Pedro Roberto Almeida Viégas

Growth and total-N content of Prosopis juliflora (SW) D. C. are stimulated by low NaCl levels

In this study the early effects of salinity on growth, total N and ion accumulation and partitioning in Prosopis juliflora (common name algaroba) were studied with 30-day-old plants grown for 8 days in aerated nutrient solution (NS) free of (control) or supplied with 25, 50, 75 and 100 mmol.L-1 NaCl. Plants grown in 25 and 50 mmol.L-1 NaCl accumulated a total dry mass (DM) and shoot N content greater than the control. However, at 75 and 100 mmol.L-1 NaCl such parameters were diminished. Whole plant transpiration rates were higher with 25 and 50 mmol.L-1 NaCl and lower with 75 and 100 mmol.L-1 NaCl. Salinity did not influence shoot (80%) and root (70%) water content (WC) but reduced the K+ content of shoot while that of root was not affected. Increasing external NaCl concentrations increased K+/Na+ ratios of both plant parts. The data support the hypothesis that increase in transpiration rates and in shoot total N may account for growth stimulation of algaroba under mild salinity.

Redução assimilatória de NO-3 em plantas de cajueiros cultivados em meio salinizado

Com o objetivo de se avaliar os efeitos e mecanismos iniciais da acao da salinidade sobre a reducao de NO-3 e a acumulacao de solutos nitrogenados, plantas de cajueiro (Anacardium occidentale L.), CCP - 1001, com 42 dias de idade foram cultivadas em solucao nutritiva contendo 100 mmol L-1 de NaCl, durante 8 dias, em casa de vegetacao. A transpiracao foi o principal fator de regulacao da atividade de redutase de NO-3 (RN) que foi fortemente reduzida nas folhas. Contrariamente, a atividade de glutamina sintetase (GS) aumentou nas folhas em resposta a salinidade. Esta tendencia de aumento da atividade de GS nas folhas foi acompanhada pelas concentracoes de aminoacidos soluveis totais, particularmente prolina e proteinas soluveis totais. Por outro lado, o aumento nas concentracoes das fracoes orgânicas de N, nas folhas, foi seguido por decrescimos nas concentracoes de clorofilas e por acrescimos nas concentracoes de NH+4 . E provavel que o aumento da atividade de GS nas folhas de plantas de cajueiro, tenha sido induzido por um adicional suprimento de NH+4 e glutamato, a partir do catabolismo de aminoacidos e de proteinas e por aumentos na atividade fotorrespiratoria.

Plant growth, accumulation and solute partitioning of four forest species under salt stress

Em condicoes de estresse salino a acumulacao de Na+ e Cl-, na parte aerea e nas raizes, difere substancialmente entre plantas glicofitas; este fato deve-se, principalmente, a diversidade genetica existente e tem sido utilizado como indicador da resposta das plantas a salinidade. Este estudo objetivou avaliar a acumulacao e a distribuicao de Na+ e Cl-, bem como o efeito da salinidade sobre o ganho de massa seca e a distribuicao de K+, na parte aerea e raizes, em plantas jovens de Prosopis juliflora, Leucaena leucocephala, Piptadenia macrocarpa e Mimosa hostilis, com um mes de idade, cultivadas durante 30 dias em areia e irrigadas com solucao nutritiva contendo 100 mol m-3 NaCl, em casa de vegetacao. A acumulacao de Na+ e Cl-, e nao a distribuicao desses ions entre parte aerea e raizes, foi dependente da especie de planta. Em todas as especies estudadas a acumulacao de Cl- na parte aerea e nas raizes foi maior que a de Na+. A excecao da parte aerea, todas as plantas apresentaram reducao significativa no conteudo de K+ nas raizes em resposta a salinidade. A habilidade dessas plantas em proteger o metabolismo do efeito deleterio da salinidade pode resultar, em parte, de uma alta relacao K+/Na+. Desta forma, a Leucaena leucocephala apresentou a maior reducao na producao da massa seca total (60%) e a menor relacao K+/Na+ na parte aerea (0,40) enquanto que a Prosopis juliflora apresentou a menor reducao na massa seca total (15%) e uma relacao K+/Na+ na parte aerea, aproximadamente tres vezes maior. Esses resultados sugerem que maiores relacoes K+/Na+ desempenham um importante papel na adaptacao da planta aos estresses ionico e osmotico.

Rendimento e qualidade da fruta do maracujazeiro-amarelo adubado com potássio, esterco de frango e de ovino

The majority of soils grown with passion fruit plants in Sergipe State present low natural fertility and this has caused reduced productivity of this plant. Thus, the aim of this work was to evaluate the combination of organic fertilization sources from poultry and sheep manure, with potassium doses on yield and quality of yellow passion fruits. This experiment was carried out in the Research Station of the Universidade Federal de Sergipe. The experiment design was in a 2x5 randomized blocks (organic fertilizer x potassium doses) +1 factorial scheme. The treatments were constituted by 2 sources of organic fertilizers (T1=10 L of poultry manure and T2 = 20 L of sheep manure) and five potassium doses (0, 27, 54, 81 e 108 g plants-1) and an additional treatment (2.5 L of poultry manure + 7.5 L of sheep manure). The variables studied were: total soluble solid concentration (SST), total acidity by titration (ATT), cortex thickness (ESPC) (mm), number of fruit per plant (NFPLM) and yield (REND) (t ha-1), in the first year. Yellow passion fruits presents adequate attributes for consumption in natura and for the industry, when fertilized with poultry and sheep manure combined with potassium doses, promoting SST between 10.8 and 14.02%, ATT of 8.48 to 7.57 g 100 mL-1 of juice, ESPC between 6.52 and 7.12 mm, REND between 27.5 and 30.24 t ha-1 and NFPLM of 28 to 29 fruits, respectively.

Characterisation of the optimal hydric interval for a Yellow Argisol cultivated with sugarcane on the coastal plains of Alagoas, Brazil

This work had as its objective to study the optimum water range (OWR) of a Yellow Argisol of the coastal plains, planted with sugarcane, when subjected to different levels of compaction. For the laboratory tests soil samples with a non-preserved structure were used, removed from depths of from 0.20 m to 0.40 m and 0.40 m to 0.60 m, representing the AB and Bt horizons respectively. The treatments consisted of different soil densities represented by specimens contained in volumetric rings. The critical densities of the AB and Bt horizons for samples of upturned soil, were 1.84 and 1.63 Mg m -3 respectively. In undisturbed soil a critical density of 1.63 and 1.64 Mg m -3 was observed for the same horizons. However, the soil density at which root development begins to be restricted was 1.61 Mg m -3 for samples of upturned soil, and 1.50 Mg m -3 for samples of undisturbed soil at a depth of from 0.20 to 0.40 m. From 0.40 to 0.60 m the critical density was 1.45 and 1.18 Mg m -3 for samples of upturned and undisturbed soil respectively. It can be concluded that upturning the soil increased the IHO of the AB and Bt horizons of the Yellow Argisol, compared to the undisturbed soil cultivated with sugarcane. The subsurface movement of the studied Argisol increases the IHO at higher densities, due to the increase in the critical density of the AB and Bt horizons, improving their hydro-mechanical behavior.

Chlorophyll and macronutrients content in leaf tissue of Musa sp ‘Prata-Anã’ under fertigation

1 Paraiba State University, Av. das Baraunas, 351, Bodocongo, CEP 58109-753, Campina Grande-PB, Brazil. 2 Department of Agricultural Engineering, Sergipe Federal University, Av. Marechal Cândido Rondon, Jardim Rosa Elze, CEP 49100-000, Sao Cristovao-SE, Brazil. 3 Campina Grande Federal University, Academic Unit of Agricultural Sciences, Av. Jairo Vieira de Feitosa, Pereiros, CEP 58840-000, Pombal-PB, Brazil. 4 EMBRAPA, Agricultural Research Center of Tabuleiros Costeiros, Av. Beira Mar, 3250, Jardins, CEP 49025-040, Aracaju-SE, Brazil. 5 Department of Agronomy, Paulistan State University Julio de Mesquita, CEP 14884-900, Jaboticabal, SP, Brazil.

Bioremediation potential of filamentous fungi in methylene blue: Solid and liquid culture media

The evaluation of the bioremediation potential of microbial with dyes in solid and liquid culture media has been described, but prior studies have not mentioned which culture method is most appropriate for selection of microorganisms. Therefore, the aim of this work was to evaluate the bioremediation potential of filamentous fungi in liquid and solid culture media with methylene blue. The fungi isolates tested were Pleurotus ostreatoroseus (POR-SP1, POR-SP2), P. ostreatus (DF39, EF58 and EF60), Pycnoporus sanguineus (PS) and Fusidium sp. (FUS). The methylene blue concentrations tested were 0, 5, 10, and 50 mg L-1 in the solid medium and 0, 5, 25, 50, and 100 mg L-1 in the liquid medium. In the solid medium, the mycelial diameters of DF39, EF58, FUS, and PS were not influenced by the increase in dye concentration. In the liquid medium, DF39, EF58, EF60, and FUS showed a constant methylene blue degradation rate with increasing dye concentration. The dye degradation rate was correlated with the pH of the liquid medium for EF58, EF60, and FUS. The lower diameter growth in the solid medium did not influence the methylene blue dye degradation rate in the liquid medium.

Nutritional status of orange tree ‘Pêra Rio’ variety after Huanglongbing disease infection, leaf spray fertilization and application of resistance-inducing bioinductors

Citrus industry is widespread in the world. The Huanglongbing is an important disease of citrus species and has been spread around the world. This research analyzed the nutritional status of tree ‘Pêra Rio’ variety infected with Candidatus Liberibacter spp., under leaf nutrients spray and bioinductors of resistance. The experiment was carried out from September 2013 to June 2014, in a citrus commercial orchard located in the city of Ibitinga (SP). A completely randomized design was used in a factorial 3 × 4 × 6, consisting of three plants status (healthy, infected with asymptomatic HLB, and symptomatic HLB), four rates of spray solutions (0, 2, 4 and 6 L ha), six application stages (A1, A2, A3, A4, A5, and A6 with intervals of 45 days between each stage) and four replications. Macro and micronutrients leaf levels were quantified. Data were submitted to exploratory factor analysis with multivariate statistics. Three factors were extracted from the variables, namely, Factor 1 formed by variables S, Cu, Fe, and Zn; Factor 2 by N, K and B, and Factor 3 by Ca, Mg, and Mn. ‘Pêra Rio’ plants nutritional status was destabilized with the infection of Candidatus Liberibacter spp. Progressive treatment with leaf fertilization and resistance bioinductors temporarily re-established nutritional standards of plants affected by Huanglongbing but did not promote stability of the plants nutritional status.