Quarterly Newsletter - Issue 7, March 2017

Reducing the threat of Sunn Pest

A groundbreaking study is the first to identify a major locus for resistance to Sunn Pests at the vegetative stage of crop growth. This could provide a critical building block in the development of resistant wheat varieties, and a practical and cost-effective strategy to strengthen food security in Eastern Europe and West and Central Asia.

Sunn pest is one of the most destructive insect pests of bread and durum wheat in Eastern Europe and West and Central Asia. Infestation of wheat fields causes stunting, floret abortion, and the shriveling of kernels. Yield losses of up to 50-90 percent are common. The insect also injects a proteolytic enzyme during feeding, which breaks down gluten and compromises the quality of baking flour.

Management strategies exist, but these usually involve chemical forms of control – which are costly, unsustainable, and over time result in growing resistance to insecticides. Integrated pest management strategies - comprising biological control, cultural practices, and host plant resistance – are more cost-effective and sustainable.

Although genetic variation for resistance to Sunn pest has been identified in wheat, no information yet exists on the chromosome location of genetic factors that underlie this resistance at vegetative stage to Sunn pest feeding. Without this information, the task of breeding Sunn pest-resistant wheat varieties becomes that much harder. 

Identifying the major locus of resistance

Scientists from the New South Wales Department of Primary Industries (Australia) and ICARDA addressed this knowledge gap. The team used phenotypic data of Sunn pest screening carried out at ICARDA’s station in Terbol, Lebanon, and genotyping data with single nucleotide polymorphisms (SNPs) –genetic variations at a single position in the DNA sequence of different lines. When associated with a trait, scientists may use the information to identify the gene or genes responsible for the trait variations.

The study identified a single genetic locus on the short arm of chromosome 4B with a significant impact on resistance to Sunn pest feeding at the vegetative stage, which demonstrated impressive stability in different genetic backgrounds. SNP markers closest to the locations of peak Sunn pest resistance were then converted into breeder-friendly formats, and this utility for selecting resistance was validated in a large population of wheat cultivars, landraces, and synthetic lines.

A novel breakthrough

This is the first report of a major locus being associated with Sunn pest resistance at the vegetative stage, which could prove to be a major breakthrough in efforts to breed resistant wheat varieties that are able to withstand the destructive impacts of Sunn pest. Communities and farmers who regularly struggle to contain this threat could now have a useful resource to fight back.    

This research was supported by the Grains Research and Development Corporation and the New South Wales Department of Primary Industries.

This article is based on a scientific paper – ‘QTL mapping identifies a major locus for resistance in wheat to Sunn pest feeding at the vegetative growth stage’ - recently published in Theoretical and Applied Genetics. 

Author: Mustapha El-Bouhssini, Entomologist (ICARDA).

Measuring rangeland degradation for greater resilience

Can new image analysis software inform the development of responsive support systems, strengthening the resilience of rangeland communities on the frontline of climate change?

Rangelands suffer from low productivity and increasing rates of degradation and desertification – challenges that are exacerbated by the impacts of climate change. Protecting pastoral communities is dependent on accurate assessments of grazable biomass. Without this information, governments are unable to decide on the amount of feed needed to maintain livestock production, for instance, or the measures required to support poor farmers during periods of prolonged drought.    

Measuring canopy cover and biomass

It is widely assumed that plant biomass is positively correlated with canopy cover, but conventional techniques to measure canopy cover, often involving quadrat sampling in the field, can be time consuming, expensive, and generate detailed records in only a few locations worldwide – ill-suited to the development of robust and responsive support systems.

Non-destructive, accurate, and more rapid alternatives are urgently needed. One potential alternative, developed by scientists at ICARDA and Oregon State University, uses image processing software to determine rangeland ground cover from color digital images.

Vegmeasure quantifies areas of defined classes such as bare ground and vegetation using built-in algorithms. Its effectiveness was tested by a team of scientists from ICARDA and Tunisia’s Institut des Régions Arides, who measured the biomass and canopy cover of three plants across a 20 hectare (ha) research site in southern Tunisia: Artemisia herba-alba Asso. Rhanterium suaveolens Desf., and Stipa tenacissima L.

Can new image analysis software deliver?

Twenty tufts of each species were selected for measurement. Canopy cover was estimated using images taken by cameras pointed vertically downwards at a height of 1.25 meters. Clippings were then taken from half of the selected plants, which were dried at 105֯ C for 24 hours, and reweighed to obtain the dry biomass.

Results demonstrated a significant correlation between biomass and canopy cover for all three plant species: linear regression relationships were 0.46, 0.90, and 0.69 for A. herba-alba, R. suaveolens and S.  tenacissima, respectively. The correlation is an encouraging development for more accurate and less destructive biomass measurements.

This research was supported by the CGIAR Research Program on Dryland Systems.

The article is based on an article recently published in Botany Letters: ‘Measurement of the aboveground biomass of some rangeland species using a digital non-destructive technique.’

Author: Mounir Louhaichi, Range Ecology and Management Research Scientist (ICARDA).

Energy efficiency: a critical driver of sustainability?

A recent ICARDA study into the energy efficiency of Morocco’s commercial vegetable sector offers important insights to enhance the country’s investment in sustainable agricultural production.

Although agricultural innovation has undoubtedly strengthened global food security, there has also been an environmental cost: agriculture has become increasingly energy-dependent and is now a major emitter of greenhouse gases. Improving the sector’s energy efficiency – the ability to produce the same level of output with minimal resources - is therefore a critical issue.

ICARDA and its partners measured energy efficiency in the commercialized vegetable sector of Morocco’s El Hajeb region, specifically the production of onions and potatoes. In order to investigate current energy consumption trends and identify unsustainable practices, researchers surveyed 60 randomly-chosen farmers and estimated greenhouse gas emissions using PLANETE – a tool designed to measure fossil energy consumed directly or indirectly through inputs into an agricultural system.

Energy consumption was generally inefficient. Onion production consumed 107483 MJ ha-1, with butane as the main source of direct energy (79.5 %), and chemical fertilizers (61.53%) and water for irrigation (30%) as the main sources of indirect energy. The figure for potato production was 74270 MJ ha-1, with butane (70%) and diesel (19.14%) as primary sources of direct energy, and chemical fertilizers (60 %) as the main source of indirect energy.

Energy indices were also estimated: the energy efficiency index, the ratio of energy emitted to energy sequestered in production, was 0.78 for onions and 1.54 for potatoes; energy productivity, a measure of the amount of product obtained per unit of input energy, was 0.54 kg MJ-1 and 0.45 kg MJ-1; and energy profitability, calculated by dividing total produced energy by total consumed energy was estimated to be 0.22 and 0.54.

The results suggest the need for several policy changes: the over-reliance on butane demonstrates a need for subsidy reform and a shift towards cleaner sources of energy; inefficient irrigation systems require the improved speed, duration, and frequency of water application – such as that provided by drip irrigation; and more rational fertilizer application is also called for – given the significant amount of energy sequestered in its production. 

This research was supported by the CGIAR Research Program on Dryland Systems.

This article is based on a paper recently published in the Journal of Agricultural Science entitled: Energy Consumption in Onion and Potato Production within the Province of El Hajeb (Morocco): Towards Energy Use Efficiency in Commercialized Vegetable Production.

Author: Boubaker Dhehibi, Agricultural Research Economist (ICARDA)

Estimating water consumption rates more effectively

A new understanding of the relationship between evapotranspiration and available soil moisture is yielding critical information on water consumption and crop-water productivity. 

Almost 75 percent of global freshwater is used for agriculture annually, and most of this water returns to the atmosphere via evapotranspiration. Consequently, an accurate estimation of evapotranspiration over agricultural fields provides critical information about water consumption across various scales, and in turn, crop water productivity – the amount of grain produced per unit of water.

Given current water shortages, a better understanding of water consumption and productivity is critical for global food security. It helps identify when and where interventions are needed, and provides the information that decision makers require to implement more sustainable water policies.    

Estimating evapotranspiration more effectively    

It is generally assumed that evapotranspiration is mainly constrained by soil moisture: a typical way to characterize evapotranspiration is to therefore calculate potential evapotranspiration and then account for soil moisture constraints – an estimation known as the evaporative fraction.

ICARDA contributed to a study that calculated evaporative fraction from field observations in a dryland wheat field in Australia, obtaining information on water availability at the surface and various layers of the root zone. Available Water Fraction – the plant available water between field capacity and wilting point – was used as a proxy for soil moisture at different depths.

Scientists attempted to: examine seasonal and inter-annual variability of soil moisture stress, vegetation biomass, and net radiation in two cropping seasons; investigate how surface or root zone soil moisture content varied with net radiation, soil wetness, and season; and determine the meteorological and bio-physical factors controlling the relationship between evaporative function and root zone soil moisture.

Data collected included: turbulent fluxes; surface reflectance – to represent vegetation dynamics; soil moisture; soil and vegetation surface temperatures; air temperatures; relative humidity; and wind speed and direction. 

Understanding the relationship between evapotranspiration and soil moisture

The relationship between the evaporative fraction and the available water fraction in the root zone was non-linear in 2012 but linear in 2013, and this was mostly attributed to the marked difference in rainfall distribution and crop growth.

The different temporal rainfall patterns between these two years caused wheat’s different response to water stress. It was also found that evapotranspiration is not strongly related to soil moisture under energy-limited conditions. Under water-limited conditions, the variability in evapotranspiration is constrained by soil moisture and crop growth stage. 

Understanding this relationship between the Evaporative Fraction and Available Water Fraction is extremely useful, enabling us to more effectively estimate water consumption patterns, predict soil moisture stresses, and create more sustainable water consumption policies in response.       

This research was supported by the Australian Centre for International Agriculture Research (ACIAR).

The article is based on a Paper – Seasonal and inter-annual variability of soil moisture stress function in dryland wheat field, Australia – recently published in the Journal, Agricultural and Forest Meteorology.  

Author: Biju Alummoottil George, Irrigation and Water Management Specialist (ICARDA).

Reducing gender inequity in Sudan’s wheat-growing regions

A wheat initiative in Sudan is strengthening the decision-making power of rural women and raising their incomes - in one of the most gender inequitable countries in the world. Lessons learned here could benefit millions of women worldwide

Gender inequality is a recurring feature of many agricultural production systems across the dry areas of the developing world. Women farmers often lack access to credit, land, and other inputs. The result: the limited adoption of new innovations, low productivity and income gains, and a missed opportunity to enhance food security and prosperity at the household level.  

Challenging the obstacles that rural women face is one of the key priorities of a wheat initiative managed by ICARDA and supported by the African Development Bank and the CGIAR Research Program on Wheat. This initiative is exploring obstacles in the wheat-growing regions of Sudan and designing a strategy that seeks to enhance women’s access to key inputs and services at both the community and institutional level.      

Increasing incomes; reducing workloads

Results have been promising so far: participating women have seen an increase in their incomes; a reduction in workload – as a result of mechanization and improved access to key inputs such as pesticides; and stronger decision-making power through participation in trainings and field days, and enhanced access to microcredit - which has provided more sustained control over income-related activities.

Lessons learned: a gender strategy for the dry areas?

Research in four states (Gezira, River Nile and Northern) helped identify a number of steps that similar initiatives elsewhere can apply to enhance women’s integration. The project employed context-specific interventions related to grain growing, technology demonstration, value addition, and microcredit provision. Women’s involvement was often secured by gaining the trust and approval of male kin, a strategic approach which advocated for women’s involvement as something beneficial for the whole family.

Other key recommendations include: extending credit to women farmers – so they can purchase inputs, extend their farmlands, and move into commercial farming; providing access to markets so women can sell value-added products and become more entrepreneurial; and closely monitoring the progress of women farmers alongside their male counterparts.     

This research was supported by the African Development Bank and the CGIAR Research Program on Wheat as part of the project ‘Support to Agricultural Research for Development of Strategic Crops in Africa (SARD-SC).

The article is based on an ICARDA Working Paper: ‘Gender Roles in the Wheat Production of Sudan: Strengthening the Participation of Women.’

Author: Dina Najjar, Associate Social and Gender Scientist (ICARDA).