Marcelo Bento Paes de Camargo

Definição e esquematização das fases fenológicas do cafeeiro arábica nas condições tropicais do Brasil

The arabic coffee (Coffea arabica L.) takes two years to complete the entire phenological cycle of the frutification, unlike most of the other crops, that complete the reproductive cycle in one year. Six different phenological phases, taking a total of two years, are proposed, starting in September of each year. The phases are: 1st phase: vegetative, with seven months, September to March, with long days; 2nd phase: also vegetative, April to August, with short days, when occurs the transformation of the vegetative buds of the knots formed in the 1st phase to reproductive buds. At the end of this phase, July and August, the plants enter in relative dormancy with formation of one or two small pair of leaves, that usually do not flourish. The maturation of the reproductive buds comes after the accumulation of about 350 mm of potential evapotranspiration (ETp), starting by the beginning of April; 3rd phase: flowering and grain expansion, September to December. Usually the flowering happens about 8 to 15 days after the increase of the water potential inside the floral buds caused by rain or irrigation; 4th phase: grain formation, January to March; 5th phase: grain maturation, when about 700 mm of ETp accumulates since the main flowering; 6th phase: senescence and death of the non-primary productive branches, in July and August.

Uma revisão analítica da evapotranspiração potencial

This work refers to the potential evapotranspiration (ETp) considered as a meteorological element according to Thornthwaite and Wilm. Later on Penman and Sanderson have published also pioneer works on ETp. ETp can be considered the opposite of the rainfall. While this one means the water transferred from atmosphere to the surface, the former means the water back to the atmosphere. ETp represents the transformation of the liquid water state to the gaseous state. This process depends on the energy received from the sun and of the energy balance on a vegetated surface.The soil moisture depends on the water balance between the rainfall and the ETp data. The rainfall data can be easily measured by raingages, but the ETp measurement is more difficult: it is required equations based on several meteorological elements. The Thornthwaite model works well under humid climate conditions, but in dry and arid climates it underestimates the ETp because does not consider the saturation deficit of the air, that is very high in these climatic conditions. Recent studies showed that the problem may be reduced by using a modified mean daily temperature model that uses an adjusted mean temperature based on the daily thermometric amplitude (Tmax-Tmin). This amplitude is usually higher in dry climate and lower in superhumid climate, allowing the correction to estimate the ETp values in both cases.

Escala para avaliação de estádios fenológicos do cafeeiro arábica

A scale to evaluate coffee phenological stages is proposed based on images of twelve stages, considering lot for reproductive period, from dormant buds up to dry beans (harvest). During the growing season 2001/02 the scale was used for different coffee cultivars in field trials located at Campinas and Mococa, Sao Paulo State, Brazil. The scale showed to be useful to relate meteorological variation and crop yield, development and maturation period for the different evaluated cultivars.

The impact of climatic variability and climate change on arabic coffee crop in Brazil

A variabilidade climatica e o principal fator responsavel pelas oscilacoes e frustracoes da producao de cafe no Brasil. As relacoes entre os parâmetros climaticos e a producao agricola sao bastante complexas, pois fatores ambientais afetam o crescimento e o desenvolvimento das plantas sob diferentes formas durante as fases de crescimento da cultura do cafe. Modelos agrometeorologicos que relacionam o crescimento, desenvolvimento e a produtividade podem prover importantes informacoes para o monitoramento das condicoes hidricas da cultura e estimativa da produtividade com base no estresse hidrico. Resultados do balanco observados durante os diferentes estadios fenologicos quantificam o efeito da agua disponivel no solo sobre a produtividade da cultura. Outros fatores climaticos podem reduzir a produtividade, como temperaturas adversas ocorridas durante as diferentes fases criticas da cultura. Radiacao solar e umidade relativa influenciam tambem os processos fisiologicos da planta, mas normalmente nao penalizam a produtividade como as condicoes hidricas e termicas. Segundo o ultimo relatorio do Painel de Intergovernamental de Mudancas Climaticas (IPCC), preve-se que a temperatura global aumente de 1,1 oC a 6,4 oC e a chuva em 15% nas areas tropicais de Brasil. Alguns trabalhos inferem que estes cenarios previstos pelo IPCC causarao forte reducao na producao de cafe no Brasil, com tendencia de se mover para regioes de altitude e Sul do Brasil. Este trabalho de revisao analisa o efeito que estes possiveis cenarios teriam no zoneamento agroclimatico do cafe arabica no Brasil; aborda tambem os metodos de adaptacao e mitigacao agronomicos como manejo e desenvolvimento de cultivares adaptadas a temperaturas elevadasThe climatic variability is the main factor responsible for the oscillations and frustrations of the coffee grain yield in Brazil. The relationships between the climatic parameters and the agricultural production are quite complex, because environmental factors affect the growth and the development of the plants under different forms during the growth stages of the coffee crop. Agrometeorological models related to the growth, development and productivity can supply information for the soil water monitoring and yield forecast, based on the water stress. A soil water balance during different growth stages of the coffee crop, can quantify the effect of the available soil water on the decrease of the final yield. Other climatic factors can reduce the productivity, such as adverse air temperatures happened during different growth stages. Solar radiation and relative humidity influence many physiological processes of the coffee tree but are not generally thought to play an important role as thermal and rainfall conditions in defining potential yield or ecological limitations for this crop. According to the last report of the Intergovernmental Panel on Climate Change (IPCC, 2007), the global temperature is supposed to increase 1.1oC to 6.4oC and the rainfall 15% in the tropical areas of Brazil. Some Global warming projections as presented by IPCC will cause a strong decrease in the coffee production in Brazil. According to the literature besides the reduction of suitable areas for coffee production, the crop will tend to move South and uphill regions. This review article analyze the effect that these possible scenarios would have in the agro-climatic coffee zoning in Brazil, and adaptive solutions, such as agronomic mitigations and development of cultivars adapted to high temperatures is considered.

Exigência térmica do café arábica cv. Mundo Novo no subperíodo florescimento-colheita

Base temperature and heat requirement, using degree-days were evaluated for coffee cv. Mundo Novo. The sum of reference (ETo) and actual (ETr) evapotranspiration were also determined for the flowering-harvest phenological stage, using coffee phenological data for the growing season from 1971 to 2004. A correction factor was proposed for the degree-days sum related to available water on the first eighty days during the beginning of flowering. The obtained values of base temperature and degree-days requirements were, respectively, 10.2oC and 2887 degree-days and 10.5oC and 2761 degree-days when evaluated with and without adjustement for water deficit. The mean value for ETo sum was 761 mm, and for ETr, 689 mm. When considered the sum of ETr during the development of the berries (first 80 days after flowering) was considered the mean values were 721 mm. The correction factor for water deficit improved the determination of base temperature and heat sum for the flowering-harvest stage for Mundo Novo coffee plants.

Spatial and temporal variability of daily weather variables in sub-humid and semi-arid areas of the united states high plains

Ensuring continuous, quality data from weather station networks requires a knowledge of spatial and temporal variability. This knowledge is essential to identifying suspect data and providing estimates for bad data and for data gaps. This study was conducted to quantify and contrast the spatial and temporal variability for daily weather variables for two climatic areas, eastern (sub-humid) and western (semi-arid), in the High Plains of the US. For a period of 7 years (1989‐1995) complete data were available from 38 automated weather stations, 19 stations in each area. The daily meteorological variables studied were: maximum and minimum air temperature, relative humidity, solar radiation, wind speed and precipitation and potential evapotranspiration (ETp). The coefficient of variation (r 2 ) and standard error of estimate (SEE) were calculated by regression of daily measurements between like weather variables for various station pairings within the two climatic areas. A temporal analysis was conducted with a subset of the data and it was determined that 7 years of record are required to stabilize the variation between stations. In the spatial analysis, a central station was paired with each of the other stations in the area. The SEE and r 2 were plotted against separation distance from the central station. Best fit lines were determined for the variograms (r 2 ) and errograms (SEE). Analyses were repeated for each month. Generally, the r 2 decreased while the SEE increased with distance of separation between sites. As separation distance between sites increased: SEE for maximum and minimum temperature were greater in the semi-arid than in the sub-humid area, especially during the winter season; while SEE for wind run were lesser in the semi-arid than in the sub-humid area. SEE for relative humidity were greater in the semi-arid than in the sub-humid area. There was no difference in SEE for solar radiation between the two areas. At short separation distances, there was minimal difference in SEE for ETp between the west and east; however at greater separation distances, SEE for ETp were greater in the semi-arid area. A significant seasonal cycle was found in the SEE data for maximum and minimum temperature, solar radiation, and ETp. Results indicate that the accuracy of estimated data and associated confidence limits will vary with the time of the year. # 1999 Elsevier Science B.V. All rights reserved.

Discovery of a new focus of human onchocerciasis in central Brazil.

An autochthonous case of human onchocerciasis was reported 13 years ago in the town of Minaçu, northern Goiás (Brazil), but a subsequent survey of the population using the traditional technique of examining skin biopsies with the light microscope failed to detect other cases. Recent surveys using more sensitive diagnostic techniques (serodiagnosis, DNA probes, Mazzotti test) that are detailed in this paper revealed the presence of other cases of the disease in Minaçu, the nearby town of Formoso and at the Buracão gold mine near Paranã. The data show that transmission of the disease has occurred to local people living in town and on farms and that gold miners (garimpeiros) are a likely source of infection.

TESTE E ANÁLISE DE MODELOS AGROMETEOROLÓGICOS DE ESTIMATIVA DE PRODUTIVIDADE PARA A CULTURA DA SOJA NA REGIÃO DE RIBEIRÃO PRETO

The agrometeorological models allow better knowledge of the quantitative influence of the climatic conditions, such as drought effects on the soybean development and grain production. A good model requires the evaluation of the sensitivity indices and test for a specific variety and region. Phenological and yield data were taken from planting date experiments conducted at Ribeirao Preto, Instituto Agronomico Experimental Station during four growing seasons. Three cultivars were considered according the maturation group: IAC-13 (early), IAC-12 (semi-early) and IAC-11 (median). Additive and multiplicative type models were tested based upon the penalization of the crop yield potential according the ER/EP relation (actual/potential evapotranspiration) and water excess, derived by a 10-day soil water balance, occurred during four growth stages. Based on the models statistics, additive and multiplicative type models presented similar performance. The model which considers penalization including water excess presented the best performance for the three maturation groups, with R2 of 0.69 and d-index of agreement of 0.85 for the IAC-13 (early) cultivar; R2 of 0.72 and d-index of 0.73 for the IAC-12 (semi early) cultivar; and for the IAC-11 (median) cultivar, R2 of 0.79 and d-index of 0.73. Index terms: soybean, growth stage, soil water balance, agrometeorological models, crop production.

Relações radiométricas de uma cultura de cana-de-açucar

Durante o periodo de maximo indice de area foliar de uma cultura de cana-de-acucar, cv. NA56-79, os coeficientes de reflexao, transmissao e absorcao da radiacao solar incidente variaram em funcao do ângulo de incidencia dos raios solares e da faixa espectral considerada. A radiacao fotossinteticamente ativa (PAR) foi sempre menos refletida e transmitida e mais absorvida que a radiacao do infravermelho proximo (NIR). Em geral, para as fracoes consideradas, obtiveram-se as seguintes relacoes radiometricas: (1) radiacao disponivel, NPAR = 1,2 NNIR; (2) radiacao refletida, RPAR = 0,1 RNIR; (3) radiacao transmitida, TPAR = 0,2 TNIR; (4) radiacao absorvida, APAR = 1,6 ANIR.

Solar radiation regime in three cassava (Manihot esculenta Crantz) canopies

Abstract For solar elevation greater than 20° and clear sky conditions, the near infrared (NIR) and photosynthetically-active radiation (PAR) were, respectively, 0.54 and 0.46 of the incoming solar radiation. During the period of maximum leaf area index (LAI), plant structure had no apparent effect upon the crop reflection, transmission and absorption coefficients which were, however, functions of solar elevation. NIR was always more reflected and transmitted but less absorbed than PAR regardless of the plant structure. For the wavebands considered the following radiometric relations were, in general, obtained: (1) incoming radiation, IPAR = 0.85 INIR; (2) reflected radiation, RPAR = 0.07 RNIR; (3) net solar radiation, NPAR = 1.29 NNIR; (4) transmitted radiation, TPAR = 0.5 TNIR.