896 resultados para Invertebrate availability


Relevância:

20.00% 20.00%

Publicador:

Resumo:

O objetivo deste trabalho foi avaliar o efeito de compostos orgânicos de extratos de plantas de seis espécies e da fertilização fosfatada na disponibilidade de fósforo no solo. Tubos de 30 cm de altura e 5 cm de diâmetro foram preenchidos com Latossolo Vermelho-Amarelo. Cada tubo constituiu uma parcela, em delineamento completamente casualizado, em arranjo fatorial 7x2, com quatro repetições. Extratos líquidos de aveia-preta (Avena strigosa), nabo forrageiro (Raphanus sativus), milho (Zea mays), milheto (Pennisetum glaucum), soja (Glycine max), sorgo forrageiro (Sorghum bicolor) e água (testemunha) foram aplicados em cada parcela, com ou sem fertilização com fosfato solúvel. Após sete dias de incubação, amostras de solo foram coletadas em várias profundidades, e foram analisadas as formas lábil, moderadamente lábil e não lábil de fósforo no solo. Houve acúmulo de fósforo inorgânico nas frações lábil e moderadamente lábil do solo, como conseqüência da adição dos extratos de plantas, principalmente na camada superficial (0-5 cm). O nabo forrageiro, com maior concentração de ácido málico e maior conteúdo de P no tecido do que outras espécies, foi o mais eficiente em incrementar a disponibilidade de P no solo.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In studies on the evaluation of methodologies for the analysis of soil, phosphorus (P) has been the single most studied aspect, due to the complexity of this dynamic element in soil. However, these studies have been limited regarding soil conditions in Paranaa. The present study aimed to evaluate the efficiency of the Mehlich-1, Mehlich-3 and ion exchange resin methods in the evaluation of available P for soybean (Glycine max) in the soils of Paranaa State. Twelve soil samples collected from the upper 0-20 cm were planted with soybean for a period of 42 days in the greenhouse. The ability to extract soil P followed the order of decreasing average amount of extracted P: Mehlich-3 > resin > Mehlich-1. The correlation coefficients between the content of P extracted by Mehlich-1, Mehlich-3 and resin and the amount of P accumulated in the plants were 0.86, 0.90 and 0.93, respectively. Mehlich-1, Mehlich-3 and resin showed similar efficiency in the evaluation of P availability to plants and, under conditions of natural fertility and in soils that had received no application of poorly natural reactive phosphates, can be used to quantify the concentrations of P in the soils of Parana State.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Apparent amino acid availability coefficients and protein digestibility of four animal products [fish meal (FM), meat and bone meal (MBM), poultry by-product and feather meal] and four plant protein-rich products [soybean meal (SBM), cottonseed meal-28, cottonseed meal-38 and corn gluten meal (CGM)] were determined for Nile tilapia, Oreochromis niloticus. Ingredients were incorporated to a practical reference diet at a 7 : 3 ratio (70% of reference diet and 30% of test ingredient). Chromic oxide was used as external digestibility marker. Among animal products poultry by-product meal (PBM; 89.7%) and FM (88.6%) presented the highest apparent protein digestibility (APD) while MBM (78.4%) and feather meal (78.5%) presented the lowest APD. Among plant protein-rich products CGM (91.4%) and SBM (92.4%) presented the highest APD values while cottonseed meal-28 presented the lowest APD (78.6%). Average apparent amino acid availability of feed ingredients was similar to protein digestibility with 92.3%, 89.6%, 73.4%, 80.7%, 88.9%, 84.4%, 91.2% and 79.7% values for SBM, CGM, cottonseed meal-28 and 38, FM, MBM, PBM and feather meal respectively. These results indicate that O. niloticus is able to utilize efficiently different feedstuffs.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The present study analyzed the composition of the aquatic fauna associated to the mangrove forest in a southeastern Brazilian river. The composition of the macrofauna in the roots of the marginal vegetation located at three different salinity stretches was analyzed by sampling pieces of the submerged branches of the vegetation (natural substrate) and pieces of sisal rope (artificial substrate), installed close to the natural vegetation and sampled after a period of 14 colonization days. In both types of substrate, twelve taxonomic groups were sampled, representing three phyla (Cnidaria, Annelida and Arthropoda). The crustaceans, corresponding to the most diversified group, were represented by Copepoda, Tanaidacea, Isopoda, Amphipoda and Decapoda. The highest salinity stretch showed the highest abundance, with a progressive decrease from high to low salinity for both substrates. Copepoda and Tanaidacea predominated on both substrates, although the artificial substrate exhibited the highest total abundance and species richness. Considering the relative abundance of the taxonomic groups on both substrates, the majority of groups predominated in the highest salinity range. Significant differences on the longitudinal distribution of abundance were associated to the variation on salinity and with the complexity of the substrate.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Invertebrate predation on zooplankton was investigated in mesocosms in the shallow tropical Lake Monte Alegre, Sauo Paulo State, Brazil, in the summer of 1999. Two treatments were applied: one with natural densities of prey and the predators Chaoborus brasiliensis and the water mite Krendowskia sp. (Pr+), and another without predators (Pr-). Three enclosures (volume: 6.6 m(3) of water per enclosure) per treatment were installed in the sediment of the deepest area of the lake (5.0 m). At the beginning, Chaoborus larvae were present in Pr- enclosures, because of technical difficulties in preventing their entrance, but they virtually disappeared in the course of the experiment. Water mites were almost absent in Pr- enclosures. Chaoborus predation negatively influenced the Daphnia gessneri population, but not the populations of the copepods Tropocyclops prasinus and Thermocyclops decipiens and the rotifers Keratella spp. Death rates of Daphnia were generally significantly higher in the Pr+ treatment; Daphnia densities increased after the disappearance of Chaoborus in Pr-. Copepod losses to predation in the experiment may be compensated by higher fecundity, shorter egg development time, and lower pressure on egg-bearing females, resulting in a lower susceptibility to Chaoborus predation. The predation impact of water mite on microcrustaceans and rotifers in the experiment was negligible.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

O experimento foi realizado no Departamento de Produção Vegetal da Escola Superior de Agricultura Luiz de Queiroz, ESALQ/USP, Piracicaba, São Paulo, Brasil, utilizando-se as culturas de guaranazeiro (Paullinia cupana Kunth), cafeeiro (Coffea arabica L.), cajueiro (Anacardium occidentale L.), goiabeira (Psidium guajava L.) e seringueira (Hevea brasiliensis Muell. - Arg.). No período de seca (setembro/94) e de chuvas (novembro/94), realizaram-se determinações de resistência estomática (RE) (s cm-1) e transpiração (T) (µg cm-1 s-1) nas diferentes espécies. O delineamento experimental foi em blocos casualizados com cinco repetições. A partir das análises dos dados pode-se concluir: 1. diferenças significativas entre espécies, em termos das variáveis avaliadas no período de deficiência hídrica, com valores decrescentes de resistência estomática e crescente de transpiração na seguinte ordem: guaranazeiro > cafeeiro > cajueiro > goiabeira > seringueira; 2. Nas águas as diferenças entre espécies, para ambas as variáveis, foram menos evidentes, continuando a cultura da seringueira a apresentar menor resistência estomática e maior transpiração dentre as espécies; 3. As culturas de guaraná e café apresentaram maior resistência à perda de água, em relação às demais culturas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this work the influence of the anhtropogenic activities in the uptake of metals at a reservoir for public water supply in Araraquara City, São Paulo State, Brazil was studied. For this, the distribution of Cr, Ni, Cu, Cd and Pb in sediments collected from Anhumas reservoir, at seven sampling points and at three depths for each point was investigated. The pseudo-total and available metals contained in the different sediment samples were assessed using an ICP-AES technique. Among the five metals studied, cadmium possesses the largest relative potential availability, with percentages of 20 to 98% for the three different sediment types. In addition, the following decreasing availability order was characterized: Cd > Cu > Pb > Ni > Cr.