Level of nitrate in lettuce as a result of fertilization, harvesting time and storage period

O experimento foi conduzido na Fazenda Água Limpa, UnB em Brasília, de janeiro a março de 2004, com o objetivo de avaliar o acúmulo de nitrato em alface, cv. Verônica, sob cultivo protegido, em função da adubação, horário de colheita e tempo de armazenamento (8ºC). O delineamento experimental foi de blocos ao acaso, em esquema fatorial 5 x 4 x 4, em quatro repetições. Os cinco tratamentos de adubação foram: 1,5 kg m-2 de cama-de-frango (T1); 3,0 kg m-2 de esterco bovino (T2); mineral, de acordo com a análise química do solo - M (T3); M acrescida de 1,5 kg m-2 de cama-de-frango (T4) e M acrescida de 3,0 kg m-2 de esterco bovino (T5). Os horários de colheita foram 7; 11; 15 e 18 horas, e os períodos de armazenamento foram 0; 3; 5 e 7 dias. Os tratamentos T1 e T4 resultaram em plantas com os maiores teores de nitrato foliar, 1240,12 e 1303,66 mg NaNO3 kg-1, respectivamente; enquanto T2 resultou no menor acúmulo de nitrato, 547,26 mg NaNO3 kg-1. Porém, quando o esterco bovino foi associado ao adubo mineral (T5), ocorreu um aumento de 2,18 vezes no teor de nitrato foliar (1195,25 mg NaNO3 kg-1). Plantas colhidas às 7 horas apresentaram os menores teores de nitrato, sugerindo ser este o melhor horário para colheita da alface no Distrito Federal. O armazenamento proporcionou uma redução de 29,3% no teor de nitrato ao longo de 7 dias. ________________________________________________________________________________ ABSTRACTThe experiment was carried out in Brasilia, Brazil, from January to March 2004, aiming to evaluate the level of nitrate in lettuce, cv. Veronica, as a result of fertilization, harvesting time and storage period (8ºC). We used the ramdomized blocks experimental design in a factorial 5 x 4 x 4, with four replicates. The five fertilization treatments tested were: 1,5 kg m-2 of chicken manure (T1); 3,0 kg m-2 of cattle manure (T2); mineral, as a result of soil chemical analysis - M (T3); M with 1,5 kg m-2 of chicken manure (T4); and M with 3,0 kg m-2 of cattle manure (T5). The harvesting times were 7 and 11 a.m., and 3 and 6 p.m. The storage periods were 0; 3; 5 and 7 days. The treatments T1 and T4 resulted in plants with the highest levels of nitrate, 1240,12 and 1303,66 mg NaNO3 kg-1, respectivelly, while T2 resulted in the lowest nitrate level, 547,26 mg NaNO3 kg-1. However, when cattle manure was added to M (T5), an increase of 2,18 times was observed in the nitrate level (1195,25 mg NaNO3 kg-1). Plants harvested at 7 a.m. showed the lowest levels of nitrate, suggesting that it is the best moment to harvest lettuce in the Distrito Federal region. During the storage period of seven days, nitrate level was reduced by 29,3%

EMPREGO DA METODOLOGIA DE DETECÇÃO DE MUDANÇAS A PARTIR DE MISTURA ESPECTRAL NO PROJETO DE ASSENTAMENTO AMERICANA, MUNICÍPIO DE GRÃO MOGOL-MG

In this paper we used the technique to change detecting by spectral mixing with the objective to assess the evolution of a rural settlement project: before the creation, once installed and in current situation. The study area was the American Project located in the municipality of Grão Mogol, in the north of the state of Minas Gerais. TM images used in this study were acquired at different dates 1997, 2001 and 2009. The identification of endmembers was performed by following steps: Minimun Noise Fraction, Pixel Purity Index and N-Dimensional Visualizer. The endmembers identified were: soil, vegetation photosynthetic active (VFA) and nonphotosynthetically active vegetation (NPV). Fraction images generated from the Linear Mixture Analysis show small changes over the twelve years (1997-2009). The soil fraction image had a small increase in the area since 2001 and the changes more pronounced for VNFA occurred in areas outside the settlement in 1997 and 2001.No presente trabalho é utilizada a técnica de detecção de mudança a partir de mistura espectral com o objetivo de avaliar a evolução da cobertura vegetal de um projeto de assentamento (PA) em três momentos: antes da criação do PA, após sua implantação e na situação atual. A área de estudo foi o PA Americana localizado no município de Grão Mogol no Estado de Minas Gerais. As imagens utilizadas são do sensor TM-Landsat referentes às datas de 1997, 2001 e 2009. A identificação de membros finais foi realizada pelas as seguintes etapas: Minimun Noise Fraction, Pixel Purity Index e N-Dimensional Visualizer. Os membros finais identificados foram: solo, vegetação fotossinteticamente ativa (VFA) e vegetação não fotossinteticamente ativa (VNFA). As imagens-fração geradas a partir da Análise Linear de Mistura apresentam poucas alterações, para a área de estudo, ao longo dos doze anos (1997-2009). A imagem de fração solo teve um pequeno aumento na área do assentamento a partir de 2001 e as alterações mais pronunciadas para VNFA ocorreram nas áreas externas ao assentamento nos anos de 1997 e 2001

Spatial-Temporal patterns of bean crop in Brazil over the Period 1990–2013

The understanding of spatial dependence and distribution of agricultural production factors is a key issue for the territorial planning and regional development. This study evaluates the spatial-temporal dynamics of bean crops in Brazil over the period 1990–2013. Common bean (Phaseolus vulgaris L.) is one of the staple foods for the Brazilian population, with nationwide production and cultivated mostly by family farmers. The analyzed variables of this crop included harvested area, produced quantity, and average crop yield. We investigated spatial autocorrelations using the Global and Local Moran Index. The global spatial autocorrelation statistics demonstrated a general spatial dependence of bean production over Brazil, while the local spatial autocorrelation statistics detect statistically significant zones of high and low bean-production attributes. Maps of growth and acceleration rate of the variables were constructed, showing the areas that increased, decreased, or stagnated during the time series. The results showed a considerable reduction of the bean harvested area, but there were significant increases in produced quantity and average crop yield. Results showed distinct and significant patterns of bean-production variables in Brazilian territory over the different years. Regional differences and peculiarities are evident, emphasizing the need for directing investments to agricultural research and public policy

Spatial-Temporal Patterns of Bean Crop in Brazil over the Period 1990–2013

The understanding of spatial dependence and distribution of agricultural production factors is a key issue for the territorial planning and regional development. This study evaluates the spatial-temporal dynamics of bean crops in Brazil over the period 1990–2013. Common bean (Phaseolus vulgaris L.) is one of the staple foods for the Brazilian population, with nationwide production and cultivated mostly by family farmers. The analyzed variables of this crop included harvested area, produced quantity, and average crop yield. We investigated spatial autocorrelations using the Global and Local Moran Index. The global spatial autocorrelation statistics demonstrated a general spatial dependence of bean production over Brazil, while the local spatial autocorrelation statistics detect statistically significant zones of high and low bean-production attributes. Maps of growth and acceleration rate of the variables were constructed, showing the areas that increased, decreased, or stagnated during the time series. The results showed a considerable reduction of the bean harvested area, but there were significant increases in produced quantity and average crop yield. Results showed distinct and significant patterns of bean-production variables in Brazilian territory over the different years. Regional differences and peculiarities are evident, emphasizing the need for directing investments to agricultural research and public policy