Water availability is a crucial factor in the final productivity of cowpea. The objective of this work was to evaluate the production and productivity components of cowpea under different irrigation depths in Amazonian conditions. The experiment was carried out at the School Farm of the Federal Rural University of Amazonia, in the municipality of Castanhal-PA, using the cultivar BR3 Tracuateua, from September to November 2014, 2015, and 2016. The experimental design was conducted on six blocks and four treatments, where the four irrigation depths of 0, 25, 50, and 100% of crop evapotranspiration were tested. The productivity analysis was performed when 90% of the plants were in the phenological stage R9. The evaluated production components were pod length, number of pods per plant, number of grains per pod, mass of one hundred grains, and harvest index. There was a statistical difference among all treatments for the components of production and among productivities. An average reduction of 827 kg ha⁻¹ in cowpea productivity was observed during the three years of study, when the treatment without irrigation was compared with the treatment irrigated with 100% of the crop’s water demand. It was found in this research that the simple fulfillment of the nutritional and phytosanitary demands of the crop, associated with an adequate planning of when to plant in the region, would already help in the improvement of local production when choosing times where the water deficit in the reproductive phase is less than 33 mm.

Com objetivo de fornecer informações técnicas sobre a produção da couve-flor irrigada em casa de vegetação no nordeste paraense, instalou-se um experimento na Fazenda Experimental da UFRA, no município de Igarapé-Açu, com a cultivar híbrida Desert, que apresenta adaptabilidade para o clima da região. O delineamento utilizado foi em blocos casualizados em esquema fatorial 4 x 3, com 12 tratamentos e 3 repetições. Os tratamentos foram constituídos por quatros tensões de água no solo (15, 30, 45 e 60 kPa), com indicativo no momento de irrigar e três doses de boro (0, 3 e 6 kg ha-1) aplicadas via foliar. O método de irrigação utilizado foi o gotejamento e o manejo de irrigação foi via tensiometria. As parcelas experimentais apresentaram 3,6 m2 constituídas de 8 plantas, com espaçamento de 0,8 m entre linhas e 0,5 m entre plantas. Em cada parcela, foram avaliadas 4 plantas centrais, totalizando 288 plantas. De acordo com os dados obtidos, a cultivar híbrida Desert mostrou-se promissora para o cultivo nas condições edafoclimáticas da região nordeste do Pará. A tensão que apresentou melhores resultados foi a de 37 kPa, obtendo produtividade de cabeça de 11,3 t ha-1, massa fresca de 450 g, massa seca de 31,48 g, diâmetro de 15,6 cm, circunferência de 50,99 cm e altura de 9,87 cm. As doses de boro não apresentaram diferença significativa.

Water-use efficiency (WUE) plays a crucial role in sustainable crop production, particularly in water-limited environments where maximizing natural resource use is essential. This study evaluated the physiological and agronomic performance of two Piper nigrum cultivars, Clonada and Uthirankotta, grown under different soil water potential conditions. The trial was conducted in a 1930 m² field using a randomized block design and drip irrigation system, calibrated to 3.55 L h⁻¹ with a uniformity of 97%. Soil water availability was managed based on daily tensiometer readings at 20 and 30 cm depths, triggering irrigation at defined tensions (10–55 kPa). Clonada exhibited higher net CO₂ assimilation rates (A) and stomatal conductance (g_s), but these responses did not lead to higher yields. In contrast, Uthirankotta consistently maintained superior water-use efficiency and yield across all soil moisture conditions by favoring water conservation and targeted biomass allocation over maximized gas exchange. Both cultivars performed optimally at a soil water potential range of 25–35 kPa, with declines in yield and gas exchange parameters at higher tensions (45–55 kPa). Under such conditions, Uthirankotta was 51.3% more water-use efficient and 40.8% more productive than Clonada. Based on this, a Principal Component Analysis (PCA) further demonstrated distinct physiological profiles, underscoring trade-offs between yield and water-use strategies. These results highlight the significance of cultivar selection for optimizing WUE and provide valuable insights into irrigation management and breeding programs aimed at boosting black pepper performance under water-limited conditions.

FENOLOGIA DO COQUEIRO IRRIGADO EM FUNÇÃO DE DIFERENTES TAXAS EVAPOTRANSPIRATIVAS MARIA DO BOM CONSELHO LACERDA MEDEIROS1; LOURENÇO EMÍDIO CARRÉRA VALENTE2; FLÁVIO HENRIQUE SANTOS RODRIGUES1; WILLIAM LEE CARRERA DE AVIZ1; PAULO MANOEL PONTES LINS3 E JOAQUIM ALVES DE LIMA JÚNIOR4 1Discente do curso de pós-graduação em agronomia, Universidade Federal Rural da Amazônia (UFRA), Avenida Presidente Tancredo Neves, 2501, Terra Firme, 66.077-830, Belém, Pará, Brasil. E-mail: melmedeirosagro@gmail.com, flaviohsrodrigues2@gmail.com, william.aviz@gmail.com. 2Discente do curso de agronomia, Universidade Federal Rural da Amazônia (UFRA), Av. Barão de Capanema, 5514, Caixa d’água, 68700-005, Capanema, Pará, Brasil. E-mail: lourencovalente.agro@gmail.com 3Superintendente agrícola Sococo S.A., Sococo Fazenda Reunidas, Estrada Colônia Ferreira Pena Km 04, S/N, Distrito Americano, 68790-000, Santa Isabel, Pará, Brasil. E-mail: paulom@sococo.com.br 4Professor titular do curso de agronomia, Universidade Federal Rural da Amazônia (UFRA), Av. Barão de Capanema, 5514, Caixa d’água, 68700-005, Capanema, Pará, Brasil. E-mail: joaquim.junior@ufra.edu.br 1 RESUMO O coqueiro (Cocus nucifera L.), popularmente conhecido como ‘coqueiro anão verde’, é uma monocotiledônea da família Arecaceae que possui grande importância econômica. A fertirrigação, técnica na qual os fertilizantes são aplicados via água de irrigação, o que favorece uma maior absorção dos nutrientes, conjuntamente com a irrigação, são técnicas eficientes para o pleno desenvolvimento das culturas. O objetivo do estudo foi avaliar a fenologia do Cocus nucifera L sobre diferentes taxas da evapotranspiração (ET0). O experimento foi realizado na Fazenda Reunidas Sococo na cidade de Santa Izabel do Pará, PA. Foi adotado o delineamento em blocos casualizados em esquema fatorial 3 x 9 (três taxas de ET0, calculadas pelo método de Penman-Monteith, com nove períodos de análise) e três blocos. A irrigação foi realizada por microaspersão com turno de rega fixo. Foram selecionadas três plantas da parcela útil, nas quais foram avaliadas as seguintes características: comprimento do estipe, circunferência do coleto e número de folhas vivas e de folhas mortas. As características fenológicas avaliadas foram diretamente influenciadas pelas taxas evaporativas e condições climáticas, se destacando positivamente o tratamento com reposição de 100% da ET0, confirmando que em situações de estresse, o coqueiro não apresenta um desenvolvimento vegetativo adequado. Palavras-chave: condições climáticas, fertirrigação, irrigação. MEDEIROS, M.B.C.L.; VALENTE, L.E.C.; RODRIGUES, F.H.S.; DE AVIZ, W.L.C.; LINS, P.M.P.; LIMA JÚNIOR, J.A.; PHENOLOGY OF IRRIGATED COCONUT PALM AS A FUNCTION OF DIFFERENT EVAPOTRANSPIRATION RATES. 2 ABSTRACT The coconut palm (Cocus nucifera L.), popularly known as the 'green dwarf coconut', is a monocot of the Arecaceae family with great economic importance. Fertigation, a technique in which fertilizers are applied via irrigation water, which favors a greater absorption of nutrients, with irrigation, an efficient technique for the full development of crops. This study aimed to evaluate the phenology of Cocus nucifera L under different evapotranspiration (ET0) rates. The experiment was conducted at Reunidas Sococo Farm in the city of Santa Izabel do Pará, PA. The randomized block design was adopted in a 3 x 9 factorial scheme (three ET0 rates, calculated by the Penman-Monteith method, with nine periods of analysis) and three blocks. The irrigation was performed by micro-sprinkler with a fixed irrigation scheduling. Three plants were selected from the useful plot, in which the following characteristics were evaluated: stipe length, collar circumference, and number of live and dead leaves. The phenological characteristics evaluated were directly influenced by evapotranspiration rates and climatic conditions, with the treatment with the replacement of 100% of the ET0 standing out positively, confirming that in stress situations, coconut does not present an adequate vegetative development coconut. Keywords: climatic conditions, fertigation, irrigation.

Jambu (Acmella oleracea (L.) R.K.) is a short-cycle leafy vegetable from the Amazon region, which needs an adequate availability of water and nutrients, mainly nitrogen, to obtain a rapid mass increase. This research aimed to study the effect of different soil-water stresses and nitrogen doses on jambu cultivation in the state of Pará. The experiments were conducted at the Igarapé-Açu experimental farm of the Federal Rural University of Amazonia (UFRA). The Jamburana variety was used in a 10 × 10 cm spacing, using a randomized block design in a 4 × 4 factorial scheme with three replications. Each plot had a dimension of 0.4 × 0.5 m (0.2 m2), totaling 20 plants in 4 rows, but only the plants of the central rows were useful. Treatments consisted of four soil-water stresses (12, 18, 24, and 30 kPa) as an indication of the irrigation time (critical stress), using drip irrigation, and four nitrogen doses (0, 50, 100, and 150 kg ha−1). The use of soil-water stress of 12 kPa associated with nitrogen fertilization at a dose of 150 kg ha−1 is recommended for better development and production of jambu under the conditions this experiment was conducted.

Water-use efficiency (WUE) is a crucial parameter for sustainable crop production, particularly in water-limited environments where optimizing resource utilization is essential for maintaining productivity and resilience. This study investigates the physiological and agronomic responses of two black pepper (Piper nigrum) cultivars, Clonada and Uthirankotta, under varying soil water potentials and along the time. Results indicate that WUE varies significantly between cultivars due to distinct physiological strategies. Clonada exhibited higher photosynthetic rates, stomatal conductance, and gas exchange efficiency, leading to greater yield performance under moderate stress conditions. Conversely, Uthirankotta demonstrated consistently higher WUE across all water conditions, prioritizing water conservation and biomass accumulation over gas exchange efficiency. Both cultivars displayed peak performance at 25–35 kPa soil water potential, with yield and physiological efficiency declining at higher tensions. Principal Component Analysis (PCA) confirmed distinct physiological profiles, reinforcing the trade-offs between productivity and water-use strategies. These findings highlight the importance of cultivar selection for optimizing WUE in black pepper cultivation and provide insights for improving irrigation management and breeding programs.