17 de September de 2019

Olive trees suffer from climate change too

Recent studies show that olive trees suffer considerable damage due to global climate change.

Researchers at the Department of Agronomy at Spain’s University of Córdoba, working in collaboration with the Agroforestry Sciences of the University of Seville, the Ifapa Venta del Llano de Jaén, and Citoliva, have verified the incidence of climate change in olive grove crops, as recently reported by the Fundación Descubre.

The scientists simulated the conditions of a temperature increase of four degrees in two varieties of olives and concluded there was a reduction in the amount of fruit, the ripening begins earlier and pulp shrinks, so that less oil can be obtained.

The study – the first to analyze in the field the changes in each stage of the development of the olive tree related to temperature variations – took place in the Campus de Rabanales de Córdoba between 2015 and 2017.

“We have generated the maximum temperature gradient expected in the Mediterranean Basin through the use of open-air chambers,” said María Benlloch-González of the University of Córdoba. Their findings were published in the report “Global warming effects on yield and fruit maturation of olive trees growing under field conditions” in the journal Scientia Horticulturae. “The flowering and thus the beginning of the maturation period occurs earlier, but the time that elapses until maturity is greater,” Benlloch-González said.

Among the observable common patterns, it was noted that, on average, there is an advance of two or three weeks in maturation. “The size of the olive pit does not vary, but the size of the pulp does, and the ratio between them steadily dropping from one harvest to the next” Benlloch-González said.

By measuring trunk diameter, the researchers found that olive trees grow more when the average temperature is 4 degrees warmer, requiring significantly more pruning.

The study involved housing the 11 olive trees in the sample in a chamber open only at the top with hot air pumped in at the base. Temperature sensors ensured it was always 4 degrees warmer inside than outside, but otherwise, growing conditions were optimal and natural. “Exposure to the wind, pollination and rain remained,” said Benlloch-González.

Previous studies have sought to determine the effects of climate change by comparing the growth of olive trees in two regions with different average temperatures. “Our result is more precise since many physiological processes are not determined only by the average temperature, but by the duration of the day and thermal fluctuations,” Benlloch-González said.