Utilização da termografia para avaliação do estresse hídrico na cultura do tomate cereja cultivado sob diferentes estratégias de irrigação e uso de hidrogel

Abstract

Tomato (Solanum lycopersicum) is among the main vegetables produced in the world. In tomato cultivation irrigation is used to express maximum productivity in the field. The Brazilian Northeast is one of the main tomato producers, with water scarcity it is important to seek efficient methods to maintain productivity in line with water and soil conservation. In this context, deficit irrigation appears as a method of applying the water deficit in the less sensitive phenological stage, so that productivity is expressed. The use of remote sensing in agriculture makes irrigation management more accurate by obtaining data in real time and remotely. Thermography, which uses infrared sensors to detect surface temperature, can be carried on satellites, planes, drones, or portable devices. This way, thermography is applied in the field to identify plots that present water stress, indicating the water conditions. Therefore, it was necessary to understand for the culture under study, the temperature during its cycle that indicates the water deficiency in the plant. This study aimed to evaluate if thermography can be used to detect water deficit in cherry tomatoes with different irrigation strategies based on gas exchange and use of hydrogel. The chosen experimental design was in randomized subdivided blocks (DBC) with a factorial scheme of 5 irrigation strategies and 3 evaluation times (5x3). The strategies were divided into IP - Full Irrigation (control), DR - Irrigation with regular deficit (50% of ETcloc), E3 - Irrigation with deficit (50% ETcloc) in the vegetative phase, E4 - Deficit Irrigation (50% ETcloc) in the flowering and fruiting phase, E5 – Deficit irrigation (50% ETcloc) in the maturation and harvest phase. For the second factor, the days after transplanting (DAT) were analyzed, namely: 30 DAT (vegetative phase), 60 DAT (flowering/fruiting phase) and 90 DAT (maturation/harvest phase). Gas exchanges and canopy temperature were also evaluated, gas exchanges were stomatal conductance (gs), transpiration (E) and water potential (Ѱ) with IRGA. Canopy temperature was evaluated in the first evaluation with a Fluke thermal camera and in the second and third evaluations with a Flir camera. The results of the experiment allowed us to conclude that the adoption of strategy 3, even when water deficit was applied in the vegetative phase, showed better efficiency in water use. Thus, the thermal cameras detected the physiological changes of plants under stress with higher temperatures.