Carbon dioxide can reduce the incidence of leaf miner in coffee plants

A study developed by Embrapa Meio Ambiente indicates that increased carbon dioxide (CO2) emissions reduce the incidence of the leaf miner, one of the worst pests of coffee plants in Brazil, capable of causing losses of up to 50% in the crop. The conclusion is the result of an experiment such as FACE - Free Air Carbon-dioxide Enrichment (learn more in the table in this article), which has been widely used by scientific research to obtain answers in intact natural agroecosystems. The work, carried out between 2011 and 2015, also showed positive impacts on plant height, number of leaves and stem diameter, but no effect on the incidence of rust, another disease that is very harmful to this crop in the country.

FACE-type experiments allow the emission of carbon dioxide in the open air to evaluate the effects of the gas on plants of agricultural interest. FACE Climapest, created by then Embrapa Environment researcher Raquel Ghini, based on this model, was the first in Latin America and the only one in the world to study coffee culture in this environment. Furthermore, he was also a pioneer in prioritizing the study of phytosanitary problems.

For Embrapa Environment researcher Katia Nechet, climate change represents a threat to plants, but few studies consider its effect on plant diseases and pests, especially in tropical biomes with perennial crops. However, it is crucial information to point out crop management strategies in the future, especially in relation to climate, since cumulative carbon dioxide emissions will largely determine global warming at the end of the 1,5st century, with a projected increase around of XNUMX°C in the planet's temperature, according to the Intergovernmental Panel on Climate Change (IPCC).

“FACE Climapest provided information on the effect of this increase in coffee and its main diseases and pests, in studies conducted outdoors, in more realistic conditions, to understand the effect of the increase in carbon dioxide on the incidence of pests and diseases. Experiments like this require studies that can take more than three years for perennial plants, such as coffee”, explains Wagner Bettiol, also a researcher at Embrapa Meio Ambiente.

Brazil, the largest coffee producer in the world, was responsible for 33,6% of world production in the 2021/2022 harvest. Coffee rust and leaf miner can lead to losses ranging from 30% to 50% and 30% to 70%, respectively. The study of the relationship between climate variables and agricultural production is essential, not only to identify the vulnerability of production systems, but also to propose adaptation strategies, aiming to guarantee the supply of food in the most diverse environmental conditions.

How FACE Climapest works

FACE Climapest was implemented in March 2011 at Embrapa Meio Ambiente, using seedlings of the Catuaí Vermelho IAC and Obatã IAC coffee cultivars. The seedlings were transplanted in an area of ​​7 hectares with 12 experimental plots, half of which received enrichment with carbon dioxide and the other half of the area, plants under natural concentration of carbon dioxide.

The gas was injected so that the wind mixed the injected dioxide with the air and transported it to the center of the plots. Embrapa Instrumentação was responsible for the structure based on a network of wireless sensors, which allowed changes in carbon dioxide concentration, influenced by the wind, to be quickly monitored.

Plant growth

Over the three years of evaluation, the diameter of coffee trees grown under high carbon dioxide was 3% to 12% larger than those subjected to ambient carbon in all evaluations. The number of leaves varied throughout the period, as it was influenced by external factors, in addition to carbon dioxide, such as manual harvesting and incidence of pests. “Even so, of the 17 evaluations carried out, 10 showed a greater number of leaves”, explains Regiane Iost, who during her master's and doctorate studies at the Universidade Estadual Paulista “Júlio de Mesquita Filho” (Unesp), participated in conducting the experiment.

The incidence of coffee rust in treatments with increased carbon dioxide was low and statistically similar in 2014 and 2015, depending on climatic conditions and the application of fungicides. On the other hand, the incidence of the leaf miner was lower in plants grown under increased carbon dioxide, which showed the same trend presented in preliminary results conducted at FACE Climapest between 2011 and 2013.

“It is known that the duration of the total miner cycle is strongly influenced by temperature. In the experiment, the temperature was similar for treatments with different concentrations of carbon dioxide, which suggests that the increase may be responsible for the lower occurrence of the disease”, explains Nechet.