Tayssa Menezes Franco

Climate variability poses a major challenge to tropical citrus production, especially in regions with marked water seasonality. This study aimed to evaluate the effects of irrigated and rainfed regimes on the crop coefficient, energy partitioning, and yield of ‘Tahiti’ acid lime grafted onto Swingle citrumelo. The study was conducted from 2023 to 2025 in Capitão Poço, Pará State, Brazil, using a completely randomized design with two treatments (irrigated and rainfed) and 10 replications, totaling 20 plots. Micrometeorological data were obtained from an automatic weather station installed in the experimental area, and crop evapotranspiration (ETc) was estimated using the soil water balance method. An irrigation depth of 4.42 mm (66.3 L) per plant per day was sufficient to increase the average fruit yield and to concentrate 50.8% of the 2024 agricultural production during the off-season. During dry periods, the irrigated regime showed an average ETc of 3.7 mm per day and a crop coefficient (Kc) of 1.0, both indicating conditions close to atmospheric evaporative demand. In contrast, the rainfed regime had an average ETc of 2.9 mm per day and a Kc of 0.8. Despite the yield increase, radiation balance analysis revealed sensible heat flux values approaching latent heat flux values, indicating differences in flux partitioning under drip irrigation. Total yield was higher in the irrigated system (40.67 t ha−1) compared to the rainfed system (19.50 t ha−1), with significantly greater yields during the off-season.

The coconut palm (Cocos nucifera L.) is a perennial fruit palm of great global socioeconomic importance. To increase production and mitigate water deficit during the less rainy season, irrigation systems have been expanded across various fruit species, especially coconut palms, which are sensitive to water deficits. This study aimed to evaluate the influence of irrigation depths, based on crop evapotranspiration, on the physical variables of the fruits, fruit yield, and water productivity (in terms of fruits and coconut water) in a commercial coconut plantation in Santa Izabel do Pará, in the state of Pará, Brazil. The experiment was conducted in the municipality of Santa Izabel do Pará (PA), using a randomized block design with six blocks and four treatments corresponding to irrigation depths of 0 (rainfed), 50, 100, and 125% of crop evapotranspiration, with 24 experimental plots. The evaluation was carried out in relation to production variables: fruit mass and fruit water volume. Fruit yield and water productivity were assessed in terms of fruit number and coconut water volume. Statistical analyses were performed at a significance level equivalent to p ≤ 0.05. The variables of fruit production and yield were influenced by irrigation. Irrigation had a positive effect on water productivity in terms of fruit production; however, no differences were observed among treatments for water volume. It is concluded that irrigation is essential to maximize the production and yield of dwarf green coconut, especially in regions with prolonged dry periods.

Understanding soil, plant attributes, and carrot crop dynamics is vital for optimizing site-specific management practices and enhancing crop yield and soil quality. This study aimed to ascertain the dependence and spatial variability between irrigated carrot yield and soil physical attributes in a clayey Oxisol. The research took place during the 2021 growing season in a commercial carrot production area in Campos Altos, MG, Brazil. One hundred sampling points were established within the irrigated area, distributed across a square expanse of 40,000 m², positioned at the centers of 20 × 20 m grids. The study revealed high yield in the irrigated carrot crop (99.74 t ha^-1) with moderate variability. Soil attributes displayed a range of heterogeneity, ranging from low to extremely high, contingent on the variable assessed, as determined by the coefficient of variation. Among the variables exhibiting spatial dependence, particle density exhibited a minimum range of 40 m, which is recommended for further studies on irrigated carrot cultivation in a clayey Oxisol. Total soil water availability demonstrated a positive spatial correlation and proved to be the recommended variable for estimating the spatial variability of carrot crop yield.

The collapse of the Fundão Dam in Mariana, MG, in 2015 introduced the challenge of using Technosol, a soil type formed by deposition of iron mining waste along the Doce River banks, for agricultural purposes. This study aimed to determine the optimal water depth for enhancing production of tropical forage, Megathyrsus maximus cv. Mombasa, when grown on iron ore tailings. Additionally, it sought to establish a crop coefficient applicable to the edaphoclimatic conditions of Viçosa, MG, Brazil. The experiment was conducted throughout the summer, fall, and winter of 2022, employing 21 drainage lysimeters. A completely randomized experimental design was adopted, featuring six treatment groups (plants in Technosol receiving water depths ranging from 20 to 120% of the crop’s evapotranspiration, as derived from the control treatment), along with a control group (plants in Latosol with a depth of 100%), each with three repetitions. Our findings showed that irrigation must replace 40% of the crop evapotranspiration. Moreover, cultivating in Technosol resulted in a reduction of productive capacity by 37.39% during the summer/fall and fall seasons. For Mombasa grass grown in Oxisol, crop coefficients of 1.2 during the summer and 1.5 during the fall and winter are advised.

Cedro-rosa (Cedrela fissilis) is native to Brazil with great potential for seedling production. However, soil correction is necessary to improve its performance, due to the edaphoclimatic conditions in Brazil, where soils have a high weathering degree and large amounts of Fe and Al oxides. Here, we evaluated the combined effect of soil acidity correction by liming and phosphate fertilization using single superphosphate on the growth and development of cedro-rosa seedlings cultivated in Amazonian soil. The study was carried out in a greenhouse at the Universidade Federal Rural da Amazônia (UFRA) – Campus Capitão Poço, between July and December 2019. Different levels of base saturation (V%) showed no influence on the variables analyzed. On the other hand, phosphorus (P), calcium (Ca), and sulfur (S) supplied by single superphosphate significantly influenced growth and development of cedro-rosa seedlings. The optimum P levels for stem diameter (SD), leaves number (LN), root dry matter (RDM), stem dry matter (StDM), leaf dry matter (LDM), total dry matter (TDM) were 405, 286, 385, 421.87, 393.75, 445 mg dm^-3 of P, respectively. Seedling quality (DQI) showed a positive linear response to levels of P, Ca, and S in single superphosphate. Thus, fertilization with P was necessary at the nursery stage for the cultivation of the species in soil of low chemical fertility. For better quality of cedro-rosa seedlings grown in pots, the application of 400 mg dm^-3 of P is recommended.

O milho nos tempos contemporâneos tornou-se o grão mais produzido no mundo. Portanto esse trabalho objetivou avaliar o efeito da absorção de fósforo nas características biométricas e produtivas da cultura do milho nas fases V6, V8, florescimento e colheita. Os atributos avaliados foram: teor de fósforo, massa fresca de folha no florescimento, massa fresca de caule no florescimento, massa seca de folha no florescimento, massa seca de caule no florescimento, massa seca do caule, massa fresca do caule, massa fresca da folha na colheita, massa seca da folha, massa fresca de folha em V6, massa seca de folha em V6, massa fresca de caule em V6, massa seca de caule em V6, massa seca de caule em V8, massa fresca de caule em V8, massa fresca de folha em V8, massa seca de folha em V8. Através da análise de trilha foi permitido estabelecer correlações entres estas variáveis que são indicativos de produtividade e qualidade do milho. Resultados mostram pela correlação de Pierson que massa fresca de caule e massa seca de caule nas diferentes fases estudadas, apresentam altos níveis de correlação positiva indicando que suas massas frescas e secas tendem, após testes e análises, ter proximidade de relações. Como conclusões, compreende-se que de maneira direta e positiva o fósforo obteve maior correlação com o peso médio de grãos. Efeito direto e negativo apenas massa fresca de folha no florescimento obteve resultados consideráveis em relação ao teor de fósforo.

A andiroba possui grande importância socioeconômica para a Amazônia. Com isso, objetivou-se avaliar o uso da adubação orgânica e turno de rega no desenvolvimento de mudas de andiroba. O experimento foi conduzido em casa de vegetação na UFRA Campus de Capitão Poço - PA. Foram analisadas as seguintes proporções de adubos orgânicos: a) 100% de solo, b) 90% de solo + 10% de adubo orgânico, c) 80% de solo + 20% de adubo orgânico e d) 70% de solo + 30% de adubo orgânico. Além disso, as mudas foram submetidas aos seguintes regimes hídricos: a) diário, b) 5 em 5 dias e c) 10 em 10 dias. Avaliaram-se a altura de plantas (AP), comprimento (CC) e diâmetro do caule (DC), número de folhas (NF), transpiração foliar (E), resistência estomática (Rs), matéria seca de raiz (MSR), caule (MSC), folha (MSF), parte aérea (MSPA) e total (MST), relação MSR/MSPA e as alocações de biomassa nas diferentes partes vegetativas. O delineamento utilizado foi de blocos ao acaso, em esquema fatorial 4 x 3 x 5 (proporções de adubo orgânico, regimes hídricos e tempos de avaliação) para AP, CC, DC e NF e, em esquema fatorial 4 x 3, para as demais variáveis. As médias foram submetidas ao teste de Tukey (p<0,05). As plantas apresentaram desenvolvimento satisfatório com irrigação diária. As doses mais adequadas foram de 10% e 20% para a maioria das variáveis. Dessa forma, fica evidente a necessidade do uso da adubação orgânica com irrigação diária na produção de mudas de andirobeira.

A região amazônica contribui expressivamente para o setor mineral brasileiro, entretanto, vem ocorrendo o aumento de áreas degradadas por mineração. Diante disso, o objetivo da pesquisa foi avaliar o efeito do uso da revegetação nos atributos químicos do solo em área sob a ação de extração de seixo na Amazônia. O experimento foi conduzido em uma área de mineração de seixo em Capitão Poço – PA. O delineamento experimental usado foi em blocos ao acaso, em parcelas subdivididas. As parcelas foram constituídas de dois tratamentos: calagem + escarificação e sem calagem e sem escarificação. As subparcelas foram compostas de cinco tratamentos: 1) plantio de mudas de sete espécies + 500 kg de serrapilheira; 2) plantio de mudas de sete espécies + 50 g planta-1 de NPK + 200 g planta-1 de cama aviária; 3) plantio de mudas de sete espécies + 50 g planta-1 de NPK + 200 g planta-1 de cama aviária + plantio de duas linhas de feijão-caupi entre as linhas das sete espécies; 4) plantio de mudas de sete espécies + 50 g planta-1 de NPK + 200 g planta-1 de cama aviária + 500 kg de topsoil e 5) regeneração natural. Em geral, os teores de MOS, P e K, no solo construído foram inferiores se comparados com os valores obtidos na área de floresta secundária. Além disso, verificou-se redução dos teores de Al e Na nos solos construídos. Dessa forma, o uso da técnica de revegetação mostrou-se promissora, porém é necessário o acompanhamento em longo prazo.