Evaluation of crop water status of melon plants in tropical semi-arid climate using thermal imaging/Imagens termicas para avaliar o estado hidrico do meloeiro sob clima tropical semiarido

HIGHLIGHTS: Deficit irrigation strategies effectively increase water productivity. Thermal images may be used as an irrigation management strategy Mulching is essential for increasing melon fruit yield and water use efficiency The objective of this study was to analyze the feasibility of using thermal images to estimate the water status of melon plants (Cucumis melo L.) in tropical semi-arid climates. The study was conducted in a randomized block design with a split-plot arrangement. The plots comprised of soil cover (with and without mulching), and subplots were constructed using five irrigation regimes (120, 100, 80, 60, and 40% crop evapotranspiration), with five replicates. The following variables were evaluated: canopy temperature ([T.sub.canopy]), leaf water potential, air temperature ([T.sub.air]), soil moisture, crop yield, and thermal index ([DELTA]T), which is definedas the difference between [T.sub.canopy] and [T.sub.air] [DELTA]T exhibited high correlations with crop yield and water consumption, indicating that thermography is an efficient tool for identifying the water status of melon plants, which could be employed for proper irrigation scheduling under tropical semi-arid scenarios. Moreover, thermal images identified the beneficial effects of soil cover on leaf water status and crop yield, primarily under moderate deficit irrigation. These results demonstrate that mulching is essential for increasing melon yield and water productivity in tropical regions. Key words: Cucumis melo, dryland agriculture, irrigation management, leaf temperature, water stress O objetivo principal deste trabalho foi avaliar o uso de imagens termicas para estimar o estado hidrico de plantas de meloeiro (Cucumis melo L.) sob clima tropical semiarido. O estudo foi realizado em delineamento de blocos casualizados, em esquema de parcelas subdivididas. As parcelas foram compostas pela cobertura do solo (com e sem cobertura morta) e as subparcelas por cinco regimes de irrigacao (120, 100, 80, 60 e 40% da evapotranspiracao da cultura - ETc), com cinco repeticoes. Foram avaliadas as seguintes variaveis: temperatura do dossel ([T.sub.dossel]), potencial hidrico foliar ([[psi].sub.folha]), temperatura do ar ([T.sub.air]), umidade do solo, produtividade da cultura e indice termico ([DELTA]T), sendo este definido como a diferenca entre [T.sub.dossel] e [T.sub.air] O [DELTA]T apresentou altas correlacoes com a produtividade da cultura e o consumo de agua da cultura, evidenciando