Cocoa plantations in Brazil have been expanding beyond the borders of traditional regions by implementing a strategy based on irrigation and the establishment of crops exposed to full sunlight. The ...quantification of transpiration is essential to the establishment and management of crops, and is the main factor in the determination of water demand. This study had as its objective the estimating of transpiration of young cocoa trees as a function of reference evapotranspiration (ETo) and soil matric potential (Ψw). Two experiments were conducted, one in a greenhouse and the other in the field, using clones and seminal plants. Soil water content, plant transpiration and reference evapotranspiration were monitored. Cocoa trees were subjected to soil moisture reduction and their transpiration decreased linearly both in the field and in the greenhouse, due to decreases in the soil matric potential beyond a critical point. In the greenhouse average transpiration could be linearly estimated as a function of ETo when Ψw was higher than –24.89 kP. Drying soil conditions resulted in a reduction in transpiration by approximately a 2 % per unit decrease in Ψw. Under field conditions; clonal plant transpiration decreased linearly beyond the critical matric potential of –65.02 kPa, while in seminal plants this reduction occurred beyond –79.48 kPa. Clonal plants were more sensitive to soil water variations with average transpiration lower than that of seminal cocoa tree plants.
Production of lettuce with brackish water in NFT hydroponic system Silva, Jucicléia Soares da; Paz, Vital Pedro da Silva; Soares, Tales Miler ...
Semina. Ciências agrárias : revista cultural e científica da Universidade Estadual de Londrina,
05/2018, Volume:
39, Issue:
3
Journal Article
Peer reviewed
Open access
Groundwater reserves in the semi-arid regions, which are mostly brackish, could be used to meet local water demands. Hydroponic cultivation is an alternative of rational use of water. Thus, the ...objective of this work was to evaluate the technical feasibility of using brackish groundwater in the semi-arid region of Bahia and Recôncavo of Bahia for hydroponic production of curly lettuce cv. ‘Verônica’ and purple lettuce cv. ‘Quatro Estações’. The experiment was conducted in a greenhouse in the city of Cruz das Almas, Bahia State, in a randomized block experimental design, composed of seven treatments T1- public-supply water; T2- water from the well of UFRB; T3- reject water from the well of Cruz das Almas; T4- water from the well of Sapeaçu; T5- reject water from the well of Sapeaçu; T6- reject water from the well of Conceição do Coité and T7- artificially salinated water (NaCl) and six replicates in an experimental hydroponic structure using the nutrient film technique (NFT). The following variables were analyzed: number of leaves, shoot fresh matter, shoot length, root length, shoot dry matter, and root dry matter. Relative shoot dry matter production in curly lettuce increased by 1, 5, and 2% in the treatments T2, T3, and T4, respectively, whereas in purple lettuce, the increments were 10, 1, and 20%, respectively, for the same treatments. The use of brackish groundwater from the deep tubular wells of the Federal University of Recôncavo da Bahia and Sapeaçu and desalination reject water from the tubular well of Cruz das Almas proved to be technically feasible for hydroponic lettuce production.
The use of treated domestic effluent in agriculture is important not only as a source of water but also as a source of nutrients for crops. In this context, the objective of this study was to ...evaluate its use for the production of ornamental sunflower cv. ‘Anão de Jardim’ in a bench-type low cost hydroponic system, inferring on its technical feasibility and observing the possible impacts on the crop. The experiment was carried out in a greenhouse adopting a completely randomized design with four treatments (T1 - nutrient solution of Furlani 100%, prepared in municipal supply water - control), T2, T3 and T4 - nutrient solution of Furlani, respectively, with 100, 75 and 50% strength, prepared in treated domestic effluent and six replicates, totalizing 24 experimental units, each consisting of 15 plants. All treatments met the nutritional requirements of the plants and presented adequate contents of N, P, K, Ca and Mg in leaf and stem at harvest leading to satisfactory plant growth and produced acceptable commercial grade chapters and stems. The plants under treatment T4 although produced chapters of commercial quality but exhibited great variability in comparison to the other treatments, therefore except this treatment any other treatment can be used for hydroponic production of ornamental sunflower utilizing treated domestic effluents.
This work evaluated the changes in physicochemical attributes in semiarid soil submitted to domestic sewage submitted to anaerobic treatment, in the presence or absence of the cultivar. The ...experimental unit was set up in the rural area of Ouro Verde, municipality of São Domingos, state of Bahia, Brazil. Five treatments were tested by diluting wastewater and supply in the percentages 0 %, 25 %, 50 %, 75 %, and 100 %. Soil samples were taken at depths of 0 - 35 cm (P1), and 35 - 70 cm (P2) from the sampling units with cultivar, control units without cultivar, and the unit without treatment (white). The cultivar was of corn (Zea mays L.), of the family Poaceae, which has a relatively short cycle (60 - 120 days). At the end of the experiments, after the harvest, the control units presented average Ca, P, K, and OM percentages from 5% to 66 % higher than white, while in the sample units, the percentages were 4% to 44 % higher, due to consumption by the cultivar. The contribution of TKN in the sampling units was the minimum sufficient for consumption by the cultivar. Compared to the control units, the sampling units presented Na, SAR, PST, and EC percentages higher by 35 - 113 % in P1, and by 29 – 456 % in P2, which indicates a higher consumption of cation by the cultivar in P2; change of ion distribution in the soil cation exchange site; as well as predisposition of the soil to sodification (increase of PST) and salinization (increase of EC). Consequently, the application of treated domestic effluents for agricultural activity, although it adds nutrients to the soil, has negative effects due to the increase in soil sodicity and salinity.
In order to generate information about the potential of ‘Biquinho’ pepper as an alternative crop for regions with limited supply of freshwater but with availability of brackish water, such as the ...semiarid region, a study was carried out with this crop grown in NFT (Nutrient Film Technique) hydroponic system for 120 days after transplanting (DAT). The experiment used nutrient solution prepared in water from the local municipal supply system (electrical conductivity of water –ECw = 0.34 dS m−1) and six other brackish waters prepared artificially by the addition of NaCl, with electrical conductivity of the nutrient solution -ECsol: 2.70 (control), 3.64, 4.58, 5.28, 6.09, 6.90 and 7.77 dS m−1, composing seven treatments repeated six times in randomized blocks. Fruit yield, salt tolerance and yield earliness index were evaluated. The yield of ‘Biquinho’ pepper cultivated in NFT hydroponic system, without restriction of salinity, was 2.87 kg per plant, corresponding to 46.1 Mg ha−1, considering an estimated area of 0.62 m2 per plant. A plateau followed by exponential decay model was fitted to determine the threshold salinity of ‘Biquinho’ pepper, which was 5.22 dS m−1 in the nutrient solution, corresponding to the relative potential yield. Salinity reduced the yield earliness index of ‘Biquinho’ pepper.
•Production of ‘Biquinho’ pepper is satisfactory in NFT hydroponic cultivation system.•The threshold salinity of ‘Biquinho’ pepper is 5.22 dS m−1 in the nutrient solution.•The increase in the salinity of the nutrient solution reduces the initial character of 'Biquinho' pepper production.•Nonlinear models better explained the reduction in the relative productivity of ‘Biquinho’ pepper, under NFT hydroponic cultivation.
The water and nutritional potential of wastewater has been frequently exploited as an alternative water source for the irrigation of crops, especially in regions affected by the scarcity of water ...resources. Thus, this study aimed to evaluate growth and production of ornamental sunflower (Helianthus annuus L.) cv. Anão de Jardim irrigated with different dilutions of treated domestic sewage in public-supply water. The experiment was conducted in completely randomized design with five treatments and four replicates, in a greenhouse, in the Experimental Area of the Agricultural Engineering Graduate Program of the Federal University of Recôncavo of Bahia, located in the municipality of Cruz das Almas - BA, Brazil. Treatments started seven days after transplanting of the seedlings and consisted of five dilutions of treated domestic sewage (TDS) in public-supply water (PSW) (100% PSW – control; 25% TDS + 75% PSW; 50% TDS + 50% PSW; 75% TDS + 25% PSW and 100% TDS). In the control treatment, plants were fertilized with 100% of the mineral fertilization recommendation, whereas plants in treatments with effluent received 50% of the nitrogen (N) and potassium (K) recommendation. Biometric (plant height, stem diameter, number of leaves, shoot fresh and dry matter and leaf area) and production (capitulum internal and external diameter, capitulum fresh and dry matter, beginning of flowering and full capitulum opening) indicators evaluated at harvest demonstrated that ornamental sunflower plants irrigated with 100% TDS showed similar performance to those irrigated with PSW, which makes it possible to infer on the possibility of replacing PSW by TDS in irrigation, along with the 50% reduction in the recommendation of N and K fertilization, with no damage to the growth and production of ornamental sunflower, cv. Anão de Jardim, thus leading to the saving of good-quality water and fertilizers.
The recent increase of irrigation practices in forage cactus crops makes appropriate irrigation management criteria necessary. In this study, the morphological and yield characteristics of forage ...cactus cultivars were evaluated for some soil-based irrigation management criteria. Five experiments were carried out simultaneously under semiarid conditions in a randomized block design, with forage cactus cultivars Orelha de Elefante (OE), IPA-Sertânia (IPA), Doce (DC), Gigante (GG), and Orelha de Onça (OO). For each cultivar, irrigation management was performed using four upper thresholds of matric potential (−0.2, −0.33, −1, and −3 atm), as well as a non-irrigated (rainfed) treatment. Forage cactus crop yield was evaluated after 12 months and responded positively and similarly to irrigation management using any of the thresholds, with a significant increase in the cladode area and, overall, a positive effect on growth and yield parameters. Very high irrigation water productivity up to 75 kg m−3 was obtained especially in the −3 atm threshold treatment, whereas an increase of the threshold potential caused a sharp reduction of water productivity. We conclude that irrigation management of forage cactus grown in semi-arid climates is highly beneficial and that unconventionally low matric potential thresholds may be used.
•Upper matric potential thresholds for forage cactus irrigation were investigated.•Even with low thresholds, irrigation resulted in significant yield increase of cactus.•A low threshold of −3 atm resulted in a very high water productivity.•Recommended thresholds for forage cactus irrigation are unconventionally low.
The determination of soil moisture is very important because it is the property with the most influence on the dielectric constant of the medium. Time-domain reflectometry (TDR) is an indirect ...technique used to estimate the water content of the soil (?) based on its dielectric constant (Ka). Like any other technique, it has advantages and disadvantages. Among the major disadvantages is the need for calibration, which requires consideration of the soil characteristics. This study aimed to perform the calibration of a TDR100 device to estimate the volumetric water content of four horizons of a Yellow Argisol. Calibration was performed under laboratory conditions using disturbed soil samples contained in PVC columns. The three rods of the handcrafted probes were vertically installed in the soil columns. Weight measurements with digital scales and daily readings of the dielectric constant with the TDR device were taken. For all soil horizons evaluated, the best fits between the dielectric constant and the volumetric water content were related to the cubic polynomial model. The Ledieu model overestimated by approximately 68 % the volumetric water content in the A and AB horizons, and underestimating by 69 % in Bt2, in relation to volumetric water content obtained by gravimetry. The underestimation by linear, Topp, Roth, and Malicki models ranged from 50 % to 85 % for all horizons.
Considering the growing water crisis, using wastewater helps reduce the pressure on good-quality water consumption. In this context, this study aimed to evaluate the growth, production, and essential ...oil content of Alfavaca Basilicão and Grecco a Palla basil genotypes with a DFT (deep flow technique) hydroponic system adapted to PVC tubes at different recirculation intervals of nutrient solutions prepared with treated domestic effluents. The experiment was performed in a greenhouse with Alfavaca Basilicão and Grecco a Palla basil genotypes analyzed individually. It was a completely randomized design with four replicates in a 2 x 3 factorial scheme: two types of water (public-supply water and wastewater) and three recirculation intervals of nutrient solutions (2, 4, and 6 hours). At 35 days after transplanting, the study evaluated plant height, stem diameter, shoot fresh mass, shoot dry mass, water consumption, water use efficiency, and essential oil content and yield. The types of water did not significantly influence the variables of growth, production, and essential oil content of the basil genotypes. Basil cultivation with the DFT system in tubes is technically feasible with nutrient solutions prepared with treated domestic effluents and recirculation every 2 and 6 hours for Grecco a Palla and Alfavaca Basilicão genotypes, respectively. The means of essential oil content were 1.6 and 1.7% (v/m) for Alfavaca Basilicão and Grecco a Palla genotypes, respectively.
The knowledge of water consumption and the efficiency of water use by crops is extremely important in the elaboration of agronomic and hydraulic projects of hydroponic systems. Thus, the present ...study determined the water consumption and water use efficiency of ‘Biquinho’ pepper cultivated in the hydroponic system using seven levels of electrical conductivity of the nutrient solution (ECsol) of 2.70, 3.64, 4.58, 5.28, 6.09, 6.90, and 7.77 dS m-1 and six replicates in randomized blocks. The hydroponic system used was the Nutrient Film Technique (NFT). The water consumption per plant was determined at an interval of ten days in the crop cycle (120 days after transplanting). The maximum mean daily water consumption was equal to 5.88 L plant-1 during the period 111-120 DAT, for ECsol of 4.58 dS m-1. The maximum water consumption for the crop cycle (120 DAT) was 275.66 L per plant for an estimated ECsol = 4.11 dS m-1. The highest water use efficiency (WUE), based on the total production of fruit fresh mass (ripe and unripe fruits) of ‘Biquinho’ pepper was 10.84 kg m-3 up to an estimated ECsol of 5.18 dS m-1, with an exponential reduction thereafter. The salinity of the nutrient solution, biomass production, and evapotranspiration are factors that influence the most water consumption of ‘Biquinho’ pepper.
RESUMO: O conhecimento do consumo hídrico e eficiência do uso da água pelas culturas são extremamente importantes para o dimensionamento de sistemas agronômicos e projeto hidráulico dos sistemas hidropônicos. Neste contexto, o presente estudo determinou o consumo de água e a eficiência do uso da água da pimenta ‘Biquinho’ cultivada no sistema hidropônico utilizando sete níveis de condutividade elétrica da solução nutritiva (CEsol) de 2,70, 3,64, 4,58, 5,28, 6,09, 6,90 e 7,77 dS m-1 e seis repetições em blocos casualizados. O sistema hidropônico utilizado foi a técnica do fluxo laminar de nutrientes. O consumo hídrico por planta foi determinado em um intervalo de dez dias no ciclo da cultura (120 dias após o transplantio). O consumo hídrico médio diário máximo foi igual a 5,88 L planta-1 no período de 111-120 DAT, para a CEsol de 4,58 dS m-1. O consumo máximo de água para o ciclo da cultura (120 DAT) foi de 275,66 L por planta para uma estimada CEsol = 4,11 dS m-1. A maior eficiência do uso da água (EUA) observada foi de 10,84 kg m-3 (frutos maduros e não maduros) até ao CEsol estimada de 5,18 dS m-1, com posterior redução exponencial. A salinidade da solução nutritiva, a produção de biomassa e a evapotranspiração são fatores que mais influenciam o consumo de água da pimenta ‘Biquinho’.
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