Avaliação da temperatura da parte aérea através da termografia na cultura do tomate cereja sob diferentes estratégias de irrigação deficitária

Abstract

The practice of irrigation is of utmost relevance for agricultural management, which, combined with remote sensing and techniques such as thermography, has gained focus in various studies, as it contributes to decision-making by assessing the plant's water status for the proper supply of water, without waste or deficiency. In light of the above, the objective was to use thermography to evaluate the temperature variation of the red cherry tomato grown in a protected environment, under different irrigation strategies. The experiment was conducted in a greenhouse at the Agrometeorological Station of the Federal University of Ceará. A randomized block design with split plots was adopted, in a 5x3 factorial scheme, referring to five irrigation strategies (IP - full irrigation, DR - continuous deficit irrigation, E3 - deficit irrigation during the vegetative phase, E4 - deficit irrigation during the flowering and fruiting phase, E5 - deficit irrigation during the maturation and harvesting phase), with a water deficit of 50% of the crop's evapotranspiration, and evaluation periods at 30 DAT (days after transplanting), 60 DAT and 90 DAT, according to the crop's phenology. The analyzed variables were: plant temperature using Flir and Fluke cameras, SPAD index using a chlorophyll meter, leaf water potential using a Scholander chamber, and physiological variables (net photosynthesis, transpiration rate, stomatal conductance) using an IRGA (Infrared Gas Analyzer). The results were subjected to analysis of variance using SISVAR, and for comparisons between treatment means, the F-test was used at the 1% and 5% probability levels. There was an increase in SPAD index values and water potential, which indicated defense mechanisms against water deficit. Both variables showed a significant response only at 60 and 90 days after transplanting, according to the irrigation strategy. Thus, the use of thermal images proved to be an efficient tool, providing consistent temperature averages regarding crop development over time and in relation to water deficit. Gas exchange measurements supported the behavior of the observed factors in line with the other analyses, especially the thermal ones.