Posts Tagged ‘Intergovernmental Panel on Climate Change (IPCC)’

Multi-disciplinary approaches to crop improvement for faster climate change adaptation

This article by Sakshi Saini was originally published on the CCAFS website

A high throughput crop phenotyping platform, the ‘Leasyscan’ located at ICRISAT’s HQ Patancheru, India. Photo: A. Whitbread (ICRISAT)
A high throughput crop phenotyping platform, the ‘Leasyscan’ located at ICRISAT’s HQ Patancheru, India. Photo: A. Whitbread (ICRISAT)

Ever-increasing emissions of greenhouse gases (GHG) is a global concern due to the association of high atmospheric GHG concentrations with global warming and climate change. A large and growing body of evidence predicts that this would further have a multifaceted impact on the human population, especially the poor and vulnerable groups, further exacerbating their vulnerabilities.

But what about crops? Plants use carbon dioxide (CO2)—one of the most abundant GHGs, for photosynthesis. So shouldn’t an increase in atmospheric carbon dioxide aid crops to flourish? A counter-argument to this would be that at the same time there would be changes in other factors such as a change in precipitation rate, frequency and intensity of rains, among others, which might negatively impact crop production. So, how exactly would climatic variations impact the yield and productivity of crops? These are some of the questions that have been a global concern. Many studies have researched this, employing varied approaches such as systems biology, physiology and crop modelling. However, unprecedented changes in climatic conditions still pose uncertainties on the impacts on crops.

Recent research by an interdisciplinary team of scientists from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), the CGIAR Research Program on Climate Chanage, Agriculture and Food Security (CCAFS)-Africa and CCAFS-Asia aspires to answer some of these questions. As part of this research, they have compiled recent progress made in the physiological and molecular attributes in plants, with special emphasis on legumes under elevated CO2 conditions in a climate change scenario. The study proposes a strategic research framework for crop improvement that integrates genomics, systems biology, physiology and crop modelling approaches to cope with the changing climate. Some of the prime results of the study are as follows:

1. Major physiological and biochemical alterations in legumes triggered by elevated CO2

A range of physiological and biochemical alterations take place in plants exposed to elevated CO2. In the case of legumes, elevated atmospheric COconcentrations also affect the nutritional quality and nodulation, causes changes in rhizosphere and Biological Nitrogen Fixation (BNF), among others. Studies have shown that elevated CO2 would stimulate plant growth under nitrogen-sufficient conditions, but under nitrogen-limited conditions, it may have the detrimental effect of reducing plant growth by altering its primary metabolism. The anatomical differences between C3 and C4 plants (plants with C3 and C4 photosynthetic pathways) and their different ways of sequestering carbon (removing carbon dioxide from the atmosphere), have been an area of interest for climate scientists. Elevated COcombined with limited nitrogen may also promote biological ageing (senescence) rates as observed in flag leaves of rice and wheat. Studies also show that a higher level of carbon dioxide increases senescence rate in legumes.

2. Impact of elevated carbon-dioxide interaction with other abiotic stresses

As mentioned earlier, CO2 is not the only factor that is impacting plant growth, it is dependent on other environmental factors such as water deficit stress and temperature, among others. Thus, these factors also need to be considered in combination with the atmospheric concentration. Studies have reported that elevated CO2 induced a decrease (of 10%) in evaporation rates in both C3 and C4 plants. This caused an increase in canopy temperature (0.7 °C) coupled with a 19% yield increase in C3 crops. There is evidence that an increase in CO2 has also phased down the effect of oxidative stress. Though, there is limited literature available about the impact of elevated carbon dioxide keeping into consideration the drought and heat responses of various crops.

3. Elevated carbon dioxide and its interaction with biotic stress-altered pathogen aggravation and virulence

The changing climate has affected pest-crop dynamics with more frequent outbreaks and changed the geographical distribution of pests, posing an economic threat to crops. Sometimes, other abiotic stresses like drought could increase fungal virulence as reported in drought-tolerant peanut and Aspergillus interaction. However, a combined interaction is not always additive as both unique and common responses have been observed. Increased COcauses greater photosynthate availability, but reduced foliage quality along with an increased concentration of plant defensive compounds after a pest infestation. This, in turn, affects insect feeding and increases disease incidence and predator parasitism interactions.

4. Molecular interventions for crop improvement under elevated carbon-dioxide

While elevated CO2 may cause greater photosynthate availability, the interaction of elevated CO2 with mentioned biotic and abiotic stresses calls for the development of climate change ready crop varieties. Thus, genomics assisted breeding along with other modern approaches can be very powerful tools to develop superior varieties, to de-risk the existing food system. This transformative approach towards the production of plants and crops would be instrumental in sustainably ensuring food security.

An integrated research framework for the future

The discussion and evidence presented illustrate that the effect of elevated CO2 under a changing climate scenario is multifaceted and aggravated by the overlapping interaction of stressors. The notion that CO2 has beneficial effects in terms of increased productivity is now being questioned since the photosynthetic fertilization effect is short term and often not time-tested for major crop species. The IPCC 2018 special report highlights several policy-level approaches that are aimed at limiting greenhouse gas emission. The scientific community needs to be prepared with suitable research outcomes to cope with the effects of elevated atmospheric CO2 levels. In this regard, an integrated framework combining different biological disciplines has been proposed by the team (Fig. 1).

Figure 1: A representation of a multifaceted strategy that could be employed to harness cutting edge technologies and greater precision to cope with elevated CO2, and generally with a changing climate.
Figure 1: A representation of a multifaceted strategy that could be employed to harness cutting edge technologies and greater precision to cope with elevated CO2, and generally with a changing climate.

While significant advances have been made in crop genomics, systems biology and genomics-assisted breeding, the success of trait dissection and trait deployment is very much dependent on the quality and precision of phenotyping. Recent advances in plant phenotyping using high throughput phenotyping tools have revolutionized the uptake of phenotype and allelic information in a more precise and robust way and complemented high throughput genomic resources

In the opinion of the authors of the publication, an integrated research framework that includes genomics/ systems biology and phenomics together with crop modelling would result in faster data-driven advances for understanding the optimal GxExM (genotype x environment x management) scenarios for current and projected climates. Interdisciplinary approaches as has been done through the Climate-Smart Village approach, are key to graduating from a descriptive level to an improved quantitative and process-level understanding of sustainable crop productivity.

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Warmer night temperatures reduce wheat yields in Mexico, scientists say

International gathering highlights cutting edge efforts to improve yields, nutrition, and climate change resilience of a globally vital staple food 

by Julie Mollins

A view from the Norman E. Borlaug Experiment Station, Ciudad Obregón, Sonora, Mexico. Photo: M. Ellis/CIMMYT.

As many regions worldwide baked under some of the most persistent heatwaves on record, scientists at a major conference in Canada shared data on the impact of spiraling temperatures on wheat.

In the Sonora desert in northwestern Mexico, nighttime temperatures varied 4.4 degrees Celsius between 1981 and 2018, research from the International Maize and Wheat Improvement Center (CIMMYT) shows. Across the world in Siberia, nighttime temperatures rose 2 degrees Celsius between 1988 and 2015, according to Vladimir Shamanin, a professor at Russia’s Omsk State Agrarian University who conducts research with the Kazakhstan-Siberia Network on Spring Wheat Improvement.

“Although field trials across some of the hottest wheat growing environments worldwide have demonstrated that yield losses are in general associated with an increase in average temperatures, minimum temperatures at night – not maximum daytime temperatures –are actually determining the yield loss,” said Gemma Molero, the wheat physiologist at CIMMYT who conducted the research in Sonora, in collaboration with colleague Ivan Ortiz-Monasterio.

“Of the water taken up by the roots, 95% is lost from leaves via transpiration and from this, an average of 12% of the water is lost during the night. One focus of genetic improvement for yield and water-use efficiency for the plant should be to identify traits for adaptation to higher night temperatures,” Molero said, adding that nocturnal transpiration may lead to reductions of up to 50% of available soil moisture in some regions.

Climate challenge

Saskatchewan farmer Brian Rugg in his wheat fields. Photo: Marcia MacNeil/CIMMYT

The Intergovernmental Panel on Climate Change (IPCC) reported in October that temperatures may become an average of 1.5 degrees Celsius warmer in the next 11 years. A new IPCC analysis on climate change and land use due for release this week, urges a shift toward reducing meat in diets to help reduce agriculture-related emissions from livestock. Diets could be built around coarse grains, pulses, nuts and seeds instead.

Scientists attending the International Wheat Congress in Saskatoon, the city at the heart of Canada’s western wheat growing province of Saskatchewan, agreed that a major challenge is to develop more nutritious wheat varieties that can produce bigger yields in hotter temperatures.

As a staple crop, wheat provides 20% of all human calories consumed worldwide. It is the main source of protein for 2.5 billion people in the Global South. Crop system modeler Senthold Asseng, a professor at the University of Florida and a member of the International Wheat Yield Partnership, was involved in an extensive study  in China, India, France, Russia and the United States, which demonstrated that for each degree Celsius in temperature increase, yields decline by 6%, putting food security at risk.

Wheat yields in South Asia could be cut in half due to chronically high temperatures, Molero said. Research conducted by the University of New South Wales, published in Environmental Research Letters also demonstrates that changes in climate accounted for 20 to 49% of yield fluctuations in various crops, including spring wheat. Hot and cold temperature extremes, drought and heavy precipitation accounted for 18 to 4% of the variations.

CIMMYT wheat physiologist Gemma Molero shares her findings with IWC attendees. Photo: Marcia MacNeil/CIMMYT

At CIMMYT, wheat breeders advocate a comprehensive approach that combines conventional, physiological and molecular breeding techniques, as well as good crop management practices that can ameliorate heat shocks. New breeding technologies are making use of wheat landraces and wild grass relatives to add stress adaptive traits into modern wheat – innovative approaches that have led to new heat tolerant varieties being grown by farmers in warmer regions of Pakistan, for example.

Collaborative effort

Matthew Reynolds, a distinguished scientist at CIMMYT, is joint founder of the Heat and Drought Wheat Improvement Consortium (HeDWIC), a coalition of hundreds of scientists and stakeholders from over 30 countries.

“HeDWIC is a pre-breeding program that aims to deliver genetically diverse advanced lines through use of shared germplasm and other technologies,” Reynolds said in Saskatoon. “It’s a knowledge-sharing and training mechanism, and a platform to deliver proofs of concept related to new technologies for adapting wheat to a range of heat and drought stress profiles.”

Aims include reaching agreement across borders and institutions on the most promising research areas to achieve climate resilience, arranging trait research into a rational framework, facilitating translational research and developing a bioinformatics cyber-infrastructure, he said, adding that attracting multi-year funding for international collaborations remains a challenge.

Nitrogen traits

Another area of climate research at CIMMYT involves the development of an affordable alternative to the use of nitrogen fertilizers to reduce planet-warming greenhouse gas emissions. In certain plants, a trait known as biological nitrification inhibition (BNI) allows them to suppress the loss of nitrogen from the soil, improving the efficiency of nitrogen uptake and use by themselves and other plants.

Victor Kommerell, program manager for the CGIAR Research Program on Wheat and Tim Searchinger, senior fellow at the World Resources Institute, answer media questions. Photo: Marcia MacNeil/CIMMYT

Scientists with the BNI research consortium, which includes Japan’s International Research Center for Agricultural Sciences (JIRCAS), propose transferring the BNI trait from those plants to critical food and feed crops, such as wheat, sorghum and Brachiaria range grasses.

“Every year, nearly a fifth of the world’s fertilizer is used to grow wheat, yet the crop only uses about 30% of the nitrogen applied, in terms of biomass and harvested grains,” said Victor Kommerell, program manager for the multi-partner CGIAR Research Programs (CRP) on Wheat and Maize led by the International Maize and Wheat Improvement Center.

“BNI has the potential to turn wheat into a highly nitrogen-efficient crop: farmers could save money on fertilizers, and nitrous oxide emissions from wheat farming could be reduced by 30%.”

Excluding changes in land use such as deforestation, annual greenhouse gas emissions from agriculture each year are equivalent to 11% of all emissions from human activities. About 70% of nitrogen applied to crops in fertilizers is either washed away or becomes nitrous oxide, a greenhouse gas 300 times more potent than carbon dioxide, according to Guntur Subbarao, a principal scientist with JIRCAS.

Although ruminant livestock are responsible for generating roughly half of all agricultural production emissions, BNI offers potential for reducing overall emissions, said Tim Searchinger, senior fellow at the World Resources Institute and technical director of a new report titled “Creating a Sustainable Food Future: A Menu of Solutions to Feed Nearly 10 Billion People by 2050.”

To exploit this roots-based characteristic, breeders would have to breed this trait into plants, said Searchinger, who presented key findings of the report in Saskatoon, adding that governments and research agencies should increase research funding.

CGIAR Research Program on Wheat Director Hans Braun (Photo: Marcia MacNeil/CIMMYT)

Other climate change mitigation efforts must include revitalizing degraded soils, which affect about a quarter of the planet’s cropland, to help boost crop yields. Conservation agriculture techniques involve retaining crop residues on fields instead of burning and clearing. Direct seeding into soil-with-residue and agroforestry also can play a key role.