Alexandre Nascimento dos Santos

Produção de alface em NFT e Floating aproveitando água salobra e o rejeito da dessalinização

Plants of lettuce cv. Elba were grown under two hydroponic systems, Floating and NFT, aiming to evaluate three water resources: natural brackish water (2,47 dS m-1) obtained from a deep well; fresh water (0,11 dS m-1) produced by reverse osmosis desalination; and reject brine (5,15 dS m-1), a wastewater from desalination process. These waters were combined in six treatments resulted from their alternated use to prepare nutrient solution (NS) and/or replace the evapotranspiration loss (ETc). The experiment was carried out under a greenhouse condition in the semiarid region of Pernambuco State, Brazil; 48 experimental units were used for both hydroponic systems. The lettuce yield (shoot fresh matter) was higher under Floating conditions. The single use of deep well water and reject brine decreased 22.7 and 39.6% the lettuce yield, respectively. For a better combination of fresh and brackish waters, the use of brackish water to replace ETc loss may increase the lettuce yield in comparison to use these waters to prepare the NS; this result was registered for deep well water and reject.

Nutrientes minerais em pimentão fertirrigado sob lâminas de irrigação e doses de potássio

The aim of this study was to evaluate the macronutrient concentrations in leaves and fruits of sweet pepper plants subjected to irrigation depths and potassium doses by fertigation. The experimental design was completely randomized in factorial scheme 5x2, with four replications, the factors being five water depths (80, 90, 100, 110 and 120% of ETc) and two potassium doses (80 and 120 kg ha-1 of K2O) parceled according to phenological phase. The fertirrigation was made by a drip irrigation system, with self-compensable emitters, installed in a battery of 40 drainage lysimeters cultivated with sweet pepper plants (Hybrid Maximos F1), located at the Federal Rural University of Pernambuco (UFRPE) in Recife, Pernambuco state, Brazil, whose experimental plot consisted of three plants in each lysimeter. The results showed the following order of nutrients content: N>K>Cl>Mg>Ca>P>S>Na, in the leaves, and K>N>Cl>P>Ca>S>Mg>Na, in the fruits. The highest concentrations of K and Mg in the leaves were obtained with the water depths of 103.43 and 105.54% of crop evapotranspiration, respectively; the K doses did not inhibit the absorption of nutrients, except for Mg and S in the leaves.

Production, water consumption and nutrient content of Chinese cabbage grown hydroponically in brackish water

Underground water reserves in the semi-arid region of Brazil are stored in the crystal formations that in large part have high concentrations of salt. However, the scarcity of this resource makes the use of this water necessary for various activities, including agriculture. The aim of this study was to evaluate the use of brackish water on the electrical conductivity and pH of the nutrient solution, and on the production, water consumption and the uptake of nutrients in Chinese cabbage (Brassica pekinensis L.) under a hydroponic system. The experimental design was completely randomised, with four replications and six levels of water salinity (0.2, 1.2, 2.2, 3.2, 4.2 and 5.2 dS m-1), obtained by adding NaCl to the local water supply, with this water being used to prepare the nutrient solution and to make up the volume lost through evapotranspiration. The results showed that with the exception of the treatment at the lowest salinity, there was a tendency to increased electrical conductivity of the nutrient solution with the increasing salinity of the water; that the pH of the nutrient solution remained within the normal range throughout the cycle; that with the increasing salinity of the solution there was a reduction in all growth and production variables under analysis, in water consumption, and in leaf N, K, Ca and Mg, and an increase in leaf concentrations of Na and Cl. It is possible to use brackish water for the production of Chinese cabbage when grown hydroponically as an alternative for those producers who have an available supply of brackish water and a restricted supply of fresh water, however with a reduction in productivity.

Produção e biometria do milho verde irrigado com água salina sob frações de lixiviação

O trabalho teve como objetivo avaliar o desempenho da cultura do milho em relacao a producao e biometria, irrigado por gotejamento com agua salina e sob diferentes fracoes de lixiviacao em estacao lisimetrica de drenagem. Os tratamentos consistiram de dois niveis de salinidade da agua (CEa- 1,2 e 3,3 dS m-1) e cinco fracoes de lixiviacao (FL- 0, 5, 10, 15 e 20%) em delineamento inteiramente casualizado em esquema fatorial 2 x 5. O experimento foi conduzido na area experimental do Departamento de Tecnologia Rural da Universidade Federal Rural de Pernambuco, Recife, PE. Foram avaliados a produtividade de polpa hidratada e desidratada e de espiga com e sem palha, materia fresca e seca da parte aerea, diâmetro de caule e altura de planta. As variaveis producao de graos verdes, materia seca e fresca da parte aerea apresentaram resultados semelhantes, obtendo elevados valores quando se utilizou agua de 3,3 dS m-1 com a fracao de lixiviacao de 10%, obtendo efeito deleterio com o aumento da fracao de lixiviacao.

Relationship between nematode assemblages and physical properties across land use types

The purpose of this study was to determine the influence of land use types on nematode assemblage in sugarcane production in Pernambuco State, Brazil. One forest and two managed agricultural soils were characterized by their nematode assemblages to assess their biological characteristics. Soil samples were collected between 2009 and 2010 at three 10-cm depth increments along two 200-m transects with points at 20-m intervals from each other. Nematodes were extracted by sucrose centrifugation, and the physical properties of the soil were analysed, including soil mechanical resistance, bulk density, total porosity, water content, and texture. The effects of agricultural land management on the soil’s physical properties and nematode assemblage composition were significant. Soil mechanical resistance has critical implications for the abundance and distribution of plant-parasitic nematodes in agricultural soils. Thus, a new approach is needed for the design and management of an integrated ecosystem mainly to optimize antagonistic systems to plant-parasitic nematodes.

Cultivo hidropônico de tomate cereja utilizando-se efluente tratado de uma indústria de sorvete

The objective of this study was to evaluate the effect of ice cream raw effluent doses on consumption and vegetative development of cherry tomato under hydroponic system. The experiment was conducted in completely randomized design with six treatments and four replications. Treatments consisted of 5 different levels of effluent (0, 25, 50, 75 and 100%) complemented with the amount of nutrient recommended for growing tomatoes and 100% of effluent without nutrient complementation. Increasing doses of effluent provided linear reduction in water consumption.Addition of effluent in proportion of 25% provided best production results. Addition up to 50% ice cream effluent to nutrient solution allowed growth of cherry tomato without yield reduction providing better efficiency of water use in terms of dry weight of shoots and fruit production as well as maximum substitution of soluble mineral fertilizers in nutrient solution.

Concentração de nutrientes em tomate cereja sob manejos de aplicação da solução nutritiva com água salobra

Objetivou-se com este trabalho avaliar a concentracao dos nutrientes no tecido foliar das plantas de tomate cereja cv. “Rita”, cultivadas em sistema hidroponico utilizando agua com crescentes niveis de salinidade no preparo da solucao nutritiva, submetendo as plantas a diferentes tempos de exposicao a salinidade e turnos de rega. O experimento foi conduzido em casa de vegetacao em sistema hidroponico em vasos com substrato. O delineamento experimental foi em blocos inteiramente casualizados em esquema fatorial 6 x 2 x 2, sendo seis niveis de salinidade da solucao nutritiva (3,01; 4,51; 5,94; 7,34; 8,71 e 10,40 dS m-1), dois tempos de exposicao das plantas a salinidade (51 e 6 dias) e dois turnos de rega (uma irrigacao por dia e uma irrigacao a cada dois dias). Foram avaliadas as concentracoes de nitrogenio, fosforo, potassio, calcio, magnesio, enxofre, sodio e cloro no tecido foliar das plantas. O uso de agua salobra no preparo da solucao nutritiva promoveu efeitos de interacoes antagonicas entre os nutrientes, afetando as concentracoes dos mesmos. O aumento da salinidade provocou aumentos nas concentracoes de sodio e cloro e reducao nas concentracoes de potassio e nitrogenio no tecido foliar. O menor tempo de exposicao das plantas a salinidade proporcionou reducoes de menores magnitudes nas concentracoes de potassio e nitrogenio e diminui as concentracoes de sodio e cloro. O turno de rega com uma irrigacao a cada dois dias afetou as concentracoes foliares de nitrogenio, calcio e magnesio.