ABSTRACT 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.

RESUMO O rompimento da Barragem do Fundão em Mariana, MG, ocorrida em 2015, trouxe o desafio de usar o Tecnossolo (tipo de solo) formado pela deposição do rejeito de mineração de ferro nas margens do Rio Doce para agricultura. O objetivo desta pesquisa foi obter a lâmina de água para otimizar a produção da forragem tropical Megathyrsus maximum cv. Mombaça, cultivada em rejeito de mineração de ferro e determinar seu coeficiente de cultura para as condições edafoclimáticas de Viçosa, MG. O experimento foi realizado durante as estações de verão, outono e inverno do ano de 2022, com a utilização de 21 lisímetros de drenagem. O experimento foi distribuído em delineamento inteiramente casualizado com 6 tratamentos (plantas em Tecnossolo com lâminas variando de 20 a 120% da evapotranspiração da cultura, obtida do tratamento-testemunha) e adição de uma testemunha (plantas em Latossolo com lâmina de 100%) com três repetições. Recomenda-se irrigação com reposição de 40% da evapotranspiração da cultura. O cultivo em Tecnossolo diminuiu a capacidade produtiva em 37,39% nos ciclos das estações do verão/outono e outono. Recomenda-se os coeficientes de cultura de 1,2 no verão e 1,5 no outono e no inverno, para o capim-Mombaça cultivado em um Latossolo.

ABSTRACT The collapse of the Fundão dam in Brazil caused one of the biggest environmental disasters. One of the challenges was how to manage the tailings so that affected areas could be reused. This study aimed to verify whether applying different irrigation depths to Xaraés grass grown with iron mining tailings would affect grass shoot and root dry masses. The experiment was set up in a randomized design with five irrigation depths (40%, 60%, 80%, 100%, and 120% of crop evapotranspiration) and two additional treatments (grass grown in tailings with soil conditioner, and grass grown in natural soil), each with three repetitions. The grass was cut four times, and the shoot dry mass was evaluated after each cut, while the root dry mass was evaluated at the end of the experiment. Our results showed that irrigation depths had a positive linear effect on shoot dry mass and an exponentially increasing effect on root dry mass, with the highest averages in the treatment applying 120% of crop evapotranspiration. This study showed that even in adverse conditions, Xaraés grass was able to grow and develop well.

ABSTRACT This study aimed to explore the efficacy of utilizing wastewater from fish farming tanks for fertigating lettuce crops as an alternative to inappropriate disposal methods. A randomized block experimental design was employed in a 3 x 8 factorial scheme, comprising three treatments: two varying percentages of wastewater (50% and 100%), alongside a control treatment employing only well water, with eight replications each. The trial was conducted in a field under protected cultivation, within a low tunnel-type structure. Biometric parameters of the lettuce plants were analyzed, including stem diameter, plant height, stem length, head diameter, root length, leaf fresh matter, leaf dry matter, stem fresh matter, stem dry matter, root fresh matter, root dry matter, leaf count, fresh shoot mass, and commercial productivity. Significant results were observed with the application of 100% wastewater treatment up to 20 days after transplanting (DAT), particularly for the biometric variables: plant head diameter (average 37.4 cm) and leaf count (average 13.7 units) at 36 DAT, of crisp lettuce Grand Rapids loose leaf seedlings. The reuse of wastewater during the experiment showed promising potential in replacing chemical fertilizers throughout the crop cycle. This practice facilitates the repurposing of water from fish farming, providing farmers with an alternative income source during the fish development phase, and mitigates improper wastewater disposal.

Abstract Among agricultural components, crop ecophysiological parameters play an essential role in garlic growth and yield. This study aimed to characterize the structure and spatialization of garlic crop parameters, evaluating spatial correlations among yield, lateral shoot growth, and plant ecophysiological components. These consisted of intercellular CO2 concentration, stomatal conductance, transpiration, water-use efficiency, carboxylation efficiency, photosynthetically active radiation, relative humidity around leaves, relative humidity in leaves, air temperature, leaf temperature, vapor pressure deficit, and water content in the air and leaves. Our results showed that irrigated purple garlic yield, lateral shoot growth, and ecophysiological components are spatially dependent. A cross-semivariogram between plant ecophysiological parameters showed negative spatial correlations and spatial dependence, with a coefficient of determination (r2) above 0.730. These findings indicate a close correlation between garlic yield and lateral shoot growth with the ecophysiological parameters studied. In short, purple garlic production had a high inter-spatial correlation with plant transpiration and water contents in the air and leaves.

ABSTRACT Peanut (Arachis hypogaea L.) is a legume belonging to the Fabaceae family, whose production aims at high pod yields and quality. This study aimed to investigate peanut physical traits and point out their relationship with total pod mass. Therefore, we evaluated total pod mass and the pod physical components: grain mass, pod shell mass, pod length, greatest and smallest transverse pod diameters, number of grains per pod, pod area, pod perimeter, and fruit volume. Initially, these morphological variables were correlated by Pearson’s coefficient, and a correlation network was used to graphically express the obtained results. Path analysis identified that pod total mass has a cause-and-effect relationship with the variables number of grains per pod, grain mass, and pod shell mass. As a result, these variables can be used in indirect selection for higher crop yields; therefore, monitoring pod total mass before harvest is a strategy to predict the final yield of peanuts.

ABSTRACT Iron mining tailings have limitations for plant growth and development due to low fertility, coupled with great restriction of physical characteristics such as low water retention, high density, and lack of structure. This study aimed to evaluate whether different irrigation depths applied to Xaraés grass grown in mining tailings influence its yield and bromatological aspects. The experiment was carried out in a completely randomized design with five irrigation depths (40, 60, 80, 100, and 120% of the crop evapotranspiration), two additional treatments consisting of grass grown in tailings with soil conditioner and in natural soil, and three repetitions. Forage dry mass, plant height, leaf: stem ratio, as well as neutral detergent fibre, acid detergent fibre, crude protein, and mineral matter content, were evaluated during four cutting cycles. Xaraés grass could establish and produce forage despite cultivation limitations in iron mining tailings, which are due to their properties. Irrigation depths showed positive and linear effects on Xaraés grass dry matter yield and heights of plants grown in iron mining tailings. The soil conditioner has potential for use in pasture cultivation in iron mining tailing.

RESUMO O aumento das disputas pelo uso de água no Cerrado brasileiro, tem demandado melhorias no manejo de irrigação e aumento da produtividade de uso da água. Neste contexto, a irrigação com déficit se apresenta como uma estratégia de manejo interessante, possibilitando economia de água sem prejuízos significativos à produtividade. O presente estudo teve como objetivo avaliar a fenologia e produtividade de uma cultivar de soja submetida a diferentes condições de déficit hídrico no solo. O delineamento experimental utilizado foi em blocos casualizados com cinco tratamentos e quatro repetições. Em cada tratamento, uma estratégia de irrigação foi aplicada com base na água disponível no solo (AD). O tratamento T1 foi realizado aplicando 80 a 100% AD; no tratamento T2, a variação permitida foi de 60 a 80% AD; no tratamento T3, foi de 40 a 60% AD; em T4, de 20 a 40% AD; e em T5, de 0 a 20% AD. Verificou-se que tanto no inverno quanto no verão, mesmo sem a necessidade de redução da retirada de água, é recomendável aplicar 60 a 80% da água disponível no solo para a cultura da soja, sem diminuir a produtividade. Em situações de restrição hídrica, é possível ter produtividade em torno de 55 e 70% no inverno e no verão, respectivamente, para a condição de 20 a 40% da água disponível no solo.

ABSTRACT The increase in disputes over water use in the Brazilian Cerrado has demanded improvements in irrigation management and increase in water use productivity. In this context, deficit irrigation is an interesting management strategy, as it enables water savings without significant losses of yield. The present study aimed to evaluate the phenology and yield of a soybean cultivar subjected to different soil moisture contents. The experimental design used was randomized blocks with five treatments and four replicates. In each treatment, an irrigation strategy was applied based on the available water in the soil (AW). The T1 treatment was performed by applying from 80 to 100% AW; in T2 treatment, the allowed variation was from 60 to 80% AW; in T3 treatment, it was from 40 to 60% AW; in T4, from 20 to 40% AW; and in T5, from 0 to 20% AW. It was verified that, in winter and summer, even without the need to reduce water withdrawal, it is recommended to apply from 60 to 80% of the available water in the soil for soybean crop, without decreasing yield. In situations of water restriction, it is possible to have yield of around 55 and 70% in winter and summer, respectively, for the condition from 20 to 40% of the available water in the soil.

ABSTRACT Chayote is originally from southern Mexico and Guatemala and has been a staple food highly appreciated in Brazil and worldwide. This study was carried out on a Red Yellow Latosol in 2020 to investigate the relationship between the physical properties of chayote fruit of the variety Cambray and their mass, aiming to indicate criteria for direct selection of more attractive fruits. The fruit parameters evaluated were mass (MAS), largest transverse diameter (LTD), smallest transverse diameter (STD), length (FTL), volume (FTV), area (FTA), and perimeter (FTP), as well as seed area (SDA) and seed perimeter (SDP). Initially, correlations among these morphological variables were assessed by Pearson's correlation coefficient, and a correlation network was used to express the results graphically. A diagnosis of multicollinearity was performed, and a condition number of 6639 (multicollinearity severe) was found. Path analysis considered the fruit mass as the main dependent variable. Our analyses showed that MAS, FTV, FTA, FTP, and STD are physical attributes with the greatest potential for selection and identification of more attractive chayote fruits of the variety Cambray for commercial purposes.

ABSTRACT Studies that seek to identify a smaller number of soil attributes that represent others can generate less expenditure of time and financial resources for monitoring cultivated areas. Thus, this study aimed to analyze the spatial distribution and spatial autocorrelation of physical attributes of an Oxisol (Latossolo Vermelho Amarelo, Brazilian Soil Classification System). The evaluated attributes consisted of soil density (SD), total porosity (TP), free porosity (FP), field capacity (FC), permanent wilt point (PW), and total water availability (TW). Semivariogram adjustments and semivariance estimates were performed to characterize the structure and magnitude of the spatial dependence of soil attributes. The attributes were distributed on thematic maps and the spatial autocorrelation was estimated by the Moran index, which quantifies the degree of autocorrelation. TP showed a high positive correlation with PWP. Soil TW showed a high positive correlation with SD and a high negative correlation with FP. In turn, FP showed a high negative correlation with SD. The results showed spatial dependence for all attributes, standing out the apparent soil density and permanent wilt point, which were good evaluators of strong spatial dependence.

ABSTRACT This study aimed to investigate relationships between the soil attributes that most affect garlic yield, which can be useful to choose a new area for the growing of this vegetable. We also aimed to study the effects of irrigation deficit at bulb formation stage (cloves) on final garlic quality and yield. The variables evaluated were garlic yield, irrigation, nitrogen, lateral shoot growing, plant water potential, bulb volume, leaf area index, soil electrical conductivity, soil mechanical resistance to penetration, and volumetric soil moisture content. Initially, the Pearson's correlation was estimated for the phenological indexes, and a correlation network was used to graphically express the results and to correct multicollinearity between variables. A track analysis was performed considering yield as the main dependent variable. The analyses showed that, of the primary garlic yield components, bulb volume is the phenological index with the greatest potential for selection and identification of garlic production. Moreover, soil resistance to penetration impaired garlic yield. Finally, irrigation deficit at clove formation stage has a negative relation with lateral shoot growing and bulb volume.

RESUMO A couve-flor é uma brássica bastante produzida e consumida no Brasil, cujo cultivo é dependente do suprimento adequado de água e nutrientes. Portanto, objetivou-se com este estudo, avaliar o efeito da aplicação de lâminas de irrigação e doses de nitrogênio nos componentes de produção e na produtividade da água da cultura da couve-flor híbrida ‘Barcelona CMS’. Foram avaliadas as lâminas de 0, 75, 100, 125 e 150% da evapotranspiração da cultura combinadas com cinco doses de nitrogênio (0, 75, 150, 300 e 450 kg ha-1). O experimento foi conduzido em delineamento inteiramente casualizado com arranjo em parcelas subdivididas. Os efeitos da desses fatores foram avaliados pela metodologia de superfície de resposta. Observou-se que a produtividade da água pela cultura apresenta relação decrescente com a lâmina de água aplicada; portanto, a produtividade é maior quando a reposição de água é menor que o recomendado. A maior produtividade total da couve-flor estimada é de 24.547,80 kg ha-1, com diâmetro médio de 19,60 cm, altura média de 12,25 cm e massa fresca da inflorescência de 858,90 g por planta, obtida com irrigação equivalente a 132,09% da evapotranspiração da cultura e 450 kg ha-1 de nitrogênio. Para obtenção do maior diâmetro e altura de inflorescência é necessária lâminas de irrigação equivalentes a 128,70 e 108,20% da evapotranspiração da cultura, respectivamente, na dose de 450 kg ha-1 de nitrogênio. Portanto, a melhor resposta da produtividade da couve-flor híbrida ‘Barcelona CMS’ pode ser obtida com lâmina de irrigação superior à evapotranspiração da cultura, independentemente da dose de nitrogênio aplicada.

ABSTRACT Cauliflower is a brassica produced and consumed in Brazil, whose cultivation depends on the adequate supply of water and nutrients. The objective of this study was to evaluate the effect of irrigation depths and nitrogen doses on the production components and water yield of cauliflower hybrid Barcelona CMS. The treatments consisted of five irrigation water depths (0, 75, 100, 125 and 150% of the crop evapotranspiration) combined with five nitrogen doses (0, 75, 150, 300 and 450 kg ha-1). The experiment was conducted in a completely randomized design with a split-plot arrangement. The effects of these factors were evaluated using the response surface methodology. The water yield of the crop decreases with increasing irrigation water depth; therefore, the yield is higher when water replenishment is lower than the recommended. The highest estimated total inflorescence yield is 24,547.80 kg ha-1, with a inflorescence mean diameter of 19.60 cm, a inflorescence mean height of 12.25 cm, and an inflorescence fresh weight of 858.90 g plant-1, obtained with an irrigation water depth equivalent to 132.09% of the crop evapotranspiration (ETc) and a nitrogen dose of 450 kg ha-1. The highest inflorescence diameter and height are obtained with an irrigation depth equivalent to 128.70 and 108.20% of ETc, respectively, and a nitrogen dose of 450 kg ha-1. Therefore, the best productivity response of the Barcelona CMS cauliflower hybrid can be obtained using an irrigation depth greater than the crop evapotranspiration, regardless of the nitrogen doses.

RESUMO A cebola é considerada a terceira hortaliça mais importante em termos de valor econômico na horticultura brasileira. A água e os nutrientes são os fatores de produção que mais limitam a produtividade da espécie, de forma que, o controle da irrigação e da fertilidade do solo são critérios preponderantes para o êxito da cultura. O objetivo neste trabalho foi avaliar a influência de diferentes lâminas de água e doses de nitrogênio sobre a produtividade da cebola, híbrido Aquarius. Foram estudadas cinco lâminas de água [0, 75, 100, 125 e 150% da evapotranspiração da cultura (ETc)] e cinco doses de nitrogênio (0, 120, 180, 240 e 300 kg ha-1, na forma de ureia), arranjados no esquema de parcelas subdivididas no espaço, no delineamento inteiramente casualizado, com quatro repetições. A irrigação foi realizada usando-se o método de aspersão. O manejo da irrigação e as lâminas de água foram definidas com uso do Irrigâmetro. A colheita foi realizada quando mais de 60% das plantas estavam estaladas. A lâmina de água correspondente a 150% da evapotranspiração da cultura proporcionou maiores produtividades total e comercial da cebola, aplicando-se doses de 226,8 e 229,8 kg ha-1 de nitrogênio, respectivamente.

ABSTRACT Onion is considered the third most important vegetable in terms of economic value in Brazilian horticulture. The factors of production which most limit the productivity of the species are water and nutrients; so, irrigation and soil fertility control are determinant criteria for crop success. The aim of this study was to evaluate the influence of different water depths and nitrogen doses on the productivity of onion, Aquarius hybrid. Five water depths [(0, 75, 100, 125 and 150% of crop evapotranspiration (ETc)] and five nitrogen doses (0, 120, 180, 240 and 300 kg ha-1, urea form), arranged in a scheme of subdivided plots, in a completely randomized design with four replicates. We used sprinkler irrigation system. Irrigation management and water depths were estimated using Irrigameter. Plants were harvested when more than 60% of them completed the vegetative period. The water depth corresponding to 150% of the crop evapotranspiration provided higher total and commercial onion productivities, applying doses of 226.8 and 229.8 kg ha-1 of nitrogen, respectively.

RESUMO Devido à importância socioeconômica do feijoeiro no Brasil, estudos que permitem estabelecer condições favoráveis ao não comprometimento da lavoura com o mofo-branco tornam-se vitais para a agricultura brasileira, haja vista os enormes prejuízos causados por este fungo, , razão por que se objetivou, neste trabalho, avaliar a incidência e severidade do mofo-branco na cultura do feijoeiro-comum (Phaseolus vulgaris L.), cultivar Madrepérola, submetido a diferentes turnos de rega, densidades de plantio e aplicação de fungicida. A pesquisa foi conduzida em Viçosa, nos anos 2011 e 2012. Na análise estatística foi utilizado o esquema de parcelas sub-subdivididas. Nas parcelas foi alocado o efeito do fungicida (com ou sem fungicida), nas subparcelas os turnos de rega (3, 6, 9 e 12 dias) e nas sub-subparcelas as densidades de plantio (6, 9, 12 e 15 plantas por metro linear), no delineamento experimental em blocos casualizados, com três repetições. A variação do turno de rega não colaborou significativamente para o controle do mofo-branco. Recomenda-se a utilização de menores densidades de plantio a fim de minimizar os danos ocasionados pela doença. A utilização do fungicida foi o principal método de controle do mofo-branco nos dois anos consecutivos.

ABSTRACT Due to the socioeconomic importance of common bean in Brazil, studies that allow establishing favorable conditions for not compromising the crop with white mold, in view of the enormous damages caused by this fungus, become vital to Brazilian agriculture. Therefore, the aim of this study was to evaluate the incidence and severity of white mold in common bean (Phaseolus vulgaris L.), cultivar ‘Madrepérola’, subjected to different irrigation intervals, planting densities and fungicide application. The research was conducted in Viçosa-MG, Brazil, in the years 2011 and 2012. The statistical analysis used the split-split-plot scheme. The fungicide applications (with or without fungicide) were allocated to plots, the irrigation intervals (3, 6, 9 and 12 days) to sub-plots and planting densities (6, 9, 12 and 15 plants per linear meter) to sub-subplots, in a randomized block design with three replicates. The variation of the irrigation intervals did not contribute significantly to the control of white mold. It is recommended to use lower planting densities in order to minimize the damages caused by the disease. The use of the fungicide was the main method of white mold control in two consecutive years.

RESUMO A escolha do método mais apropriado para estimar a evapotranspiração depende da disponibilidade de dados meteorológicos, do nível de precisão exigido e do custo de aquisição dos equipamentos. Para tal estimativa, o Irrigâmetro é de simples operação, preciso e economicamente viável aos produtores rurais, haja vista que colabora para a aplicação da lâmina de água necessária às culturas, evitando o consumo desnecessário de energia e a degradação do meio ambiente, além de aumentar a produtividade e melhorar a qualidade das culturas. Neste contexto, objetivou-se, por esta pesquisa, estimar a evapotranspiração de referência utilizando o Irrigâmetro, para as condições climáticas do Sul do Estado do Tocantins. O delineamento experimental foi inteiramente casualizado com Irrigâmetros operando com sete alturas da água no evaporatório do aparelho, representando os tratamentos, e três repetições. A evapotranspiração de referência foi obtida pelo método de Penman-Monteith – FAO 56. Para as condições climáticas analisadas, a altura da água recomendada no evaporatório do aparelho para estimar a evapotranspiração de referência na primavera é 3,4 cm; no verão, 4,0 cm; no outono, 3,8 cm e no inverno, 2,3 cm.

ABSTRACT The choice for the most appropriate method to estimate evapotranspiration depends on the availability of meteorological data, required level of precision and cost of equipment acquisition. For this estimate, the Irrigameter is simple to operate, precise and economically viable to farmers. In addition, it collaborates in the application of the necessary water depth to crops, thus avoiding unnecessary energy consumption, environmental degradation, and increasing crop yield and improving crop quality. In this context, the objective of this research was to estimate the reference evapotranspiration using the Irrigameter, for the climatic conditions of the Southern Tocantins state, Brazil. The experimental design was completely randomized with Irrigameters operating with seven water heights in the evaporator, as treatments, with three replicates. The reference evapotranspiration was obtained by FAO-56 Penman-Monteith method. For the analyzed climatic conditions, the water height in the evaporator recommended to estimate the reference evaporation in the spring is 3.4 cm; summer, 4.0 cm; fall, 3.8 cm; and winter, 2.3 cm.

ABSTRACT In the correct pasture management, nutritional factors such as nitrogen and potassium fertilization play an important role in the forage production and quality. The aim was to evaluate the effects of the application of water levels, nitrogen and potassium doses in the Xaraés grass in the south of the State of Tocantins. For this, Xaraés grass was cultivated in the experimental field of the Federal University of Tocantins, municipality of Gurupi, TO. We used a mixture of fertilizer, combinations of N and K2O following the 1 N: 0.8 K2O ratio. To evaluate the effect of irrigation water levels and combinations of N and K2O doses in Xaraés grass, the plant height, the crude protein content and neutral detergent fiber were determined. The greatest height observed in the grass was 61.6 cm, with the dose application of 700 kg ha-1 yr-1 of N: 0.8 K2O and a water level of 120% of the ETc. The highest protein content was 11.7%, with the highest dose application of fertilizer and absence of irrigation. The highest fiber content in neutral detergent was 64%, with the estimated amount of 385.5 kg ha-1 yr-1 of N: 0.8 K2O and a water level of 120% of ETc. The conclusion was that the plant height, fiber detergent and crude protein content were influenced by the change in water level of irrigation and fertilizer doses. The values of plant height and crude protein increased with the increase of water levels and manure dose, while the fiber content of neutral detergent decreased with the increase of irrigation and varied little with the increase of fertilizer dose.