrop or others that could benefit from its use.
Looking forward
Natalia Palacios Rojas, CIMMYT maize quality and nutrition expert and a co-author of this article, notes that calculations of this and other milpa studies consider raw nutrients and that research is needed on the nutritional contributions of cooked food and non-milpa foods such as poultry, livestock, home-garden produce, and purchased food.
“Further work should also address the effects of storing milpa produce on its nutrient stability and how the seasonal availability of milpa crops impacts diets and nutrition,” Palacios said.
The authors are grateful for funding from the United States Agency for International Development (USAID) as part of Feed the Future, the U.S. Government’s global hunger and food security initiative, under the Buena Milpa project, as well as the support of the CGIAR Research Program on Maize.
