[GOIÂNIA, BRAZIL] The last days of summer in the southern hemisphere have yet to bring relief from high temperatures in the region where Ervino Kogler grows bananas.
His plantation is in a semi-arid area in the state of Bahia, northeastern Brazil.
There are fears that the upcoming dry months will revive the difficult times of 2023, when a heatwave caused a 15 per cent reduction in the following year’s harvest.
Even under normal conditions, 60 per cent of Kogler’s 100-hectare fruit farm requires irrigation.
“Some regions are already very hot, near the limit for commercial production, and these will become too hot.”
Dan Bebber, professor of ecology, University of Exeter
“But when the temperature reaches around 40 degrees Celsius and humidity levels are very low, the plants stop functioning, even with irrigation,” he says.
With global temperatures continuing to rise, the outlook is far from promising.
A study published in Nature Food has found that by 2080, rising temperatures will lead to a 60 per cent reduction in suitable areas for export banana production in Latin America and the Caribbean without urgent interventions to tackle climate change.
Yield declines are expected in most of the region’s current banana-growing areas.
The researchers also found that socioeconomic factors such as labour availability and infrastructure severely limit climate adaptation.
Researchers used satellite imagery to map regions of intensive banana production, identifying climatic, soil-related, and socio-economic factors that influence the viability of cultivation.
The findings show that banana production is concentrated in low-altitude regions with high, stable temperatures, and slightly acidic soils. Most banana farms are located near ports and urban centres, making location to more suitable areas difficult.
“Some regions are already very hot, near the limit for commercial production, and these will become too hot,” Dan Bebber, a professor of ecology at the University of Exeter, UK, who led the study, told SciDev.Net.
According to Bebber, Colombia and Costa Rica are particularly vulnerable, which is concerning for the export industry to Europe and North America.
The only regions with a favourable outlook are southern Brazil, which already has a cooler climate, and Ecuador, where projections do not indicate significant warming.
“We found that remote sensing using satellite-based radar was very useful for detecting high-intensity banana production,” Bebber explained.
“However, many Caribbean island nations, like Haiti, produce bananas in a less intensive way, and we were not able to accurately detect these production systems.
His team plan to develop other methods to monitor this type of production, he said.
US$11 billion
Bananas are one of the most exported agricultural products worldwide, with a market valued at around US$11 billion a year.
The fruit is a crucial source of income for low- and middle-income countries. In Colombia, the banana trade accounts for about five per cent of the agricultural gross domestic product (GDP) and provides employment for nearly 300,000 workers, directly or indirectly, according to the study.
Additionally, as a staple food consumed globally, threats to banana production also pose risks to food security in several countries.
Since 2020, Brazil has included banana cultivation in the Agricultural Climate Risk Zoning—a mapping system that assesses planting and production risks under different climate conditions.
Mauricio Coelho, a researcher at the Brazilian Agricultural Research Corporation, told SciDev.Net that the Agricultural Climate Risk Zoning has shown that previously semi-humid regions of Brazil are becoming semi-arid.
“Some regions where banana cultivation was still viable without irrigation, albeit with high climate risk, now require irrigation to mitigate those risks,” he explained.
Mitigation strategies
Various strategies have been adopted to mitigate the impacts of climate change on banana yields. On his banana farm, Ervino Kogler has increased the number of daily irrigations and directed water to more parts of the plants.
However, water availability is also affected by global warming. To address this issue, researchers have been studying drought-tolerant banana varieties.
Among these are two varieties developed by the Brazilian Agricultural Research Corporation, which require 25 per cent less water than traditional cultivars.
According to Coelho, these hybrid bananas were initially developed to be resistant to fungal diseases such as black and yellow sigatoka. However, they unexpectedly proved to have lower water requirements as well.
Indian scientists have also found that exposing Grand Nain banana plants—one of the most common vareties—to a gradual temperature increase from 30 to 42 degrees Celsius can help them withstand higher temperatures in the future.
Through these experiments, researchers identified the genes and metabolic pathways involved in acquiring heat tolerance.
“Some molecular memory will be there for them to cope with the higher stress,” Kundapura Ravishankar, a researcher at the Indian Institute of Horticultural Research, told SciDev.Net.
He added that the findings of the study were relevant to a number of areas around the world.
In another technological development, the Brazilian Agricultural Research Corporation, in partnership with a biofertiliser company, has created a “sunscreen” for plants, which reduces leaf and fruit damage caused by excessive heat.
The substance, diluted in water, can be sprayed using backpack sprayers, tractors, or even drones. According to Coelho, the protective layer enhances the plant’s ability to exchange gases during photosynthesis.
He said ongoing experiments in banana plantations have shown that plants without the sunscreen had 30 per cent less chlorophyll – the green pigment essential for photosynthesis – compared to those treated with the product.
This article was produced by the Latin America and Caribbean edition of SciDev.Net.