Degradation of Caatinga biome has created desertification processes in several areas, inducing big microclimate and surface changes. Therefore, it is fundamental develop research methods capable of identifying areas under degradation process. Satellite images in different spatial, temporal, radiometric and spectral resolutions are being used to monitor big areas from several biomes worldwide. The objective of this study was to evaluate and quantify the degree of degradation and preservation of the Caatinga biome, using geoprocessing methods and remote sensing products, using surface data and Landsat-8 images for 2013, 2014 and 2015. Remote sensing methods were used to estimate the Normalized Difference Vegetation Index (NDVI), surface albedo (α) and Moving Standard Deviation Index (MDSI). The results showed that the vegetation indexes and the techniques of degradation and change detection satisfactorily identified the behavior of the surrounding vegetation in the study area, standing out as good indices for degradation processes in the semiarid. It was concluded that change detection and classification by decision tree methods were efficient in the identification of anthropized areas during the experimental period. Monitoreo de la degradación en el bioma de Caatinga en la región semiárida del Noreste de Brasil ResumenLa degradación del bioma Caatinga ha creado procesos de desertificación en varias áreas, induciendo grandes cambios en el microclima y la superficie. Por lo tanto, es fundamental que se desarrollen métodos de investigación capaces de identificar áreas en proceso de degradación. Las imágenes de satélite con diferentes resoluciones espaciales, temporales, radiométricas y espectrales se están utilizando para monitorear grandes áreas de varios biomas en todo el mundo. El objetivo de este estudio fue evaluar y cuantificar el grado de degradación y preservación del bioma Caatinga, utilizando métodos de geoprocesamiento y productos de teledetección, usando datos de superficie e imágenes Landsat-8 para 2013, 2014 y 2015. Se utilizaron métodos de teledetección para estimar el Índice de Vegetación de Diferencia Normalizada (NDVI), el albedo de superficie (α) y el Índice de Desviación Estándar Móvil (MDSI). Los resultados mostraron que los índices de vegetación y las técnicas de monitoreo de la degradación y detección de cambios identificaron satisfactoriamente el comportamiento de la vegetación circundante en el área de estudio, destacándose como buenos índices de los procesos de degradación en el semiárido. Se concluyó que los métodos de detección y clasificación de cambios por árbol de decisión fueron eficientes en la identificación de áreas antrópicas durante el período experimental.Palabras clave: Árbol de decisión, Caatinga, Degradación, NDVI.

Cover crops (CCs) have demonstrated their significance in enhancing the agronomic and economic performance of corn in succession. In this paper, we assess the agronomic responses and short-term economic returns of adopting cover crops (CCs) for corn cultivation in the sandy soils of the semiarid region of northeast Brazil, with the aim of addressing the additional challenges of CCs adoption in semiarid regions. The field study was conducted in Arapiraca, Alagoas, under no-tillage conditions for two cropping seasons. A randomized complete block design was employed, comprising six CCs (sunn hemp, spectabilis, jack bean, pigeon pea, lab lab, and millet) treatments and one fallow, with 18 replications. The CCs were cultivated for 60 days before corn planting. Drip irrigation was applied during the grain-filling stage of corn growth. Over the two cropping seasons, the biomass and nutrient cycling of the CCs, corn yield, and economic returns were determined, as well as the total organic carbon (TOC) and Mehlich-1 extractable P levels in the soil after corn harvest. The grain yields with sunn hemp, spectabilis, and jack bean were superior (~10%) to that of the fallow (7.7 vs. 7.1 Mg ha⁻¹), irrespective of the cropping season. Sunn hemp exhibited a higher biomass accumulation and ensured greater nutrient cycling, except for K, while lab lab and millet displayed a similar potential, although substantial variations were observed between seasons. Under sunn hemp and jack bean, the TOC increased by ~9%, particularly in the second season. Regarding the available P, spectabilis and jack bean exhibited the highest levels, with an increase of ~74% compared to the fallow (~31.1 vs. 17.9 mg dm⁻³). Spectabilis and lab lab demonstrated more promising results, both agronomically and economically. However, millet and sunn hemp have the potential to reduce costs over multiple cropping seasons. Therefore, the adoption of cover crops is a sustainable and economically viable agricultural practice. However, it is essential to acknowledge that our results do not represent rainfed conditions and require further investigation.

The objective, in this research, was to evaluate the agricultural productivity and the financial performance of levels of irrigation in the cassava. For this, experiment was carried out, under a randomized block design, with six irrigation levels, as a function of crop evapotranspiration (L₀ = 0% (rainfed), L₁ = 40%, L₂ = 80%, L₃ = 120%, L₄ = 160% and L₅ = 200% of ET_C) and four repetitions. Was evaluated: length and mass of roots, productivity of maximum physical and economic efficiency of roots and productivity of the aerial part. The irrigation level L₅ or total useful water of 1,023 mm, got greatest productivity of the aerial part, 57 Mg ha^-1. With a total useful water of 926 mm, this irrigation level, generated the greatest length and mass of roots per plant and the maximum physical productivity, 94 Mg ha^-1. As well as the root yield of maximum economic efficiency, which is achieved with a total usable water, 914 mm. Among the irrigation levels studied, L₃ (963 mm) is the one that provides the greatest productivity of roots, 90 Mg ha^-1, and gross revenue 167% higher than in areas cultivated under rainfed conditions. Therefore, irrigation of cassava is economically viable.

Water availability is a limiting factor for plant production, especially in Brazilian semi-arid regions. The main aim of the study was to investigate the physiological effects of drought during the fruiting stage of watermelon cultivation. A completely randomized block design with four replications and six treatments varied by the number of lateral drip tapes (1 or 2) and the duration of drought stress (0, 4, and 8 days) was used. The following parameters were evaluated: relative chlorophyll content, relative leaf water content, electrolyte leakage, CO₂ assimilation (A), stomatal conductance (g_s), internal CO₂ concentration, leaf temperature, transpiration (E), water use efficiency (WUE), carboxylation efficiency (CE), yield, thickness, diameter, length, and fruit °brix, at 4 and 8 days of drought. Drought negatively affected photosynthesis, particularly in treatments with a single dripper and 4 days of drought, resulting in reductions of up to 60% in A, 68% in g_s, 44% in E, 58% in WUE, and 59% in CE, but did not have a significant effect on watermelon yield after 4 or 8 days of irrigation. It was concluded that drought influences the physiological responses of watermelon plants, mainly in reducing photosynthesis, but does not drastically affect fruit productivity in short periods of stress.

Myrciaria floribunda is a species native to the restinga areas of the Atlantic Forest that presents great phenotypic variation in fruits, great socioeconomic importance in regions of natural occurrence and high productive potential. The characterization of heterogeneous populations is crucial for plant selection and breeding programs, since it allows the distinction of superior individuals. The aim of this study was to characterize the reproductive structure of M. floribunda accessions, and to observe the influence of climate and environment on its reproductive process, through floral biology, floral morphoanatomy and reproductive phenology. Apis mellifera and Trigona spinipes are the main floral visitors of cambuí. Stigma receptivity lasts up to 5 hours after flower opening and pollen viability was above 90%. Regarding the flower structure, the female sexual organ is monocarpic, the ovary is efferent, bilocular, with two ovules per locule, the inflorescence is fascicle-like and consists of small white flowers, actinomorph symmetry, heteroclamid and monoclines. Plants bloomed irregularly throughout the year, concentrating flowering in two periods of the year with the greatest peaks in March and August, while the greatest fruiting peaks were observed in April and September.