Assessing the role of vertical leaves within the photosynthetic function of Styrax camporum under drought conditions

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

Photoacclimation in a tropical population of Cladophora glomerata (L.) Kützing 1843 (Chlorophyta) from southeastern Brazil

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

Photosynthetic characteristics of the freshwater red alga Batrachospermum delicatulum (Skuja) Necchi & Entwisle

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

Photosynthetic rate of the aquatic macrophyte Egeria densa Planch. (Hydrocharitaceae) in two rivers from the Itanhaém River Basin in São Paulo State, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Photosynthetic response of soybean to twospotted spider mite (Acari: Tetranychydae) injury

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

CO2 assimilation, photosynthetic light response curves, and water relations of 'Pêra' sweet orange plants infected with Xylella fastidiosa

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

Water deficit affects photosynthetic induction in Bauhinia forficata Link (Fabaceae) and Esenbeckia leiocarpa Engl. (Rutaceae) growing in understorey and gap conditions

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

Indirect method for quantifying the content of photosynthetic pigments in genotypes of dwarf elephant grass

O objetivo deste ensaio foi determinar equações que indiretamente associem os valores obtidos no medidor de clorofila SPAD-502 aos teores de clorofila e carotenóides de genótipos de capim-elefante anão. Folhas de genótipos de capim-elefante anão foram utilizadas e, depois de coletadas, foram transportadas em caixas de isopor, protegidas da luz, até o laboratório de Fisiologia Vegetal da UENF. Posteriormente, os discos foliares de área conhecida foram extraídos. Com o auxílio do medidor portátil de clorofila (MPC) SPAD-502, foi obtida a média de 5 leituras/disco foliar e utilizaram-se 6 discos para cada intervalo, distribuídos de acordo com a seguinte escala de valores do MPC: 0-10; 10-20; 20-30; 30-40; 40-50; 50-60. O medidor de clorofila SPAD-502 possibilitou uma rápida e eficaz estimativa do conteúdo de clorofila total, clorofila-a e clorofila-b em genótipos de capim-elefante anão.

Serpentine leafminer (Liriomyza trifolii) on potato (Solanum tuberosum): field observations and plant photosynthetic responses to injury

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fotossíntese, condutância estomática e transpiração em pupunheira sob deficiência hídrica

Resultados de pesquisa envolvendo aspectos fisiológicos da pupunheira (Bactris gasipaes Kunth), fruteira nativa da América Tropical, são escassos. Procurando completar essa lacuna, um experimento sob deficiência hídrica foi conduzido em casa de vegetação, durante um período de 13 dias, utilizando plantas de 12 meses de idade. O objetivo principal foi avaliar as respostas da pupunheira à deficiência hídrica. As variáveis observadas foram: taxa de assimilação de CO2, transpiração, condutância estomática e potencial de água das folhas. As coletas dos dados foram realizadas diariamente em laboratório e sob fluxo de 1200 mim-2 s-1. Os resultados foram submetidos à análise de variância e de regressão. Verificou-se decréscimo no potencial de água da folha e nas trocas gasosas quando a irrigação foi interrompida por mais de seis dias. Valores mínimos foram obtidos no décimo dia, com redução de 92% da fotossíntese líquida, 87% da condutância estomática e 70% da transpiração. O menor potencial de água nas folhas (-1,9 MPa) foi também observado nesse período. Houve recuperação total de todas as variáveis dois dias após reirrigação, com exceção da condutância estomática. A diminuição da condutância estomática e a queda mais rápida da taxa de transpiração que a queda na fotossíntese, indicam a existência de mecanismos de aclimatação em pupunheira, no sentido de diminuir as perdas de água, quando sob condição de estresse hídrico moderado.

Growth responses and photosynthetic characteristics of wild and phycoerythrin-deficient strains of Hypnea musciformis (Rhodophyta)

The phycoerythrin-deficient strain (green phenotype) of Hypnea musciformis (Rhodophyta) originated from a green branch, which had arisen as a spontaneous mutation in a wild plant (brown phenotype) collected from the Brazilian coast. The present study describes the growth responses to irradiance, photoperiod and temperature variations, pigment contents, and photosynthetic characteristics of the brown and green strains of H. musciformis. The results showed that growth rates increased as a function of irradiance (up to 40 mu mol photons m(-2) s(-1)) but, with further increase in irradiance (from 40 to 120 mu mol photons m(-2) s(-1)), became light-saturated and remained almost unchanged. The highest growth rates of the brown and green strains were observed in temperatures of 20-25 degrees C under long (14:10 h LD) and short (10:14 h LD) photoperiods. The brown strain had higher growth rates than the green strain in the short photoperiod, which could be related to the high concentrations of phycobiliproteins. Phycoerythrin was not detected in the green strain. The brown strain had higher concentrations of allophycocyanin and phycoerythrin in the short photoperiod while the green strain had higher concentrations of phycocyanin. The brown strain presented higher photosynthetic efficiency (alpha), and lower saturation parameter (I-k) and compensation irradiance (I-c) than the green strain. The brown strain exhibited the characteristics of shade-adapted plants, and its higher value of photosynthetic efficiency could be attributed to the higher phycoerythrin concentrations. Results of the present study indicate that both colour strains of H. musciformis could be selected for aquaculture, since growth rates were similar (although in different optimal light conditions), as the green strain seems to be adapted to higher light levels than the brown strain. Furthermore, these colour strains could be a useful experimental system to understand the regulation of biochemical processes of photosynthesis and metabolism of light-harvesting pigments in red algae.

Acclimation of broiler chickens to chronic high environmental temperature

The present study was conducted to evaluate the zootechnical parameters and age related changes in physiological responses of broiler chickens exposed to hot environment from early age onwards. The broiler chickens were exposed to high temperature (30 degreesC) at 15 d of age and maintained to Day 38 or maintained under thermoneutral environment (control).No significant decrease in feed consumption (FC) and body weight (BW) gain was observed in high temperature group after 7 d of exposure, but in the subsequent period, heat exposure lowered BW and FC, compared to control group. However, the weight gain was not significantly changed after 24 d of exposure, and the feed efficiency was not affected throughout the experimental period.The venous pCO(2) pressure was only significantly decreased by temperature after 24 d of heat exposure. The glucose, non-esterified fatty acid (NEFA), triglyceride (TG), glucose, lipid peroxidation (LPO), creatine kinase (CK), and corticosterone were not influenced by the temperature treatment. The significant decrease in uric acid and increase in lactate concentration due to high temperature were observed respectively at 28 and 35 d of age. The concentrations of triiodothyronine (T-3) and thyroxine (T-4) were changed oppositely at 28 d of age, as T-3 was decreased and T-4 was elevated by high temperature. However, the concentration of T-4 in plasma was decreased whereas T-3 was not changed at 38 d of age. The relationships between the blood parameters were changed due to the temperature treatment, suggesting that not only absolute values but also their interrelationships have to be considered when studying the effects of a particular treatment on physiological functioning.These results suggest the growth and physiological responses of broiler chickens, exposed to high temperature from early age onwards, differed at different stages of acclimation. The process of heat acclimation is related to the mode of heat exposure imposed and is not only reflected in the changes in the absolute concentrations, but also in the correlations among the blood indices.

Cold-acclimation improves cold-tolerance of diabetic rats

1. 1. The aim of these experiments was to study the extent to which previous cold-acclimation improves the cold-tolerance of diabetic rats. 2. 2. Alloxan diabetic rats (fasting blood glucose higher than 200mg/dl) were used in the experiments. 3. 3. In Expt. 1, non-cold-acclimated control and diabetic rats were exposed to cold environment (7-9°C), and the percentage of survival calculated during a 12-day experimental period. In Expt. 2, the rats were previously cold-acelimated before alloxan or saline injection (diabetic and control cold-acclimated rats) and the survival rate was also assessed during a 12-day period in the cold. 4. 4. The percentage of survival of the non-cold-acclimated diabetic rats (Expt.l) was 19% compared with 79% of the diabetic cold-acclimated animals (Expt. 2). There were no deaths in the control groups. 5. 5. Cold-acclimated diabetic rats maintained a near-normal thermogenic response after noradrenaline injection. This response was impaired in non-cold-acclimated diabetic rats. 6. 6. The results of these experiments suggest that the enhanced cold-tolerance of diabetic cold-acclimated rats could be related to the increased sympathetic activity and enhanced insulin sensitivity in thermogenic tissues, such as brown fat. © 1987.

Thermal limits in relation to acclimation in the neotropical millipede Gymnostreptus olivaceus (Diplopoda, Spirostreptidae)

The neotropical millipede, Gymnostreptus olivaceus, lives at ambient temperatures of about 20°C. Its thermal tolerance was tested after acclimation to lower and higher temperatures as occurs under winter and summer conditions in the south and southeast regions of Brazil. An increase in tolerance to low temperatures was found in adapted specimens. The ecological aspects of this capability are discussed.