77 research outputs found
Hydrogels in Brazilian Agriculture
Get PDFThe rational use of water is essentual as it is a finite resource. Consequerntly, studies of methids that minimize water use water are essential. As a result, agricultural hydrogels have been extensively tested in as a means of promoting agriculture improvements because of their water- and nutriente-retention characteristics. However, even though hydrogels are used in several sectors of Brazilian agriculture, there are still very few
studies on their applications, the best methods and the quantities to be used. Consequently, there is a need for research into the applicability of this technology in Brazil, so that future research needs can be identified and appropriate decisions made at the production level. Therefore, the aim of this study was to collate currently available information on the applicability of agricultural hydrogels in Brazilian agriculture. Over the last decade, forestry is the sector in Brazil that has most studied and used hydrogels, but others such as fruit- and coffeegrowing have also been involved. The method of applying the polymer in granules directly mixed-in with growth substrates is the most used in the production of seedlings. However, use of hydrated gel at planting sites has also been explored. While synthetic hydrogels are most commonly used, those made of natural materials have great potential due to the low preparation costs and their in-soil biodegradability. The quantities
of hydrogel used vary according to the target species, application method and objective.</jats:p
Teores de nutrientes e fertirrigação em cultivo de camu-camu (Myrciaria dubia (Kunth) McVaugh) com diferentes doses de nitrogênio
Get PDFO camu-camu (Myrciaria dubia (Kunth) McVaugh) é uma fruteira nativa que está em processo de domesticação, portanto, o conhecimento das necessidades nutricionais é essencial para melhorar a eficiência da adubação durante seu desenvolvimento. O trabalho teve como objetivo determinar os teores de nutrientes em plantas de camu-camu em função da adubação nitrogenada via fertirrigação no primeiro ano de cultivo. O experimento foi conduzido mediante delineamento experimental em blocos casualizados, com 5 tratamentos: 0; 40; 80; 120 e 160 kg ha-1 de N, oito repetições e sete plantas por unidade experimental. As variáveis avaliadas foram a massa seca total e os teores de nutrientes nas folhas. Os resultados mostram que a massa seca total das plantas de camu-camu apresentou comportamento quadrático significativo em resposta às doses crescentes de N, sendo que doses maiores a 128 kg ha-1 propiciaram efeitos depressivos. Além disso, os teores foliares de N, K, Ca tiveram uma resposta quadrática significativa, sendo que as maiores concentrações foram registradas entre as doses de 113 e 115 kg de N ha-1. Por outro lado, os micronutrientes tiveram um comportamento polinomial depressivo de acordo com os incrementos das doses de N. Pode-se concluir que os teores foliares dos nutrientes estão dentro dos adequados para o desenvolvimento das plantas de camu-camu, e os nutrientes mais exigidos foram o N, Ca, K, Fe, Mn e B, e finalmente os teores de macro e micronutrientes determinados nas folhas responderam a seguinte ordem decrescente: N > Ca > K > Mg > S > P > Mn >Fe > B > Zn > Cu, respectivamente
Avaliação técnica e econômica de uma usina teórica de hidrogênio verde fotovoltaica de 1,0 MWe considerando o potencial solar brasileiro
Get PDFEnergy is essential for the survival and quality of life of populations and for the economic and social development of nations. However, in recent years, concern about the use of energy resources has become one of the most important problems of collective interest to most nations in the world, for the following reasons: continuous increase in the world population; growing global demand for energy; environmental problems associated with CO2 emissions due to the use of fossil fuels as the main source of energy; the policy responses of some nations are accelerating the emergence of a global economy based on clean energy; the need for a new paradigm capable of maintaining global energy security, reliability and accessibility, and reducing emissions, simultaneously. So, this shows that the need to identify and develop clean and sustainable alternative fuels is becoming increasingly urgent. Among the existing alternatives, green hydrogen stands out, which is being seen as the energy vector of the future, which could replace fossil fuels. The green hydrogen is emerging as a low-carbon fuel option for the transportation, industrial and electrical generation sectors, as it could decarbonize these three large sectors of the world economy. This is explained by the fact that hydrogen has a higher energy content per unit of weight than all fossil fuels, it can be produced only with water and renewable energy, and when used as a fuel it produces only energy and water. Although the consumption of hydrogen as a fuel is not yet widespread, there is growing interest in its use as a potential source of energy, in the so-called hydrogen economy. In this context, this work aimed to simulate and evaluate the production potential of a 1.0 MWe off-grid hydrogen plant powered by photovoltaic energy along the largest Brazilian highway, 4,660 km long, connecting the Northeast Regions, Southeast and South of Brazil. In the end, this work presented: Rankings of the energy production and hydrogen production potential of 23 cities along BR-116; the LCOE – Leveled Cost of Energy and LCOH – Leveled Cost of Hydrogen costs obtained for each of the 23 cities evaluated, using as economic and financial premises, the recommendations of the International Energy Agency for the Group of Twenty (G20). In the end, the work presented ten conclusions and closed by stating that the Northeast Region has a strong vocation for the production of energy and photovoltaic hydrogen, with production of 1,742,078 kWh/year/MW and 27,392 kg of hydrogen/year/MW of installed power, with an average LCOH cost of 4.20 US/kg.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas GeraisCAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superio
Shade nets and substrates in seedling production of Annona squamosa L. in the Roraima Cerrado.
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The change in atmospheric guavas var. Paluma to reduce the effect of mechanical damage in postharvest
Get PDFIn the postharvest management, the fruits can be exposed to injuries that depreciated the quality and the shelf life. Thus, it was evaluated the modified atmosphere effects on guavas var. Paluma subjected to different mechanical damages. Once harvested, the fruits were selected, sanitized and submitted to the treatments T1 (control) - without injuries or packaging in bags of low density polyethylene (LDPE); T2 - without injuries + LDPE bags; T3 - damage by fall of 1 m + LDPE bags; T4 - damage by compression of 9 N + LDPE bags; T5 - damage by fall of 1 m + damage by compression of 9 N + LDPE bags and T6 - damage by fall of 1 m + damage by compression of 9 N without LDPE bags. The treatments were kept in cold storage at 10 ± 1 o C and 94 ± 2% de R.H. The analysis of CO2/ethylene production, enzymatic activity, total and soluble pectins, pulp firmness, titratable acidity (TA), soluble solids (SS), reducing sugars and ascorbic acid were performed every 10 days of refrigeration, and an additional day outside cold storage (22 ± 1o C and 75 ± 3% R.H.) for 30 days. Guavas packed in LDPE bags, not subject to mechanical damage, presented the best quality standards. The fruits suffered only one kind of damage, when packaged, presented satisfactory pattern compared to the fruits without package and not exposed to any mechanical damages. Applying the two kinds of damages, the LDPE packaging was not adequate to decrease the metabolic rate of these fruits, making them unfit for marketing.No manejo pós-colheita, os frutos podem estar expostos a injúrias que depreciam sua qualidade e vida útil. Assim, avaliou-se o efeito da atmosfera modificada em goiabas var. Paluma submetidas a diferentes tipos de danos mecânicos. Depois de colhidos, os frutos foram selecionados, sanitizados e submetidos aos tratamentos: T1 (testemunha) - sem injúrias nem acondicionamento em sacolas de polietileno de baixa densidade (PEBD); T2 - sem injúrias + PEBD; T3 - queda de 1 m + PEBD; T4 - compressão de 9 N + PEBD; T5 - queda de 1 m + compressão de 9 N + PEBD e T6 - queda de 1 m + compressão de 9 N + sem PEBD. Os tratamentos foram frigoarmazenados a 10 ± 1 o C e 94 ± 2% de U.R. As análises da produção de CO2 /etileno, atividade enzimática, pectina total/solúvel, firmeza de polpa, acidez titulável (AT), sólidos solúveis (SS), açúcares redutores e ácido ascórbico foram realizadas a cada 10 dias de refrigeração mais um dia fora da câmara frigorífica (22 ± 1 o C e 75 ± 3% de U.R.), durante 30 dias. As goiabas acondicionadas em sacolas de PEBD, não submetidos às injúrias mecânicas, apresentaram os melhores padrões de qualidade. Os frutos submetidos apenas a um tipo de injúria, quando embalados, apresentavam qualidade satisfatória em comparação aos frutos sem embalagem e não submetidos às injúrias. Na aplicação dos dois tipos de injúria, simultaneamente, o uso da embalagem não foi suficiente para reduzir a velocidade metabólica desses frutos, tornando-os inaptos à comercialização.Universidade Federal de Roraima (UFRR), Departamento de Fitotecnia, Boa Vista-RR, BrasilEmpresa Brasileira de Pesquisa Agropecuária (Embrapa)Universidade Estadual Paulista Júlio de Mesquita Filho, Departamento de Gestão e Tecnologia Agroindustrial, Faculdade de Ciências Agronômicas de Botucatu, Botucatu, Fazenda Experimental Lageado - Caixa Postal 237, Lageado, CEP 18603-970, SP, BrasilUniversidade Estadual Paulista Júlio de Mesquita Filho, Departamento de Gestão e Tecnologia Agroindustrial, Faculdade de Ciências Agronômicas de Botucatu, Botucatu, Fazenda Experimental Lageado - Caixa Postal 237, Lageado, CEP 18603-970, SP, Brasi
Cultivos intercalares em fase inicial de desenvolvimento e desempenho produtivo de cultivares de palma de óleo em diferentes ambientes de Roraima
Get PDFThe expansion of oil palm cultivation in already deforested areas of Amazonia is recognized as an excellent alternative for the production of oil for food and energy purposes. The state of Roraima has the appropriate environmental conditions for its development and introduction in the structure of family farming. The objective of this work is to develop systems of crops between the rows of oil palm in an area of disturbed forest, during the initial period of development of culture, as well as evaluate the productive potential of three intraspecific varieties of oil palm in areas of savanna and forest changed from Roraima. To achieve the objectives were different and conducted experiments in areas of disturbed forest and savannah of Roraima. For intercropping systems with cultivation of palm oil had a randomized block design with three replications, and treatments for the compounds: palm oil x banana x cowpea; palm oil x pineapple; palm oil x cassava; oil palm x cowpea x maize; oil palm x cassava x maize; oil palm x cowpea; oil palm x peanuts and palm oil in single system. For the productive performance of three cultivars of palm oil had a randomized with six replications and three treatments in two blocks environments. In the first experiment evaluated the vegetative development of oil palm through the girth circumference, 9 leaf length, width and thickness of the rachis, number of leaflets leaf 9 and number of leaves per plant issued at 2:18 months after planting ( site A) and at 12 and 28 months after planting (Site B) . Moreover, evaluations of BRS C - 2528, 1 BRS C - 370 and BRS C - 2301 of oil palm joint analyzes of the periods 4-6 years old , as the number of clusters ha-1 were performed, weight average and total production of ha-1 clusters. We conclude that systems favored the vegetative growth of the crop of oil palm were the cowpea intercropping systems with x maize, groundnuts and cassava, proving to be economically viable and may also be indicated as a cheap alternative for the production of palm oil facing family farmers. Cultivars of oil palm in the disturbed forest environment, showed higher than in the savanna environment productive performance.A expansão da cultura da palma de óleo nas áreas já desflorestadas da Amazônia legal é reconhecida como uma excelente alternativa para a produção de óleo para fins alimentícios e energéticos. O estado de Roraima apresenta as condições edafoclimáticas adequadas para seu desenvolvimento e introdução na estrutura da agricultura familiar. Objetivou-se com este trabalho desenvolver sistemas de cultivos nas entrelinhas da palma de óleo em área de floresta alterada, durante o período inicial de desenvolvimento da cultura, bem como, avaliar o potencial produtivo de três cultivares de palma de óleo em áreas de savana e floresta alterada de Roraima. Foram avaliados diferentes experimentos e conduzidos em áreas de floresta alterada e savana de Roraima. Para os sistemas de cultivo consorciados com palma de óleo o delineamento foi em blocos casualizados com três repetições, sendo utilizado oito tratamentos compostos por: palma de óleo x banana x feijão caupi; palma de óleo x abacaxi; palma de óleo x mandioca; palma de óleo x feijão caupi x milho; palma de óleo x milho x mandioca; palma de óleo x feijão caupi; palma de óleo x amendoim e palma de óleo em sistema solteiro. Para o desempenho produtivo das três cultivares de palma de óleo o delineamento foi em blocos casualizados com seis repetições e três tratamentos em dois ambientes. No primeiro experimento foi avaliado o desenvolvimento vegetativo da palma de óleo por meio da circunferência do coleto, comprimento da folha 9, largura e espessura do ráquis, número de folíolos da folha 9 e número de folhas emitidas por planta aos 02 e 18 meses após o plantio (local A) e aos 12 e 28 meses após o plantio (local B). Por outro lado, nas avaliações das cultivares BRS C-2528, BRS C-3701 e BRS C-2301 da palma de óleo foram realizadas análises conjuntas dos períodos de 4 a 6 anos de idade, quanto ao número de cachos ha-1, peso médio e produção total de cachos ha-1. Conclui-se que os sistemas que favoreceram o crescimento vegetativo da cultura da palma de óleo foram os sistemas consorciados com feijão caupi x milho, amendoim e mandioca, mostrando-se também economicamente viáveis e podendo ser indicados como alternativa económica para produção de palma de óleo voltada para agricultura familiar. As cultivares de palma de óleo no ambiente de floresta alterada, apresentaram desempenho produtivo superior ao obtido no ambiente de savana
Uso de diferentes revestimentos na produção de pré-secado de gramíneas tropicais
Get PDFTwo experiments were carried out with haylage, one with marandu grass and the other with
tanzania grass, both with the same objective, which consisted of evaluating the gas
quantification, temperature, fermentation characteristics, chemical composition and aerobic
stability of the haylage coated with films of different thicknesses. Four plastic films of different
thicknesses were tested as haylage coating (10, 11, 13 and 27µm) associated to storage times
and during aerobic stability (0, 48 and 96 h) in a completely randomized design with three
replications organized in factorial schemes. Gas quantification and temperature were evaluated
in the first 48 h (4 × 4), being four films and four storage times (0, 12, 24 and 48 h) and over
the storage days (4 × 5), four films and five storage times (0, 7, 15, 30 and 60 d). The
fermentative characteristics were evaluated in a factorial scheme (4 × 4), being four films and
four storage times (7, 15, 30 and 60 d). In the evaluations during aerobic stability (4 × 3), there
were four films and three storage times (0, 48 and 96 h). The chemical composition was
evaluated only after the opening at 60 days. In the marandu grass, the oxygen concentration
stabilized at 12 h below 5% and the carbon dioxide after 7 d with 37.17%. There was little
variation in pH, and the lowest values were observed at 60 days (pH 5.13 to 5.4). There was a
predominance of molds and yeasts with little variation between the films (7.02 to 7.51 log10 cfu
g
-1
), as well as lactic acid bacteria (5.54 to 6.11 log10 cfu g-1
) and enterobacteria (6.34 to 6.84
log10 cfu g-1
). There was effect only on the dry matter, with the highest average in the treatment
of 13µm (522.4 g kg-1 DM). In the Tanzania grass, the O2 concentration stabilized at 12 h below
4%. The highest pH was in the 27 µm film at 7 and 15 days (pH 7.15 and 6.54, respectively),
whereas at 60 days, all films had a similar pH. Higher averages of molds and yeasts were
observed in the film of 27µm (7.13 log10 cfu g-1
) and 13µm (7.32 log10 cfu g-1
) in the effect of
the film. The film of 13µm provided a higher content of dry matter (655 g kg
-1
) and crude
protein (140.9 g kg-1 DM). In both experiments, all coatings allowed low fermentation of
organic acids and low ammoniacal nitrogen concentration, as well as a stable temperature
during the aerobic stability of 96 h. Thus, films of 10, 11, 13 and 27µm of thickness can be used
in the coating of haylage of marandu and tanzania grass. The use is recommended after 60 days
of storage.Foram realizados dois experimentos com pré-secado, um com capim-marandu e outro com
capim-tanzânia, ambos com o mesmo objetivo, que consistiu em avaliar a quantificação gasosa,
temperatura, características de fermentação, composição química e estabilidade aeróbia em pré secado revestido com filmes de diferentes espessuras. Foram testados quatro filmes plásticos
de diferentes espessuras no revestimento de pré-secado (10, 11, 13 e 27µm) associado aos
tempos de armazenamento e durante a estabilidade aeróbia (0, 48 e 96 h) em delineamento
inteiramente casualizado com três repetições organizados em esquemas fatoriais. A
quantificação gasosa e a temperatura foram avaliadas nas primeiras 48 h (4 × 4), quatro filmes
e quatro tempos de armazenamento (0, 12, 24 e 48 h) e nos dias de armazenamento (4 × 5),
quatro filmes e cinco tempos de armazenamento (0, 7, 15, 30 e 60 d). As características
fermentativas foram avaliadas em esquema fatorial (4 × 4), quatro filmes e quatro tempos de
armazenamento (7, 15, 30 e 60 d). Nas avaliações durante a estabilidade aeróbia (4 × 3), quatros
filmes e três tempos de armazenamento (0, 48 e 96 h). A composição química foi avaliada
apenas na abertura de 60 dias. No capim-marandu a concentração de oxigênio estabilizou às 12
h abaixo de 5% e o dióxido de carbono após 7 d com 37,17%. Houve poca variação no pH, os
menores valores foram aos 60 dias (pH 5,13 a 5,4). Teve predominância de mofos e leveduras
com pouca variação entre os filmes (7,02 a 7,51 log10 ufc g-1
), bactérias lácticas (5,54 a 6,11
log10 ufc g-1
) e enterobactérias (6,34 a 6,84 log10 ufc g-1
). Houve efeito apenas para matéria
seca, com maior média para 13µm (522,4 g kg-1 MS). Já no capim-tanzania, a concentração de
O2 estabilizou às 12 h abaixo de 4%. O pH mais elevado foi no filme de 27µm aos 7 e 15 dias
(pH 7,15 e 6,54), respectivamente, já aos 60 dias, todos os filmes tiveram pH semelhante.
Maiores médias de mofos e leveduras foram observadas no filme de 27µm (7,13 log10 ufc g-1
)
e 13µm (7,32 log10 ufc g-1
) no efeito do filme. O filme de 13µm proporcionou maior teor de
mareia seca (655 g k-1
) e proteína bruta (140,9 g kg-1
de MS). Em ambos experimentos todos
os revestimentos permitiram baixa fermentação de ácidos orgânicos e concentração de
nitrogênio amoniacal, assim como temperatura estável durante estabilidade aeróbia de 96 h.
Dessa forma, filmes de 10, 11, 13 e 27µm de espessura podem ser utilizados no revestimento
de pré-secado de capim-marandu e capim-tanzânia. Recomenda-se a utilização aos 60 dias de
armazenamento
Genetic diversity in populations of Brazil nut.
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Tipo de explante e diferentes concentrações de sais em meio de cultura MS no estabelecimento in vitro de Aniba canelilla.
No full textGenetic Diversity Between and Within Astrocaryum acaule Mart. (Arecaceae) Populations
Get PDFAbstract This article sought to assess the genetic diversity within and between natural populations of Astrocaryum acaule by means of AFLP markers. Ninety individuals were sampled in three populations located in Manaus (state of Amazonas) across regions with different intensities of anthropogenic activity. Two clusters were differentiated by means of dendrograms and Bayesian cluster analysis, the first consisting of individuals from the Tarumã-Açu population in an intensely agricultural region, and the second, of populations from UFAM and Tupé conservation areas. The physical isolation of A. acaule populations has resulted in good conservation of its genetic identity, since anthropogenic activity is an important modifier of the genetic diversity of natural populations. Genetic diversity was higher within populations (74.58%) than between them (25.42%), which means that we have to collect representative samples from each of the genetically distinct groups for genetic conservation of the species. Therefore, in situ conservation is recommended
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