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Monday, February 24, 2020

How can crops adapt to climate change and still feed the world? This institute has some answers

Understanding the impending change can help scientists, farmers, and policymakers today to take remedial steps to ensure food and nutrition security are not undermined.

Written by Rahul V Pisharody | Hyderabad | Updated: February 9, 2020 11:33:39 am
“Rice plants growing swiftly inside the open-top chamber, whil rice plants are growing slower in ambient conditions.” (Source: Rahul V Pisharody)

In the face of a warming planet and spiralling greenhouse gas emissions, how plants can cope and adapt to a changing climate and still feed the world’s growing population is a case study in itself. Through a series of experiments, this Hyderabad-based crop research institute is doing just that: offering a glimpse into a future world where climate has already changed.

Global mean annual temperatures are expected to increase by 1.5 degree Celcius by 2030-52 and by as much as 3 degree Celcius by 2100, with an increase in greenhouse gases, mainly carbon dioxide which is expected to rise from the current ambient level of 410 ppm to 700 ppm by the end of the century. In such scenarios, crops and their interaction with the environment are expected to change.

Understanding the impending change can help scientists, farmers, and policymakers today to take remedial steps to ensure food and nutrition security are not undermined. Scientists at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) are subjecting food crops to elevated temperature, and elevated carbon dioxide levels to understand changes to plant traits, pests and diseases, and their nutritional value.

The pest, pot borer Helicoverpa, at the climate change facility. (Source: Rahul V Pisharody)

“It takes as long as a decade or many years to develop improved crop varieties with desired traits incorporated. These traits are climate-sensitive. So, if done without considering the science of climate change in the present scenario of increasing rate of change, efforts to increase food production may not be expectedly beneficial as a lot can change during the long years of crop varietal development,” said Dr Mamta Sharma, Theme Leader, Integrated Crop
Management at ICRISAT.

Three facilities at the Department of Science and Technology-supported Centre of Excellence on Climate Change Research for Plant Protection on ICRISAT’s campus are helping Dr Sharma and her team simulate various scenarios.

In open-top chambers, a fixed level of carbon-dioxide is maintained for the length of a crop season to see effects on multiple crops and major pests that affect them. At the moment, the team is testing chickpea and rice in the chambers, comparing them to those grown outside in ambient conditions. At carbon dioxide concentrations of 550 ppm, the crops in the chamber are visibly bigger and have matured faster, thanks to higher concentration of the gas that is responsible for photosynthesis.

Aphid infested mung bean at the FACE facility. (Source: Rahul V Pisharody)

However, that does not necessarily mean higher yields for farmers, cautions Dr Sharma. What more, the changes to pest lifecycle and behaviour, the reduced nutritive value, which is strongly suspected, is likely to dent any gains in yield that may accrue when crops are grown in higher Co2 levels. Studies are underway to test our suspicions, she
added.

At the same time, the team is also looking at how gradual variations in Co2 and temperature, mimicking variation across geographical regions, can change plant traits, and pest behaviour. This is being done inside Carbon dioxide and Temperature Gradient Tunnel (CTGT) where the temperature and Co2 levels change as one walks across the tunnel.

At every stop where a combination of temperature and Co2 varies, the scientists are seeing marked changes to plant traits and pest behaviour. “At different levels of Co2 and temperature, we know that there is a huge change in crop phenology, and pests and diseases. These changes are being assessed in leaf size, chlorophyll content, plant height, nutritional content in seeds etc,” the scientist said.

An overview of all three facilities in the Centre of Excellence on Climate Change Research for Plant Protection(CoE-CCRPP). (Source: ICRISAT)

The gradient tunnels can also help understand cut-offs where anymore increase in Co2 may not be supported by plant growth. It can reveal to researchers the climate preferences and the motivation of a pest to travel as was seen in the case of Fall Armyworm, which hopped across the Atlantic to infest crops in Africa and Asia. Experiments with
pigeonpea (toor dal) and its nemesis, the pod borer (Helicoverpa), have already confirmed the observations seen in fields; the pest prefers warmer climes and can reproduce faster in such conditions.

The researchers are aware of the need to verify findings in near-world conditions. The third facility, Free-Air Carbon dioxide Enrichment (FACE) facility, which is an enclosure that is open to air but is infused with carbon dioxide at set levels, corroborates the closed enclosure observations.

Dr Mamta Sharma explaining the carbon dioxide and temperature gradient tunnel(CTGT) from the control room. (Source: Rahul V pisharody)

“In a world that has reached a point of no return from warming, producing food may be a challenge that is hard to meet. Knowing well ahead of time what lies in store, can help us adapt and keep food production sustainable even as we attempt to mitigate climate change,” Dr Sharma observed.

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