The Institut de Recerca i Tecnologia Agroalimentàries (IRTA) has carried out various studies in recent months to determine how fruit trees behave in situations of extreme drought and what management strategies work best to deal with the lack of water.
One of the conclusions is that fruit trees that do not receive water for four months can only survive if all fruit production is removed. The study has been presented within the framework of the XXVIII Mollerussa Fruit Day.
Concern about the low level of reservoir reserves and the lack of rain and snow, which have marked this year’s irrigation campaign, have led the Department of Climate Action, Food and Rural Agenda, through IRTA , has carried out several trials in real drought conditions to learn more about the behavior of trees and work towards different measures.
These trials have been carried out on apple, pear and almond trees, in the main varieties of the three crops, with water stress conditions of varying severity. The trees have been subjected to different strategies, such as fruit thinning, reduction of the tree canopy, or the application of biostimulant products, to determine if the survival of the trees can be ensured and if there are effects on the volume. or quantity of production.
The methodology of the studies has involved subjecting the trees in the sample to even more extreme drought situations than those that most of the Ponent plots have already suffered. Thus, irrigation water contributions were cut off during different periods. The longest, from May, and the latest, from the beginning of June.
To simulate a case of extreme drought, in some cases, the trees have not had any water supply for more than 3 months, except for the scarce rains in June and July. In this last situation, there has been a great mortality of the trees when no management measures have been implemented in the plantation, as explained by Luis Asín, head of the IRTA Fruit Culture program.
Of the measures that have been tested in the experiment, the total elimination of the fruits was the most effective in ensuring the survival of the trees in the most extreme cases. On the other hand, those strategies based on thinning or severe but not total pruning have not worked enough, since the levels of water stress and the trees’ ability to survive have not been so clear. And the production of fruits requires a very large need for water on the part of the tree.
In more favorable situations, a strategy that has been interesting has been the reduction of the crown or volume of the tree, important enough depending on the availability of water. “It is important to keep in mind in this case that not all plantations are designed to be able to undergo very rigorous pruning, such as eliminating more than 30% of the tree’s volume,” Asín explained.
Biostimulants, for their part, cannot save trees in cases of extreme drought, but with better conditions they can make trees produce larger fruits.
The Mollerussa Fruit Day is celebrated on October 18 and 19, the first day in Catalan and the second in Spanish. It plans to bring together more than 2,000 professionals and is considered the main outdoor fruit event in southern Europe.
This year it brings together nearly ninety companies. Among its main attractions are the presentations and demonstrations that are carried out, explained the general director of Irta, Josep Usall. 14 presentations and 11 outdoor demonstrations have been organized. Drought, the main pest problems that have affected trees this year or the opportunities offered by the digitalization of agriculture are some of the topics discussed.
