Perspectives and challenges on isotopic ecology of terrestrial birds in Brazil

Although stable isotopes have been increasingly used in ornithology since 1980 in many places, Brazil has been slow in adopting this methodology, especially when it comes to terrestrial birds. The most common elements in bird ecology studies are carbon, nitrogen, hydrogen, and oxygen stable isotopes, which provide information on diet, trophic interactions, habitat use, migration, geographic patterns, and physiology. It is important that Brazilian ornithologists become aware of the potential of stable isotope analysis in ecological studies, and the shortcomings of this tool. The use of stable isotopes to study bird ecology has great potential in Brazil, since many ecological questions about Neotropical birds can be addressed by it (e.g., resource and habitat use, migratory routes, isotopic niches, anthropogenic impacts, individual specialization). Brazilian museums and other Natural History collections can provide samples to study long-term temporal dynamics in bird ecology. Additionally, the integration of avian tissue sample information into a database may increase the collaboration among researchers and promote sample reuse in a variety of studies. All biomes in Brazil have been under pressure from anthropogenic impacts (e.g., land-use change, habitat loss, fragmentation, intensive agriculture), affecting several taxa, including terrestrial birds. Considering the negative effects of human expansion over natural areas and that stable isotopes provide useful ecological information, ornithologists in Brazil should increase their use of this tool in the future.(AU)

Influence of summer crop residues on 15N present in organic matter fractions under two lowland soils / Influência de resíduos de culturas de verão sobre o 15 N em frações da matéria orgânica de dois solos de terras baixas

The state of Rio Grande do Sul has about 20% of the total area as lowland soils, suitable for flooded rice (Oryza sativa). In order to mitigate damage caused by rice monoculture, new crops such as sorghum (Sorghum bicolor) and soybean (Glycine max) have been cultivated in these areas. With different qualities of crop residues, it is expected a change in soil organic matter (SOM) dynamics and consequently, nitrogen (N) availability. The objective of this study was to evaluate the influence of rice, soybean and sorghum crop residues on the N present in physical fractions of SOM of two lowland soils, using labeled 15N technique, under incubation for 180 days in aerobic condition and more 180 days in anaerobic condition. At 30, 180 and 360 days of incubation the remaining N of the plant residues and N destination from the residues in both soils were quantified in the physical fractions of SOM >250 μm, 250-53 μm and <53 μm. The soil with higher amount of clay+silt received a larger quantity of 15N from residues, while flooding of the soil after 180 days caused a loss of N added to the soil by the soybean and sorghum residues. In general, larger amounts of 15N were reported in the fraction <53 μm, associated with clay minerals, throughout the incubation period. These N losses should be considered in N fertilization for the following crops in rotation with flooded rice.(AU)

O Rio Grande do Sul possui cerca de 20% da área total de solos de terras baixas, propícias para o cultivo do arroz (Oryza sativa) irrigado por inundação. Buscando mitigar danos ocasionados com o monocultivo de arroz, novas culturas, como o sorgo (Sorghum bicolor) e a soja (Glycine max), têm sido cultivadas nestas áreas. Com diferentes qualidades de resíduos culturais, espera-se uma alteração na dinâmica da matéria orgânica do solo (MOS) e, consequentemente, do nitrogênio (N). O objetivo deste estudo foi avaliar a influência de resíduos culturais de arroz, soja e sorgo na quantidade de N em frações físicas da MOS de dois solos de terras baixas, utilizando a técnica de marcação isotópica de 15N das culturas e uma incubação por um ciclo de 180 dias em condição aeróbica e mais 180 dias em condição anaeróbica. Aos 30, 180 e 360 dias de incubação foi quantificado o N remanescente dos resíduos vegetais e destino do N proveniente dos resíduos nos dois solos em frações físicas da MOS >250 μm, 250-53 μm e <53 μm. O solo com maior quantidade de argila+silte recebeu maior quantidade de 15N dos resíduos, enquanto que o alagamento do solo após 180 dias de incubação ocasionou uma perda do N adicionado ao solo pelos resíduos de soja e sorgo. De maneira geral, foram encontradas maiores quantidades de 15N na fração <53 μm, associado aos argilominerais. As perdas de N devem ser consideradas na adubação nitrogenada para as culturas sequentes nos sistemas de rotação de culturas com arroz irrigado.(AU)

Natural abundance of 15N of N derived from the atmosphere by different strains of Bradyrhizobium in symbiosis with soybean plants / Abundância natural de 15 N do N derivado da atmosfera por diferentes estirpes de Bradyrhizobium em simbiose com plantas de soja

To quantify the BNF contribution to legumes using the 15N natural abundance technique, it is important to know the abundance of 15N of the plants grown entirely dependent on BNF (value ‘B’). The aim of the study was to determine the 15N natural abundance of N2 fixed by different Bradyrhizobium strains in symbiosis with one soybean cultivar. Treatments consisted of soybean plants cultivated with and without inoculation with ten Bradyrhizobium strains, in five replicates planted in Leonard jars in a sand/vermiculite mixture. Plants were harvested after 46 days. The ‘B’ values of the aerial tissue (‘Bs’) ranged from -2.6 to -3.9 ‰. There was a tendency for the ‘Bs’ values of plants inoculated with strains of B. elkanii to be more negative than plants inoculated with other strains. All ‘B’ values of the whole plant were less than 1 unit of δ15N (‰) different from zero, suggesting that the symbioses have little tendency to show significant isotopic fractionation during N2 fixation, but there is considerable depletion in 15N of the N translocated to the shoot tissue.

Para quantificar a FBN em leguminosas, através da técnica de abundância natural de 15N, é importante conhecer a abundância de 15N da planta leguminosa crescida inteiramente dependente da FBN (valor ‘B’). O objetivo deste estudo foi determinar a abundância natural de 15N do N2 fixado por diferentes estirpes de Bradyrhizobium em simbiose com uma cultivar de soja. Os tratamentos consistiram de plantas cultivadas sem e com inoculação com dez estirpes de Bradyrhizobium, em cinco repetições. Foram utilizados vasos de Leonard, substrato de areia e vermiculita. As plantas foram colhidas após 46 dias. Os valores de ‘B’ parte aérea (‘Bpa’) variaram entre -2.6 to -3.9 ‰. Houve tendência para a abundância de 15N dos valores de ‘Bpa’ das plantas inoculadas com estirpes de B. elkanii a serem mais negativos que as plantas inoculadas com as outras estirpes. Todos os valores de ‘B’ da planta inteira foram menos de 1 unidade de δ 15N (‰) diferente de zero, sugerindo que as simbioses têm pouca tendência de mostrar fracionamento isotópico significativo, mas houve considerável empobrecimento do isótopo 15N no N translocado a parte aérea.

Natural abundance of 15N of N derived from the atmosphere by different strains of Bradyrhizobium in symbiosis with soybean plants / Abundância natural de 15 N do N derivado da atmosfera por diferentes estirpes de Bradyrhizobium em simbiose com plantas de soja

To quantify the BNF contribution to legumes using the 15N natural abundance technique, it is important to know the abundance of 15N of the plants grown entirely dependent on BNF (value ‘B). The aim of the study was to determine the 15N natural abundance of N2 fixed by different Bradyrhizobium strains in symbiosis with one soybean cultivar. Treatments consisted of soybean plants cultivated with and without inoculation with ten Bradyrhizobium strains, in five replicates planted in Leonard jars in a sand/vermiculite mixture. Plants were harvested after 46 days. The ‘B values of the aerial tissue (‘Bs) ranged from -2.6 to -3.9 ‰. There was a tendency for the ‘Bs values of plants inoculated with strains of B. elkanii to be more negative than plants inoculated with other strains. All ‘B values of the whole plant were less than 1 unit of δ15N (‰) different from zero, suggesting that the symbioses have little tendency to show significant isotopic fractionation during N2 fixation, but there is considerable depletion in 15N of the N translocated to the shoot tissue.(AU)

Para quantificar a FBN em leguminosas, através da técnica de abundância natural de 15N, é importante conhecer a abundância de 15N da planta leguminosa crescida inteiramente dependente da FBN (valor ‘B). O objetivo deste estudo foi determinar a abundância natural de 15N do N2 fixado por diferentes estirpes de Bradyrhizobium em simbiose com uma cultivar de soja. Os tratamentos consistiram de plantas cultivadas sem e com inoculação com dez estirpes de Bradyrhizobium, em cinco repetições. Foram utilizados vasos de Leonard, substrato de areia e vermiculita. As plantas foram colhidas após 46 dias. Os valores de ‘B parte aérea (‘Bpa) variaram entre -2.6 to -3.9 ‰. Houve tendência para a abundância de 15N dos valores de ‘Bpa das plantas inoculadas com estirpes de B. elkanii a serem mais negativos que as plantas inoculadas com as outras estirpes. Todos os valores de ‘B da planta inteira foram menos de 1 unidade de δ 15N (‰) diferente de zero, sugerindo que as simbioses têm pouca tendência de mostrar fracionamento isotópico significativo, mas houve considerável empobrecimento do isótopo 15N no N translocado a parte aérea.(AU)

Grain yield, efficiency and the allocation of foliar N applied to soybean canopies

Soybean [Glycine max (L.) Merr.] grain yield is closely associated with the level of optimal nitrogen (N) supply, especially during the reproductive stages. Foliar fertilization with low rates of N have been considered as a strategy for furnishing additional N and enhancing grain yields. Field studies using 15N tracer were conducted over two growing seasons to investigate the impact of foliar N fertilization on grain yield, plant N content, the amount of N derived from fertilizer (NDFF) and N recovery efficiency (NRE). Four foliar N rates (0, 1300, 2600 and 3900 g ha−1) were supplied by two equal split applications at the R1 and R3 stages. Foliar N fertilization of soybean canopies did not affect grain yield, grain N content, shoot N content nor plant N content. Total NDFF was increased from 0.7 to 2.0 kg ha−1 across the N rates. Nonetheless, NRE was unaffected by foliar N fertilization, which averaged 53 %. Soybean plants allocated the same amount of N fertilizer to both grains and shoots. No significant effects of low rate foliar N fertilization were registered on soybean grain yield nor plant N content, despite considerable N fertilizer recovery by plant organs.

Grain yield, efficiency and the allocation of foliar N applied to soybean canopies

Soybean [Glycine max (L.) Merr.] grain yield is closely associated with the level of optimal nitrogen (N) supply, especially during the reproductive stages. Foliar fertilization with low rates of N have been considered as a strategy for furnishing additional N and enhancing grain yields. Field studies using 15N tracer were conducted over two growing seasons to investigate the impact of foliar N fertilization on grain yield, plant N content, the amount of N derived from fertilizer (NDFF) and N recovery efficiency (NRE). Four foliar N rates (0, 1300, 2600 and 3900 g ha−1) were supplied by two equal split applications at the R1 and R3 stages. Foliar N fertilization of soybean canopies did not affect grain yield, grain N content, shoot N content nor plant N content. Total NDFF was increased from 0.7 to 2.0 kg ha−1 across the N rates. Nonetheless, NRE was unaffected by foliar N fertilization, which averaged 53 %. Soybean plants allocated the same amount of N fertilizer to both grains and shoots. No significant effects of low rate foliar N fertilization were registered on soybean grain yield nor plant N content, despite considerable N fertilizer recovery by plant organs.(AU)

Trophic ecology of citrus pests based on stable isotope analysis

ABSTRACT: Macrodactylus pumilio Burm. (Coleoptera: Scarabeidae) and Naupactus cervinus (Boh.) (Coleoptera: Curculionidae) are considered primary pests in citrus crops in Brazil, causing damage to plants and decreasing productivity. However, few studies investigate the ecology of these insects. In this context, the use of stable isotopes analysis (SIA) emerges as an alternative technique to conventional studies of behavioral ecology because it is faster and may explain feeding behavior based on the food source for each species. Field sampling and laboratory experiments were carried out to examine the changes of carbon and nitrogen stable isotope ratios (13C and 15N) among pests and host plants (C3 citrus and C4 grasses), providing means to examine trophic interactions. Beetles were collected at the municipality of Gavião Peixoto, São Paulo State, identified and kept at 5 °C in saturated saline solution until the SIA. Two patterns for both species were found: 13C value for N. cervinus was -23.6 and -13 for M. pumilio, indicating similarity between the results of 13C of N. cervinus and citrus plants (-26 ) and dependence on grasses (-12 ) for M. pumilio individuals. The mean 15N value was 4.3 and 5.8 for citrus plants and grass leaves, respectively, and the mean 15N value was 4.4 for N. cervinus and 4.9 for M. pumilio. The results showed a higher affinity of N. cervinus for citrus roots since the larval stage compared with the alternative diet on M. pumilio.

Trophic ecology of citrus pests based on stable isotope analysis

Macrodactylus pumilio Burm. (Coleoptera: Scarabeidae) and Naupactus cervinus (Boh.) (Coleoptera: Curculionidae) are considered primary pests in citrus crops in Brazil, causing damage to plants and decreasing productivity. However, few studies investigate the ecology of these insects. In this context, the use of stable isotopes analysis (SIA) emerges as an alternative technique to conventional studies of behavioral ecology because it is faster and may explain feeding behavior based on the food source for each species. Field sampling and laboratory experiments were carried out to examine the changes of carbon and nitrogen stable isotope ratios (13C and 15N) among pests and host plants (C3 citrus and C4 grasses), providing means to examine trophic interactions. Beetles were collected at the municipality of Gavião Peixoto, São Paulo State, identified and kept at 5 °C in saturated saline solution until the SIA. Two patterns for both species were found: 13C value for N. cervinus was -23.6 and -13 for M. pumilio, indicating similarity between the results of 13C of N. cervinus and citrus plants (-26 ) and dependence on grasses (-12 ) for M. pumilio individuals. The mean 15N value was 4.3 and 5.8 for citrus plants and grass leaves, respectively, and the mean 15N value was 4.4 for N. cervinus and 4.9 for M. pumilio. The results showed a higher affinity of N. cervinus for citrus roots since the larval stage compared with the alternative diet on M. pumilio.(AU)

Trophic ecology of citrus pests based on stable isotope analysis

ABSTRACT: Macrodactylus pumilio Burm. (Coleoptera: Scarabeidae) and Naupactus cervinus (Boh.) (Coleoptera: Curculionidae) are considered primary pests in citrus crops in Brazil, causing damage to plants and decreasing productivity. However, few studies investigate the ecology of these insects. In this context, the use of stable isotopes analysis (SIA) emerges as an alternative technique to conventional studies of behavioral ecology because it is faster and may explain feeding behavior based on the food source for each species. Field sampling and laboratory experiments were carried out to examine the changes of carbon and nitrogen stable isotope ratios (13C and 15N) among pests and host plants (C3 citrus and C4 grasses), providing means to examine trophic interactions. Beetles were collected at the municipality of Gavião Peixoto, São Paulo State, identified and kept at 5 °C in saturated saline solution until the SIA. Two patterns for both species were found: 13C value for N. cervinus was -23.6 and -13 for M. pumilio, indicating similarity between the results of 13C of N. cervinus and citrus plants (-26 ) and dependence on grasses (-12 ) for M. pumilio individuals. The mean 15N value was 4.3 and 5.8 for citrus plants and grass leaves, respectively, and the mean 15N value was 4.4 for N. cervinus and 4.9 for M. pumilio. The results showed a higher affinity of N. cervinus for citrus roots since the larval stage compared with the alternative diet on M. pumilio.

Contribution of nitrogen from sugarcane harvest residues and urea for crop nutrition

Sugarcane (Saccharum spp.) harvested without burning provides a substantial amount of remains (trash) on soil profiles which can be decomposed and release nutrients contributing to reduce fertilizer needs. The contribution of nitrogen (N) from sugarcane plant residues and fertilizer in sugarcane nutrition was assessed. Plant cane treatments were micro plots of 15N-labeled urea, sugarcane trash and root system; the last two to simulate the previous crop residues incorporated into the soil after crop renewal. For ratoons, N-ammonium nitrate (N-AN) micro plots, 150 kg ha-1 of N-AN and control (0 kg ha-1) were set up to evaluate the contribution of trash in N supply and quantify the effects of N-fertilizer on N-trash mineralization. The N balances derived from each 15N source were calculated after four crops and resulted in: 15N-urea applied at planting, 31 % was recovered by plant cane, 12 % by the following ratoons, 20 % remained in the soil and 37 % was not found in the soil-system (NOC). For crop residues 15N-trash + roots 26 % was recovered by sugarcane, 51 % remained in soil, and 23 % was NOC. N-fertilizer applied to ratoons nearly doubled the amount of N from green harvest residues recovered by sugarcane; 17 vs. 31 %. Water balances and crop evapotranspiration were correlated with 15N-sources recoveries and cumulative N recovery presented a positive correlation with evapotranspiration (2005 to 2009). The 15N balances indicated that crop residues are supplementary sources of N for sugarcane and may contribute to reduce N fertilizer needs since trash is annually added to the soil.

Contribution of nitrogen from sugarcane harvest residues and urea for crop nutrition

Sugarcane (Saccharum spp.) harvested without burning provides a substantial amount of remains (trash) on soil profiles which can be decomposed and release nutrients contributing to reduce fertilizer needs. The contribution of nitrogen (N) from sugarcane plant residues and fertilizer in sugarcane nutrition was assessed. Plant cane treatments were micro plots of 15N-labeled urea, sugarcane trash and root system; the last two to simulate the previous crop residues incorporated into the soil after crop renewal. For ratoons, N-ammonium nitrate (N-AN) micro plots, 150 kg ha-1 of N-AN and control (0 kg ha-1) were set up to evaluate the contribution of trash in N supply and quantify the effects of N-fertilizer on N-trash mineralization. The N balances derived from each 15N source were calculated after four crops and resulted in: 15N-urea applied at planting, 31 % was recovered by plant cane, 12 % by the following ratoons, 20 % remained in the soil and 37 % was not found in the soil-system (NOC). For crop residues 15N-trash + roots 26 % was recovered by sugarcane, 51 % remained in soil, and 23 % was NOC. N-fertilizer applied to ratoons nearly doubled the amount of N from green harvest residues recovered by sugarcane; 17 vs. 31 %. Water balances and crop evapotranspiration were correlated with 15N-sources recoveries and cumulative N recovery presented a positive correlation with evapotranspiration (2005 to 2009). The 15N balances indicated that crop residues are supplementary sources of N for sugarcane and may contribute to reduce N fertilizer needs since trash is annually added to the soil.

SISTEMAS DE CULTIVO E COMPOSIÇÃO ISOTÓPICA DE CARBONO E NITROGÊNIO EM PALMA FORRAGEIRA (OPUNTIA E NOPALEA)

A palma forrageira (Nopalea e Opuntia) apresenta o metabolismo ácido das crassuláceas (MAC), o que confere a essas plantas adaptações as condições adversas da região semiárida. Características morfológicas, produtivas, e composição mineral e isotópica podem ser afetadas pela densidade de plantio, frequência de colheita e níveis de adubação residual aplicados a essa cultura. O objetivo do primeiro experimento foi avaliar o efeito da frequência de colheita associado a diferentes densidades de plantio sobre o rendimento, eficiência de uso da chuva e composição química mineral da palma forrageira cv. Miúda no Agreste Pernambucano. O segundo experimento objetivou avaliar o efeito residual da adubação orgânica e nitrogenada da palma forrageira cv. Miúda na produtividade, eficiência do uso da chuva e características morfológicas, em duas frequências de colheita. No terceiro experimento objetivou-se avaliar a composição isotópica de clones de palma (Opuntia e Nopalea). Os experimentos foram instalados na Estação Experimental do Instituto Agronômico de Pernambuco IPA, em Caruaru PE, no período de agosto de 2013 a agosto de 2015. No experimento 1, avaliou-se a combinação entre densidades de plantas (10.417; 20.833; 41.666 e 83.333 plantas ha-1), e frequências de colheita (anual e bienal). O delineamento experimental foi o casualizados em blocos, com 4 repetições e arranjo de parcelas subdivididas, sendo a parcela principal formada pelas diferentes densidades de plantio e frequências de colheita. As variáveis avaliadas foram produtividade, eficiência do uso da chuva, número de cladódios por planta, índice de área de cladódios (IAC), altura e largura de plantas (cm), teores de MS, proteína bruta, Na, K, Ca e Mg. O aumento da densidade de plantio favoreceu a produtividade, que apresentou na densidade 10.417 plantas ha-1 a produtividade de 9,42 t de MS ha-1 2 anos-1, e na densidade 83.336 plantas ha-1 a produtividade foi de 30,01 t de MS ha-1 2 anos-1, recomendando-se adensidade populacional de 83.336 plantas por hectare com frequência de colheita bienal. Os teores de matéria seca, nitrogênio e cálcio foram de: MS 71,2 e 85 g kg-1; N 25,7 e 16,9 g kg-1; Ca 12,4 e 9,4 g kg-1 nas densidades de 10.417 e 83.336 plantas ha-1, respectivamente. Os teores de sódio, magnésio e potássio foram: Na 0,003 g. kg-1; Mg 0,0001798 g. Kg-1; K 26,84 g kg-1 na colheita bienal. A eficiência de uso da chuva na maior densidade de plantio foi de 32,23 kg MS ha-1 mm-1. No experimento 2, avaliou-se o efeito da adubação orgânica e mineral residual em duas frequências de colheita, nas características morfológicas da palma forrageira cv. Miúda. O delineamento experimental utilizado foi o casualizado em blocos ao acaso, com arranjo de parcelas subsubdivididas, com quatro repetições. As parcelas principais (14,4 x 8,0 m) foram utilizadas para testar os níveis de matéria orgânica; as subparcelas (7,2 x 8,0 m) para avaliar as frequências de colheita e a subsubparcela (14,4 x 2,0 m) para avaliar os níveis de nitrogênio. As variáveis mensuradas foram produtividade (t ha-1), eficiência do uso da chuva, matéria seca, número de cladódios por planta, índice de área de cladódios (IAC), altura de plantas, largura de plantas, teores de proteína bruta, MS, Na, K, Ca e Mg (g kg-1). A medida que o nível de adubação orgânica residual aumentou, na frequência bienal, produtividade, eficiência de uso da chuva, altura e largura da planta, número de cladódios por planta e o índice de área de cladódios também aumentaram. No terceiro experimento, avaliou-se a composição isotópica de clones de palma (Opuntia e Nopalea). Para o ensaio preliminar com 20 clones de palma forrageira, foi utilizado um delineamento de blocos ao acaso com três repetições, contendo sete plantas por parcela, sendo 5 plantas na área útil e uma fileira por parcela, exceto na cultivar Miúda que apresentou três fileiras. O espaçamento utilizado foi de 1,0 x 0,5 m, com área total de 3,5 m² e área útil de 2,5 m². Os clones estudados apresentam valores de 13C entre -14,43 e -13,22, o que permite observar que os valores obtidos são típicos da fixação via PEP-carboxilase e indicam que independentemente das condições ambientais e da idade da planta, a fotossíntese se dá pelo processo CAM, possivelmente com fixação de CO2 durante a noite. Para a composição isotópica de 15N (), em clones de palma forrageira, não houve diferença significativa entre os períodos avaliados, havendo diferença significativa apenas entre os clones. Para o experimento com a palma forrageira cv. Miúda, o delineamento experimental utilizado foi o casualizado em blocos ao acaso, com arranjo de parcelas subsubdivididas, com quatro repetições. As parcelas principais (14,4 x 8,0 m) foram utilizadas para testar os níveis de matéria orgânica; as subparcelas (7,2 x 8,0 m) para avaliar as frequências de colheita e a subsubparcela (14,4 x 2,0 m) para avaliar os níveis de nitrogênio. A composição isotópica do 13C da palma forrageira cv. Miúda não foi influenciada por nenhum dos fatores testados (adubação orgânica residual, adubação mineral residual e frequência de colheita). A média do valor isotópico 13C foi de -13,97, o indica que nas condições apresentadas a palma forrageira cv. Miúda comporta-se como uma planta CAM obrigatória. Os valores de 15N variaram entre 13,71 e 12,99 e indicam ausência ou níveis mínimos de fixação biológica de N2 atmosférico pela palma forrageira cv. Miúda.

The cactus pear (Nopalea and Opuntia) presents the acid metabolism of crassulaceae (MAC), which gives these plants adaptations to the adverse conditions of the semiarid region. Morphological, productive and mineral and isotopic characteristics can be affected by planting density, harvest frequency and levels of residual fertilization applied to this crop. The objective of the first experiment was to evaluate the effect of harvest frequency and cut intensity associated with different planting densities on yield and mineral chemical composition of cactus pear cv. Miúda in Agreste Pernambucano. The second experiment aimed to evaluate the residual effect of organic and nitrogen fertilization of forage palm cv. Productivity and morphological characteristics and isotopic composition, at two harvest frequencies. In the third experiment the objective was to evaluate the isotopic composition of twenty palm clones (Opuntia and Nopalea). Both experiments were installed at the Experimental Station of the Instituto Agronômico de Pernambuco IPA, Caruaru - PE, from August 2013 to August 2015. The experiment 1 evaluated the combination of plant densities (10,417, 20,833, 41,666 and 83,333 plants ha-1), harvest frequencies (annual and biennial). The experimental design was the randomized blocks, with 4 replications and arrangement of subdivided plots, being the plot formed by the different planting densities and the subplots by the factorial arrangement between harvest frequencies and cut intensities. The variables evaluated were productivity, number of cladodes per plant, cladodes area index (IAC), height and width of plants (cm), crude protein, Na, K, Ca and Mg (mg kg -1). The increase in planting density favored productivity, which presented in the density 10,417 plants ha-1 the yield of 9.42 t of DM ha-1 2 years-1, and in the density 83,336 plants ha-1 the yield of 30.01 t of MS ha-1 2 years-1. the population density of 83,336 plants per hectare with biennial crop frequency is recommended. The contents of dry matter, nitrogen and calcium were: MS 71,2 and 85 g kg-1; N 25,7 and 16.9 g kg-1; Ca 12,4 and 9,4 g kg-1 at the densities of 10,417 and 83,336 plants ha-1, respectively. The sodium, magnesium and potassium contents were: Na 0,00257 g kg-1; Mg 0,01798 g Kg-1; K 26,84 g kg-1 in the biennial crop. Experiment 2 evaluated the effect of organic and mineral fertilization on two harvest frequencies, on the morphological characteristics and isotopic composition of the forage palm cv. Miúda. The experimental design was a randomized complete block design, with arrangement of sub - divided plots, with four replications. The main plots (14,4 x 8,0 m) were used to test the organic matter levels; the subplots (7,2 x 8,0 m) to evaluate the harvesting frequencies and the sub-plot (14,4 x 2,0 m) to evaluate the nitrogen levels. The variables measured were productivity (t ha-1), dry matter, number of cladodes per plant, cladode area index (IAC), plant height, plant width, crude protein, Na, K, Ca and Mg (g kg-1) and the isotopic composition of 13C and 15N. As the level of residual organic fertilizer increased, at biennial frequency, plant productivity, height and width, number of cladodes per plant and cladodes area index also increased. The 13C isotopic composition was not influenced by any of the factors tested (residual organic fertilization, residual mineral fertilization and harvest frequency). The average of the isotopic values 13C was -13,97 and indicate that under the conditions presented the forage palm cv. Miúda behaves like a mandatory CAM plant. The values of 15N ranged from 13, 71 to 12,99 and indicate absence or minimum levels of biological fixation of atmospheric N2 by Miúda palm. In the third experiment the isotopic composition of twenty palm clones (Opuntia and Nopalea) was evaluated. A randomized block design with three replications was used, containing seven plants per plot, with 5 plants in the useful area and one row per plot, except in the small cultivar that presented three rows. The spacing used was 1,0 x 0,5 m, with a total area of 3,5 m² and a floor area of 2,5 m². The clones studied present values of 13C between -14.43 and -13.22 , which allows to observe that the values obtained are typical of the PEP-carboxylase fixation and indicate that, independently of the environmental conditions and the age of the plant, the photosynthesis occurs through the CAM process, possibly with CO2 fixation at night. For the isotopic composition of 15N (), in forage palm clones, there was no significant difference between the evaluated periods, with a significant difference only between the clones.

EFICIÊNCIA E INCORPORAÇÃO DE METIONINA E CISTINA EM FRANGOS DE CORTE EM ENSAIOS DE DOSE RESPOSTA E ISÓTOPOS ESTÁVEIS MARCADOS

O objetivo deste estudo será determinar a relação entre metionina e cistina para otimizar o desempenho de frangos de corte usando ensaios de dose-resposta e isótopos estáveis. Para o ensaio de dose-resposta serão utilizados 600 machos da linhagem Cobb 500®, de 14 a 28 dias de idade, respeitando a exigência de aminoácidos sulfurados para a idade (0,851% de met+cis), as proporções de met:cis digestíveis de 60:40; 54:46; 48:52; 43:57; 37:63, serão obtidas através da inclusão de aminoácidos sintéticos (DL-metionina e L-cistina) à ração basal, nas proporções: 100:0; 75:25; 50:50; 25:75 e 0:100. Serão avaliados o desempenho (consumo, ganho de peso e conversão alimentar) e a composição aminoacídica do corpo depenado e penas será obtida pela técnica do abate comparativo. As eficiências de utilização serão obtidas pela inclinação da reta entre consumo e deposição do aminoácido e relacionadas aos valores obtidos no ensaio de isótopos para validação do método. A relação ótima entre metionina e cistina será determinada por uma análise de regressão entre as variáveis resposta e consumo dos aminoácidos. Para o ensaio com a técnica de isótopos estáveis, serão utilizados 60 machos da linhagem Cobb 500®. A ração enriquecida com L-(15N) metionina e L-(15N) cistina será administrada em função do peso corporal da ave. Serão 3 tratamentos em referência ao dose resposta com as proporções de met:cis digestíveis: 60:40; 48:52; 37:63, obtidas através da inclusão de aminoácidos sintéticos (L-metionina e L-cistina) à ração basal, nas proporções: 100:0; 50:50 e 0:100. Serão coletadas penas, corpo depenado e excreta, analisadas por um espectrômetro de massa de razão isotópica (IRMS) para quantificar o enriquecimento isotópico dos tecidos. Este estudo pretende promover o melhor entendimento do metabolismo da metionina e da cistina e contribuir com os métodos tradicionais de quantificação das exigências e a relação ideal entre estes aminoácidos na dieta de frangos de corte.

The aim of this study is to determine the relationship between methionine and cystine to optimize the performance of broiler chickens using dose response and stable isotope assays. For the dose-response assay, 600 males, Cobb 500®, 14-28 days old, meeting the requirement for sulphurised amino acids for age (0.851% met+cys), digestible Of 60:40; 54:46; 48:52; 43:57; 37:63, will be obtained by adding synthetic amino acids (DL-methionine and L-cystine) to the basal diet, in the proportions: 100: 0; 75:25; 50:50; 25:75 and 0: 100. The performance (consumption, weight gain and feed conversion) will be evaluated and the amino acid composition of the plucked body and feathers will be obtained by comparative slaughter technique. The efficiency of utilisation will be obtained by sloping the line between consumption and deposition of the amino acid and related to the values obtained in the isotope test for validation of the method. The optimal ratio of methionine to cystine will be determined by a regression analysis between the response and consumption of amino acids. For the stable isotope technique, 60 males, Cobb 500®, will be used. The feed enriched with L-(15N) methionine and L- (15N) cystine will be administered as a function of the body weight of the bird. There will be 3 treatments in reference to the dose response with the ratios of digestible met: cis: 60:40; 48:52; 37:63, obtained by adding synthetic amino acids (L-methionine and L-cystine) to the basal diet, in the proportions: 100: 0; 50:50 and 0: 100. Feathers, plucked and excreted bodies will be collected, analyzed by na isotope ratio mass spectrometer (IRMS) to quantify isotopic enrichment of tissues. This study aims to promote a better understanding of the metabolism of methionine and cystine and contribute to the traditional methods of quantification of the requirements and the ideal relationship between these amino acids in the diet of broilers.

Nitrogen contributions of legume roots to cabbage nutrition

The effects of roots are generally not considered in studies assessing crop responses to green manure. However, measuring such effects can contribute to a better understanding of crop rotation. In two experiments, we evaluated the content of legume-N in crop tissue and the fertilizer value of the roots and shoots of two legume species. Roots, shoots, or whole plants of the legumes sunhemp (Crotalaria juncea) and jack beans (Canavalia ensiformis) were cropped as green manure to supply nitrogen to cabbage crops (Brassica oleracea var. capitata). The principle of the A-value technique was applied to estimate the fertilizer value of each plant part. In a pot experiment, both the content of legume-N in cabbage and the fertilizer value of the whole plant was higher than the shoots, which was in turn higher than that of the roots. In field condition, roots had a decreasing effect on the N content of cabbage plants. Growing cabbage on legume root residue resulted in an increased absorption of 15N-urea, resulting in negative values for legume-N content: -13.59 g kg-1 and -3.51 g kg-1 for sunhemp and jack beans, respectively. Suggesting both low N supply by roots and N immobilization in soil organic matter or microbial biomass. Future research should focus on estimating the net N acquisition by plants from root residues under field conditions, where rooting patterns and biomass distribution differ from those in pot experiments, therefore giving a more realistic quantitative estimate.

Nitrogen contributions of legume roots to cabbage nutrition

The effects of roots are generally not considered in studies assessing crop responses to green manure. However, measuring such effects can contribute to a better understanding of crop rotation. In two experiments, we evaluated the content of legume-N in crop tissue and the fertilizer value of the roots and shoots of two legume species. Roots, shoots, or whole plants of the legumes sunhemp (Crotalaria juncea) and jack beans (Canavalia ensiformis) were cropped as green manure to supply nitrogen to cabbage crops (Brassica oleracea var. capitata). The principle of the A-value technique was applied to estimate the fertilizer value of each plant part. In a pot experiment, both the content of legume-N in cabbage and the fertilizer value of the whole plant was higher than the shoots, which was in turn higher than that of the roots. In field condition, roots had a decreasing effect on the N content of cabbage plants. Growing cabbage on legume root residue resulted in an increased absorption of 15N-urea, resulting in negative values for legume-N content: -13.59 g kg-1 and -3.51 g kg-1 for sunhemp and jack beans, respectively. Suggesting both low N supply by roots and N immobilization in soil organic matter or microbial biomass. Future research should focus on estimating the net N acquisition by plants from root residues under field conditions, where rooting patterns and biomass distribution differ from those in pot experiments, therefore giving a more realistic quantitative estimate.

The role of sediment on the energy availability for fishes in the upper Paraná river floodplain / O papel do sedimento na disponibilidade de energia para peixes da planície de inundação do alto rio Paraná

This study aimed to identify potential sources of organic matter in sediment, using stable isotopes of carbon (δ13C) and nitrogen (δ15N). Sediment samples were gathered from the margin and in center of three subsystems: Ivinheima, Paraná and Baia, in August/2001. The samples were fractionated granulometrically and separated by size (< 200 µm; 70-200 µm; > 70 µm), prepared and sent to CENA / USP, for identifying the isotopes proportions. Significant differences were detected in the isotopic ratios of the sediment only between sampling stations. The Baía channel presented the lowest δ13C values, while the highest ones were recorded in Paraná river. At this last, δ15N values were negative (-14.41‰). We did not verify significant difference in isotopic composition between the particle sizes of sediment, and between the sampling points. The main sources of carbon for the sediment were C3 macrophytes, periphyton and particulate organic carbon (POC).

O presente trabalho teve por objetivo identificar as fontes potenciais de matéria orgânica do sedimento, utilizando isótopos estáveis de carbono (δ13C) e nitrogênio (δ15N). Foram coletadas amostras de sedimento das margens e do centro de três subsistemas: Ivinheima, Paraná e Baía, em agosto/2001. As amostras foram fracionadas granulometricamente e <200 µm; 70-200 µm; >70 µm, e enviadas ao CENA/USP para identificação das proporções dos isótopos. Foram verificadas diferenças significativas nas razões isotópicas do sedimento apenas entre as estações de coleta. O canal Baía, exibiu s baixos valores de δ13C, enquanto altos valores foram registrados no rio Paraná. Nesta última estação, os valores de δ15N foram negativos (-14.41‰). Não foram registradas diferenças significativas na composição isotópica entre os tamanhos de partículas do sedimento e nem entre os pontos de coleta. As principais fontes de carbono para o sedimento foram as macrófitas C3, perifíton e carbono orgânico particulado (COP).

Nitrogen supply to corn from sunn hemp and velvet bean green manures

Due to their nitrogen fixation potential, legumes represent an alternative for supplying nutrients, substituting or complementing mineral fertilization in cropping systems involving green manuring. The objective of this study was to evaluate the N balance in a soil-plant system involving green manures [sunn hemp (Crotalaria juncea L.) and velvet bean (Mucuna aterrima Piper & Tracy)], both labeled with 15N. They were incorporated into two soils of contrasting textural classes: a clayey Eutrudox and a sandy-clayey Paleudalf, both cultivated with corn. The research was carried out in a greenhouse, using pots containing 6 kg of air dried soil, to which the equivalent to 13 Mg ha-1 dry matter of above-ground mass plus 2.7 or 2.2 Mg ha-1 of velvet bean and sunn hemp roots were incorporated, respectively, with 15N labeling of either shoots or roots. One hundred days after emergence of the corn, the velvet bean residues provided higher accumulation of N in the soil, higher absorption by corn plants and accumulation in the shoot. The green manure decomposition was more intense in the medium-textured Paleudalf. The highest nitrogen losses were also observed in this soil.

Em função de seu potencial de fixação de nitrogênio, as leguminosas representam uma alternativa ao suprimento, substituição ou complementação da adubação mineral em sistemas de cultivos envolvendo adubação verde. O objetivo deste estudo foi avaliar o balanço do N no sistema solo planta com adubos verdes crotalária júncea (Crotalaria juncea L.) e mucuna-preta (Mucuna aterrima Piper & Tracy), marcadas com 15N, incorporadas em dois solos de diferentes classes texturais: Latossolo Vermelho eutroférrico textura argilosa, A moderado (LVef) e Argissolo Vermelho-Amarelo distrófico textura arenosa/média, A moderado (PVAd), e cultivados com milho. O trabalho foi desenvolvido em casa-de-vegetação, em vasos contendo 6 kg de terra aos quais foi incorporado o equivalente a 13 Mg ha-1 de massa seca da parte aérea e 2,7 ou 2,2 Mg ha-1 de raízes de mucuna-preta e de crotalária júncea, respectivamente. A marcação com 15N foi efetuada ou nas raízes ou na parte aérea. Cem dias após emergência do milho, a incorporação de mucuna-preta aos solos proporcionou maior acúmulo de nitrogênio no solo, maior absorção do elemento pelas plantas de milho e sua acumulação na parte aérea. A decomposição da parte aérea e raízes dos adubos verdes foi mais intensa no solo de textura média (PVAd). Neste solo, também, foram observadas as maiores perdas de nitrogênio.

Nitrogen supply to corn from sunn hemp and velvet bean green manures

Due to their nitrogen fixation potential, legumes represent an alternative for supplying nutrients, substituting or complementing mineral fertilization in cropping systems involving green manuring. The objective of this study was to evaluate the N balance in a soil-plant system involving green manures [sunn hemp (Crotalaria juncea L.) and velvet bean (Mucuna aterrima Piper & Tracy)], both labeled with 15N. They were incorporated into two soils of contrasting textural classes: a clayey Eutrudox and a sandy-clayey Paleudalf, both cultivated with corn. The research was carried out in a greenhouse, using pots containing 6 kg of air dried soil, to which the equivalent to 13 Mg ha-1 dry matter of above-ground mass plus 2.7 or 2.2 Mg ha-1 of velvet bean and sunn hemp roots were incorporated, respectively, with 15N labeling of either shoots or roots. One hundred days after emergence of the corn, the velvet bean residues provided higher accumulation of N in the soil, higher absorption by corn plants and accumulation in the shoot. The green manure decomposition was more intense in the medium-textured Paleudalf. The highest nitrogen losses were also observed in this soil.

Em função de seu potencial de fixação de nitrogênio, as leguminosas representam uma alternativa ao suprimento, substituição ou complementação da adubação mineral em sistemas de cultivos envolvendo adubação verde. O objetivo deste estudo foi avaliar o balanço do N no sistema solo planta com adubos verdes crotalária júncea (Crotalaria juncea L.) e mucuna-preta (Mucuna aterrima Piper & Tracy), marcadas com 15N, incorporadas em dois solos de diferentes classes texturais: Latossolo Vermelho eutroférrico textura argilosa, A moderado (LVef) e Argissolo Vermelho-Amarelo distrófico textura arenosa/média, A moderado (PVAd), e cultivados com milho. O trabalho foi desenvolvido em casa-de-vegetação, em vasos contendo 6 kg de terra aos quais foi incorporado o equivalente a 13 Mg ha-1 de massa seca da parte aérea e 2,7 ou 2,2 Mg ha-1 de raízes de mucuna-preta e de crotalária júncea, respectivamente. A marcação com 15N foi efetuada ou nas raízes ou na parte aérea. Cem dias após emergência do milho, a incorporação de mucuna-preta aos solos proporcionou maior acúmulo de nitrogênio no solo, maior absorção do elemento pelas plantas de milho e sua acumulação na parte aérea. A decomposição da parte aérea e raízes dos adubos verdes foi mais intensa no solo de textura média (PVAd). Neste solo, também, foram observadas as maiores perdas de nitrogênio.

Aproveitamento pelo trigo do nitrogênio residual da crotalária (Crotalaria juncea) e da uréia aplicado ao solo em cultivo precedente

The cultivation of green manures in the production system aims to supply nitrogen to the soil, but often the benefits are not in the short term. In this sense, to accompany the rate of nitrogen supply from the residues over the years is necessary. The aim of this research was to evaluate the use of green manure nitrogen (Crotalaria juncea L.)-15N and urea-15N in conjugated and separate fertilization in the previous cultivation by the wheat (Triticum aestivum L.). The experiment was carried out in pots with 4kg of a Rhodic Hapludox in the completely randomized design with 5 treatments and 4 replicates. The quantities of residual N of the first crop were: Urea-15N (11.2mg kg-1 de 15N); Crotalaria juncea-15N (85.0mg kg-1de 15N); Urea-15N+crotalária (19.8mg kg-1 de 15N); Crotalaria juncea-15N+urea (81.6mg kg-1de 15N); Control (without source with N). All the treatments received 36.0mg kg-1 of N-urea in the topdressing. Evaluated the recovery of residual 15N sources, the dry weight, the concentration and content of N in plants. The N-urea recovery isolated was larger compared to N-crotalária or N-crotalária with urea, without, however, influence the accumulation of weight and nutrition of plants of wheat. In the system soil-plant, the recovery percentage of the N-crotalária was similar to the N-urea. After two years of cultivation in pots without apparent loss by percolation and leaching around 26% of the N-urea and 75% of the N-crotalaria applied the first crop are in the soil, showing the benefit of the incorporation of green manure in the supply of N to the system gradually.

O cultivo de adubos verdes no sistema produtivo tem por objetivo o fornecimento de nitrogênio ao solo. Porém, muitas vezes os benefícios não são a curto prazo. Nesse sentido, acompanhar a taxa de fornecimento de nitrogênio proveniente dos resíduos ao longo dos anos se faz necessário. O objetivo do trabalho foi avaliar o aproveitamento do nitrogênio residual no solo do adubo verde (Crotalaria juncea L.)-15N e da uréia-15N, em fertilização conjugada e separada, no segundo ano de cultivo pelo trigo (Triticum aestivum L.). O experimento foi desenvolvido em vasos com 4kg de solo (Latossolo Vermelho distrófico típico), em delineamento inteiramente casualizado com cinco tratamentos e quatro repetições. As quantidades de 15N residual do primeiro cultivo eram: Uréia-15N (11,2mg kg-1 de 15N); Crotalária juncea-15N (85mg kg-1de 15N); Uréia-15N+crotalária (19,8mg kg-1 de 15N); Crotalária juncea-15N+uréia (81,6mg kg-1de 15N); Controle (sem adição de fontes de N). Todos os tratamentos receberam 36mg kg-1 de N-uréia (sem marcação) em cobertura. Foram avaliados a recuperação do 15N residual das fontes, a massa de matéria seca, a concentração e o conteúdo de N nas plantas. A recuperação do N-uréia residual aplicado isoladamente foi superior quando comparada à recuperação do N-crotalária ou crotalária mais uréia, sem, contudo, influenciar o acúmulo de massa e a nutrição das plantas de trigo. No sistema solo-planta, a porcentagem de recuperação do N-crotalária foi igual ao N-uréia. Após dois anos de cultivo do solo em vasos sem aparentes perdas por percolação e lixiviação, em torno de 26% do N-uréia e 75% do N-crotalária aplicados no primeiro cultivo ainda se encontram no solo, evidenciando o benefício da incorporação de adubo verde no fornecimento de N gradativamente ao sistema.

Aproveitamento pelo trigo do nitrogênio residual da crotalária (Crotalaria juncea) e da uréia aplicado ao solo em cultivo precedente

The cultivation of green manures in the production system aims to supply nitrogen to the soil, but often the benefits are not in the short term. In this sense, to accompany the rate of nitrogen supply from the residues over the years is necessary. The aim of this research was to evaluate the use of green manure nitrogen (Crotalaria juncea L.)-15N and urea-15N in conjugated and separate fertilization in the previous cultivation by the wheat (Triticum aestivum L.). The experiment was carried out in pots with 4kg of a Rhodic Hapludox in the completely randomized design with 5 treatments and 4 replicates. The quantities of residual N of the first crop were: Urea-15N (11.2mg kg-1 de 15N); Crotalaria juncea-15N (85.0mg kg-1de 15N); Urea-15N+crotalária (19.8mg kg-1 de 15N); Crotalaria juncea-15N+urea (81.6mg kg-1de 15N); Control (without source with N). All the treatments received 36.0mg kg-1 of N-urea in the topdressing. Evaluated the recovery of residual 15N sources, the dry weight, the concentration and content of N in plants. The N-urea recovery isolated was larger compared to N-crotalária or N-crotalária with urea, without, however, influence the accumulation of weight and nutrition of plants of wheat. In the system soil-plant, the recovery percentage of the N-crotalária was similar to the N-urea. After two years of cultivation in pots without apparent loss by percolation and leaching around 26% of the N-urea and 75% of the N-crotalaria applied the first crop are in the soil, showing the benefit of the incorporation of green manure in the supply of N to the system gradually.

O cultivo de adubos verdes no sistema produtivo tem por objetivo o fornecimento de nitrogênio ao solo. Porém, muitas vezes os benefícios não são a curto prazo. Nesse sentido, acompanhar a taxa de fornecimento de nitrogênio proveniente dos resíduos ao longo dos anos se faz necessário. O objetivo do trabalho foi avaliar o aproveitamento do nitrogênio residual no solo do adubo verde (Crotalaria juncea L.)-15N e da uréia-15N, em fertilização conjugada e separada, no segundo ano de cultivo pelo trigo (Triticum aestivum L.). O experimento foi desenvolvido em vasos com 4kg de solo (Latossolo Vermelho distrófico típico), em delineamento inteiramente casualizado com cinco tratamentos e quatro repetições. As quantidades de 15N residual do primeiro cultivo eram: Uréia-15N (11,2mg kg-1 de 15N); Crotalária juncea-15N (85mg kg-1de 15N); Uréia-15N+crotalária (19,8mg kg-1 de 15N); Crotalária juncea-15N+uréia (81,6mg kg-1de 15N); Controle (sem adição de fontes de N). Todos os tratamentos receberam 36mg kg-1 de N-uréia (sem marcação) em cobertura. Foram avaliados a recuperação do 15N residual das fontes, a massa de matéria seca, a concentração e o conteúdo de N nas plantas. A recuperação do N-uréia residual aplicado isoladamente foi superior quando comparada à recuperação do N-crotalária ou crotalária mais uréia, sem, contudo, influenciar o acúmulo de massa e a nutrição das plantas de trigo. No sistema solo-planta, a porcentagem de recuperação do N-crotalária foi igual ao N-uréia. Após dois anos de cultivo do solo em vasos sem aparentes perdas por percolação e lixiviação, em torno de 26% do N-uréia e 75% do N-crotalária aplicados no primeiro cultivo ainda se encontram no solo, evidenciando o benefício da incorporação de adubo verde no fornecimento de N gradativamente ao sistema.