Desenvolvimento vegetativo de plantas de café arábica enxertadas sobre café robusta e submetidas à reposição hídrica

O objetivo deste trabalho foi avaliar o crescimento de plantas de café arábica (Coffea arabica) enxertadas sobre café robusta (C. canephora), submetidas a diferentes níveis de reposição de água. O experimento foi realizado em Lavras, MG, em delineamento experimental de blocos ao acaso, em arranjo fatorial 2x2x5, com quatro repetições. Foram feitas avaliações em: duas cultivares de C. arabica - Catuaí IAC-99 e Topázio MG-1190 -, dois tipos de plantas - pé-franco e enxertadas sobre C. canephora 'Apoatã IAC-2258' - e cinco níveis de reposição de água - testemunha sem irrigação e quatro coeficientes de cultura, nos valores 0,2, 0,3, 0,4 e 0,5, do plantio até 24 meses, e 0,4, 0,6, 0,8 e 1,0, de 24 a 29 meses -. Utilizou-se turno de rega fixo, com irrigações às terças e às sextas-feiras. Foram avaliados: altura de plantas, diâmetro de copa e diâmetro de caule. Cafeeiros enxertados têm menor crescimento em comparação aos de pé-franco, no período de implantação da lavoura. A substituição do sistema radicular de C. arabica por C. canephora não altera a resposta das plantas à irrigação.

Microsatellite markers in analysis of resistance to coffee leaf miner in Arabica coffee

The objective of this work was to analyze coffee (Coffea arabica) genotypes resistant to the coffee leaf miner (Leucoptera coffeella) using microsatellite markers. Sixty-six loci were evaluated, of which 63 were obtained from the Brazilian Coffee Expressed Sequence Tag (EST) database. These loci were amplified in bulks of individuals from F5 progenies of 'Siriema' (C. arabica x C. racemosa) resistant and susceptible to the insect, in eight samples of C. racemosa, and in a F6 population of 'Siriema' with 91 individuals segregating for resistance to the leaf miner. Polymorphisms were verified for two simple sequence repeat (SSR) loci in bulks of the susceptible progenies. The two polymorphic alleles were present in around 70% of the susceptible genotypes in F5 and in approximately 90% of the susceptible individuals in F6. However, the polymorphic EST-SSR markers among populations contrasting for resistance to leaf miner were not correlated to the evaluated characteristics. SSR markers show inter- and intraspecific polymorphism in C. arabica and C. racemosa.

Leaf miner incidence in coffee plants under different drip irrigation regimes and planting densities

The objective of this work was to evaluate the effect of different drip irrigation regimes and planting densities on the incidence of the leaf miner, Leucoptera coffeella, in arabica coffee plants for one year. The experiment was carried out in 2008, in a complete randomized block design, in a split-plot in time arrangement, with four replicates. The treatments consisted of four drip irrigation regimes - soil water balance, irrigations at 20 and 60 kPa soil tensions, and a nonirrigated treatment -, which were distributed at three plant densities: 2, 500, 5, 000, and 10, 000 plants per hectare. The evaluations were made on a monthly basis between January and December 2008. The highest pest occurrence period was from August to November, a season with low-air relative humidity preceded by a drought period. Irrigated coffee plants showed an incidence of intact mines 2.2 times lower than that of nonirrigated plants. Irrigation and increasing of plant density contribute to the reduction of coffee leaf miner occurrence.

Análise temporal e controle da mancha-anular e do ácaro vetor do Coffee ringspot virus

O objetivo deste trabalho foi avaliar a flutuação populacional do ácaro Brevipalpus phoenicis, vetor do Coffee ringspot virus (CoRSV) - agente causal da mancha-anular do cafeeiro -, bem como a sua distribuição em plantas de café e o efeito de acaricidas no seu controle em lavouras cafeeiras. O experimento foi realizado no Município de Coromandel, na região do Alto do Paranaíba, MG, durante dois anos. No segundo ano, avaliou-se o progresso da doença, e determinou-se a relação entre o crescimento populacional do ácaro e a incidência da doença. Observou-se que a mancha-anular e o ácaro ocorreram durante todo o ano, com maiores populações e incidência da doença nos meses com menores índices pluviais e temperaturas amenas. As análises de Pearson mostraram correlação negativa entre os parâmetros climáticos e a população do ácaro. Na análise da incidência da doença em diferentes épocas, verificou-se correlação positiva entre a primeira avaliação e as avaliações subsequentes. Quanto à distribuição espacial, foi observada a presença do ácaro em toda a planta; porém, as folhas são preferidas pelos adultos, enquanto os frutos são preferidos para oviposição. Os acaricidas são eficientes para manter a população do ácaro em baixos níveis, com consequente diminuição da incidência da doença.

Gene expression profile during coffee fruit development and identification of candidate markers for phenological stages

The objective of this work was to identify genes that could be used as suitable markers for molecular recognition of phenological stages during coffee (Coffea arabica) fruit development. Four cultivars were evaluated as to their differential expression of genes associated to fruit development and maturation processes. Gene expression was characterized by both semi-quantitative and quantitative RT-PCR, in fruit harvested at seven different developmental stages, during three different seasons. No size polymorphisms or differential expression were observed among the cultivars for the evaluated genes; however, distinct expression profiles along fruit development were determined for each gene. Four out of the 28 evaluated genes exhibited a regular expression profile in all cultivars and harvest seasons, and, therefore, they were validated as candidate phenological markers of coffee fruit. The gene α-galactosidase can be used as a marker of green stage, caffeine synthase as a marker of transition to green and yellowish-green stages, and isocitrate lyase and ethylene receptor 3 as markers of late maturation.

Toxicity of organic farming‑compatible products to the coffee leaf miner

The objective of this work was to evaluate the toxicity of organic farming‑compatible products to the coffee leaf miner Leucoptera coffeella. Lime sulphur, enriched Bordeaux mixture (Viça Café Plus), and the "supermagro" biofertilizer were first tested in laboratory. The most promising product was tested afterwards under field conditions. In laboratory, different concentrations of each product were applied on L. coffeella eggs and on infested coffee‑mined leaves. Only lime sulphur had ovicidal effects at an acceptable concentration (1.6%) for field applications, but no significant effect on larvae mortality was found. Enriched Bordeaux mixture and the "supermagro" biofertilizer had no effect on L. coffeella eggs and larvae. In the field trial, biweekly or monthly sprayings of lime sulphur at different concentrations caused population decrease after 30 days; however, this effect was not significant after 60 or 90 days.

Root system distribution and yield of 'Conilon' coffee propagated by seeds or cuttings

The objective of this work was to evaluate the root system distribution and the yield of 'Conilon' coffee (Coffea canephora) propagated by seeds or cuttings. The experiment was carried out with 2x1 m spacing, in an Oxisol with sandy clay loam texture. A randomized complete block design was used, following a 2x9x6 factorial arrangement, with two propagation methods (seeds and cuttings), nine sampling spacings (0.15, 0.30, 0.45, 0.60, 0.75, and 0.90 m between rows, and 0.15, 0.30, and 0.45 between plants within rows), six soil depths (0.10-0.20, 0.20-0.30, 0.30-0.40, 0.40-0.50, and 0.50-0.60 m), and six replicates. Soil cores (27 cm3) with roots were taken from 12 experimental units, 146 months after planting. The surface area of the root system and root diameter, length, and volume were assessed for 13 years and, then, correlated with grain yield. The highest fine root concentration occurred at the superficial soil layers. The variables used to characterize the root system did not differ between propagation methods. Moreover, no differences were observed for net photosynthetic CO2 assimilation rate, stomatal conductance, internal CO2 concentrations, and instantaneous water-use efficiency in the leaves. Cutting-propagated plants were more productive than seed-propagated ones.

Field data and prediction models of pesticide spray drift on coffee crop

The objective of this work was to generate drift curves from pesticide applications on coffee plants and to compare them with two European drift-prediction models. The used methodology is based on the ISO 22866 standard. The experimental design was a randomized complete block with ten replicates in a 2x20 split-plot arrangement. The evaluated factors were: two types of nozzles (hollow cone with and without air induction) and 20 parallel distances to the crop line outside of the target area, spaced at 2.5 m. Blotting papers were used as a target and placed in each of the evaluated distances. The spray solution was composed of water+rhodamine B fluorescent tracer at a concentration of 100 mg L-1, for detection by fluorimetry. A spray volume of 400 L ha-1 was applied using a hydropneumatic sprayer. The air-induction nozzle reduces the drift up to 20 m from the treated area. The application with the hollow cone nozzle results in 6.68% maximum drift in the nearest collector of the treated area. The German and Dutch models overestimate the drift at distances closest to the crop, although the Dutch model more closely approximates the drift curves generated by both spray nozzles.

Microclimate and development of 'Conilon' coffee intercropped with rubber trees

The objective of this work was to evaluate the influence of intercropping 'Conilon' coffee (Coffea canephora) with rubber trees on coffee tree microclimate, nutrition, growth, and yield. Rubber trees were planted in two double rows 33 m apart, with 4x2.3 m spacing between plants. Treatments consisted of the distances from the coffee plants to the rubber trees: 3, 6, 9, 12, and 15 m. Measurements of atmospheric variables (temperature, irradiance, and relative humidity), leaf nutrient concentration, internode length of plagiotropic and orthotropic branches, individual leaf area, chlorophyll content, and yield were performed. Intercropping promotes changes in the microclimatic conditions of coffee plants close to rubber trees, with reduction of temperature and irradiance level and increase in air relative humidity. The proximity of the coffee tree to the rubber trees promotes the elongation of the plagiotropic and orthotropic branches and increases the individual leaf area; however, it does not affect leaf concentrations of N, K, Mg, Fe, Zn, and B in 'Conilon' coffee and does not have a negative impact on yield.

Uma abordagem robusta de cálculo aplicada a um sistema potenciométrico de medida de concentrações hidrogeniônicas em soluções aquosas

The data analyzed in this work were generated following the methodology developed by Molina et al.(J. Electroanal. Chem., 1979) for the calibration of a potentiometric system of measurement of hydrogen-ion concentrations resulting from neutralizations, at 25 ºC, of acidic or alkaline solutions at constant ionic strength (0.1 mol.l-1) held with NaClO4. The observed data present a serious deviation in relation to the mathematical model derived from the Nernst equation, for pH values ranging from 3 to 11, where pH=-log[H+]. We show that the minimization of the sum of the absolute values of the residuals gives estimates that are not influenced by outlying values.

Metodologia para análise simultânea de ácido nicotínico, trigonelina, ácido clorogênico e cafeína em café torrado por cromatografia líquida de alta eficiência

A reverse phase liquid chromatography method was developed for simultaneous determination of trigonelline, caffeine, nicotinic and chlorogenic (5-CQA) acids in roasted coffee. A gradient of acetic acid/acetonitrile was used as mobile phase and detection was carried out in the UV. The samples were extracted with acetonitrile/water (5:95 v/v) at 80 ºC/10 min. Good recovery (89 to 104%), repeatability and linearity were obtained. Detection limits of 0.01, 0.15, 0.04 and 0.04 mg mL-1 were observed for nicotinic acid, trigonelline, 5-CQA and caffeine. The method, applied to arabica and robusta coffees with different degrees of roasting, was efficient and fast (~35 min) and also allowed identification of cinnamic acids.

Supercritical CO2 recovery of caffeine from green coffee oil: new experimental solubility data and modeling

The caffeine solubility in supercritical CO2 was studied by assessing the effects of pressure and temperature on the extraction of green coffee oil (GCO). The Peng-Robinson¹ equation of state was used to correlate the solubility of caffeine with a thermodynamic model and two mixing rules were evaluated: the classical mixing rule of van der Waals with two adjustable parameters (PR-VDW) and a density dependent one, proposed by Mohamed and Holder² with two (PR-MH, two parameters adjusted to the attractive term) and three (PR-MH3 two parameters adjusted to the attractive and one to the repulsive term) adjustable parameters. The best results were obtained with the mixing rule of Mohamed and Holder² with three parameters.

Chaetoglobosinas produzidas por Chaetomium globosum, fungo endofítico associado a Viguiera robusta Gardn. (Asteraceae)

Endophytes live in association with host plants during all or part of their life cycle without causing any apparent disease. They are considered outstanding and underexploited sources of novel bioactive compounds. Chaetomium globosum was isolated as an endophytic fungus from the healthy leaves of Viguiera robusta. C.globosum is a remarkable producer of chaetoglobosins, which are typically cytotoxic. In this work, chaetoglobosins B (1), D (2) and E (3) have been produced by the endophytic C. globosum strain. Chaetoglobosin B was evaluated against Jurkat (leukemia) and B16F10 (melanoma) tumoral cells and showed 89.55% and 57.10% of inhibition at 0.1 mg mL-1, respectively. Chaetoglobosin B also showed weak antibacterial activity against Staphylococcus aureus (MIC 120 µg/mL) and Escherichia coli (MIC 189 µg/mL).

Determinação simultânea de precursores de serotonina - triptofano e 5-hidroxitriptofano - em café

Epidemiological studies attributed positive effects in the central nervous system (CNS) to coffee. Among possible active constituents, serotonin, a neurotransmitter in the CNS, is present; but dietary sources do not cross the blood-brain barrier. Tryptophan and 5-hidroxytryptophan (5-HTP) are serotonin precursors and can affect brain concentrations. An ion-pair-HPLC, post-column derivatization with o-phthalaldehyde and fluorimetric detection before and after hydrolysis with NaOH and extraction with methanol:water was developed for the simultaneous determination of these compounds. It was selective, sensitive (LOD = 0.3 and 0.2 μg/mL), precise (91.3 and 94.2% recovery for tryptophan and 5-HTP, respectively), and linear from 0.3 to 40 μg/mL for both compounds. It was applied to green and roasted arabica and robusta coffees.

Teores de compostos bioativos em cafés torrados e moídos comerciais

The amounts of nicotinic acid, trigonelline, 5-CQA, caffeine, kahweol and cafestol in 38 commercial roasted coffees ranged from 0.02 to 0.04; 0.22 to 0.96; 0.14 to 1.20; 1.00 to 2.02; 0.10 to 0.80 and 0.25 to 0.55 g/100 g, respectively. Evaluation of color and content of thermo-labile compounds indicated similarity in roasting degree. Differences in the levels of diterpenes and caffeine, components less influenced by the roasting degree, could be mainly explained by the species used (arabica and robusta). Gourmet coffees showed high concentrations of diterpenes, trigonelline and 5-CQA and low levels of caffeine, indicating high proportion of arabica coffee.