Development of an effective and sustainable system to monitor fruit tree water status with precision devices

In recent years, sustainable water resource management has become a significant and debated issue in the agro-environmental context. Agriculture, as one of the major water-consuming sectors, plays a crucial role in water resource management. Indeed, global climate change is leading to a general temperature rising, with a consequent increase in drought phenomena. As a result, this leads to an overuse of water resources for irrigation. Therefore, understanding tree crop responses to water availability is becoming increasingly urgent, aiming to increase their water use efficiency.In this regard, one of the primary objectives of scientific research today is to optimize the use of water resources, minimizing inputs without compromising outputs. Water resource savings alone will lead to increased profits. In recent years, deficit irrigation methods, such as regulated deficit irrigation (RDI) and partial rootzone drying (PRD), have allowed farmers to save water while increasing profit by irrigating only during specific phenological stages or with reduced volumes on alternated sides of the rootzone, inducing the plant to activate physiological mechanisms (partial stomatal closure) useful for maximizing water use efficiency. However, real-time knowledge of fruit tree water requirements with consequent automation of precise irrigation applications would allow farmers to further increase water use efficiency. In this regard, last-generation sensors allow continuous data acquisition directly from the plant, greatly increasing the level of information. The combined use of plant-based proximal sensors can provide highly precise information about its water status. Furthermore, remote sensing technologies allow strategic use of proximal sensors, taking into account the spatial variability of the orchard.Based on these premises, the main objective of this dissertation was to develop an effective and sustainable system for monitoring the water status of fruit trees using proximal and remote sensing technologies. Firstly, the use of plant-based proximal and remote sensing technologies, as well as the combination of the two techniques, was reviewed. Subsequently, some techniques for assessing the water status of young olive trees placed in a growth chamber were tested. In the subsequent trial, fruit growth sensors (fruit gauges) were used to study responses of fruit growth from five different species (peach, mango, olive, orange, and loquat) to vapor pressure deficit. In the last trial, the combined use of proximal and remote sensing technologies was tested for estimating the water status of 'Calatina' olive trees under open field conditions.