Effect of nitrogen supply on growth and photosynthesis of sunflower plants grown in the greenhouse

The effects of nitrogen availability on growth and photosynthesis were followed in plants of sunflower (Helianthus annuus L., var. CATISSOL-01) grown in the greenhouse under natural photoperiod. The sunflower plants were grown in vermiculite under two contrasting nitrogen supply, with nitrogen supplied as ammonium nitrate. Higher nitrogen concentration resulted in higher shoot dry matter production per plant and the effect was apparent from 29 days after sowing (DAS). The difference in dry matter production was mainly attributed to the effect of nitrogen on leaf production and on individual leaf dry matter. The specific leaf weight (SLW) was not affected by the nitrogen supply. The photosynthetic CO2 assimilation (A) of the target leaves was remarkably improved by high nitrogen nutrition. However, irrespective of nitrogen supply, the decline in photosynthetic CO2 assimilation occurred before the end of leaf growth. Although nitrogen did not change significantly stomatal conductance (gs), high-N grown plants had lower intercellular CO2 concentration (C-i) when compared with low-N grown plants. Transpiration rate (E) was increased in high-N grown plants only at the beginning of leaf growth. However, this not resulted in lower intrinsic water use efficiency (WUE). (C) 2004 Elsevier B.V.. All rights reserved.

Photosynthesis in eucalyptus studied by the open photoacoustic technique: Effects of irradiance and temperature

This work demonstrates the usefulness of the Open Photoacoustic Cell Technique to study the effects of irradiance and temperature on photosynthesis. bl vivo and ill situ photosynthetic induction measurements were performed in three different species of eucalyptus plants (E. grandis, E. urophylla, and E, urograndis) previously dark-adapted at different temperatures. Photosynthetic activity curves were built as a function of light intensity, indicating the occurrence of photosynthesis saturation. E. urograndis presented higher photosynthetic activity than the other species, especially at low temperature, indicating its tolerance to stress conditions. The incidence of background saturation light of various intensities allowed the irt situ study of photoinhibition in eucalyptus plants through open photoacoustics. (C) 2001 MAIK Nauka/Interperiodica.

Photosynthesis induction in Eucalyptus urograndis seedlings and cuttings measured by Open Photoacoustics

In this work we study the photosynthetic induction in Eucalyptus urograndis leaves using the Open Photoacoustic Cell Technique. In vivo and in situ measurements were performed in leaves of four months-old E. urograndis seedlings and C041 cuttings previously dark-adapted for at least 10 h. Experimental results for the gas exchange component of the photoacoustic (PA) signal are interpreted considering that a gas uptake component would have a phase angle nearly opposite to that of the oxygen evolution component. Analysis of the photosynthetic induction data shows that seedlings present a net oxygen evolution before cuttings, but cuttings reach a higher steady-state photosynthetic activity.

Effects of different sampling intervals on apparent protein and energy digestibility of common feed ingredients by juvenile oscar fish (Astronotus ocellatus)

O presente estudo avaliou a digestibilidade aparente da proteína e da energia de ingredientes (farelo de soja, farinha de peixe, farelo de trigo e milho) por juvenis de apaiari (Astronotus ocellatus) usando dois diferentes intervalos de coleta (30 min. e 12h). Os 160 juvenis de apaiari utilizados (22,37 ± 3,06 g de peso corporal) foram divididos em quatro tanques rede plásticos e cilíndricos, cada um colocado em um tanque de alimentação de 1.000 L. O experimento foi inteiramente casualizado em esquema fatorial 2 x 4 (2 intervalos de coleta de fezes e 4 ingredientes foram) com quatro repetições. Os testes estatísticos não detectaram efeito da interação entre o intervalo de coleta e tipo de ingrediente nos coeficientes de digestibilidade. O intervalo de coleta não afetou a digestibilidade da proteína e da energia. As características físicas das fezes dos juvenis de apaiari aparentemente as tornam menos sensíveis à perda de nutrientes por lixiviação, permitindo intervalos de coleta maiores. A digestibilidade da proteína dos ingredientes avaliados foi semelhante, mostrando que a digestibilidade aparente de ingredientes animais e vegetais por juvenis de apaiari é eficiente. Os coeficientes de digestibilidade da energia foram maiores para a farinha de peixe e o farelo de soja comparado a farelo de trigo e milho. Ingredientes ricos em carboidratos (farelo de trigo e milho) apresentaram os piores coeficientes de digestibilidade da energia e, portanto, não são usados eficientemente pelos juvenis de apaiari.

Long-term high-fat diet-induced obesity decreases the cardiac leptin receptor without apparent lipotoxicity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Determination of chromium by GFAAS in slurries of fish feces to estimate the apparent digestibility of nutrients in feed used in pisciculture

This paper presents a simple, fast and sensitive method to determine chromic oxide (used as a biological marker of fish feed) in samples of fish feces by GFAAS through the direct introduction of slurries of the samples into the spectrometer's graphite tube. The standard samples of feces and of fish feed containing 0.10-1.00 mg kg(-1) of Cr2O3 were pre-frozen for I min in liquid nitrogen and then ground a cryogenic mill for 2 min, which reduced the samples' grain size to less than 60 mu m. The standard slurries were prepared by mixing 20 mg of standard samples of fish feed or feces with I mL of a solution containing 0.05% (v/v) of Triton X-100 and 0.50% (v/v) of suprapure HNO3 directly in the spectrometer's automatic sampling glass. The final concentrations of Cr2O3 present in the standard slurries were 2, 4, 8, 16 and 20 mu g L-1. After sonicating the mixture for 20s, 10 mu L of standard slurries were injected into the graphite tube, whose internal wall was lined with a metallic palladium film that acted as a permanent chemical modifier. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (2%, m/v of feces or feed devoid of minerals) were 0.81 and 2.70 mu g L-1 of Cr2O3 for the standard feces slurries, 0.84 and 2.83 mu g L-1 of Cr2O3 for the standard feed slurries. The proposed method was applied in studies of nutrient digestibility of different fish feeds and its results proved compatible with the results obtained from samples pre-mineralized by acid digestion. (c) 2005 Elsevier B.V. All rights reserved.

Comparison of indigestible markers from in situ and in vivo incubation to predict apparent digestibility in hay- and corn-fed horses

Foram utilizados quatro cavalos castrados sem raça definida pelo delineamento em blocos casualizados. Objetivou-se viabilizar os indicadores internos indigestíveis, FDNi e FDAi, obtidas pelas técnicas in situ nos bovinos e in vivo nos equinos por meio do saco de náilon móvel (SNM). Os tratamentos consistiram de digestibilidade determinada por método direto com a coleta total de fezes (CT) e indireto pelo uso de FDNi e FDAi obtidos pelas técnicas in situ (IS) na cavidade ruminal de bovinos e in vivo (IV) nos equinos por meio do SNM. As FDNi-IV e FDAi-IV promoveram a melhor taxa de recuperação (TR) do indicador, igualando-se ao grupo CT, em 91,50%, enquanto a técnica in situ resultou nas piores taxas, na média 86,50%, para ambos os indicadores indigestíveis (p < 0,05). As estimativas dos CD dos nutrientes foram adequadamente preditos pela FDAi-IV, para equinos alimentados com feno, no qual os valores observados foram de 46,41; 48,16; 47,92 e 45,51% para MS, MO, FDN e EB, respectivamente. Concluiu-se que o SNM em equinos pode ser usado para obter a FDAi em equinos alimentados exclusivamente com feno de coast-cross e para cavalos consumindo dieta mista, as FDNi e FDAi foram eleitas para predizer CD de nutrientes.

Indigestible cellulose and lignin in determining feces production and apparent digestibility in horses

Foram utilizados quatro cavalos castrados sem raça definida, distribuídos em blocos casualizados. Objetivou-se estudar a viabilização dos indicadores internos, celulose (CELi) e lignina indigestíveis (LIGi), para predizer a digestibilidade em cavalos. Os tratamentos consistiram na determinação da digestibilidade por método direto com a coleta total de fezes (CT) e indireto pelo uso CELi e LIGi obtidos pelas técnicas in situ (IS) na cavidade ruminal de bovinos e in vivo (IV) nos equinos por meio do saco de náilon móvel (SNM). A produção fecal e taxa de recuperação (p > 0,05) médios encontrados foram de 2,80 kg na MS e 101%, respectivamente. As estimativas dos CD dos nutrientes (p > 0,05) foram adequadamente preditos pela CELi e LIGi, obtidos in situ e in vivo, no qual os valores médios observados foram de 52,63, 54,17, 64,90, 43,73 e 98,28% para MS, MO, PB, FDN e Amido, respectivamente. Concluiu-se que a CELi e LIGi podem ser obtidas in vivo por meio do SNM em equinos, para predizer os coeficientes de digestibilidade de nutrientes, consumindo dieta mista.

Apparent nutrient digestibility and mineral availability of protein-rich ingredients in extruded diets for Nile tilapia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Use of high moisture corn silage replacing dry corn on intake, apparent digestibility, production and composition of milk of dairy goats

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

Apparent digestibility of diets with different concentrations of lysine and energy in piglets with different body weights and post-weaning age

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

Seasonal changes in vegetative growth and photosynthesis of Arabica coffee trees

Seasonal changes in vegetative growth, leaf gas exchanges, carbon isotope discrimination (Delta) and carbohydrate status were monitored in de-fruited coffee trees (Coffea arabica L.) grown in the field, from October 1998 through September 1999, in Vicosa (20degrees45'S, 42degrees15'W, 650 m a.s.l.), southeastern Brazil. of the total growth over the 12-month study period, 78% occurred in the warm, rainy season (October-March), and 22% during the cool, dry season (April-September). Throughout the active growth period, the rate of net carbon assimilation (A) averaged 8.6 mumol m(-2) s(-1), against 3.4 mumol m(-2) s(-1) during the period of reduced growth. In the active period, growth, unlike A or Delta, was strongly negatively correlated with air temperature. In contrast, growth and A were both correlated positively, and Delta correlated negatively, with air temperature during the reduced growth period. However, the depressions of A and growth might have simply run in parallel, without any causal relationship. Changes in A appeared to be largely due to stomatal limitations in the active growing season, with non-stomatal ones prevailing in the slow growth period. Foliar carbohydrates seemed not to have contributed appreciably to changes in growth rates and photosynthesis. (C) 2004 Elsevier B.V. All rights reserved.

Influence of light intensity and salt-treatment on mode of photosynthesis and enzymes of the antioxidative response system of Mesembryanthemum crystallinum

The metabolic switch From C-3-photosynthesis to crassulacean acid metabolism (CAM),and the antioxidative response of Mesembryanthemum crystallinum L. plants cultured under severe salt stress and high light intensities, and a combination of booth stress conditions, were studied. High light conditions led to a more rapid CAM induction than salinity. The induction time was still shortened when both stress factors were combined. A main pattern observed in CAM plants was a decrease in mitochondrial Mn-superoxide dismutase (SOD) activity during the day. The activities of the chloroplastic Fe-SOD and cytosolic CuZn-SOD were increased due to salt treatment after a lag phase, while catalase activity was decreased. Combination of salt and light stress did not lead to a higher SOD activity as found after application of one stress factor alone, indicating that there is a threshold level of the oxidative stress response. The fact that salt-stressed plants grown under high light conditions showed permanent photoinhibition and lost the ability for nocturnal malate storage after 9 d of treatment indicate serious malfunction of metabolism, leading to accelerated senescence. Comparison of CuZn-SOD activity with CuZn-SOD protein amount, which was determined immunologically, indicates that the activity of the enzyme is at least partially post-translationally regulated.

Seasonal effects on the relationship between photosynthesis and leaf carbohydrates in orange trees

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

Cytogenetics of a new species of Paratelmatobius cardosoi group (Anura : Leptodactylidae), with the description of an apparent case of pericentric inversion

The karyotype of a new species of Paratelmatobius from the P cardosoi group is described. As with other Paratelmatobius and Scythrophrys karyotypes, Paratelmatobius sp. (aff. cardosoi) shows a diploid number of 24 chromosomes, in addition to other similarities with the former karyotypes. The Paratelmatobius sp. (aff. cardosoi) karyotype differs from that of P. cardosoi in the morphology of pair 4, the NOR location and the C-bands in pairs 3 and 8 (exclusive to Paratelmatobius sp.) and those of pairs 7 and 9 (exclusive to P. cardosoi). Both karyotypes also differ in the amount of heterochromatin in pair 1. The presence of interstitial heterochromatin in the long arm of pair 1 and the interstitial C-bands in both arms of chromosome 5 are apparently synapomorphic characters of P. cardosoi and Paratelmatobius sp. (aff. cardosoi), since they are absent in the other Paratelmatobius and Scythrophrys karyotypes. In Paratelmatobius sp. (aff. cardosoi), the nucleolus organizer region is on the short arm of a small metacentric chromosome (pair 9), an arrangement similar to the NOR-bearing chromosome pair in the karyotype of P. poecilogaster and in karyotype 11 of Scythrophrys. A conspicuous heteromorphism unrelated to the sex determining mechanism was also observed and probably arose from a pericentric inversion.