Nildo da Silva Dias

Melon yield in a hydroponic system with wastewater from desalination plant added in the nutrient solution

To use of waster water from desalting in the hydroponic cultivation, an experiment was carried out at the Department of Environmental Science of the Universidade Federal Rural do Semi-Arido-UFERSA, in the municipal district of Mossoro-RN, in pots with substrates of coconut fiber under greenhouse conditions. The experimental design was in randomized blocks, with three repetitions. Treatments were composed of five levels of salinity of the nutrient solution obtained with, and without, dilution of the waster water from desalting (2.1, 3.6, 4.9, 6.0 and 7.0 dS m-1). The variables plant height, stem diameter, leaf area, mean weight of fruit and total and marketable yield were detemined. In general, the variables decreased linearly with the increase of the salinity of the nutrient solution, showing that the salinity with waster water from desalting reduces the absorption of water by the plants due to the osmotic effect.

Manejo da fertirrigação e controle da salinidade do solo sob ambiente protegido, utilizando-se extratores de solução do solo

Com o objetivo de avaliar o uso de extratores de solucoes do solo no auxilio ao manejo da fertirrigacao e no controle da salinidade em solo cultivado com melao rendilhado, conduziu-se um estudo em ambiente protegido na area experimental do Departamento de Engenharia Rural da ESALQ/USP, localizada no municipio de Piracicaba, SP. Os tratamentos se compunham da combinacao de dois fatores: 6 niveis de salinidade inicial do solo (S1 = 1,0; S2 = 2,0; S3 = 3,0; S4 = 4,0; S5 = 5,0 e S6 = 6,0 dS m-1) e dois manejos de fertirrigacao: tradicional e com controle da condutividade eletrica da solucao do solo. Procedeu-se a salinizacao inicial do solo por meio da aplicacao de solucoes salinas preparadas a partir de fertilizantes, em que a quantidade de sais a ser adicionada foi determinada tomando-se por base uma curva de salinizacao artificial, obtida previamente em laboratorio. Os resultados mostraram que, com o uso de extratores de solucao do solo, pode-se monitorar a concentracao ionica da solucao do solo, com precisao satisfatoria. A salinidade do solo evoluiu com o tempo, estando os maiores niveis proximos a superficie do solo e do gotejador. A diferenca no consumo de agua entre os niveis de salinidade foi mais evidenciada no manejo controlado da fertirrigacao, ajustando-se a um modelo quadratico.

Crescimento e acúmulo de N, P e K pelo meloeiro irrigado com água salina

The use of saline water for irrigation is very common in cultivation of melon in semiarid zones, which can result in the soil salinization if irrigation management is not appropriate. The growth and accumulation of N, P and K by melon (Cucumis melo, L.) irrigated with saline water was evaluated. Treatments resulted from the combination of the factors irrigation water salinity levels (1.1; 2.5 and 4.5 dS m-1) and melon materials (hybrid Trusty and cultivar Orange Flesh). Treatments were arranged following a completely randomized block design with four replications, arranged in 3 x 2 factorial. Another factor analyzed was time of sampling and results were interpreted by multivariate analysis. Plants were divided into two portions after sampling (leaves plus stems and fruit), and dry matter, N, P and K contents were determined. Nutrient accumulation in fruits and plant growth decreased with increasing water salinity. On average, 57.1%, 67.1% and 70.0% of N, P and K absorbed by plant were allocated in fruits, showing that fruits are the main drain for these nutrients in melon.

Produção de aquênio do girassol irrigado com água salobra

The aim of this study was to determine yield components and achene production of sunflower (Helianthus annuus L.) variety Embrapa 122/V-2000 irrigated with water of different salinities in a greenhouse. The treatments consisted of six levels of salinity of irrigation water (ECw), N1 - 0.5, N2 - 1.0; N3 - 2.0; N4 - 3.0; N5 - 4.0 and N6 - 5.0 dS m-1 at 25 oC in a randomized design with five replications. The internal diameter of the chapter, number of seeds, weight of 100 seeds, the total mass of seeds, dry weight of shoot and root, ratio of dry weight of root and shoot, water consumption, electrical conductivity of drainage water and the saturation extract of soil. The total mass of seeds and number of seeds decreased 11.39 and 9.64%, respectively, with per unit increase in electrical conductivity of irrigation water, the root dry mass was more affected by salinity of irrigation water than dry mass of aerial parts, salinity levels of drainage water at the end of experiment were about 2.2 times of electrical conductivity of saturation extract.

Cultivo de girassol em sistema hidropônico sob diferentes níveis de salinidade

Hydroponic systems have constituted an alternative for combating the adverse natural factors of agricultural production in the semi-arid regions of Brazil, such as shallow rocky and infertile soils, and the scarcity of good quality water resources (high salt content). This work studied the yield of the sunflower (variety EMBRAPA 122/V-2000) destined for achene and fodder (phytomass) production, grown hydroponically, using coconut fiber as substrate and irrigated with brackish water of varying salinities. The experimental layout used was completely randomized into a 5 x 2 factorial design with three replications, five levels of water salinity and two planting density - with one or two plants per pot being studied. The irrigation water was composed of 50% standard nutrient solution and 50% municipal water supply, with added levels of NaCl, resulting in an eletrical conductivity (ECw) of 1.7; 4.3; 6.0; 9.0 and 11.5 dS m-1. The differential density of the sunflower plants positively affected the yield components of grain and biomass, showing greater viability when using two plants per pot.

Doses de boro e água residuária na produção do girassol

The availability of water of quality has become worldwide, a major constraint to expanding agricultural frontiers. Within this context, this study aimed to evaluate the effects of boron doses and irrigation with two types of water, wastewater and municipal supply water, on yield components of sunflower (Helianthus annuus L.) cv. EMBRAPA 122/V-2000. The study was conducted in a greenhouse at the Federal University of Campina Grande, in a randomized block design, analyzed in a 5 x 2 factorial with five B of boron (0; 1.0; 2.0; 3.0 and 4.0 mg L-1) combined with two types of irrigation water (R - wastewater and AB - municipal supply water) with three replications. Statistical analysis consisted of analysis of variance (F test) and means were compared by Tukey test to compare qualitative factors at 0.05 probability. It was found that the boron levels and types of water did not affect any varieble related to production of seeds, however, irrigation with wastewater variables positively influenced the fresh and dry leaves, stem and shoot all related to forage production.

Climate variations in greenhouse cultivated with gerbera and relationship with external conditions

Black meshes used in greenhouses provide shade to plants, affecting photosynthesis and presenting certain properties that change the microclimatic conditions in these environments. The objective of this study was to evaluate the variation in climate elements in greenhouse cultivated with gerbera (Gerbera jamesonii, Vr. Rambo) in relation to external conditions and the reference evapotranspiration (ETo) at Teresina, State of Piaui, Brazil. The measurements were obtained from July to October 2007 by an automatic data acquisition system installed inside and outside the greenhouse. The global solar radiation, evapotranspiration, precipitation, temperature, relative humidity, and wind speed were estimated. The results showed that major effect of the shading occurred on the mean air temperature during the 120 days, making it higher than the external environment. Inside the greenhouse, mean values of relative air humidity, reference evapotranspiracao, global solar radiation and wind speed were lower compared to those outside the greenhouse.

Produção de tomate hidropônico utilizando rejeito da dessalinização na solução nutritiva aplicados em diferentes épocas

The objective of this study was to evaluate the response of tomato (Lycopersicon esculentum) in a hydroponic system, adding water from desalination in the composition of the nutrient solution, resulting in three levels of salinity of nutrient solution: 7,1; 8,7 and 10 ,1 dS m-1, and the control (without addition of water from desalination: 2.1 dS m-1), starting its application at different stages of crop development: 7, 32 and 58 days after transplanting (DAT). The design was completely randomized with 9 treatments and 3 replications, arranged in a 3x3 factorial design (levels of salinity x starting time of the application of salinity), and control. The salinity of the nutrient solution produced by the saline water, significantly reduced the fresh weight of shoot, dry weight of shoots, and fruit production of tomato. The stage of the application of water in the nutrient solution only reduced the dry matter of shoot and fruit yield of tomato, when applied from 7 DAT, while the interaction of these factors did not produce significant effects for the variables.

Spatial variability and seasonality of the water quality in the Lagoa do Apodi Lagoon, RN, Brazil

The objective of this study was to evaluate the water quality of the Apodi lagoon, in the State of Rio Grande do Norte, Brazil, at points along its surface. The monitoring of the water quality is emphasized as it is under influence of the urban basin of Apodi and due to incorporation of material by the influx of continental waters that lead to eutrophization of the lagoon water in periods of extreme temperatures and precipitation. Systematic samples were collected from the lagoon water surface throughout its length. The electrical conductivity of the Apodi water varies along the surface, mainly in the west and southeast extremities. The water salinity increased with the beginning of the dry period and decreased after the rains. There is a great spatial variability in the physical and chemical characteristics, mainly for pH, CE, RAS and Na and Cl contents. In the lagoon, the most frequent ions were sodium and chloride, both for sample points and time of collection. The change in the bacteriological quality of water compromises the balneary of the Apodi lagoon, especially after the rainy season.

Crescimento e produção de tomate cereja em sistema hidropônico com rejeito de dessalinização.

Resumo - A produtividade agricola sustentavel e o maior desafio nas regioes aridas e semiaridas por causa da escassez de agua para irrigacao, sendo comum o uso de agua salobra para irrigacao. O objetivo desta pesquisa foi avaliar a resposta do tomate cereja (Lycopersicon esculentum L., cv. Samambaia) sob quatro niveis de salinidade da solucao nutritiva com adicao de rejeito salino em sistema de producao hidroponico. As plantas de tomate foram cultivadas em vasos com substrato de fibra de coco e irrigadas com solucoes nutritivas preparadas com agua de abastecimento e com aguas salinas preparadas diluindo-se agua de rejeito coletado em um dessalinizador a 75%; 50% e 25% e 0%, correspondendo a condutividades eletricas de 2,1; 3,55; 4,88, 6,02 e 6,96 dS m -1 , respectivamente. O delineamento experimental foi inteiramente casualizado, com 5 tratamentos (niveis de salinidade da solucao nutritiva) e quatro repeticoes. A altura e a massa seca das plantas reduziram com o aumento da salinidade da agua de irrigacao. O consumo hidrico da cultura foi influenciada pela adicao de rejeito salino na solucao nutritiva e a salinidade limiar, considerando-se a produtividade da cultura, ficou em torno de 3,51 dS m -1 . A adicao de ate 25% de rejeito de dessalinizador (diluicao de 75%) a solucao nutritiva permite o cultivo do tomate cereja, cv. ‘Samambaia’, sem haver reducao na produtividade. Palavras-chave - Lycopersicon esculentum Mill. Solucao nutritiva. Salinidade. Evapotranspiracao.