Spain: Heat wave taking heavy toll on citrus crops

"This year, we will see a very notable drop in our production of oranges and mandarins because of the severe heat in June, which is causing a lot of fruit to drop due to dehydration. Some varieties will record significant losses," explains the producer and engineer Carlos Arenes.

According to the specialist, with temperatures above 30 degrees, plants close the stomata of the leaves to prevent dehydration, since they lose water at a faster rate than they can get it from the soil.

"This is a natural safety mechanism; however, the fruits do not have this ability. They become dehydrated, die and fall to the ground."

To prevent problems like this, Carlos Arenes has developed a mixed system of frost and heat control by low water application.

"With our system, water is administered on top of the plant and this protects it from the heat. Technically, every gram of water evaporated above the plant 'steals' heat from it, as each gram of evaporated water absorbs 580 calories per gram; therefore, if we administer 12 cubic metres per hectare and hour, that totals 12,000 litres, which translates into 12,000,000 grams of water. If every gram absorbs 580 calories, 7,000,000,000 calories are 'stolen' per hectare every hour," explains the engineer.

"In a day with over 40 degrees Celsius, we get the temperature in the plantation down to between 24 and 25 degrees in the sun and to a little above 27 degrees in the shade, since without the sun, you lose the main factor of evaporation, which is followed by the wind," affirms Carlos Arenes.

"It is not easy, because we need the water to evaporate as much as possible in the crop without saturating the atmosphere with moisture, because if that happens, we would see the opposite effect. That is why the water is administered in droplets in a controlled manner, so that the water arrives to the crop and evaporation takes place on top of the plant, without saturating the atmosphere and without causing any burning through the feared 'magnifying effect'."