The aim of this study was to evaluate the accumulation of salts in the soil from irrigation water and of N and K from fertilization. The experiment was conducted in PVC columns (20 cm in diameter and 100 cm in height), filled with non-saline soil, and cultivated with maize. A completely randomized block design in a 4 x 4 factorial was used, with four levels of salinity (0.5, 2.5, 5.0 and 7.5 dS m-1), four N rates, and five replicates. Nitrogen was applied as urea and potassium nitrate at the following rates: N1: N recommendation for maize (2.6 g column-1); N2: 0.3 times (0.78 g column-1) the recommended N1 dose; N3 and N4 with N based on N1 and N2 doses, respectively, reduced proportionally based on the evapotranspiration reduction caused by salinity. After 74 days from sowing, root and soil samples were collected at different soil depths. The electrical conductivity of the saturated extract (ECe) and the concentration of ions (Ca2+, Na+, and Cl-) increased as a function of salinity and soil depth. The opposite was observed for the root system. The increase in salinity also resulted in K+ and NO3- accumulation in the soil column, mainly in treatments with higher N rates (N1 and N3). At the end of the experiment, 88% of the NO3- applied at the highest salinity treatment (7.5 dS m-1) and the highest N rate (N1) was below 20 cm soil depth, evidencing a N loss process caused by leaching.

Influence of salinity on the development of the banana colonised by arbuscular mycorrhizal fungi ABSTRACT -This study evaluated the effect of salt stress on the growth of banana seedling colonized with mycorrhizal fungi (AMF) on a substrate from a Quartzipsamment. The experiment was conducted in a greenhouse, using a completely randomized design in split plots; the plots had 5 levels of salinity in irrigation water (0.5, 1.5, 2.5, 3.5 and 4 5 dS m -1 ) and the subplots of four collection periods (40, 60, 80 and 100 days after transplanting), with 4 repetitions, totaling 80 experimental units. The seedlings of banana cv. "Prata" was produced by micropropagation and inoculated with arbuscular mycorrhizal and acclimatization for 40 days. Evaluations were made of leaf gas exchange, shoot dry mass, nutrient content, mycorrhizal root colonization and spore density. Increased levels of salinity caused reduction in dry matter production and photosynthetic rate, which may be associated with osmotic effects of salts in the soil, the increase in sodium and reduced the levels of N in leaves. Salinity reduced root mycorrhizal colonization, but did not influence the density of AMF spores under the conditions of this study. Key words: Musa ssp.. Arbuscular Mycorrhizal Fungi. Salt stress.RESUMO -Este trabalho teve o objetivo de avaliar o efeito do estresse salino no crescimento inicial de mudas de bananeiras colonizadas com fungos micorrízicos arbusculares (FMA) em um substrato proveniente de um Neossolo Quartzarênico. O experimento foi conduzido em casa de vegetação, utilizando-se delineamento inteiramente casualizado em parcelas subdivididas, sendo as parcelas representadas por cinco níveis de salinidade aplicados na água de irrigação (0,5; 1,5; 2,5; 3,5 e 4,5 dS m -1 ) e as subparcelas por quatro períodos de coleta (40; 60; 80 e 100 dias após transplantio das mudas), com quatro repetições, totalizando 80 unidades experimentais. As mudas de bananeira cv. "Prata" foram produzidas por micropropagação e inoculadas com FMA e passaram por um período de micorrização e aclimatação de 40 dias. Foram realizadas avaliações das trocas gasosas foliares, massa seca da parte aérea, teores de nutrientes, colonização micorrízica arbuscular e densidade de esporos. O aumento nos níveis de salinidade provocou redução na produção de matéria seca e na taxa fotossintética, o que pode estar associado aos efeitos osmóticos dos sais no solo, ao aumento nos teores de Na e a redução dos teores de N nas folhas. A salinidade reduziu a colonização micorrízica, porém não influenciou na densidade de esporos no substrato.Palavras-chave: Musa ssp.. Fungos micorrizicos arbusculares. Estresse salino.

Although leaching fraction (LF) is used to remove salts from the root zone under conditions of salinity, if miscalculated, it can decrease water use efficiency and lead to major losses of essential nutrients. This study evaluated the water use efficiency, leaf nutrient concentrations in maize plants, and nutrient losses as a function of two ways of determining the LF in maize crop grown in soil columns under salt stress. The experimental design used was completely randomized, with treatments arranged in split plots, with seven replicates. The plots were formed by two methods of determination of LF, and the subplots by four electrical conductivities of irrigation water - ECw (0.5, 2.0, 4.0, and 6.0 dS m-1). The leaching fractions were established according to 1) the formula proposed by Rhoades (RHO) and 2) by applying a LF of 0.15 calculated according to the soil water balance (SWB). The leaf concentrations of N, P, Ca, and Mg were higher in plants under SWB than under RHO method. The leaf concentrations of N, P, and K decreased with increased salinity, regardless of the LF. Adding a LF of 0.15 according to SWB resulted in decreased losses of nutrients and higher physical water productivity, as compared to the RHO. Thus, a more precise determination of the LF is needed to increase economic returns for maize cultivation in semi-arid regions when using brackish water for irrigation.

EFFECT OF LEACHING FRACTION DETERMINED BY TWO METHODS ON GROWTH AND YIELD OF MAIZE SUBMITTED TO SALT STRESS1     EMANUEL DIAS FREITAS2; CLAUDIVAN FEITOSA DE LACERDA3; JULIANA MATOS VIEIRA4; BRUNO GABRIEL MONTEIRO DA COSTA BEZERRA5 E AURELIANO DE ALBUQUERQUE RIBEIRO6   1Parte da tese de doutorado do primeiro autor. Projeto financiado pelo CNPq; 2 Departamento de Engenharia Agrícola, Universidade Federal do Ceará – UFC, CEP: 60451-970, Fortaleza, CE, e-mail:emanueldiasfreitas@gmail.com; 3 Departamento de Engenharia Agrícola, Universidade Federal do Ceará – UFC, CEP: 60451-970, Fortaleza, CE, e-mail:cfeitosa@ufc.br; 4 Departamento de Ciência do Solo, Universidade Federal do Ceará – UFC, CEP: 60451-970, Fortaleza, CE, e-mail:julianamatosvieira@gmail.com; 5 Departamento de Engenharia Agrícola, Universidade Federal do Ceará – UFC, CEP: 60451-970, Fortaleza, CE, e-mail:brunog768@gmail.com; 6 Departamento de Engenharia Agrícola, Universidade Federal do Ceará – UFC, CEP: 60451-970, Fortaleza, CE, e-mail:alburibeiro@gmail.com.     1 ABSTRACT   The aim of this study was to evaluate the effects of the leaching fraction determined by two methods in maize cultivated in a soil column and submitted to irrigation with water of different salinities. The experiment was conducted in the meteorological station of the Federal University of Ceará, Fortaleza - CE, in a completely randomized design, composed by four levels of irrigation salinity water (0.5, 2.0, 4.0 and 6.0 dSm-1) and two methods of determination of the leaching fraction. Each treatment had seven replicates. The plots were constituted by maize cultivated in soil columns, measuring 20 cm in diameter and 100 cm in length. The leaching fractions (LF) were defined as follows: A. Application of the LF calculated according to the formula proposed by Rhoades (1974), Rhoades and Merrill (1976); B. Application of the LF of 15% calculated from the soil water balance of the experimental plots. The results showed that plants that were irrigated with ECw of 0.5 and 4 dS m-1, the LF of 5 and15%, respectively, were able to minimize the effects of salinity. For ECw of 6 dS m-1, the LF of 15 and 92% showed no improvement in maize growth and yield.   Keywords: Zea mays L. soil columns, saline water.     FREITAS, E. D.; LACERDA, C. F. DE; VIEIRA, J. M.; BEZERRA, B. G. M. DA C. E RIBEIRO, A. DE A. EFEITO DA FRAÇÃO DE LIXIVIAÇÃO DETERMINADO POR DOIS MÉTODOS NO CRESCIMENTO E PRODUÇÃO DO MILHO SUBMETIDO A ESTRESSE SALINO           2 RESUMO   Objetivou-se com o trabalho avaliar os efeitos da fração de lixiviação determinado por dois métodos na cultura do milho cultivado em coluna de solo e submetido a irrigação com água de diferentes salinidades. O experimento foi instalado na estação meteorológica da Universidade Federal do Ceará, Fortaleza – CE, em delineamento inteiramente casualizado, composto por quatro salinidade de água de irrigação (0,5, 2,0, 4,0 e 6,0 dS m-1) e duas formas de determinação da fração de lixiviação (FL). Utilizou-se sete repetições para cada tratamentos. As parcelas foram constituídas por milho cultivado em colunas de solo, medindo 20 cm de diâmetro e 100 cm de comprimento. As frações de lixiviação foram determinadas pelos seguintes métodos: A. Aplicação das FL de acordo com a fórmula de Rhoades (1974), Rhoades e Merrill (1976); B. Aplicação de FL de 15 % calculada a partir do balanço hídrico do solo. Os resultados mostraram que as plantas que foram irrigadas com CEa de 0,5, 4 dSm-1 as LF de 5 e 15%, respectivamente, foram capazes de dirimir os efeitos da salinidade. Para a CEa de 6 dSm-1 as LF de 15 e 92% não apresentaram melhoria no crescimento e produção do milho.   Palavras-chave: Zea mays L., colunas de solo, água salina.

The aim of this study was to evaluate the accumulation of salts in the soil from irrigation water and of N and K from fertilization. The experiment was conducted in PVC columns (20 cm in diameter and 100 cm in height), filled with non-saline soil, and cultivated with maize. A completely randomized block design in a 4 x 4 factorial was used, with four levels of salinity (0.5, 2.5, 5.0 and 7.5 dS m-1), four N rates, and five replicates. Nitrogen was applied as urea and potassium nitrate at the following rates: N1: N recommendation for maize (2.6 g column-1); N2: 0.3 times (0.78 g column-1) the recommended N1 dose; N3 and N4 with N based on N1 and N2 doses, respectively, reduced proportionally based on the evapotranspiration reduction caused by salinity. After 74 days from sowing, root and soil samples were collected at different soil depths. The electrical conductivity of the saturated extract (ECe) and the concentration of ions (Ca 2+ , Na + , and Cl-) increased as a function of salinity and soil depth. The opposite was observed for the root system. The increase in salinity also resulted in K + and NO 3 accumulation in the soil column, mainly in treatments with higher N rates (N1 and N3). At the end of the experiment, 88% of the NO 3 applied at the highest salinity treatment (7.5 dS m-1) and the highest N rate (N1) was below 20 cm soil depth, evidencing a N loss process caused by leaching. Evidências de perdas de nitrogênio e potássio em colunas de solo cultivadas com milho sob estresse salino R E S U M O Objetivou-se com o trabalho avaliar o acúmulo no solo de sais provenientes da água de irrigação e de N e K provenientes da adubação. O experimento foi conduzido em colunas de PVC (20 cm de diâmetro e 100 cm de altura), preenchidas com solo arenoso, não salino, cultivado com milho. Utilizou-se delineamento em blocos inteiramente casualizados em arrajamento fatorial 4 x 4, composto por quatro níveis de salinidade (0,5, 2,5, 5,0 e 7,5 dS m-1) e quatro doses de N, com cinco repetições. As quatro doses de N, aplicadas como ureia e nitrato de potássio, foram as seguintes: N1: seguindo a recomendação de N para o milho (2,6 g coluna-1); N2: 0,3 vezes N1 (0,78 g coluna-1); N3 e N4: Taxa reduzida de N1 e N2, respectivamente, com base na redução da evapotranspiração causada pela salinidade. Aos 74 dias após o plantio foram coletadas as raízes e amostras de diferentes camadas do solo. A condutividade elétrica do extrato saturado (CEes) e as concentrações de íons (Ca, Na e Cl) aumentaram em função da salinidade e da profundidade. O contrário foi observado no sistema radicular. O aumento da salinidade provocou o acúmulo de K e NO 3 nas colunas de solo, principalmente nas maiores doses de N (N1 e N3). Para o tratamento de maior salinidade (7,5 dS m-1) e maior dose de N (N1) verificou-se que 88% do NO 3 encontrava-se abaixo de 20 cm do solo ao final do experimento, mostrando perda por lixiviação.