Fabiano Guimarães Silva

Seasonal variability in the essential oils of wild and cultivated Baccharis trimera

The seasonal variations in the chemical composition of the essential oil of wild and cultivated Baccharis trimera populations indicated the presence of three clusters of oils regarding population and phenophase. The first included flowering, wild, and cultivated samples from a period of March-May, with high percentages of globulol and spathulenol. In cluster II, with wild samples collected from June-February, the major constituents were germacrene D and (E)-caryophyllene, while cluster III included cultivated samples from June-February containing a high content of ledol. The canonical correlation analysis revealed that (E)-caryophyllene, Mn, Al saturation, and precipitation were quite strongly related to wild samples (cluster II), whereas ledol and guaiol were related to chemical balance in soils (P, K, S, Cu, Zn, and base saturation) of cultivated samples (cluster III). Both essential oils have predominantly hydrocarbon compositions, although for a couple of months the oxygenated sesquiterpene content is over 40% for both samples. The observed chemovariation might be environmentally determined.

Influence of radiation level on plant growth, yield and quality of essential oil in carqueja

A influencia do nivel de radiância no crescimento da planta, rendimento e qualidade do oleo essencial de Baccharis trimera foi estudado neste trabalho. As plantas foram cultivadas sob 4 niveis de radiância: 100, 60, 50 e 20% durante um periodo de 259 dias. Foram avaliadas, quanto ao comprimento, numero de nos, ramos, diâmetro do caule (altura do colo), acumulo de fitomassa, conteudo e composicao do oleo essencial. O nivel mais elevado de radiacao causou aumento em todas as caracteristicas avaliadas, exceto para o comprimento, que foi reduzido com o aumento na radiacao. O rendimento de oleo essencial tambem aumentou com a elevacao do nivel de radiância.

Phosphate solubilization and phytohormone production by endophytic and rhizosphere Trichoderma isolates of guanandi (Calophyllum brasiliense Cambess)

This work aimed to isolate and evaluate the phosphate solubilization and phytohormone production abilities of endophytic and rhizosphere fungi belonging to the genus Trichoderma isolated from guanandi (Calophyllum brasiliense Cambess). From the guanandi collected from the field, 12 isolates obtained were grown in potato dextrose broth and supplemented with the phosphate sources, to test their capacity to solubilize phosphates. A strain of Trichoderma asperellum from a commercial inoculant was also used. One isolate was able to solubilize calcium phosphate, 12 solubilized iron phosphate and two solubilized aluminum phosphate. Only the rhizosphere isolates were able to synthesize indole acetic acid (IAA) and none of the rhizosphere or endophytic isolates produced cytokinin or gibberellin. There are Trichoderma isolates that can benefit plant development, both for their known antagonistic ability against phytopathogenic fungi and for their ability to provide phosphates and or to produce phytohormones. Key words: Trichoderma, inoculants, calcium, iron, aluminum, solubilization, plant growth promotion.

Planting time for maximization of yield of vinegar plant calyx (Hibiscus sabdariffa L.)

The objective of this work was to evaluate the yield of calyxes of Hibiscus sabdariffa L, a medicinal plant, at four planting times in Lavras - MG. The treatments were four planting times (October 18th, November 15th, December 18th 2001 and January 15th 2002) and a harvest was proceeded when practically there were no developing calyxes, almost at the end of the plant cycle. The numbers of calyxes per plant, the fresh and dry biomasses of calyxes and quality were taken into account. It follows that planting time influenced yield per plant and the fresh and dry biomasses of calyxes, differing from each other by Tukey test at 5%. In October planting, there was a higher yield (2,522kg/ha) with a yield 5.24 as high relative to the planting of the month of January (481 kg/ha). The planting s in the month of November to December showed yields of 1,695 and 1,093 kg/ha of dry calyxes, respectively and in relation to the same months of January, yield was of 3.52 to 2.27 times more. Harvest must be done as soon as the calyxes are ripe in order to preserve quality.

Métodos de superação de dormência em sementes de croada (Mouriri elliptica Mart)

Sementes de croada (Mouriri elliptica Mart.) Melastomataceae, especie frutifera nativa do cerrado, foram submetidas aos seguintes tratamentos, visando a superacao de dormencia: pre-resfriamento a 5° C por 7 dias; pre-aquecimento em estufa com circulacao de ar a 40o C por 7 dias; escarificacao quimica em acido sulfurico concentrado por 5 e 15 minutos; imersao em agua fervente por 5 e 15 minutos; imersao em acido giberelico a 100 e 200 mg L-1 por 48 horas; imersao em agua destilada por 24 e 48 horas; escarificacao mecânica com lixa no 80 na parte superior e oposta ao eixo embrionario e testemunha (sementes sem tratamento previo). Quatro repeticoes de quinze sementes foram colocadas para germinar sobre papel umedecido com agua destilada ou nitrato de potassio a 0,2%, em temperatura de 30o C em presenca de luz. Foram realizadas contagens diarias do 2o dia apos a implantacao do experimento ate a estabilizacao da porcentagem de germinacao, que acorreu no 60o dia. A germinacao foi mais rapida em sementes pre-embebidas em acido giberelico (em substrato umedecido com agua ou com solucao de nitrato de potassio 0,2%), pre-embebidas em agua por 24 horas, em substrato umedecido com agua, e pre-embebidas em agua por 48 horas ou escarificadas mecanicamente e colocadas para germinar em substrato umedecido com agua. Taxas de germinacao mais elevadas ocorreram em sementes pre-embebidas em acido giberelico a 100 ou 200 mg L-1, em substrato umedecido com solucao de nitrato de potassio 0,2%.

Efeito da concentração de sais e fitorreguladores na indução de calos em carqueja

Realizou-se este trabalho com o objetivo de estudar condicoes nutricionais e hormonais para maximizar a producao de calos friaveis de carqueja [Baccharis trimera (Less.) DC]. Foi verificado que a iniciacao de calo e dependente de fitorreguladores e da concentracao do meio. A melhor inducao de calo ocorreu em meio MS contendo 50% da concentracao de sais, inositol e vitaminas, suplementado com 15,0 mM ANA. Proliferacao de brotos foi obtida pelo uso de TDZ.

Germinação de sementes de café (Coffea arabica L.) submetidas a diferentes concentrações e tempos de embebição em celulase

As sementes de cafe germinam lentamente em razao de a semeadura ser feita logo apos a colheita, o que coincide com o periodo frio do ano, e tambem por causa de o pergaminho constituir uma barreira que dificulta a absorcao de agua pela semente. Objetivando avaliar o efeito da aplicacao exogena da enzima celulase sobre a germinacao de sementes de cafe, foi realizado o experimento com sementes de cafe, cultivar Acaia do Cerrado, imersas em solucao de celulase em diferentes concentracoes (0; 1,6; 3,2 e 6,4 g.L-1 em tampao citrato de potassio 0,05 M e pH 4,8), por 0, 72 e 144 horas. Observou-se que a enzima celulase na concentracao de 6,4 g.L-1 proporcionou maior indice de velocidade de germinacao (IVG) e porcentagem de germinacao, quando as sementes ficam em contato com a solucao por 144 horas.

Application of polymeric nanoparticles for controlled release of ethanolic extract of guapeva leaves ( Pouteria gardneriana Radlk) against Riphicephalus (Boophilus) microplus through in vitro studies

The study was designed to evaluate the ethanolic extract acaricide action from Pouteria gardneriana Radlk specie adsorbed in chitosan nanoparticles for controlled release against Riphicephalus ( Boophilus ) microplus . Leaves of P. gardneriana Radlk were collected, air-dried, ground and extracted with ethanol. Chitosan nanospheres were obtained by the phase inversion method. Conductometric titration, UV-Vis and FTIR analysis were conducted with the materials to evaluate the chitosan anchoring ability. In vitro test was performed using engorged females for each treatment, which consisted of the control, raw extract and three treatments diluted, with increasing concentrations of 0.2, 0.4 and 1%. The most effectiveness extract was for 0.4% concentration by observing reduction in the eggs mass compared to control group. The nanomaterial proved to be able to anchor and release the insecticide gradually in pH between 5 and 6 regions, which makes it feasible for use in cattle, prolonging the exposure time between the tick and acaricide. Key words: Extracts, nanoparticle, controlled release, tick.

Production and quality of Anacardium othonianum Rizz. seedlings grown in different substrates

This study aimed to evaluate the effect of substrate on growth, emergence, nutrition, and quality of Anacardium othonianum Rizz. (cerrado cashew tree) seedlings. The experiment was conducted in a greenhouse at the Plant Tissue Culture Laboratory on the Rio Verde campus. The following substrates were used: 1) Bioplant®, 2) Mecplant® (MP) + carbonized rice husk (CRH) (7:3), 3) fine-grained vermiculite (FGV), 4) FGV+CRH (3:1), 5) FGV+CRH (1:1), 6) FGV+CRH (1:3), and 7) sugarcane bagasse (SB) + sugarcane mill filter cake (FC) (3:2). Emerged seedlings were counted at 2-day intervals for 38 days following emergence of the first seedling. At 39, 64, and 89 days after seeding (DAS), the following variables were measured: stem length (SL), stem diameter (SD), and number of leaves (NL). Accumulated dry weight, quality indices, and leaf macro- and micronutrient levels were determined at 89 DAS. Plants grown in the FGV and FGV+CFH (1:3) substrates had shorter stem lengths than the plants grown in other substrates. Increases in seedling growth were smaller between 64 and 89 DAS compared to the initial period of the experiment. The highest leaf N concentrations were found in the SB+FC substrate treatment group; P and K concentrations were higher for the MP+CRH (7:3), SB+FC, and Bioplant® treatments; and Ca levels were higher for the SB+FC and MP+CRH (7:3) substrate treatments. The MP+CRH (7:3) substrate treatment group had the highest leaf B and Mn micronutrient concentrations, and plants from the Bioplant® substrate group had the highest leaf B micronutrient content. Mg, S, Cu, Zn, and Fe concentrations did not differ among the different substrates. The plant traits that differed most among the treatments included stem length for the FGV and FGV+CRH (1:3) substrate groups and leaf nutrient concentrations, which were higher for the SB+FC group followed by the MP+CRH and Bioplant® treatments.

Efeito da celulase sobre a decomposição do pergaminho e sua influência na velocidade e porcentagem de germinação de sementes de cafeeiro

Com este trabalho, objetivou-se verificar a acao da celulase sobre a decomposicao do pergaminho das sementes de cafeeiro. Foram implantados dois experimentos, sendo o primeiro, realizado em condicoes in vitro. Constituido por tres ensaios para avaliar os efeitos das concentracoes da enzima, do substrato e sacarificacao enzimatica do pergaminho. O segundo, foi realizado em condicoes in vivo, com imersao das sementes de cafeeiro em solucao de celulase na concentracao de 1,6 g.L-1 em tampao citrato de potassio 0,05 mol.L-1. Observou-se que a quantidade de acucar liberado in vitro foi diretamente relacionada com a concentracao de enzima, e que houve aumento expressivo e linear na quantidade de acucares redutores liberados nas duas concentracoes (1,6 e 3,2 g.L-1) a medida que se aumentou o tempo de incubacao das amostras de substrato (pergaminho) com a solucao enzimatica. Foi verificado tambem, nos testes de germinacao e emergencia, que as sementes sem pergaminho apresentam maiores indices de velocidade e porcentagem de germinacao e emergencia comparado as sementes com pergaminho e que a celulase nesta concentracao ainda nao proporciona aumento na velocidade de germinacao das sementes, necessitando-se de concentracoes mais elevadas.