The aim of this study was to apply optical microscopy and scanning electron microscopy (SEM) techniques to identify and assess dripper clogging of an irrigation system. Three dripper models (Taldrip, Streamline, and Tiran) underwent 1200 hours of irrigation with three types of effluents: treated domestic wastewater, water with a high calcium content, and urban water supply. Samples of the material adhered to the inside of drippers were analyzed by means of the smear method aiming at their biological identification. Other samples were taken to obtain SEM images. The presence of algae, bacteria, and biological components of biofilm was observed in drippers operating with wastewater and water with calcium, this latter in a low number. The formation of biofilm and chemical precipitates of calcium were observed in SEM images, leading to emitter clogging. Optical microscopy and SEM analyses allowed identifying the degree of fouling by biofilm and chemical precipitates in dripper clogging.

This study aimed to evaluate the effects of chemical treatment of seeds with fungicide and insecticide on the seed physiological quality of Brachiaria brizantha cultivar MG5. Two experiments with four replicates were carried out in a completely randomized design. In the first experiment, the seeds were treated with the fungicide pyraclostrobin + fipronil + thiophanate-methyl and in the second, with the insecticide thiamethoxam, both at doses of 0, 150, 300, 450, and 600 mL of commercial product (CP)/100 kg of seeds. Physiological characterization was done on the basis of the first germination count, germination (%), emergence (%), emergence speed index, and length and dry mass of shoot and root. The treatment of B. brizantha seeds with the fungicide pyraclostrobin + fipronil + thiophanate-methyl benefits the physiological quality of seeds, improving germination and root development, with no phytotoxic effect up to the dose of 600 mL of CP/100 kg of seeds. The insecticide thiamethoxam has a biostimulating effect on B. brizantha cultivar MG5 up to the dose of 270 mL of CP/100 kg of seeds, but is phytotoxic in larger doses.

Information about the response of onion to different potassium doses may contribute to optimizing the use of fertilizers and, consequently, make the activity more profitable and environmentally sustainable. In this context, the aim of this study was to evaluate the effects of doses of potassium on onion yields. Two field experiments were carried out in the periods of September to December 2012 and April to July 2013. The experimental design used was completely randomized blocks with four replications. The treatments corresponded to the potassium doses (0, 36, 72, 108, 144 and 180 kg ha-1 of K2O). Potassium fertilization promoted an increase in the content of K in the leaf, commercial and total yield, with the maximum obtained in the dose of 180 kg ha-1 of K2O. The maximum overall and commercial yields were respectively 54.69 and 54.12 t ha-1 in the experiment of September to December 2012 and 47.39 and 46.39 t ha-1 in that of April to July 2013.

Intercropping is a production system that can reduce the production cost and increase the profitability of vegetable producers, since it permits more efficient land and agricultural inputs use. In order to evaluate the effect of lettuce plant density on the economic feasibility of lettuce-rocket intercropping system over two growing seasons (winter and summer), two experiments were conducted in the field at São Paulo State University “Júlio de Mesquita Filho” (UNESP), Jaboticabal, São Paulo, Brazil. The treatments consisted of five lettuce-rocket intercrops with spacing between lettuce rows of: 0.20; 0.25; 0.30; 0.35 and 0.40 m, five sole crop of lettuce in the same spacing between rows adopted in the intercropping system, and a sole cropping of rocket with spacing between rows of 0.20 m. The statistical design adopted was the complete randomized block with four replicates. During winter, higher profitability was achieved with the highest population density. Highest profitability of the crops in both seasons was obtained in summer.

Cassava is mostly planted in sandy soils which are usually of low fertility, thereby making it necessary to perform beneficial associations with microorganisms that can promote their growth. In this perspective, the possibility of selecting bacterial isolates efficient in promoting the growth of the culture is evident, which can provide subsidies for future inoculants. The objective of this study was to isolate, identify, select and evaluate the genetic diversity of endophytic bacteria in roots and stems of cassava grown in Garanhuns - PE, with features involved in promoting plant growth. The isolation was performed on culture medium semisolid LGI-P. The selected isolates were evaluated for the potential to fix N2, as the ability to produce indole acetic acid, for their ability to solubilize inorganic phosphate and produce exopolysaccharides. Some bacterial isolates had their 16S rRNA gene sequenced by the Sanger method. A total of 52 endophytic bacteria isolates were obtained from cassava. Regarding the potential to fix N2, 15% of the isolates were positive. As for the production of IAA, 78% of the isolates produced this phytohormone in a medium with increased L-tryptophan. Approximately 31% of the isolates were able to solubilize inorganic phosphate and 60% had exopolysaccharide. The identification of 19 isolates allowed the grouping into six bacterial genera, namely: Achromobacter, Bacillus, Burkholderia, Enterobacter, Pantoea and Pseudomonas. Cassava plants grown in Garanhuns - PE present interaction with different groups of endophytic bacteria and there are bacterial groups with several characteristics involved in promoting plant growth.

Fertilization is important for the optimization of plant growth and yield, which are necessary for agronomic activities. Soil fertilization should increase net earnings that depend on nutrient use efficiency. The aim of this study was to evaluate the agronomic efficiency of eggplant under different doses of potassium (K) and nitrogen (N). Four levels of K (0, 54, 108, and 216 kg ha-1) and four levels of N (0, 67, 134, and 268 kg ha-1) were applied weekly by fertigation. The highest plant and the largest stem diameter were found with 165-175 kg ha-1 of N. Leaf area was more influenced by N than by K. Isolated application of different K doses did not statistically influence height plant, stem diameter, or leaf dry matter. The agronomic efficiency of nitrogen is reduced with increasing levels of N and K.

Plant growth promoter microorganisms have been studied as important tools for increasing crop production. Lettuce is the most consumed hardwood crop in the world. Numerous microorganisms are capable of acting in a beneficial way in the growth of this culture. The objective of the present study was to evaluate the efficacy of Trichoderma and Pseudomonas on the microbial biomass, enzymatic activities in sandy soil and lettuce production. The experimental design was completely randomized with ten replicates and treatments: CONT (absolute control); CM (control with cattle manure fertilization); CMB (with fertilization and Pseudomonas sp.); CMF (with fertilization and T. aureoviride) and CMBF (with fertilization and the two microorganisms combined). The fertilizer used was organic with cattle manure in a dose recommended for the culture. This study evaluated the production of lettuce, microbial biomass and the enzymatic activity of acid phosphatase, alkaline phosphatase and urease. The combined application of CMBF was efficient in increasing lettuce production, because it increased 85% of the cv. Veronica cultivated on sandy soil. The combined use of plant growth promoting microorganisms resulted to an increase in microbial biomass. In lettuce crops, it is recommended to use T. aureoviride URM 5158 and Pseudomonas sp. UAGF 14 in lettuce crops, because improved lettuce production, improves the biochemical quality of soils measured by absolute and specific enzymatic activities per unit of microbial biomass.

RESUMO O presente estudo teve como objetivo caracterizar três populações naturais de mangabeira (Hancornia speciosa Gomes) localizadas em áreas de Cerrado na região de Porto Nacional-TO e estudar a variabilidade fenotípica através de atributos físico-químicos de frutos. Foram selecionados dez genótipos em cada população e coletados vinte frutos de cada genótipo para análise. Nos frutos foram mensurados: o diâmetro transversal e longitudinal, a massa total, a massa e o rendimento de polpa, o número de sementes e a massa fresca das sementes. De cada fruto foram retiradas duas sementes e mensurados o diâmetro longitudinal, transversal e espessura. Da polpa total de cada genótipo foram mensurados o pH e sólidos solúveis. Para caracterização morfológica foi realizada estatística descritiva, a comparação entre as populações foi realizada através do teste de Kruskal-Wallis seguido do teste de Dunn a 5% de probabilidade. A relação entre as variáveis foi estimada pelo coeficiente de correlação de Spearman. Para o estudo da variabilidade fenotípica foi realizada a análise de componentes principais. As populações naturais de mangabeira estudadas apresentam características semelhantes quanto à morfologia do fruto e pH, sendo encontrado diferenças significativas apenas para o diâmetro transversal da semente, com maior valor para Canaã e sólidos solúveis totais, com maior valor para Providência. As correlações significativas em cada população ocorrem para as mesmas variáveis morfológicas e pH, com exceção das correlações negativas que ocorreram na população Canaã que se destacou por apresentar frutos mais homogêneos. Providência apresentou frutos maiores e com maior massa. Nas populações São Judas Tadeu e Providência foram observadas maiores variabilidades fenotípicas. | ABSTRACT This study aimed to characterize three natural populations of mangabeira (Hancornia speciosa) located in parts of the Cerrado in the region of Porto Nacional, State of Tocantins, as well as to evaluate phenotypic variability in individual plants based on the physicochemical properties of their fruits. Ten genotypes were selected from each population, and 20 fruits of each genotype were collected for analysis. Fruits were analyzed for transverse and longitudinal diameters, total mass, pulp mass and yield, and number and fresh mass of seeds. Two seeds were taken from each fruit for the measurement of longitudinal and transverse diameter and thickness. Furthermore, pH and soluble solids were measured in the total pulp of each genotype. Descriptive statistics were performed on the data from morphological characterization, and populations were compared by the Kruskal-Wallis test, followed by Dunn's test at 5% probability level. The relationship between variables was estimated by the Spearman’s correlation coefficient. Phenotypic variability was verified using the principal component analysis. All three natural populations of mangabeira investigated here exhibited similar characteristics regarding fruit morphology and pH. Significant differences were detected only in the transverse diameter of the seed (Canaã had the highest value) and for total soluble solids content (Providência had the highest value). Significant correlations were found for corresponding morphological variables and pH in each population, except for several negative correlations that were observed in the Canaã population, which produced more homogeneous fruit. The Providência population presented the largest and most massive fruit. The greatest phenotypic variabilities were observed in the São Judas Tadeu and Providência populations.

ABSTRACT Vetiver grass is a member of the grass family Poaceae. Its fast development is probably due to the interaction with native microbiota, whose influence has not been studied yet. The objective of this work was to evaluate the colonization and development of the vetiver grass (Chrysopogon zizanioides (L.) Roberty) inoculated with arbuscular mycorrhizal fungi and dark septate endophytic fungi. The experimental design was a completely randomized design with six treatments (control, without mycorrhizal fungi, native inoculants, UFLA05 - Gigaspora albida, UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum, and UFLA401 - Acaulospora morrowiae), with three replicates each. Vetiver grass tillers as well as the native microbial inoculum were obtained from the Lower São Francisco river experimental area, located in Sergipe state, Northeastern Brazil. There was a negative interaction between all tested UFLAs mycorrhizal isolates and the native microbiota (mycorrhizal and endophytic fungi) in the treatments, especially when taking into consideration plant height and volume of roots. The effects of inoculation with UFLA isolates may have been influenced by the presence of the native mycorrhizal fungi and the dark septate endophytic fungi. Vetiver grass was responsive to the native inoculant. The mycorrhizal colonization of the vetiver grass was vesicular, but the formation of the arbuscules can be influenced by the interaction between the fungus, plant, and the environment. | RESUMO O capim vetiver é uma espécie da família poácea que apresenta rápido desenvolvimento, provavelmente decorrente da interação com a microbiota nativa, cuja influência ainda não foi estudada. O objetivo deste trabalho foi avaliar a colonização e o desenvolvimento do capim vetiver inoculado com fungos micorrízicos arbusculares e fungos endofíticos "dark septate". O delineamento experimental utilizado foi inteiramente casualizado composto por seis tratamentos (controle sem fungo micorrízico; inoculante microbiano nativo; UFLA05 - Gigaspora albida, UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum e UFLA401 - Acaulospora morrowiae), com três repetições. Os perfilhos de capim vetiver, assim como o inóculo microbiano nativo foram obtidos na área experimental do Baixo São Francisco, localizado no Estado de Sergipe, Nordeste do Brasil. O efeito da inoculação dos isolados UFLAs pode ter sido influenciado pela presença da micorriza nativa e pelos fungos endofíticos "dark septate". Houve uma interação negativa entre todos isolados UFLAs testados e a microbiota nativa (micorriza e endofítico), nos tratamentos, principalmente quando se considera a altura da planta e o volume de raízes. O capim vetiver foi responsivo ao inoculante microbiano nativo. A colonização micorrízica do capim vetiver foi vesicular, mas a formação dos arbúsculos pode ser influenciada pela interação fungo, planta e ambiente.

ABSTRACT The objective of this work was to evaluate the interaction of microorganisms and phosphorus dosages in the development of gliricidia. The experimental design was completely randomized with six treatments (control, native microbial inoculant, and four arbuscular mycorrhizal fungi isolates: UFLA05 - Gigaspora albida, UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum, and UFLA401 - Acaulospora morrowiae), with four replicates. The parameters evaluated were: height plant, the number of branches, shoot and root dry mass matter, root length and volume, leaf phosphorus, mycorrhizal colonization, the number of spores of the arbuscular mycorrhizal fungi, the number of nodules of nitrogen fixing bacteria, and the presence of endophytic dark septate fungi, after 95 days of inoculation. The high mycorrhizal colonization of gliricidia does not guarantee an increase in biomass, which depends on the interaction of the arbuscular mycorrhizal fungi, the endophytic dark septate fungi, the nitrogen fixing bacteria, and the endophytic bacteria. Gliricidia was responsive to the inoculation of the native microbiota, UFLA372 and UFLA401. Mycorrhizal colonization by UFLA401 was influenced by the presence of nitrogen fixing bacteria. Gliricidia was not responsive to the inoculation of UFLA05 and UFLA351. The presence of the endophytic dark septate fungi did not inhibit mycorrhization and the formation of nodules of nitrogen fixing bacteria in gliricidia. | RESUMO O objetivo deste trabalho foi avaliar a interação de micro-organismos no desenvolvimento da gliricídia. O delineamento experimental utilizado foi inteiramente aleatorizado composto por seis tratamentos (controle; inoculante microbiano nativo e quatro isolados fúngicos micorrízicos arbusculares: UFLA05 - Gigaspora albida, UFLA351 - Rhizoglomus clarum, UFLA372 - Claroideoglomus etunicatum e UFLA401 - Acaulospora morrowiae), com quatro repetições. Os parâmetros avaliados foram: altura da planta, número de ramos, massa da matéria seca da parte aérea e da raiz, comprimento e volume de raiz, teor de fósforo foliar, colonização micorrízica, número de esporos de fungos micorrízicos arbusculares, número de nódulos de bactérias fixadoras de nitrogênio, presença de fungos endofíticos "dark septate", após 95 dias da inoculação. A elevada colonização micorrízica da gliricídia não garante incremento da biomassa, a depender da interação de fungos micorrízicos arbusculares, de fungos endofíticos “dark septate”, de bactérias fixadoras do nitrogênio e de bactérias endofíticas. A gliricídia foi responsiva à inoculação da microbiota nativa, UFLA372 e UFLA401. A colonização micorrízica por UFLA401 foi influenciada pela presença de bactérias fixadoras do nitrogênio. A gliricídia não foi responsiva à inoculação de UFLA05 e UFLA351. A ocorrência de fungos endofíticos “dark septate” não inibiu a micorrização e a formação de nódulos de bactérias fixadoras do nitrogênio, em gliricídia.