The semi-arid region faces problems related to water deficit and the presence of brackish water that compromise crop performance. Therefore, irrigation frequency can enhance the growth of agricultural crops of interest even under salt stress conditions. In this context, the objective of the present study was to evaluate different irrigation frequencies with water of higher and lower salinity on the agronomic performance of millet. The experiment was conducted from September to November 2020, in the experimental area of the Auroras Seedling Production Unit, belonging to the Universidade da Integração Internacional da Lusofonia Afro-Brasileira, Redenção, Ceará, Brazil. The experimental design used was completely randomized in a 4 × 2 factorial arrangement, with five repetitions. The first factor corresponded to four irrigation frequencies (F1 - daily irrigation; F2 - irrigation every two days; F3 - irrigation every three days; F4 - irrigation every four days) and the second factor consisted of two levels of electrical conductivity of irrigation water (0.3 and 5.0 dS m^-1). Salt stress (5.0 dS m^-1) negatively affected leaf area, plant height, stalk diameter, panicle length, and leaf, stem, panicle, and total dry mass of millet, under daily and four-day irrigation frequencies. Increasing the interval in irrigation frequency to beyond two days negatively affects the agronomic performance of millet crop, regardless of the electrical conductivity of water used (0.3 or 5.0 dS m^-1). Under salt stress conditions, adopting irrigation frequencies between two and three days can be a viable alternative for irrigation management in pearl millet crop.

Excessive salts in irrigation water and water stress have a negative impact on the productive yield of agricultural crops. In this regard, the objective was to evaluate the effect of combined saline and water stress on the agronomic performance of the beet crop. The experiment was conducted in a greenhouse located at the Universidade da Integração Internacional da Lusofonia Afro-Brasileira, in Redenção, Ceará. The experimental design used was completely randomized with split-plots arrangement. The main plots were formed by the electrical conductivities of the irrigation water (0.8, 1.5, 3.0, 4.5, and 6.0 dS m^-1), while the irrigation depths of 50 and 100% of the crop evapotranspiration (ETc) were the subplots, with 6 replications. Saline stress negatively affected growth, biomass, tuber root length, and productivity, while increasing the soluble solids of the beet crop. Excessive salts in the irrigation water caused reductions in physiological indices of the beet crop, although with less severity under the 100% ETc.

The application of machine learning techniques to determine bioparameters, such as the leaf area index (LAI) and chlorophyll content, has shown significant potential, particularly with the use of unmanned aerial vehicles (UAVs). This study evaluated the use of RGB images obtained from UAVs to estimate bioparameters in sesame crops, utilizing machine learning techniques and data selection methods. The experiment was conducted at the Federal Rural University of Pernambuco and involved using a portable AccuPAR ceptometer to measure the LAI and spectrophotometry to determine photosynthetic pigments. Field images were captured using a DJI Mavic 2 Enterprise Dual remotely piloted aircraft equipped with RGB and thermal cameras. To manage the high dimensionality of the data, CRITIC and Pearson correlation methods were applied to select the most relevant indices for the XGBoost model. The data were divided into training, testing, and validation sets to ensure model generalization, with performance assessed using the R², MAE, and RMSE metrics. XGBoost effectively estimated the LAI, chlorophyll a, total chlorophyll, and carotenoids (R² > 0.7) but had limited performance for chlorophyll b. Pearson correlation was found to be the most effective data selection method for the algorithm.

O uso de água salobra associada ao manejo inadequado da adubação afeta a produtividade das culturas agrícolas. Objetivou-se com a pesquisa avaliar a produtividade da cultura do amendoim submetida a diferentes estratégias de irrigação com água salobra e adubação mineral e organomineral. O delineamento utilizado foi inteiramente casualizado, em esquema fatorial 5 x 2, com quatro repetições, sendo utilizadas cinco estratégias de irrigação com água salobra com condutividade elétrica de 4,0 dS m-1: EI1= água salobra a partir dos 7 dias após a semeadura – DAS; EI2= água salobra a partir dos 15 DAS; EI3= água salobra a partir dos 25 DAS; EI4= água salobra a partir dos 35 DAS e EI5= tratamento controle - sem estresse salino) com duas adubações (M= mineral, OM= organomineral). A adubação organomineral atenuou o efeito negativo do estresse salino no tratamento com início da irrigação com água salobra aos 15 e 25 dias após a semeadura para o diâmetro da vagem, 35 DAS para a massa de vagem e aos 25 e 35 para a produtividade. A estratégia de uso de água salobra aos sete dias após a semeadura afeta o desempenho da cultura em comprimento da vagem e aos 7,15, 25 e 35 o número de vagem por planta. Palavras-chave: Arachis hypogaea L.; biofertilizante; estresse salino; nutrição de plantas. Irrigation strategies with bracky water and fertilization in peanut crops The use of brackish water associated with inadequate fertilizer management affects the productivity of agricultural crops. The research objective was to evaluate the productivity of peanut crops subjected to different irrigation strategies with brackish water and mineral and organomineral fertilization. The design used was completely randomized, in a 5 x 2 factorial scheme, with four replications, using five irrigation strategies with brackish water with an electrical conductivity of 4.0 dS m-1: EI1= brackish water from 7 days after irrigation. sowing – DAS; EI2= brackish water from 15 DAS; EI3= brackish water from 25 DAS; EI4= brackish water from 35 DAS and EI5= control treatment - without saline stress) with two fertilizers (M= mineral, OM= organomineral). Organomineral fertilization attenuated the negative effect of saline stress in the treatment with the start of irrigation with brackish water at 15 and 25 days after sowing for pod diameter, 35 DAS for pod mass and at 25 and 35 for productivity. The strategy of using brackish water seven days after sowing affects crop performance in terms of pod length, and at 7,15, 25, and 35, the number of pods per plant. Keywords: Arachis hypogaea L.; biofertilizer; salt stress; plant nutrition.

Shading Screens and mulching may provide a favorable environment for radish growing in regions of adverse climates. This work aimed to evaluate the radish productivity under the influence of different shading screens associated with the presence and absence of mulch in two different years. The experiment was carried out in two different seasons (2017 dry season and 2018 rainy season), in the vegetable garden of Liberdade campus, at the University of International Integration of Afro-Brazilian Lusophony (Unilab), municipality of Redenção-CE. The experimental design was in randomized blocks in a split-plot arrangement, with four repetitions, in which the plots consisted of growing with and without mulching and in the subplots, five shading screens: 50% Black Shading Screen (50% BSS), 50% Red Shading Screen (50% RSS), 30% White Shading Screen (30% WSS), 70% Black Shading Screen (70% BSS) ), and full sunlight (FS). The red shading screens 50% and white 30%, in addition to cultivation under full sunlight, provide higher performance in terms of the number of leaves, tuberous root diameter, tuberous root matter, and the radish crop productivity, regardless of the evaluated period. The applied mulch does not influence the productivity of the rabante, influencing only the gain of dry mass of the aerial part, soluble solids and length of the tuberous root.

The interaction between agricultural environment and alternative substrates can attenuate salt stress in zucchini seedlings. Based on that, the objective of this work was to evaluate the production of zucchini seedlings irrigated with saline water and cultivated in different types of environments and substrates. The experimental design was completely randomized, using a split-split plots scheme, with the plot being the three cultivation environments (AM1= full sun; AM2= red screen with 50% shading; AM3= black screen with 50% shading), subplot the three substrates (SB1= biochar + soil; SB2= carbonized rice husk + soil; SB3= cattle manure + soil) and the subplot the two irrigation waters (AI1= 0.8 and AI2= 2.5 dS m^-1), with four replications of twenty-five seeds. The variables analyzed were: emergence percentage (EP), emergence speed index (ESI), mean time of emergence (MTE), mean speed of emergence (MSE), stem diameter (SD), seedling height (SH) , root length (RL), shoot dry mass (SDM), root dry mass (RDM) and total dry mass (TDM). The AM3 environment presented better conditions for the variables: EP, ESI and MSE. The environment AM2 presented better conditions for the variable MTE with the use of substrates SB2 and SB3 regardless of the salinity of the irrigation water. The SB3 substrate showed better growth conditions for the variables: SH, SD, SDM and TDM. The SB2 substrate provided better conditions for the variable RDM.