R. L. Cunha

In field-grown coffee trees source-sink manipulation alters photosynthetic rates, independently of carbon metabolism, via alterations in stomatal function

Perturbations of the source-sink balances were performed in field-grown coffee (Coffea arabica) trees to investigate the possible role of carbohydrates in feedback regulation of photosynthesis. Four treatments were applied at the whole-plant level: (i) complete defruiting and maintenance of the full leaf area, (ii) the half crop load and full leaf area, (iii) the full crop load and full leaf area and (iv) the full crop load and half leaf area. Sampling and measurements were performed twice during the phase of dry matter accumulation of fruits. Gas exchange, chlorophyll a fluorescence, carbon isotope labelling and steady-state metabolite measurements were assessed in source leaves. The average rate of net photosynthetic rate (A) and stomatal conductance (g(s)) were larger (> 50%), and carbon isotope composition ratio was lower, in trees with a full crop load and half leaf area than in defruited trees, with individuals of the other two treatments showing intermediate values. However, differences in A seem unlikely to have been caused either by photochemical impairments or a direct end-product-mediated feedback down-regulation of photosynthesis. It is proposed that the decreased A in defruited coffee trees was independent of carbon metabolism and was rather directly related to a lower CO(2) availability coupled to lower g(s).

Efeitos potencialmente alelopáticos dos óleos essenciais de Piper hispidinervium C. DC. e Pogostemon heyneanus Benth sobre plantas daninhas

This study aimed to characterize the potential allelopathic activity of essential oils of pimenta longa (Piper hispidinervium C. DC.) and oriza (Pogostemon heyneanus Benth), and to examine, comparatively, their allelopathic effects. Essential oils obtained were prepared at concentrations of 0.25%, 0.5% and 1.0%, with ether methanol as eluent, and tested upon the germination of seeds and the development of the radicle and the hypocotyl of the weeds of cultivated grassland areas, malicia (Mimosa pudica) and mata-pasto (Senna obtusifolia). Depending on their concentrations, oils of the two species showed intensities of allelopathic activity on the donor species, on the receptor plant and on the examined plant factor. The germination of seeds was the factor most strongly inhibited by the oils. The intensities of inhibitions were positively related to the concentration, with the maximum inhibitions verified at 1%. Mimosa pudica was the receptor species most sensitive to the effects of oil. In comparison, the essential oil of Piper hispidinervium showed a higher potential for inhibiting the germination and development of the two receptor plants, notably in relation to the germination of seeds, when the differences were more striking. The results were attributed to the chemical composition of oils, especially in relation to the presence of monoterpenes, oxygenated monoterpenes and sesquiterpenes.

Caracterização de farinhas de tapioca produzidas no estado do Pará

Tapioca flour is a typical food produced from cassava starch (Manihot esculenta Crantz), widely consumed in the Amazon Region. The aim of this study was to characterize two tapioca flours produced in Para State, Brazil one in the West Region and other in Bragantina Area. Both tapioca flour presented distinct particle-size distribution and significant difference (P 0.05) for majority of the physico-chemical and technological parameters. Flour from West Region presented high moisture (10.7%), this due the greater capacity of water adsorption, attributed at its high specific area (smaller particle-size). The optical microscopy with polarized light and the technologic properties of the products did not showed a standard process for the production of tapioca flour.

Essential Oil Components of Pogostemon heyneanus Benth, Piper hispidinervum C. DC. and Ocimum americanum L. Obtained in the Amazon

Abstract The study aimed to characterize the essential oil components of leaves and twigs of Pogostemon heyneanus Benth, Piper hispidinervum C. DC. and Ocimum americanum L. collected around the city of Belém, Pará. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography coupled to a mass spectrometer. The main components identified in the essential oils were patchouli alcohol 21.9 % (Pogostemon heyneanus Benth), safrole 64.3 % (Piper hispidinervum C. DC.) and limonene 24 % (Ocimum americanum L.).

Morphoanatomy and histochemistry analyses of cassava roots do not discriminate resistant from susceptible genotypes to soft root rot

A mandioca e uma cultura importante no Brasil e no Norte do pais, e a podridao mole da raiz tem afetado a producao. O objetivo deste trabalho foi identificar caracteres morfoanatomicos e histoquimicos da raiz associados a resistencia a podridao da raiz. Em areas sem ocorrencia da doenca, nove genotipos de mandioca foram testados, quatro resistentes e cinco suscetiveis. A colheita da raiz foi realizada doze meses apos o plantio e medidas de espessura do suber, suber e cortex e xilema secundario foram realizadas. Alem disso, foram analisados a textura, as camadas de celula do suber, o conteudo de lignina e os monomeros de lignina da porcao suber e cortex. Ainda, testes histoquimicos e microscopia eletronica de varredura (MEV) das raizes foram realizados. Os resultados foram submetidos a analise de variância e as medias foram comparadas pelo teste de Scott-Knott (p≤0.05). Os caracteres: espessura de suber e cortex nas porcoes mediana e proximal, espessura do xilema secundario nas porcoes mediana e apical, numero de camadas de celulas do suber, espessura do suber e textura da raiz apresentaram diferencas entre os genotipos, mas nao associadas a resistencia ou suscetibilidade. Nao houve diferencas para: elementos de vaso, lignina e monomeros de lignina para os testes histoquimicos com Sudan IV e Lugol. Imagens de MEV apresentaram diferencas entre os genotipos, mas nao associadas a resistencia ou suscetibilidade. Assim, os caracteres avaliados nao podem ser usados na selecao de mandioca com resistencia a podridao mole da raiz em programa de melhoramento genetico.

Differential accumulation of proteins in oil palms affected by fatal yellowing disease.

There is still no consensus on the true origin of fatal yellowing, one of the most important diseases affecting oil palm (Elaeis guineensis Jacq.) plantations. This study involved two-dimensional liquid chromatography coupled with tandem mass spectrometry (2D-UPLC-MSE) analyses to identify changes in protein profiles of oil palms affected by FY disease. Oil palm roots were sampled from two growing areas. Differential accumulation of proteins was assessed by comparing plants with and without symptoms and between plants at different stages of FY development. Most of the proteins identified with differential accumulation were those related to stress response and energy metabolism. The latter proteins include the enzymes alcohol dehydrogenase and aldehyde dehydrogenase, related to alcohol fermentation, which were identified in plants with and without symptoms. The presence of these enzymes suggests an anaerobic condition before or during FY. Transketolase, isoflavone reductase, cinnamyl alcohol dehydrogenase, caffeic acid 3-O-methyltransferase, S-adenosylmethionine synthase, aldehyde dehydrogenase and ferritin, among others, were identified as potential marker proteins and could be used to guide selection of FY-tolerant oil palm genotypes or to understand the source of this anomaly. When comparing different stages of FY, we observed high accumulation of alcohol dehydrogenase and other abiotic stress related-proteins at all disease stages. On the other hand, biological stress-related proteins were more accumulated at later stages of the disease. These results suggest that changes in abiotic factors can trigger FY development, creating conditions for the establishment of opportunistic pathogens.

Determinação dos Teores de Cu, Fe, Mn e Zn por FAAS em Raízes de Mandioca ( Manihot esculenta Crantz) da Amazônia Oriental

O objetivo deste estudo foi determinar a quantidade de micronutrientes Fe, Zn, Mn e Cu de nove amostras de raizes de mandioca por espectrometria de absorcao atomica com chama (FAAS) utilizando ferramentas quimiometricas como a analise exploratoria multivariada sem supervisao para tentar explicar possiveis diferencas nas suas caracteristicas quimicas e teste de Tukey para verificar a significância estatistica dos valores medios. Quatro amostras foram obtidas de um comercio local, cultivadas sem qualquer informacao sobre as condicoes ambientes de plantio ou colheita. As outras cinco amostras pertencem a um banco ativo de germoplasma (BAG) em condicoes de plantio e ambientes conhecidas. O teor de Fe variou de 0,54 a 5,24 mg/kg; Zn de 0,38 a 6,55 mg/kg; Cu de 0,04 a 0,89 mg/kg e Mn de 0,16 a 0,41 mg/kg. As amostras comerciais apresentaram resultados esperados para todos os elementos estudados, enquanto as amostras de BAG apresentaram vantagens na absorcao de ferro e zinco. As amostras do comercio local nao apresentaram ferro em sua composicao, mas foram as unicas que apresentaram manganes em sua composicao. Tal caracteristica foi, portanto, um parâmetro essencial para distinguir as amostras comerciais das outras amostrasis. O conhecimento das condicoes de plantio sao essenciais para assegurar provaveis fatores exogenos que podem causar variacoes na absorcao de micronutrientes. Esses fatores devem ser considerados como influentes na absorcao de micronutrientes em amostras de mandioca.

Prolina, glicina-betaína, açúcares redutores e não redutores em progênies de cupuaçuzeiro submetidas à deficiência hídrica.

Introdução O cupuaçuzeiro [Theobroma grandiflorum (Willd. ex. Spreng.) Schum.,] é uma árvore nativa da Amazônia pertencente à família Malvaceae, a qual é considerada uma espécie frutífera com alto potencial de expansão, devido a abertura do mercado para frutas exóticas tropicais, especialmente aquela oriunda da floresta Amazônica, sendo encontrada em estado rústico nas florestas tropicais de terra firme e apresenta importância econômica, social e ambiental para a região (ALVES et al., 2012). Atualmente, seu cultivo vem sendo implantado em locais que possuem a ocorrência de períodos secos bem definidos, com aproximadamente seis meses de pluviosidade abaixo de 100 mm com o intuito de prevenir o surgimento de doenças (FERNANDES, 2015). Dessa forma, o comportamento agronômico de plantas de cupuaçuzeiro necessita ser compreendido, uma vez que, entender o mecanismo de resposta dessa espécie em condição de restrição hídrica, é de suma importância ao desenvolvimento agrícola das plantas, ao manejo e a produtividade dessa espécie. Assim, o objetivo foi avaliar o potencial hídrico e os teores de prolina, glicina-betaína, açúcares redutores e não redutores em progênies de cupuaçuzeiro submetidas a deficiência hídrica.]

Trocas gasosas em progênies de cupuaçuzeiro submetidas à deficiência hídrica.

Introdução O cupuaçuzeiro [Theobroma grandiflorum (Willd. ex. Spreng.) Schum.,] é uma árvore nativa da Amazônia pertencente à família Malvaceae, a qual é considerada uma espécie frutífera com alto potencial de expansão, devido a abertura do mercado para frutas exóticas tropicais, especialmente aquela oriunda da floresta Amazônica, sendo encontrada em estado rústico nas florestas tropicais de terra firme e apresenta importância econômica, social e ambiental para a região (ALVES et al., 2012). Atualmente, seu cultivo vem sendo implantado em locais que possuem a ocorrência de períodos secos bem definidos, com aproximadamente seis meses de pluviosidade abaixo de 100 mm com o intuito de prevenir o surgimento de doenças (FERNANDES, 2015). Dessa forma, o comportamento agronômico de plantas de cupuaçuzeiro necessita ser compreendido, uma vez que, entender o mecanismo de resposta dessa espécie em condição de restrição hídrica, é de suma importância ao desenvolvimento agrícola das plantas, ao manejo e a produtividade dessa espécie. Assim, o objetivo foi avaliar o potencial hídrico e as trocas gasosas em progênies de cupuaçuzeiro submetidas à deficiência hídrica.

Diurnal Pattern of Leaf, Flower and Fruit Specific Ambient Volatiles above an Oil Palm Plantation in Pará State, Brazil

Oil palm plantations are rapidly expanding in the tropics because of insatiable global demand for fruit oil to be used in food, biofuels and cosmetics. Here we show that three tissue-specific volatiles can be quantified in ambient air above an African-American hybrid oil palm plantation in Brazil and linked photosynthesis (isoprene), floral scent (estragole), and for the first time, fruit oil processing (6-methyl-5-hepten-2-one, MHO). Plant enclosure techniques verified their tissue specific emission sources with ambient concentrations displaying distinct diurnal patterns above the canopy. Isoprene concentrations were near zero at night, but dramatically increased during the day while estragole showed elevated concentrations at night suggesting a light-independent, temperature-driven emission pattern from flowers. MHO also showed elevated concentrations at night and both estragole and MHO increased during the day. Our observations demonstrate that the African-American oil palm hybrid is strong isoprene emitter and suggest that MHO is a specific oxidation product of lycopene released during the industrial processing of palm oil. This study highlights the potential value of quantifying volatile oil palm signals in the atmosphere as a novel, non-invasive method to better understand biological functioning and its interactions with the environment including carbon assimilation, floral-insect interactions, and fruit oil production/processing.