Traditional methods for assessing crop water status have limited practicality for field applications. Conversely, remote sensing via remotely piloted aircraft (RPA) offers a promising alternative, though its effectiveness requires validation in specific studies. This study utilized RPA-derived imagery to support strategies for monitoring water deficit (WD) in corn crops and enabling yield prediction. The AG 1051 corn genotype underwent deficit irrigation levels (20, 40, 60, 80, and 100% of crop evapotranspiration—ETc) at different phenological stages: initial (E1), vegetative growth (E2), flowering (E3), and physiological maturity (E4) in Iguatu, Ceará, Brazil. We measured ten vegetation indices (VIs) and ear and biomass yield. Pearson's correlation analysis revealed that, during E2, the normalized difference vegetation index (NDVI) (r = 0.98) and green leaf index (GLI) (r = 0.99) were the most reliable for distinguishing water stress levels. These indices were also effective in predicting yield in E2 through regression analysis. The findings demonstrate that vegetation indices derived from RPA imagery provide a robust method for assessing water conditions and forecasting yield.

The aim of this study was to evaluate effects of irrigation with saline water on the germination of Gliricidia sepium seeds linked to the effect of organic matter supplementation to mitigate recurrent effects of high salt content in water. The experiment was conducted under a completely randomized statistical design in a 5 x 2 factorial treatment design, with five different irrigation water electric conductivities ECw (0.5, 1.0, 2.0, 3.0 and 4.0 dS m-1) and two organic matter supplementations (no-organic matter and organic matter supplementation), using five replicates. The experiment was carried out under tape knitted shade cloth, shading rate of 50%. Variables of average germination time (days), relative germination frequency (%) and informational entropy (bits) were analyzed. The increase in the irrigation water salinity caused a longer time needed for the Gliricidia sepium seeds to germinate, however, the use of organic matter performed as a mitigating factor for the effects caused by the high salt content in the irrigation water when a high frequency of germination was observed in shorter times.

This study evaluated the potential of VIS–NIR–SWIR leaf spectroscopy to predict N, P, and K contents in sugarcane, considering spectral variability across two growing seasons (2023/2024 and 2024/2025), phenological stages, and five varieties. Spectral signatures (350–2500 nm) were acquired using a FieldSpec 3 spectroradiometer and processed with MSC, smoothing, and the first Savitzky–Golay derivative. Diagnostic bands were identified by Spearman correlation, and prediction was performed using partial least squares regression (PLSR). PCA showed that spectral variability was driven mainly by seasonal and phenological factors, whereas varietal effects were secondary. In 2023/2024, greater spectral homogeneity was associated with lower predictive performance. In 2024/2025, greater spectral heterogeneity was associated with improved prediction for N (R² = 0.83; RMSE = 0.78 g kg⁻¹) and P (R² = 0.80; RMSE = 0.10 g kg⁻¹). Potassium remained the most challenging nutrient to predict (maximum R² = 0.25), mainly due to its ionic nature and the resulting lack of significant correlation with specific VIS, NIR, and SWIR spectral features. These results indicate strong potential for predicting N and P in fresh sugarcane leaves, although model robustness depends on the extent of spectral variability in the dataset.

The aim was to evaluate the attributes indicative of the physical quality of soils cultivated with banana trees and subjected to mechanical management through subsoiling. The evaluations were carried out in two different orchards, characterized by the fact that they had been subsoiled for five years (area considered unsubsoiled) and seven months (area considered subsoiled). The values of mechanical resistance to root penetration were obtained using a penetrometer. The following attributes were determined from the samples collected: density, solid density, total porosity and relative density, using the ratio between soil density and maximum soil density, obtained using the Proctor test. It was found that subsoiling was able to reduce the average values of soil density and relative density by approximately 9.83% and 15.84%, respectively, resulting in increases in total soil porosity of around 24.84%. Mechanical resistance to root penetration increased with depth, regardless of the mechanical management used. However, subsoiling resulted in significant reductions in this variable from a depth of 0.125m. It can therefore be concluded that subsoiling was effective in improving the physical quality of the soils evaluated.

ANÁLISE ESPAÇO-TEMPORAL DO ESPELHO D’ÁGUA DO AÇUDE TRUSSU ATRAVÉS DE SENSORIAMENTO REMOTO MATEUS LIMA SILVA¹, VINÍCIUS BITENCOURT CAMPOS CALOU², ALEXANDRE REUBER ALMEIDA DA SILVA^{3   1} Departamento de Engenharia Agrícola, Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Rodovia Iguatu - Várzea Alegre, km 05 s/n - Cajazeiras, 63500-000, Iguatu, Ceará, Brasil. mateuslimasilva5@gmail.com ² Departamento de Ensino, Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Rodovia Iguatu - Várzea Alegre, km 05 s/n - Cajazeiras, 63500-000, Iguatu, Ceará, Brasil. vinicius.calou@ifce.edu.br ³ Departamento de Ensino, Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Rodovia Iguatu - Várzea Alegre, km 05 s/n - Cajazeiras, 63500-000, Iguatu, Ceará, Brasil. alexandre.reuber@ifce.edu.br   RESUMO: Devido a irregularidade das chuvas é de suma importância em regiões semiáridas o armazenamento e a distribuição de água para consumo e irrigação, devido a irregularidade das chuvas. O espelho d’água pode ser descrito como a superfície contínua exposta à atmosfera de corpos hídricos. Deste modo, objetivou-se, analisar a espacialização do espelho d’água do Açude Trussu, localizado no Ceará, através de imagens dos satélites Landsat 7 e 8, durante período de estiagem e comprovar correlação estatística entre o volume do reservatório e índices pluviométricos no período de 2011 a 2022. Utilizou-se o Índice de Água de Diferença Normalizada (NDWI) nas imagens para realçar os corpos hídricos. Para correlação estatística usou-se o método de Spearman, em que, para correlações envolvendo índices pluviométricos, considerou-se a variação de volume armazenado e do espelho d’água em relação ao ano anterior. Dos resultados obtidos, evidencia-se que entre 2011 e 2019 o reservatório teve uma variação de -1.749,99 hectares de espelho d’água. O espelho d'água está positivamente correlacionado com o volume armazenado (0,993), e ambos apresentaram correlação com os índices pluviométricos, 0,818 e 0,627 respectivamente.   Palavras-chaves: NDWI, estiagem, reservatório.   SPATIAL-TEMPORAL ANALYSIS OF THE WATER MIRROR OF TRUSSU DAM THROUGH REMOTE SENSING   ABSTRACT: The storage and distribution of water for consumption and irrigation is of paramount importance in semi-arid regions due to the irregularity of rainfall. The water mirror can be described as the continuous surface exposed to the atmosphere of water bodies. The aim was therefore to analyse the spatialization of the water mirror of the Trussu Dam, located in Ceará, using images from the Landsat 7 and 8 satellites, during the dry season and to prove a statistical correlation between the volume of the reservoir and rainfall indices for the period 2011 to 2022. The Normalized Difference Water Index (NDWI) was used in the images to highlight the water bodies. Spearman's method was used for statistical correlation. For correlations involving rainfall indices, the variation in stored volume and water mirror in relation to the previous year was considered. The results show that between 2011 and 2019 the reservoir had a variation of -1,749.99 hectares of water mirror. The water mirror is positively correlated with the stored volume (0.993), and both were correlated with the rainfall indices, 0.818 and 0.627 respectively.   Keywords: NDWI, drought, reservoir.

COEFICIENTES DAS CULTURAS: BASE DE DADOS PARA O NORDESTE COMO SUPORTE AO MANEJO DA IRRIGAÇÃO MATEUS LIMA SILVA1; ZIDANE DE OLIVEIRA GERMANO2; JOAQUIM MAURO DE MOURA NETO3; ALEXANDRE REUBER ALMEIDA DA SILVA4 E CARLOS NEWDMAR VIEIRA FERNANDES5 1Departamento de Engenharia de Biossistemas; ESALQ – USP; Brasil; mateuslimasilva5@gmail.com; https://orcid.org/0009-0003-1044-1344 2Departamento de Ensino; IFCE; Brasil; zidane.oliveira.germano@aluno.ifce.edu.br; https://orcid.org/0009-0009-1182-130X 3Departamento de Ensino; IFCE; Brasil; joaquim.mauro.moura07@aluno.ifce.edu.br; https://orcid.org/0009-0005-5041-1996 4Departamento de Ensino; IFCE; Brasil; alexandre.reuber@ifce.edu.br; https://orcid.org/0000-0002-9757-7265 5Departamento de Ensino; IFCE; Brasil; newdmar.fernandes@ifce.edu.br; https://orcid.org/0000-0001-8678-021X 1 RESUMO O coeficiente da cultura (Kc) é o parâmetro mais comumente utilizado para estimar a necessidade de água da cultura, mediante a estimativa da evapotranspiração (ETc). Neste contexto, objetivou-se, com o presente trabalho, desenvolver e disponibilizar um atualizado banco de dados de coeficientes das culturas (Kc’s) de relevâncias agroeconômicas específicos para a região nordeste brasileira, por meio do oferecimento de informações de Kc’s padronizados em uma interface acessível e passível de apropriação aos agricultores irrigantes locais, com vistas ao oferecimento de subsídios técnicos – científicos capazes de auxiliarem ao manejo racional e sustentável da agricultura irrigada regional. Para tanto, realizou-se uma abrangente e atualizada pesquisa bibliográfica sobre os coeficientes das culturas (Kc’s), determinados especificamente nas condições edafoclimáticas da região nordeste brasileira e disponibilizou-se um banco de dados Kc’s. Identificaram-se lacunas existentes em termos de culturas de importâncias agroeconômicas regionais nas quais as informações acerca dos Kc’s não são ainda disponibilizadas e/ou encontram-se desatualizadas, sobretudo, junto às frutíferas aceroleira e goiabeira, bem como junto às espécies vegetais forrageiras, o que aponta a necessidade do desenvolvimento de pesquisas básicas e aplicadas acerca das temáticas em questão. Palavras-chave: evapotranspiração, necessidades hídricas dos cultivos, economia de água. SILVA, M. L.; GERMANO, Z. O.; MOURA NETO, J. M.; SILVA, A. R. A.; FERNANDES, C. N. V. CROP COEFFICIENTS: DATABASE FOR THE NORTHEAST TO SUPPORT IRRIGATION MANAGEMENT 2 ABSTRACT The crop coefficient (Kc) is the parameter most commonly used to estimate a crop's need for water by estimating evapotranspiration (ETc). In this context, the aim of this study was to develop and make available an up-to-date database of crop coefficients (Kc's) of specific agroeconomic relevance to the northeastern region of Brazil by offering information on standardized Kc values in an accessible interface that can be appropriated by local irrigation farmers, with the goal of providing technical and scientific support capable of assisting in the rational and sustainable management of regional irrigated agriculture. To this end, a comprehensive and up-to-date bibliographical survey was carried out on crop coefficients (Kcs), which were determined specifically in the soil and climate conditions of the northeastern Brazilian region, and a Kc database was constructed. Gaps were identified in terms of crops of regional agroeconomic importance where information on Kcs is not yet available and/or is out of date, especially for the fruit trees aceroleira and guava, as well as for fodder plant species, which points to the need to develop basic and applied research on the issues in question. Keywords: evapotranspiration, crop water requirements, saving water.