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funder_partner: Bill & Melinda Gates Foundation

Tesfaye Shiferaw Sida

Tesfaye Shiferaw Sida is a multi-disciplinary researcher, educator and R&D practitioner emphasizing on production ecology and resource conservation. He currently holds a Scientist position at International Maize & Wheat Improvement Center (CIMMYT). He organizes and runs projects that facilitate the delivery of agronomy-at-scale solutions, create links among institutions in digital decision support systems, assist implementation of next generation agronomy at scale innovations and nurture internal efficiencies for demand-driven R&D in agronomy.

He is passionate for data-driven decisions, hence proficient in advanced data analytics and programing tools including Python, R, ArcGIS, and more. He is experienced with dynamic systems modeling tools such APSIM, FARMSIM, STELLA and SMILE. He aspires to link hands-on, on-farm and practical experiences to the emerging big data and digital capabilities to assist smallholder farmers benefit from the ‘digital revolution’.

Gustavo Teixeira

Gustavo Teixeira is an Automation and Mechanization Lead with CIMMYT’s Excellence in Breeding Platform.

As a Breeding Operations and Phenotyping module leader, he provides evaluation of breeding program operations according to continuous improvement and operational excellence methodologies and lead initiatives to improve CGIAR and National Agricultural Research Systems (NARS) breeding operations capacities.

Teixeira is an expert in agriculture engineering, processes, mechanization and automatization. He has over 15 years of experience in the private sector, including as Automation Manager for R&D in Latin America at Syngenta.

Chinmay Kumar Biswal

Chinmay Kumar Biswal is a Field Research Technician based in Odisha, India.

Multi-trait genomic-enabled prediction enhances accuracy in multi-year wheat breeding trials

A CIMMYT researcher and a field worker lay out wheat seed for planting at the center's headquarters in Texcoco, Mexico. In experimental trials, hundreds or thousands of wheat lines are planted for evaluation, each in small quantities, and so they are carefully laid out and sown by hand. (Photo: CIMMYT)
A CIMMYT researcher and a field worker lay out wheat seed for planting at the center’s headquarters in Texcoco, Mexico. In experimental trials, hundreds or thousands of wheat lines are planted for evaluation, each in small quantities, and so they are carefully laid out and sown by hand. (Photo: CIMMYT)

To help feed a growing world population, wheat scientists have turned to innovative technologies like genomic selection to hasten selection for positive traits — such as high grain yield performance and good grain quality — in varieties that are still undergoing testing. Instead of being shackled by the long duration of traditional breeding cycles, genomic selection allows scientists to make predictions regarding which traits will present when crossing two varieties; allowing breeders greater guidance and lessening potential time lost when crossing varieties that do not display potential for genetic gain. To reap the benefits of genomic selection, it is vital that the predictive models employed are as accurate as possible.

Currently, wheat breeders select characteristics like grain yield performance early in the breeding process, while selecting traits like good grain quality at a later stage in the breeding process.

In an article in the journal G3 Genes, researchers from the International Maize and Wheat Improvement Center (CIMMYT), and partners, led by CIMMYT scientist José Crossa along with Leonardo A. Crespo, Maria Itria Ibba and Alison R. Bentley, endeavored to determine if genomic prediction models could select for both characteristics simultaneously in the breeding process. This would improve selection accuracy in both early and later breeding stages, resulting a reduction in time and expense in delivering improved wheat varieties. They also tested the accuracy of a set of specific mathematical corrections applied to genomic predictions. These correction models identify correlations between genomic predictions and observed breeding values, such as increased yield or grain quality.

Considering two or more traits, like grain yield and good grain quality, is an example of a multi-trait model. The team examined this multi-trait model against a single trait model that improves one specific trait. Overall, the researchers found that prediction performance was highest using the multi-trait model.

However, the team also demonstrated that when breeding programs arrive at their genetic predictions, applying a specific correction method will account for differences between the predicted breeding value and the actual observed breeding value. Current correction models tend to underestimate that difference, which results in breeding programs not running as efficiently as possible.

By partnering selections from different stages in the breeding process and examining the resulting genetic predictions through a more appropriate correction model, the team has shown that breeding programs can use this to their benefit in developing and ultimately releasing improved wheat varieties that meet growing yield needs worldwide and respond to abiotic and biotic stressors.

CIMMYT scientists join 60th All India Wheat and Barley Research Workers’ Meet

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)
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)
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.

Understanding decision support

Given the very heterogeneous conditions in smallholder agriculture in sub-Saharan Africa, there is a growing policy interest in site-specific extension advice and the use of related digital tools. However, empirical ex ante studies on the design of this type of tools are scant and little is known about their impact on site-specific extension advice.

In partnership with Oyakhilomen Oyinbo and colleagues at KU Leuven, scientists at the International Maize and Wheat Improvement Center (CIMMYT) have carried out research to clarify user preferences for tailored nutrient management advice and decision-support tools. The studies also evaluated the impact of targeted fertilizer recommendations enabled by such tools.

Understanding farmers’ adoption

A better understanding of farmers’ and extension agents’ preferences may help to optimize the design of digital decision-support tools.

Oyinbo and co-authors conducted a study among 792 farming households in northern Nigeria, to examine farmers’ preferences for maize intensification in the context of site-specific extension advice using digital tools.

Overall, farmers were favorably disposed to switch from general fertilizer use recommendations to targeted nutrient management recommendations for maize intensification enabled by decision-support tools. This lends credence to the inclusion of digital tools in agricultural extension. The study also showed that farmers have heterogeneous preferences for targeted fertilizer recommendations, depending on their resources, sensitivity to risk and access to services.

The authors identified two groups of farmers with different preference patterns: a first group described as “strong potential adopters of site-specific extension recommendations for more intensified maize production” and a second group as “weak potential adopters.” While the two groups of farmers are willing to accept some yield variability for a higher average yield, the trade-off is on average larger for the first group, who have more resources and are less sensitive to risk.

The author recommended that decision-support tools include information on the riskiness of expected investment returns and flexibility in switching between low- and high-risk recommendations. This design improvement will help farmers to make better informed decisions.

Community leaders talk to researchers in one of the villages in norther Nigeria which took part in the study. (Photo: Oyakhilomen Oyinbo)
Community leaders talk to researchers in one of the villages in norther Nigeria which took part in the study. (Photo: Oyakhilomen Oyinbo)
Members of the survey team participate in a training session at Bayero University Kano, Nigeria. (Photo: Oyakhilomen Oyinbo)
Members of the survey team participate in a training session at Bayero University Kano, Nigeria. (Photo: Oyakhilomen Oyinbo)
One of the sites of nutrient omission trials, used during the development phase of the Nutrient Expert tool in Nigeria. (Photo: Oyakhilomen Oyinbo)
One of the sites of nutrient omission trials, used during the development phase of the Nutrient Expert tool in Nigeria. (Photo: Oyakhilomen Oyinbo)

Extension agents go digital

While farmers are the ultimate recipients of extension advice, extension agents are most often the actual users of decision-support tools. In another study, the authors provided ex ante insights on the potential uptake of nutrient management decision-support tools and the specific design features that are more (or less) appealing to extension agents in the maize belt of northern Nigeria.

Using data from a discrete choice experiment, the study showed that extension agents were generally willing to accept the use of digital decision-support tools for site‐specific fertilizer recommendations. While extension agents in the sample preferred tools with a more user‐friendly interface that required less time to generate an output, the authors also found substantial preference heterogeneity for other design features. Some extension agents cared more about the outputs, such as information accuracy and level of detail, while others prioritized practical features such as the tool’s platform, language or interface.

According to the authors, accounting for such variety of preferences into the design of decision-support tools may facilitate their adoption by extension agents and, in turn, enhance their impact in farmars’ agricultural production decisions.

Interface of the Nutrient Expert mobile app, locally calibrated for maize farmers in Nigeria.
Interface of the Nutrient Expert mobile app, locally calibrated for maize farmers in Nigeria.

Impact of digital tools

Traditional extension systems in sub-Saharan African countries, including Nigeria, often provide general fertilizer use recommendations which do not account for the substantial variation in production conditions. Such blanket recommendations are typically accompanied by point estimates of expected agronomic responses and associated economic returns, but they do not provide any information on the variability of the expected returns associated with output price risk.

Policymakers need a better understanding of how new digital agronomy tools for tailored recommendations affect the performance of smallholder farms in developing countries.

To contribute to the nascent empirical literature on this topic, Oyinbo and colleagues evaluated the impact of a nutrient management decision-support tool for maize – Nutrient Expert — on fertilizer use, management practices, yields and net revenues. The authors also evaluated the impacts of providing information about variability in expected investment returns.

To provide rigorous evidence, the authors conducted a three-year randomized controlled trial among 792 maize-producing households in northern Nigeria. The trial included two treatment groups who are exposed to site-specific fertilizer recommendations through decision-support tools — one with and another one without additional information on variability in expected returns — and a control group who received general fertilizer use recommendations.

Overall, the use of nutrient management decision-support tools resulted in greater fertilizer investments and better grain yields compared with controls. Maize grain yield increased by 19% and net revenue increased by 14% after two years of the interventions. Fertilizer investments only increased significantly among the farmers who received additional information on the variability in expected investment returns.

The findings suggest including site-specific decision support tools into extension programming and related policy interventions has potential benefits on maize yields and food security, particularly when such tools also supply information on the distribution of expected returns to given investment recommendations.

The research-for-development community has tried different approaches to optimize fertilizer recommendations. In Nigeria, there are several tools available to generate location-specific fertilizer recommendations, including Nutrient Expert. As part of the Taking Maize Agronomy to Scale in Africa (TAMASA) project, CIMMYT has been working on locally calibrated versions of this tool for maize farmers in Ethiopia, Nigeria and Tanzania. The development was led by a project team incorporating scientists from the African Plant Nutrition Institute (APNI), CIMMYT and local development partners in each country.

Next steps

Some studies have shown that dis-adoption of seemingly profitable technologies — such as fertilizer in sub-Saharan Africa — is quite common, especially when initial returns fall short of expectations or net utility is negative, producing a disappointment effect.

In the context of emerging digital decision-support tools for well-targeted fertilizer use recommendations, it remains unclear whether farmers’ initial input use responses and the associated economic returns affect their subsequent responses — and whether the disappointment effect can be attenuated through provision of information about uncertainty in expected returns.

Using our three-year randomized controlled trial and the associated panel dataset, researchers are now working on documenting the third-year responses of farmers to site-specific agronomic advice conditional on the second-year responses. Specifically, they seek to better document whether providing farmers with information about seasonal variability in expected investment returns can reduce possible disappointment effects associated with their initial uptake of site-specific agronomic advice and, in a way, limit dis-adoption of fertilizer.

Cover photo: A farmer shows maize growing in his field, in one of the communities in northern Nigeria where research took place. (Photo: Oyakhilomen Oyinbo)

When it comes to maize variety choices, can farmers have it all?

Florence Ochieng harvests green maize on her 105-acre family farm near Kitale, Kenya. (Photo: P. Lowe/CIMMYT)
Farmer Florence Ochieng harvests green maize on her 105-acre family farm near Kitale, Kenya. (Photo: P. Lowe/CIMMYT)

Smallholder farmers are often torn between maize seed varieties that have multiple desirable traits. Since they cannot always have it all — there are limits on what traits breeders can integrate in any given variety — they face the dilemma of which seed to pick at the expense of an equally desirable option.

Trait preference trade-offs among maize farmers in western Kenya, published in March 2021, provides evidence of this prioritization and seeks to help breeders, seed companies and other stakeholders set priorities that account for farmers’ needs and their willingness to make preference trade-offs. The researchers evaluated responses from 1,288 male and female farmers in the mid-altitude maize growing areas of western Kenya.

The study argues that farmer-centered seed systems (including seed companies) should be guided by farmers’ priorities and reflect a greater understanding of the tradeoffs these farmers make between traits and varieties. They have two key options, according to Paswel Marenya, the study’s lead researcher and adoption and impact assessment economist at the International Maize and Wheat Improvement Center (CIMMYT). The first involves prioritizing the critical must-have traits in any one variety. The second option entails having multiple varieties that meet diverse farmers’ needs and then segmenting the seed markets.

While Marenya argues that prioritization is important for balancing commercial realities and farmers’ diverse interests, he is quick to add that “market segmentation has limits imposed by the commercial viability of each segment.”

“At every turn, from breeding to farmer varietal preferences to seed company considerations, there have to be trade-offs, as one cannot keep segmenting the market forever,” Marenya said. “At some point, you must stop and choose what traits to prioritize in your breeding or commercially viable market segments, based on the most pressing challenges already identified.”

CIMMYT researchers conduct interviews in Kenya to determine farmer preferences for maize traits. (Photo: CIMMYT)

Differences in tradeoffs among men and women

From a gender lens, the paper reveals an obvious difference in tradeoffs made by men and women. Whereas the two groups desire some similar traits in their varieties of choice, women seem to be willing to make slightly larger yield sacrifices in favor of tolerance to drought and Striga and good storability. Women also valued good storability over 90-day maturity, while men appeared to place a higher value on the closed tip, a sign of resistance to moisture infiltration which causes grain rotting.

“These results imply that unless the risks of storage or pre-harvest losses are reduced or eliminated, the value of high yielding varieties can be diminished if they are susceptible to production stresses or the grain characteristics make them susceptible to storage pests,” the study states.

The study indicates that farmers may adopt stress tolerant and high yielding varieties with somewhat low storability only if advanced grain storage technologies are available.

Until then, the suggestion to policy makers responsible for maize breeding is to use “multi-criteria evaluations” of new varieties to ensure that traits for stress tolerance and storability are given optimal weighting in variety release decisions.

Additionally, information about farmer preferences should be fed back to breeding programs in national and international institutes responsible for maize genetic improvement.

Waging war against the fall armyworm

The fall armyworm is an invasive pest that eats more than 80 different crops, but has a particular preference for maize.

It is native to the Americas. It was first reported in Africa in 2016, and quickly spread throughout the continent. It reached India in 2018. It has since been reported in many other countries across Asia and the Pacific, and it reached Australia in 2020.

Millions of families in these regions are highly dependent on maize for their income and their livelihoods. If the fall armyworm keeps spreading, it will have disastrous consequences for them.

Scientists at CIMMYT have been working hard to find solutions to help farmers fight fall armyworm. Researchers have developed manuals for farmers, with guidelines on how to manage this pest. They have also formed an international research consortium, where experts from diverse institutions are sharing knowledge and best practices. Consortium members share updates on progress in finding new ways to tackle this global challenge. Scientists are now working on developing new maize varieties that are resistant to fall armyworm.

The fall armyworm can’t be eradicated — it is here to stay. CIMMYT and its partners worldwide will continue to work on this complex challenge, so millions of smallholder farmers can protect their crops and feed their families.

For more information on the fall armyworm and CIMMYT’s work, please visit staging.cimmyt.org/fallarmyworm.

Bangladesh could largely reduce greenhouse gas emissions from agriculture while increasing efficiency in production

A graphic shows district-wide distribution of annual greenhouse gas mitigation potential through improved and more efficient fertilizer management in the crop sector of Bangladesh in 2030 and 2050. (Graphic: CIMMYT)

A number of readily-available farming methods could allow Bangladesh’s agriculture sector to decrease its greenhouse gas emissions while increasing productivity, according to a new study by the International Maize and Wheat Improvement Center (CIMMYT) and partners.

The study, published in Science of the Total Environment, measured the country’s emissions due to agriculture, and identified and analyzed potential mitigation measures in crop and livestock farming. Pursuing these tactics could be a win-win for farmers and the climate, and the country’s government should encourage their adoption, the research suggests.

“Estimating the greenhouse gas emissions associated with agricultural production processes — complemented with identifying cost-effective abatement measures, quantifying the mitigation scope of such measures, and developing relevant policy recommendations — helps prioritize mitigation work consistent with the country’s food production and mitigation goals,” said CIMMYT climate scientist Tek Sapkota, who led this work.

To determine Bangladesh’s agricultural greenhouse gas emissions, the researchers analyzed 16,413 and 12,548 datapoints from crops and livestock, respectively, together with associated soil and climatic information. The paper also breaks down the emissions data region by region within the country. This could help Bangladesh’s government prioritize mitigation efforts in the places where they will be the most cost-effective.

“I believe that the scientific information, messages and knowledge generated from this study will be helpful in formulating and implementing the National Adaptation Plan (NAP) process in Bangladesh, the National Action Plan for Reducing Short-Lived Climate Pollutants (SLCPs) and Nationally Determined Contributions (NDC),” said Nathu Ram Sarker, director general of the Bangladesh Livestock Research Institute.

Policy implications

Agriculture in Bangladesh is heavily intensified, as the country produces up to three rice crops in a single year. Bangladesh also has the seventh highest livestock density in the world. In all, the greenhouse gas output of agriculture in Bangladesh was 76.79 million metric tons of carbon dioxide equivalent (Mt CO2e) in 2014-15, according to the research. This emission is equivalent to the emission from fossil fuel burning by 28 million cars for a year.  At the going rate, total agricultural emission from Bangladesh are expected to reach 86.87 Mt CO2e by 2030, and 100.44 Mt CO2e by 2050.

By deploying targeted and often readily-available methods, Bangladesh could mitigate 9.51 Mt and 14.21 Mt CO2e from its agriculture sector by 2030 and 2050, respectively, according to the paper. Further, the country can reach three-fourths of these outcomes by using mitigation strategies that also cut costs, a boon for smaller agricultural operations.

Adopting these mitigation strategies can reduce the country’s carbon emissions while contributing to food security and climate resilience in the future. However, realizing the estimated potential emission reductions may require support from the country’s government.

“Although Bangladesh has a primary and justified priority on climate change adaptation, mitigation is also an important national priority. This work will help governmental policy makers to identify and implement effective responses for greenhouse gas mitigation from the agricultural sector, with appropriate extension programs to aid in facilitating adoption by crop and livestock farmers,” said Timothy Krupnik, CIMMYT country representative in Bangladesh and coauthor of the paper.

Mitigation strategies

The research focused on eight crops and four livestock species that make up the vast majority of agriculture in Bangladesh. The crops — potato, wheat, jute, maize, lentils and three different types of rice — collectively cover more than 90% of cultivated land in the nation. Between 64 and 84% of total fertilizer used in Bangladesh is used to cultivate these crops. The paper also focuses on the four major kinds of livestock species in the country: cattle, buffalo, sheep and goats.

For crops, examples of mitigation strategies include alternate wetting and drying in rice (intermittently irrigating and draining rice fields, rather than having them continuously flooded) and improved nutrient use efficiency, particularly for nitrogen. The research shows that better nitrogen management could contribute 60-65% of the total mitigation potential from Bangladesh’s agricultural sector. Other options include adopting strip-tillage and using short duration rice varieties.

For livestock, mitigation strategies include using green fodder supplements, increased concentrate feeding and improved forage/diet management for ruminants. Improved manure storage, separation and aeration is another potential tool to reduce greenhouse gas emissions. The mitigation options for livestock would make up 22 and 28% of the total potential emission reductions in the sector by 2030 and 2050, respectively.

RELATED RESEARCH PUBLICATIONS:

Quantifying opportunities for greenhouse gas emissions mitigation using big data from smallholder crop and livestock farmers across Bangladesh.

INTERVIEW OPPORTUNITIES:

Tek Sapkota, Agricultural Systems and Climate Change Scientist, CIMMYT

Tim Krupnik, Bangladesh Country Representative, CIMMYT

FOR MORE INFORMATION, OR TO ARRANGE INTERVIEWS, CONTACT THE MEDIA TEAM:

Marcia MacNeil, Interim Head of Communications, CIMMYT. m.macneil@cgiar.org

Rodrigo Ordóñez, Communications Manager, CIMMYT. r.ordonez@cgiar.org

ABOUT CIMMYT:

The International Maize and Wheat Improvement Center (CIMMYT) is the global leader in publicly-funded maize and wheat research and related farming systems. Headquartered near Mexico City, CIMMYT works with hundreds of partners throughout the developing world to sustainably increase the productivity of maize and wheat cropping systems, thus improving global food security and reducing poverty. CIMMYT is a member of the CGIAR System and leads the CGIAR Research Programs on Maize and Wheat and the Excellence in Breeding Platform. The Center receives support from national governments, foundations, development banks and other public and private agencies. For more information, visit staging.cimmyt.org.

Adult plant resistance (APR): the strategy to beat persistent pathogens

Scientists examine Ug99 stem rust symptoms on wheat. (Photo: Petr Kosina/CIMMYT)

The three rust diseases, yellow (stripe) rust, black (stem) rust, and brown (left) rust occur in most wheat production environments, causing substantial yield losses and under serious epidemics, can threaten the global wheat supply.

CIMMYT is one of the largest providers of elite germplasm to national partners in over 80 countries. CIMMYT nurseries, known for research in developing adaptive, high-yielding and high-quality germplasm, also carry resistance to several biotic and abiotic stresses, such as rust disease.

Through years of research and experience, CIMMYT has found that durable control of wheat rusts can be achieved by developing and deploying wheat varieties with complex adult-plant resistance (APR). A combination of both conventional and modern technologies in APR will enable breeders to address the problem of rusts and other diseases and continue progress in delivering higher genetic gains, a key goal of the Accelerating Genetic Gains in Maize and Wheat (AGG) project.

Learn more about CIMMYT’s APR strategy: CIMMYT Strategy for Adult Plant Resistance (APR)

For more information on CIMMYT’s APR strategy, contact CIMMYT’s Head of Wheat Rust Pathology and Molecular Genetics, Sridhar Bhavani.

A view from above

Scientists at the International Maize and Wheat Improvement Center (CIMMYT) have been harnessing the power of drones and other remote sensing tools to accelerate crop improvement, monitor harmful crop pests and diseases, and automate the detection of land boundaries for farmers.

A crucial step in crop improvement is phenotyping, which traditionally involves breeders walking through plots and visually assessing each plant for desired traits. However, ground-based measurements can be time-consuming and labor-intensive.

This is where remote sensing comes in. By analyzing imagery taken using tools like drones, scientists can quickly and accurately assess small crop plots from large trials, making crop improvement more scalable and cost-effective. These plant traits assessed at plot trials can also be scaled out to farmers’ fields using satellite imagery data and integrated into decision support systems for scientists, farmers and decision-makers.

Here are some of the latest developments from our team of remote sensing experts.

An aerial view of the Global Wheat Program experimental station in Ciudad ObregĂłn, Sonora, Mexico (Photo: Francisco Pinto/CIMMYT)

Measuring plant height with high-powered drones

A recent study, published in Frontiers in Plant Science validated the use of drones to estimate the plant height of wheat crops at different growth stages.

The research team, which included scientists from CIMMYT, the Federal University of Viçosa and KWS Momont Recherche, measured and compared wheat crops at four growth stages using ground-based measurements and drone-based estimates.

The team found that plant height estimates from drones were similar in accuracy to measurements made from the ground. They also found that by using drones with real-time kinematic (RTK) systems onboard, users could eliminate the need for ground control points, increasing the drones’ mapping capability.

Recent work on maize has shown that drone-based plant height assessment is also accurate enough to be used in maize improvement and results are expected to be published next year.

A map shows drone-based plant height estimates from a maize line trial in Muzarabani, Zimbabwe. (Graphic: CIMMYT)

Advancing assessment of pests and diseases

CIMMYT scientists and their research partners have advanced the assessment of Tar Spot Complex — a major maize disease found in Central and South America — and Maize Streak Virus (MSV) disease, found in sub-Saharan Africa, using drone-based imaging approach. By analyzing drone imagery, scientists can make more objective disease severity assessments and accelerate the development of improved, disease-resistant maize varieties. Digital imaging has also shown great potential for evaluating damage to maize cobs by fall armyworm.

Scientists have had similar success with other common foliar wheat diseases, Septoria and Spot Blotch with remote sensing experiments undertaken at experimental stations across Mexico. The results of these experiments will be published later this year. Meanwhile, in collaboration with the Federal University of Technology, based in Parana, Brazil, CIMMYT scientists have been testing deep learning algorithms — computer algorithms that adjust to, or “learn” from new data and perform better over time — to automate the assessment of leaf disease severity. While still in the experimental stages, the technology is showing promising results so far.

CIMMYT researcher Gerald Blasch and EIAR research partners Tamrat Negash, Girma Mamo and Tadesse Anberbir (right to left) conduct field work in Ethiopia. (Photo: Tadesse Anberbir)

Improving forecasts for crop disease early warning systems

CIMMYT scientists, in collaboration with Université catholique de Louvain (UCLouvain), Cambridge University and the Ethiopian Institute of Agricultural Research (EIAR), are currently exploring remote sensing solutions to improve forecast models used in early warning systems for wheat rusts. Wheat rusts are fungal diseases that can destroy healthy wheat plants in just a few weeks, causing devastating losses to farmers.

Early detection is crucial to combatting disease epidemics and CIMMYT researchers and partners have been working to develop a world-leading wheat rust forecasting service for a national early warning system in Ethiopia. The forecasting service predicts the potential occurrence of the airborne disease and the environmental suitability for the disease, however the susceptibility of the host plant to the disease is currently not provided.

CIMMYT remote sensing experts are now testing the use of drones and high-resolution satellite imagery to detect wheat rusts and monitor the progression of the disease in both controlled field trial experiments and in farmers’ fields. The researchers have collaborated with the expert remote sensing lab at UCLouvain, Belgium, to explore the capability of using European Space Agency satellite data for mapping crop type distributions in Ethiopia. The results will be also published later this year.

CIMMYT and EIAR scientists collect field data in Asella, Ethiopia, using an unmanned aerial vehicle (UAV) data acquisition. (Photo: Matt Heaton)

Delivering expert irrigation and sowing advice to farmers phones

Through an initiative funded by the UK Space Agency, CIMMYT scientists and partners have integrated crop models with satellite and in-situ field data to deliver valuable irrigation scheduling information and optimum sowing dates direct to farmers in northern Mexico through a smartphone app called COMPASS — already available to iOS and Android systems. The app also allows farmers to record their own crop management activities and check their fields with weekly NDVI images.

The project has now ended, with the team delivering a webinar to farmers last October to demonstrate the app and its features. Another webinar is planned for October 2021, aiming to engage wheat and maize farmers based in the Yaqui Valley in Mexico.

CIMMYT researcher Francelino Rodrigues collects field data in Malawi using a UAV. (Photo: Francelino Rodrigues/CIMMYT)

Detecting field boundaries using high-resolution satellite imagery

In Bangladesh, CIMMYT scientists have collaborated with the University of Buffalo, USA, to explore how high-resolution satellite imagery can be used to automatically create field boundaries.

Many low and middle-income countries around the world don’t have an official land administration or cadastre system. This makes it difficult for farmers to obtain affordable credit to buy farm supplies because they have no land titles to use as collateral. Another issue is that without knowing the exact size of their fields, farmers may not be applying to the right amount of fertilizer to their land.

Using state of the art machine learning algorithms, researchers from CIMMYT and the University of Buffalo were able to detect the boundaries of agricultural fields based on high-resolution satellite images. The study, published last year, was conducted in the delta region of Bangladesh where the average field size is only about 0.1 hectare.

A CIMMYT scientist conducts an aerial phenotyping exercise in the Global Wheat Program experimental station in Ciudad ObregĂłn, Sonora, Mexico. (Photo: Francisco Pinto/CIMMYT)

Developing climate-resilient wheat

CIMMYT’s wheat physiology team has been evaluating, validating and implementing remote sensing platforms for high-throughput phenotyping of physiological traits ranging from canopy temperature to chlorophyll content (a plant’s greenness) for over a decade. Put simply, high-throughput phenotyping involves phenotyping a large number of genotypes or plots quickly and accurately.

Recently, the team has engaged in the Heat and Drought Wheat Improvement Consortium (HeDWIC) to implement new high-throughput phenotyping approaches that can assist in the identification and evaluation of new adaptive traits in wheat for heat and drought.

The team has also been collaborating with the Accelerating Genetic Gains in Maize and Wheat (AGG) project, providing remote sensing data to improve genomic selection models.

Cover photo: An unmanned aerial vehicle (UAV drone) in flight over CIMMYT’s experimental research station in Ciudad Obregon, Mexico. (Photo: Alfredo Saenz/CIMMYT)

A challenge solved

Wheat stalks grow in a in India. (Photo: Saad Akhtar)
Wheat stalks grow in a field in India. (Photo: Saad Akhtar)

For scientists, determining how best to increase wheat yields to meet food demand is a persistent challenge, particularly as the trend toward sustainably intensifying production on agricultural lands grows.

The United Nations projects that the current global population of 7.6 billion will increase to more than 9.8 billion by 2050, making higher grain yield potential vital, particularly as climate instability increases due to global warming. International efforts are also focused on meeting the Zero Hunger target detailed in the UN Sustainable Development Goals before they expire in 2030.

Now, a new landmark research survey on the grain yield potential and climate-resilience of bread wheat (Triticum aestivum L.) has brought scientists a few strides closer to meeting their ambitions.

Grain yield has traditionally been an elusive trait in genomic wheat breeding because of its quantitative genetic control, which means that it is controlled by many genomic regions with small effects.

Challenges also include a lack of good understanding about the genetic basis of grain yield, inconsistent grain yield quantitative trait loci identified in different environments, low heritability of grain yield across environments and environment interactions of grain yield.

To dissect the genetic architecture of wheat grain yield for the purposes of the research, which appeared in Scientific Reports, researchers implemented a large-scale genome-wide association study based on 100 datasets and 105,000 grain yield observations from 55,568 wheat breeding lines developed by the International Maize and Wheat Improvement Center (CIMMYT).

They evaluated the lines between 2003 and 2019 in different sites, years, planting systems, irrigation systems and abiotic stresses at CIMMYT’s primary yield testing site, the Norman E. Borlaug Experimental Research Station, Ciudad Obregon, Mexico, and in an additional eight countries — including Afghanistan, India and Myanmar — through partnerships with national programs.

The researchers also generated the grain-yield associated marker profiles and analyzed the grain-yield favorable allele frequencies for a large panel of 73,142 wheat lines, resulting in 44.5 million data points. The marker profiles indicated that the CIMMYT global wheat germplasm is rich in grain yield favorable alleles and is a trove for breeders to choose parents and design strategic crosses based on complementary grain yield alleles at desired loci.

“By dissecting the genetic basis of the elusive grain-yield trait, the resources presented in our study provide great opportunities to accelerate genomic breeding for high-yielding and climate-resilient wheat varieties, which is a major objective of the Accelerating Genetic Gain in Maize and Wheat project,” said CIMMYT wheat breeder Philomin Juliana.

“This study is unique and the largest-of-its-kind focusing on elucidating the genetic architecture of wheat grain yield,” she explained, “a highly complex and economically important trait that will have great implications on future diagnostic marker development, gene discovery, marker-assisted selection and genomic-breeding in wheat.”

Currently, crop breeding methods and agronomic management put annual productivity increases at 1.2% a year, but to ensure food security for future generations, productivity should be at 2.4% a year.

So, the extensive datasets and results presented in this study are expected to provide a framework for breeders to design effective strategies for mitigating the effects of climate change, while ensuring food-sustainability and security.

Buying into new seed

Mary Nzau enters a mock agrodealer shop set up on a field on the outskirts of Tala town in Machakos County, Kenya. On display are nine 2kg bags of hybrid maize seed. She picks one. By the look of it, her mind is made up. After a quick scan of the shelf, she has in her hand the variety that she has been purchasing for years.

Regina Mbaika Mutua is less lucky. The variety she always buys is not on display in the mock shop. As part of the experiment, the research team has removed from the shelf the variety she indicated she usually buys. The team’s goal is to observe what factors influence her seed purchase decision in the absence of the variety she was expecting to purchase.

“Although I did not find the variety I was looking for, I picked an alternative as I have seen it perform well on a neighboring farm,” Mutua says, adding that she will plant it this season alongside recycled (farm-saved) seed on her one-acre farm.

Michael Mutua passes up the popular variety he has been planting for the previous two years. He picks one that has been advertised extensively on local radio. “I have heard about it severally on radio. I would like to experiment with this new seed and see how it performs on my farm. Should I like the results, I will give it a chance in ensuing seasons,” he says.

Pieter Rutsaert explains the study setup at a mock agrodealer shop. (Photo: Joshua Masinde/CIMMYT)
Pieter Rutsaert explains the study setup at a mock agrodealer shop. (Photo: Joshua Masinde/CIMMYT)

The big adoption conundrum

The goal of the out-of-stock study is to improve an understanding of how farmers make their maize seed choices, says Pieter Rutsaert, Markets and Value Chain Specialist at the International Maize and Wheat Improvement Center (CIMMYT).

“We do this by inviting farmers to a mock agrodealer store that we set up in their villages and give them a small budget to purchase a bag of seed. However, not all farmers walk into the same store: some will find their preferred variety, others won’t. Some will have access to additional trait information or see some varieties with price promotions while others don’t.”

Rutsaert acknowledges that breeding programs and their partner seed companies have done a great job at giving farmers access to maize hybrids with priority traits such as drought tolerance and high yield. CIMMYT then works closely with local seed companies to get varieties into the hands of farmers. “We want to extend that support by providing insights to companies and public breeding programs on how to get new varieties more quickly into the hands of farmers,” he says.

Pauline Muindi (left), gender research associate with CIMMYT, acts as a mock agrodealer clerk and attends a farmer. (Photo: CIMMYT)
Pauline Muindi (left), gender research associate with CIMMYT, acts as a mock agrodealer clerk and attends a farmer. (Photo: CIMMYT)

The hybrid maize seed sector in Kenya is highly competitive. Amid intensifying competition, new varieties face a daunting task breaking into the market, independent of their quality. While farmers now have more options to pick from, a major challenge has been how to get them to adopt new varieties.

“Moving farmers from something they know to something they don’t is not easy. They tend to stick with what they know and have been growing for years,” Rutsaert says.

Pauline Muindi, gender research associate with CIMMYT, acted as the stand-in clerk at the mock store. She noticed that farmers tend to spend very little time in the shop when their preferred variety is available. However, this all changes in the out-of-stock situation, pushing farmers to step out of their comfort zone and explore new options.

The first step to overcoming this challenge is to entice maize farmers to try a new seed variety, even just once, Rutsaert observes. If it is a good variety, farmers will see that and then the market will work in its favor: farmers will come back to that variety in subsequent years and tell others about it.

“The good news is that many of the varieties we are currently seeing on the market have performed well — that’s why they’re popular. But there are newer varieties that are even better, especially in terms of attributes like drought tolerance. We would like to understand how farmers can be convinced to try out these newer varieties. Is it about the need for more awareness on varietal traits? Can we use price promotions? Or are there other factors?” he says.

A researcher interviews Mary Nzau (right), a farmer from Tala town in Machakos County, after her mock purchase. (Photo: Joshua Masinde/CIMMYT)
A researcher interviews Mary Nzau (right), a farmer from Tala town in Machakos County, after her mock purchase. (Photo: Joshua Masinde/CIMMYT)

Does seed price matter?

“With today’s climate uncertainty, it is better to stick to a variety that is adapted to such climate rather than banking on a variety one is oblivious of. The risk is not worth it,” Nzau says. She adds that she would rather buy a higher-priced seed packet she knows and trusts than a lower-priced one that she has not used in the past. Radio promotions of new or other varieties have limited sway over her decision to make the switch.

Faith Voni, another farmer, agrees. “It is better to purchase a higher-priced variety whose quality I can vouch for than risk purchasing a lower-priced one that I know little about. I do not wish to take such a risk.” Voni says she would also be more inclined to experiment with another variety that she had seen perform well on a neighbor’s farm.

Michael Mutua holds a different view. “If there is an option of an equally good but new variety that is lower-priced than the variety I prefer, my wallet decides,” he says.

Vivian Hoffmann, an economist at the International Food Policy Research Institute (IFPRI) and collaborator on the study, says price can be key for convincing consumers to try a new product. “Our previous research on maize flour choice found that a provisional 10 percent discount boosted sales tremendously,” Hoffmann says. “Of course, that only gets your foot in the door; after that, a new variety will need to win farmers over based on its merits.”

Hoffmann is interested in the extent to which drawing farmers’ attention to key varietal attributes influences their seed choice. “This information is generally already available on seed packets, but we live in a world of information overload. Promoting certain attributes through in-store signage is an approach that is widely used to help consumers make more healthier food choices. Doing the same for new seed varieties makes a lot of sense.”

Michael Mutua (left) responds to preliminary questions from one of the research team members before proceeding to make his seed selection at the mock agrodealer shop. (Photo: Joshua Masinde/CIMMYT)
Michael Mutua (left) responds to preliminary questions from one of the research team members before proceeding to make his seed selection at the mock agrodealer shop. (Photo: Joshua Masinde/CIMMYT)

The value of drought tolerance

Situated on Kenya’s eastern region, Machakos is characterized by persistent water stress. Climate change induced erratic rainfall has pushed traits that can tolerate the unfavorable weather conditions in the favorite’s corner. While other traits such as high yield and disease resistance are equally important, the seed, when planted, must first withstand the effects of droughts or water stress in some seasons and germinate. This is the most crucial step in the long journey to either a decent, bare minimum or no yield. A lot of farmers still plant recycled seed alongside hybrid varieties. But these are no match to water stress conditions, which decimate fields planted with farmer-saved seed.

“If a variety is not climate resilient, I will likely not harvest anything at all,” says Nzau. She has planted a drought-tolerant variety for ten years now. Prior to that, she had planted about three other varieties as well as recycled seed. “The only advantage with recycled seed is that given the right amount of rainfall, they mature fast — typically within two months. This provides my family with an opportunity to eat boiled or roast maize,” she notes.

However, varieties need to do more than just survive harsh weather conditions. Breeders face a daunting task of incorporating as many traits as possible to cater to the overarching and the specific interests of multiple farmers. As Murenga Mwimali, a maize breeder at the Kenya Agricultural and Livestock Research Organization (KALRO) and collaborator in this research says, innovations in breeding technologies are making breeding more efficient.

“It is better to have a diversity of product profiles as different market niches are captured within a particular agroecological zones. This is such that farmers may not just benefit from the minimum traits like drought tolerance, but also more specific traits they are looking for,” Mwimali says.

Smallholder farmers continue to play a central role in the seed development process. Capturing what happens at the point of purchase, for instance, at the agrodealer, and understanding how they purchase seed offers valuable insights on the traits that are deemed essential in the breeding process. This work contributes to CIMMYT’s focus on fast-tracking varietal turnover by turning the levers towards a demand-driven seed system.

Cover photo: Pauline Muindi, gender research associate with CIMMYT, at the mock agrodealer shop where she acted as a clerk. (Photo: CIMMYT)

Digitization equipment set to accelerate Kenya’s breeding programs

Last month, the CGIAR Excellence in Breeding (EiB) platform handed over digitization equipment to the Kenya Agricultural and Livestock Research Organization (KALRO) as part of ongoing efforts to modernize the public agency’s crop breeding programs. The handover of the equipment, valued at roughly $85,000, took place at KALRO headquarters in Nairobi on March 8, 2021, with representatives from the International Maize and Wheat Improvement Center (CIMMYT), EiB and KALRO in attendance.

KALRO received 23 units of equipment including seed counters, label printers, handheld data collectors, tablets and package printers. These will help the organization speed up and enhance the accuracy of various breeding processes, including seed preparation, data collection and data analysis. They will also support inventory management within KALRO’s maize, wheat, rice, sorghum, bean, soybean and potato breeding programs at six of its research centers in Kenya.

(L-R) CIMMYT Regional Representative for Africa and Kenya Country Representatives Moses Siambi, CGIAR EiB NARS Coordinator Biswanath Das, KALRO Director General Eliud Kireger and KALRO Deputy Director General for Crops Felister Makini at the digitization equipment handover event in Nairobi, Kenya. (Photo: Joshua Masinde/CIMMYT)

Dispensing with laborious systems 

A lack of digitization equipment hampers the research efforts of many national agricultural research systems (NARS) across Africa. This adverse situation is compounded by unreliable institutional memory, which constrains NARS efforts to breed an assortment of crop varieties efficiently.

“Currently, KALRO uses very laborious systems including manual layouts and collection, followed by manual data entry into computers. This old age process is prone to data entry errors and delays in analysis, publication and reporting,” says KALRO Director General Eliud Kireger.

“With the equipment we are receiving, information and data can be recalled by a click of a button. The equipment will also significantly reduce research costs related to labor, thus freeing our scientists to focus on core research activities.”

The equipment will also support KALRO’s ongoing efforts to digitize its historical data, especially for the maize and wheat programs using the Breeding Management System (BMS). So far, 20 years of maize historical data has been uploaded onto the BMS platform for ease of access.

Prepped for emerging challenges  

The CGIAR EiB platform was established in 2017 to help modernize public breeding programs in the CGIAR and NARS to increase their rates of genetic gain. In recent years, there has been an upsurge in challenges including climate change, population growth, rapid urbanization, changing dietary inclinations, transboundary movement of pests and diseases. These have exerted an enormous strain on food production systems and elicited the urgency to prioritize the adoption of new plant breeding techniques and technologies to address current and emerging threats. This calls for a holistic approach to tackle the issues including better agronomy and policy, according to EiB NARS Coordinator Biswanath Das.

“Modernizing our plant breeding programs to develop new, climate smart, market driven varieties will be at the heart of the solution,” says Das. “We must ensure that public plant breeding programs are not left behind because for many crops in Africa, there is limited private sector interest. Public breeding programs must shoulder the responsibility for ensuring the development and adoption of the next generation of crop varieties.”

CGIAR EiB NARS Coordinator Biswanath Das shares remarks at the digitization handover event in Nairobi, Kenya. (Photo: Joshua Masinde/CIMMYT)

Already, KALRO breeding programs, in collaboration with international CGIAR centers, have played a leading role in supporting farmers in sub–Saharan Africa to address many emerging plant threats such as wheat rust (UG99), maize lethal necrosis (MLN) and fall armyworm.

As part of its commitment to supporting NARS partners, EiB provided over 10 million Kenyan shillings ($92,000) worth of material and in-kind support to various KALRO breeding operations in 2020. This included genotyping support for maize and wheat, support to adopt the BMS digital data management system, technical support and training of KALRO breeders.  Much of the digitization work is driven by EiB’s Operations and Phenoytyping module, led by Gustavo Teixeira. “We’ll continue to consider a whole range of devices and solutions,” says Teixeira. “It’s a part of our culture of continuous improvement, so breeding programs can focus on what really adds value to their clients.”

EiB will continue to support NARS across Africa and beyond to digitize their operations, and is working with partners to secure more equipment, training and resources. With this digitization project, EiB has targeted 24 breeding programs in 14 African countries. These include programs run by AfricaRice, CIMMYT, the International Institute of Tropical Agriculture (IITA) and the International Rice Research Institute (IRRI).

“We want to do more to support centers to improve their operations so they can achieve the most effective and cost efficient phenotypic processes — agronomic practices, seed processing and other areas,” explains Teixeira. “We aim to expand to more programs and partners.”

EiB and partners are supported by CGIAR Trust Fund Contributors and the Crops to End Hunger initiative, via the Bill and Melinda Gates Foundation, GIZ, BMZ, USAID, UK Aid, ACIAR and other partners. 

Revisiting the inverse size-productivity relationship

Field workers in Ethiopia weight the grain. (Photo: Hailemariam Ayalew/CIMMYT)
Field workers in Ethiopia weight the grain. (Photo: Hailemariam Ayalew/CIMMYT)

Quantifying agricultural productivity relies on measures of crop production and land area. Those measures need to be accurate, but it is often difficult to source reliable data. Inaccurate measurements affect our understanding of the relationship between agricultural productivity and land area.

Researchers examined the sensitivity of empirical assessments of this relationship to alternative measurement protocols. Scientists from the International Maize and Wheat Improvement Center (CIMMYT), Trinity College Dublin and the International Food Policy Research Institute (IFPRI) analyzed different methods of plot-level production and area measurement.

The study, to be published, is said to be the first to evaluate errors along the two dimensions —production and area — in all available measurement techniques.

Researchers found that errors from both production and area measurements explain the estimated inverse productivity-size relationship. When using a combination of the most accurate measures for yield and area — full plot harvest and total station — the inverse relationship vanishes. Consistent with previous studies, the study also shows that addressing one of the other sources of error — for example, either production or area estimates — does not eliminate the bias associated with measurement error.

For this study, the research team collected and used a unique dataset on maize production from Ethiopia, addressing measurement issues commonly found in other datasets that hinder accurate estimation of the size-productivity relationship. Specifically, the researchers considered six alternative land area measures: farmers’ self-reported estimates; estimates from low-cost old generation consumer-grade dedicated GPS receivers that have frequently been used in field data collection by research organizations over the past decade; estimates from single- and dual-frequency mobile phone GPS receivers; compass-and-rope estimates; and total station theodolite measurement.

An enumerator in Ethiopia measures grain moisture. (Photo: Hailemariam Ayalew/CIMMYT)
An enumerator in Ethiopia measures grain moisture. (Photo: Hailemariam Ayalew/CIMMYT)

Most cost-effective measurement methods

The study also provides a cost-effectiveness analysis of the different measurement methods. According to the researchers, the most expensive combination to use is full harvest yield with total station measurement. The cost is potentially prohibitively high for traditional surveys involving large samples.

It concludes that the optimal combination is crop-cut random quadrant measurements coupled with GPS measurement. This offers the best value for money of all the methods considered, since the results for the productivity-size regressions are like what is found when the gold-standard for yield and area measurement protocols are used.

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