Biblioteca Digital

O presente trabalho teve como objetivo avaliar o modo como os micronutrientes zinco e boro e suas interações com a adubação nitrogenada influenciam no desempenho da cultura do milho (Zea mays L.). O experimento foi conduzido em área pertencente à Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ/USP), no município de Piracicaba-SP, no ano agrícola de 2000/2001, em solo classificado como Nitossolo Vermelho, Eutrófico, onde foi semeado o híbrido Cargill 909. O delineamento experimental utilizado foi casualizado em blocos com vinte e sete tratamentos e três repetições, onde tanto o zinco como o boro foram aplicados de forma localizada no sulco, por ocasião da semeadura do milho. Os tratamentos corresponderam a cinco doses de zinco (0, 2, 4, 8 e 16 kg.ha -1 ) e cinco doses de boro (0, 1, 2, 4 e 8 kg.ha -1 ), associados ou não ao nitrogênio, o qual foi aplicado em três doses (0, 120 e 240 kg.ha -1 ). Cabe salientar que o nitrogênio foi aplicado parceladamente na forma de uréia (45% N), sendo 30 kg.ha -1 aplicados no sulco de semeadura e o complemento, específico de cada tratamento, em cobertura, no momento em que a cultura de milho apresentava cinco folhas plenamente expandidas. Como fontes de zinco e de boro...

A estimativa antecipada da produção de café das diversas regiões produtoras é muito importante para o estabelecimento da política cafeeira do país. Apesar disso, não existe no Brasil uma metodologia adequada para previsão antecipada da safra de café que permita uma avaliação segura e precisa. As poucas informações para o estabelecimento de modelos para previsão de safra de café são em conseqüência da complexidade metodológica, ocasionada pela diversidade dos fatores ambientais, culturais e econômicos, envolvidos na produtividade dessa cultura, que devem ser levados em consideração nos modelos de previsão como, por exemplo: cultivares, densidade de plantio, idade da planta, tecnologia empregada, condições edafoclimáticas, etc. Para isso a avaliação das características fenológicas determinantes do desenvolvimento e da produção do cafeeiro é uma ferramenta fundamental no estabelecimento de modelos de previsão de safra. Atualmente as previsões baseiam-se em levantamentos empíricos efetuados visualmente, requerendo, para atingir razoável precisão, técnico ou produtores altamente especializados na cultura. Esta pesquisa teve como objetivo desenvolver uma metodologia para estimar a produtividade do cafeeiro sem utilizar a contagem total de frutos na planta...

O objetivo deste trabalho foi avaliar o efeito da redução do espaçamento no índice de área foliar, na senescência foliar, na radiação fotossinteticamente ativa interceptada e no rendimento de grãos de dois híbridos de milho em três sistemas de manejo. Três experimentos em delineamento em blocos ao acaso, em fatorial 2x2x2 foram conduzidos em campo em Eldorado do Sul, RS. Em cada experimento, os tratamentos constaram de espaçamentos de 0,4 e 0,8 m; híbrido de folha ereta e de folha decumbente; e duas densidades (5 e 6,6 plantas m-2, 6,2 e 8,3 plantas m-2 e 6,5 e 8 plantas m-2, respectivamente, nos sistemas de manejo médio, alto e muito alto). Níveis de adubação e disponibilidade hídrica variaram com o sistema de manejo. O índice de área foliar e a radiação fotossinteticamente ativa interceptada variam com o espaçamento, mas dependem de estádio fenológico, densidade e arquitetura foliar e sistema de manejo. A senescência foliar não variou de acordo com o espaçamento, independentemente de sistema de manejo, densidade e híbrido. Menores espaçamentos aumentaram o rendimento apenas no sistema de manejo muito alto. As características de dossel não seguiram o comportamento do rendimento de grãos.; The objective of this work was to evaluate the effect of narrow row spacing on leaf area index...

O objetivo do trabalho foi avaliar a relação entre as fases do crescimento da cana-de-açúcar com as formas de curvas do perfil temporal do Índice de Vegetação por Diferença Normalizada - NDVI, obtidas a partir do sensor remoto orbital MODerate-resolution Imaging Spectroradiometer - MODIS, na região de estudo. A avaliação desta relação é realizada utilizando-se técnicas de sensoriamento remoto para a geração do perfil temporal do NDVI, ao longo do ciclo de desenvolvimento fenológico da cana-soca, nas maturações Precoce, Média e Tardia. Os talhões de cana-soca analisados foram agrupados de acordo com a variedade, solo, data de plantio e corte, e contigüidade. A visualização gráfica das formas de curvas analisadas é realizada através de aplicativo, desenvolvido neste trabalho na linguagem de programação Java, e do sistema gerenciador de banco de dados PostgreSQL. O aplicativo realiza a filtragem de ruídos presentes nas imagens, composição na resolução temporal de 8 dias, através dos dados da banda de controle de qualidade do produto MOD09Q1, realiza a eliminação de valores discrepantes ao longo do perfil temporal do NDVI para a safra analisada, corrige as influências dos períodos de corte e rebrota da cana-soca...

The degree of flowering and fruiting synchronization is believed to have ecological and evolutionary relevance at several scales. Here we discuss some measures that have been used to estimate synchrony and propose an index that incorporates both the entire length of an individual phenophase and variation in the number of flowers or fruits over that time period. This new index describes more accurately the phenological synchrony among individuals and populations.

Recent rapid climatic changes are associated with dramatic changes in phenology of plants and animals, with optimal timing of reproduction advancing considerably in the northern hemisphere. However, some species may not have advanced their timing of breeding sufficiently to continue reproducing optimally relative to the occurrence of peak food availability, thus becoming mismatched compared with their food sources. The degree of mismatch may differ among species, and species with greater mismatch may be characterized by declining populations. Here we relate changes in spring migration timing by 100 European bird species since 1960, considered as an index of the phenological response of bird species to recent climate change, to their population trends. Species that declined in the period 1990–2000 did not advance their spring migration, whereas those with stable or increasing populations advanced their migration considerably. On the other hand, population trends during 1970–1990 were predicted by breeding habitat type, northernmost breeding latitude, and winter range (with species of agricultural habitat, breeding at northern latitudes, and wintering in Africa showing an unfavorable conservation status), but not by change in migration timing. The association between population trend in 1990–2000 and change in migration phenology was not confounded by any of the previously identified predictors of population trends in birds...

Widespread concerns about global biodiversity loss have led to a growing demand for indices of biodiversity status. Today, climate change is among the most serious threats to global biodiversity. Although many studies have revealed phenological responses to climate change, no long-term community-level indices have been developed. We derived a 250-year index of first flowering dates for 405 plant species in the UK for assessing the impact of climate change on plant communities. The estimated community-level index in the most recent 25 years was 2.2–12.7 days earlier than any other consecutive 25-year period since 1760. The index was closely correlated with February–April mean Central England Temperature, with flowering 5.0 days earlier for every 1°C increase in temperature. The index was relatively sensitive to the number of species, not records per species, included in the model. Our results demonstrate how multi-species, multiple-site phenological events can be integrated to obtain indices showing trends for each species and across species. This index should play an important role in monitoring the impact of climate change on biodiversity. Furthermore, this approach can be extended to incorporate data from other taxa and countries for evaluating cross-taxa and cross-country phenological responses to climate change.

The objective of this study was to look into the viability of using the images acquired by the Moderated Orbital resolution Imaging Spectroradiometer (MODIS) sensor in order to determining the period of occurrence of phenological stages in order to assist determining the best conducive to harvesting of seed rice. The study area consisted of 12 farms located in the municipalities of Arroio Grande and Rio Grande - RS, of which we had information regarding to sowing, V4, R1, R6 and harvest dates. The delimitation of the field crops was performed by geodetic coordinates obtained by a GPS navigation receiver, aided by medium spatial resolution images from Landsat-5 Thematic Mapper (TM) sensor. In order to generate the spectro-temporal profiles were used daily images from MODIS sensor products MOD09GQ (Terra satellite) and MYD09GQ (Aqua satellite) with 250m spatial resolution, turned in the Enhanced Vegetation Index 2 (EVI2), ranging from before sowing to after harvest. Daily images from Terra and Aqua satellites were composited in images containing the maximum EVI2 for each day. Then we excluded from the analysis the composite images with cloud cover noise contamination and those showing values significantly discrepant with those of adjacent days. The temporal profiles of EVI2 for each crop field were associated with the dates of sowing...

Earth observation based monitoring of change in vegetation phenology and productivity is an important and widely used approach to quantify degradation of ecosystems due to climatic or human influences. Most satellite based studies apply linear or polynomial regression methods for trend detections. In this paper it is argued that natural systems hardly react to human or natural influences in a linear or a polynomial manner. At shorter time-scales of few decades natural systems fluctuate to a certain extent in a non-systematic manner without necessarily changing equilibrium. Finding a systematic model that describes this behavior on large spatial scales is certainly a difficult challenge. Furthermore, the manner vegetation phenology reacts to climate and to socio-economic changes is also dependent on the land cover type and on the bioclimatic region. In addition to this, traditional parametric methods require the fulfillment of several statistical criteria. In case these criteria are violated confidence intervals and significance tests of the models may be biased, even misleading. This paper proposes an alternative approach termed the Steadiness to traditional trend analysis methods. Steadiness combines the direction or tendency of the change and the net change of the time-series over a selected time period. It is a nonparametric approach which can be used without violation of statistical criteria...

This study proposes a new method for inverting radiative transfer models (RTM) to retrieve canopy biophysical parameters using remote sensing imagery. The inversion procedure is improved with respect to standard inversion, and achieves simultaneous inversion of leaf area index (LAI), soil reflectance (ρsoil), chlorophyll content (Ca+b) and average leaf angle (ALA). In this approach, LAI is used to constrain modelling conditions during the inversion process, providing information about the phenological state of each plot under study. Due to the small area of the vegetation plots used for the inversion procedure and in order to avoid redundant information and improve computation efficiency, existing plot segmentation was used. All retrieved biophysical parameters, except LAI, were assumed to be invariant within each plot. The proposed methodology, based on the combination of PROSPECT and SAILH models, was tested over 16 cereal fields and 51 plots, on two dates, which were chosen to ensure crop assessment at different phenological stages. Plots were selected to provide a wide range of LAI between 0 and 6. Field measurements of LAI, ALA and Ca+b were conducted and used as ground truth for validation of the proposed model-inversion methodology. The approach was applied to very high spatial resolution (VHR) remote sensing data from the QuickBird 2 satellite. The inversion procedure was successfully applied to the imagery and retrieved LAI with R2=0.83 and RMSE=0.63 when compared to LAI2000 ground measurements. Separate inversions for barley and wheat yielded R2=0.89 (RMSE=0.64) and R2=0.56 (RMSE=0.61)...

A straightforward method for categorizing temporal patterns of land-cover change is presented. Two successive years of enhanced vegetation index (EVI) data derived from the Moderate Resolution Imagery Spectrometer (MODIS) were analysed. Five phenological indicators were extracted. Based on the interannual difference of each of the five indicators, indices of change in phenology were calculated. An unsupervised classification of these five indices of change applied to pixels characterized by a high change magnitude led to the identification of seven categories of land-cover change patterns. Thirty-one per cent of the change pixels could clearly be explained by a difference in only one or two phenological indicators, e.g. a shift in the start of the growing season or an interruption of the growing season due to floods. The remaining change pixels were explained by a combination of more than two indices of change. The output of this analysis is an allocation of change pixels to broad categories of land-cover change as a preliminary step for finer resolution analyses.; JRC.H.3-Global environement monitoring

The objectives of this work were to determine the heliotropic movements of the upper trifoliates for two soybean cultivars, BR 16 and Embrapa 48, during a daily cycle, in three phenological stages and two water regimes, and to estimate the impact of irrigation and daily leaflet movements on agronomic characteristics and grain yield. Heliotropic movements were studied in three phenological stages: V4-V6, V7-V10, and R5 in irrigated and non-irrigated plots. For each stage, the leaflet elevation and azimuth were measured hourly. Under a low (V4-V6 stage) and mid (V7-V10 stage) leaf area index (LAI) the diaheliotropism was slightly more frequent and intensive in non-irrigated than in irrigated plants, only at early morning and late afternoon hours. At R5 stage (high LAI) the paraheliotropism of superior trifoliates was predominant and more intensive in non-irrigated plants. The heliotropic movements are correlated to carbon gain, but not to environment (light intensity or temperature), for measurements at 11h. 'Embrapa 48' expresses greater paraheliotropism than 'BR 16' at high LAI, while 'BR 16' displays lower heliotropic plasticity under irrigation. In spite of significant heliotropic differences, genotype and water availability treatments did not influence the final grain yield.

El presente trabajo analiza la utilidad del índice de vegetación EVI del sensor MODIS, para explicar el uso del suelo agrícola específicamente la dinámica fenológica del cultivo del arroz en sistema secano en el Departamento del Meta. El índice mide el verdor de la vegetación es posible discriminar propiedades de la vegetación como, el área foliar, la clorofila y la estructura de la cubierta. La fenología del cultivo se evalúa a partir de la adquisición y superposición de 128 imágenes con una frecuencia de 16 días que calculan el índice de vegetación EVI entre 2006 y 2011, y mediante la evaluación de tres casos de uso, se realiza el perfil temporal de la serie y el análisis del índice. Luego de evaluar la información se encontró que el índice modela correctamente el ciclo fenológico del cultivo y permite conocer de manera remota características que solo era posible identificar realizando trabajo de campo; The present study analyzes the utility of vegetation index EVI of sensor MODIS, to explain the agricultural use of land, specifically for identifying the phenological dynamics in rice crops at department of Meta. The index evaluates the greenness of vegetation, through which it is possible to discriminate properties of vegetation...

Abstract ? The objectives of this work were to determine the heliotropic movements of the upper trifoliates for two soybean cultivars, BR 16 and Embrapa 48, during a daily cycle, in three phenological stages and two water regimes, and to estimate the impact of irrigation and daily leaflet movements on agronomic characteristics and grain yield. Heliotropic movements were studied in three phenological stages: V4?V6, V7?V10, and R5 in irrigated and non-irrigated plots. For each stage, the leaflet elevation and azimuth were measured hourly. Under a low (V4?V6 stage) and mid (V7?V10 stage) leaf area index (LAI) the diaheliotropism was slightly more frequent and intensive in non-irrigated than in irrigated plants, only at early morning and late afternoon hours. At R5 stage (high LAI) the paraheliotropism of superior trifoliates was predominant and more intensive in non-irrigated plants. The heliotropic movements are correlated to carbon gain, but not to environment (light intensity or temperature), for measurements at 11h. 'Embrapa 48' expresses greater paraheliotropism than 'BR 16' at high LAI, while 'BR 16' displays lower heliotropic plasticity under irrigation. In spite of significant heliotropic differences, genotype and water availability treatments did not influence the final grain yield.; 2010

Climate change-induced shifts in phenology have important demographic consequences, and are frequently used to assess species' sensitivity to climate change. Therefore, developing accurate phenological predictions is an important step in modeling species' responses to climate change. The ability of such phenological models to predict effects at larger spatial and temporal scales has rarely been assessed. It is also not clear whether the most frequently used phenological index, namely the average date of a phenological event across a population, adequately captures phenological shifts in the distribution of events across the season. We use the long-tailed tit Aegithalos caudatus (Fig. 1) as a case study to explore these issues. We use an intensive 17-year local study to model mean breeding date and test the capacity of this local model to predict phenology at larger spatial and temporal scales. We assess whether local models of breeding initiation, termination, and renesting reveal phenological shifts and responses to climate not detected by a standard phenological index, that is, population average lay date. These models take predation timing/intensity into account. The locally-derived model performs well at predicting phenology at the national scale over several decades...

The goal of this paper was to determine the allelopathic potential of Gleichenella pectinata on three weed species (Echinochloa crus-galli (L.) Beauv (Poaceae), Ipomoea grandifolia (Dammer) O'Donell (Convolvulaceae) and Euphorbia heterophylla L. (Euphorbiaceae)). The experimental design was entirely randomized, with six replicates. The target plant responses were analyzed individually (percentage and average time of germination of the seeds and initial growth of seedlings) or combined, using the Global Effect Index. The extracts had a low effect on the percentage and average time of seed germination, but inhibited the seedling growth. The combined analysis revealed that almost all treatments caused inhibition. This analysis also showed the differences between the two phenological stages.

Estimativas do rendimento da soja são informações importantes que podem auxiliar as instituições na tomada de decisão quanto à políticas de comercialização. São consideradas também, na liberação de recursos para o financiamento da produção e seguro agrícola. Modelos matemáticos, que se baseiam nas relações clima planta, denominados modelos agrometeorológicos, podem estimar o rendimento médio de grãos, através de dados meteorológicos e biofísicos da cultura, como exemplo: o IAF (Índice de área foliar) da soja pode ser associado ao Kc (Coeficiente de cultura) para estimar o estádio fenológico, e esta informação, ser associada à parametrização dos modelos. O objetivo geral deste trabalho foi avaliar as possibilidades de se utilizar imagens do sensor MODIS, para estimar parâmetros biofísicos da soja, aplicáveis à modelagem do rendimento de grãos. A área de estudo abrangeu a porção norte do estado do Rio Grande do Sul. Foram obtidas as imagens do IAF, MOD15A2, e dos índices de vegetação NDVI (Índice de vegetação por diferença normalizada) e NDWI (Índice de umidade por diferença normalizada), do produto MOD13Q1. Foram analisadas duas safras: 2003/04 e 2004/05. O período de safra foi de 15 de outubro até 30 de abril. Foram geradas máscaras de cultivo para as safras...

Drought is a major cause of livestock mortality in the semi-arid areas of East Africa. Livestock losses during dry years can have detrimental effects on pastoralist households and result in persistent poverty [1]. Transferring this risk using an insurance scheme can help pastoralists to overcome the negative consequences of drought [2]. While high loss verification costs for traditional claim-based insurance would inhibit insurance provision to poor and remote pastoralists, an alternative approach is to determine premium and insurance payouts based on a transparent and objectively measured variable [3]. To be effective this variable should correlate strongly with what is insured, i.e. livestock losses and/or adverse forage conditions [4]. In 2010 the International Livestock Research Institute (ILRI) piloted an index-based livestock insurance (IBLI) project in Marsabit, northern Kenya [5], and gradually expanded to other areas of Kenya and southern Ethiopia. IBLI uses spatially and temporally aggregated MODIS NDVI time series as a proxy for forage conditions within an area (the insurance unit). Until recently the temporal aggregation was done for two periods of the year, i.e. the long rains-long dry (LRLD: March-September) and the short rains-short dry (SRSD: October-February) seasons. Including the dry season however meant that payouts were only made after animals suffered for long in case of adverse forage conditions; hence this scheme aimed for replacing livestock after incurred losses. It is preferable however to pay out earlier...

Phenological timing -- i.e. the course of annually recurring development stages in nature -- is of particular interest since it can be understood as a proxy for the climate at a specific region; moreover changes in the so called phenological phases can be a direct consequence of climate change. We analyze records of botanical phenology and study their fluctuations which we find to depend on the seasons. In contrast to previous studies, where typically trends in the phenology of individual species are estimated, we consider the ensemble of all available phases and propose a phenological index that characterizes the influence of climate on the multitude of botanical species.; Comment: 16 pages, 6 figures, appendix with 1 table; accepted for Physica A

Coffee production is influenced by the variations of the climatic elements, by the occurrence of adverse conditions (frost, dry spells, etc.) and by plant physiology (bieniannial). The prediction for coffee productivity is very complex due to the intricate physiological mechanisms, cultivar diversity and management conditions. Considering the importance of predicting the productivity for market regulation, with the present study we aimed at validating a model for estimating coffee productivity, based on the use of phenological indexes, submitted to the edaphoclimatic conditions of the southern region of Minas Gerais, Brazil. For this, we used 10 sample plots, distributed in the municipalities of Lavras, Varginha, Carmo de Minas, Ijaci and Santo Antonio do Amparo. The criteria for choosing the plots was based on the existence of a history of productivity superior to 40 sc ha-1 . The necessary meteorological information were collected from the Main Climatological Station belonging to INMET and installed at the campus of the Universidade Federal de Lavras (UFLA, considering as representative of the region. We conducted a hydric balance for the period in which the study was conducted, encompassing the harvests of 2012/2013 and 2013/2014. The collection of phenological data was conducted during the months of September/October...