Short-term heat wave will also lead to no harvest of coffee particles.

If "hot coffee" means that coffee crops are plagued by high temperature and pressure, then the word is not a good thing for Javanese coffee lovers.

When Arabica coffee suffers from a short heat wave, it becomes difficult to blossom and bear fruit, according to a study from Oregon State University's College of Forestry. This means there are no coffee beans and no coffee to drink.

Arabica coffee beans are the main coffee growers in the world. Commercial production of Arabica coffee accounts for 65 per cent of global coffee consumption of nearly 20 billion pounds a year. The coffee tree produces new luxuriant leaves throughout the year and grows in the tropics of 80 countries on four continents around the world.

The study investigated how leaf age and heat duration affected the recovery of Arabica coffee trees from thermal stress in greenhouse experiments. An important finding is that young and "spreading" leaves recover more slowly than mature leaves. At the same time, after the simulated heat wave experiment, no plants blossomed and bear fruit.

"this underscores how sensitive Arabica coffee is to temperature." "No flowering means no reproduction, which means no fruit," said Danielle Marias, a plant physiologist at Oregon State University who led the study. For coffee growers with poor harvests, this can be catastrophic. "

"Heat is very stressful for plants and is often associated with drought. However, in coffee growing areas, the climate may be not only hot and dry, but also hot and humid, so in this study, we want to isolate the effects of heat. " Marias explained.

In this study, Arabica coffee trees were exposed to heat that kept their leaves slightly above 48.9 degrees Celsius for 45 or 90 minutes. Marias said the leaf temperature is a realistic reflection of global climate change.

After 90 minutes of high temperature, the expanded leaves had the longest time to recover-physiological recovery was measured and determined by photosynthesis, chlorophyll fluorescence and the presence of non-structural carbohydrates.

Marias said that in both treatments, the photosynthetic recovery of young leaves was much slower than that of mature leaves, and stomatal conductance decreased. "according to the leaf energy balance model, the suppressed stomatal conductance reduces the leaf evaporative cooling, which will further increase the leaf temperature and aggravate the post-effect of high temperature and pressure under full and partial light conditions. Arabica coffee trees often grow in such an environment."

Excluding leaf age, prolonged heat exposure will lead to a decrease in water use efficiency, which may also worsen the effect of thermal stress, especially during drought. (compiled by Hu Xizi)