José Javier Peguero Pina
The cultivation of black truffle (Tuber melanosporum Vittad.) is a driving force for sustainable economic development in many rural areas of Spain with a high degree of depopulation and poor industrial development. It is considered that Spain produces more than 50% of commercialized truffles in the world, and the amount of commercialized truffle in Aragon could mean 15 to 22 million euros, occupying 10,000 ha of cultivation. However, there are still many unknowns about the truffle and especially its culture, so an increase of knowledge is required for stabilizing production of truffle orchards. Most truffle-producing plots are in areas with low precipitation and poor soils, so irrigation is a basic work to be done in these plots in order to obtain a continuous and homogeneous harvest. Therefore, knowledge of tree physiological status in response to water stress constitutes a major challenge in order to establish the need for irrigation in truffle orchards, ensuring truffle production in terms of quantity and quality.
The characterization of plant water status has been carried out using several destructive techniques - such as leaf water potential and relative water content - or by monitoring the functional response of the plant in relation to their water status. The limitations of these techniques and the interest for registering the degree of plant water stress in an accurate, fast, repeatable and non-destructive way have promoted in recent years the implementation of techniques for measuring plant water content (such as the spectral reflectance in the visible and infrared, thermography, microwaves and reflectance/transmittance in the Terahertz band) that allow the development of new sensors for monitoring water status, being i/ non-destructive, ii/ accurate, iii/ easy to interpret and iv/ able to establish a continuous monitoring. However, the development and validation of most of these new techniques for holm oak is still a challenge for the scientific community.
Therefore, the main objective of this project is the evaluation of water status of holm oak in truffle orchards through i/ the validation of techniques already used in other plant species (reflectance indices in the visible and infrared, the thermographic index CWSI) and ii/ the development and validation of new non-destructive, non-invasive and easy to use techniques (microwave bands at 2.4 and 5.5 GHz, THz band). The development and validation of these new techniques - through the collaboration between CITA (subproject 1) and Luz-WaveLabs (subproject 2) - can be decisive for the future development of valuable decision-making tools that enable the fast and accurate knowledge about when irrigation is needed, minimizing subsequent intervention in holm oak truffle orchards.
Eustaquio Gil Pelegrín, María Martín Santafé, Domingo Sancho Knapik (CITA)