Seed germination and seedling emergence of velvetleaf (Abutilon theophrasti) and Barnyardgrass (Echinochloa crus-galli)

Abutilon theophrasti and Barnyardgrass (Echinochloa crus-galli) are major weeds that affect cropping systems worldwide. Laboratory and greenhouse studies were conducted to determine the effects of temperature, pH, water and salinity stress, and planting depth on seed germination and seedling emergence of Velvetleaf and Barnyardgrass. For Velvetleaf, the base, optimum and ceiling germination temperatures were estimated as 5, 35 and 48 ºC, respectively. Seed germination was sensitive to drought stress and completely inhibited by a potential of -0.6 MPa, but it was tolerant to salinity. Salinity stress up to 45 mM had no effect on the germination of Velvetleaf, but germination decreased with increasing salt concentration. Drought and salinity levels for 50% inhibition of maximum germination were -0.3 MPa and 110 mM, respectively. Seed germination of Velvetleaf was tolerant to a wide range of pH levels. For Barnyardgrass, the base, optimum and ceiling germination temperatures were estimated as 5, 38 and 45 ºC, respectively. Seed germination was tolerant to drought stress and completely inhibited by a potential of -1.0 MPa. Salinity stress up to 250 mM had no effect on seed germination. Drought and salinity levels for 50% inhibition of maximum germination were -0.5 MPa and 307 mM, respectively. A high percentage of seed germination was observed at pH=5 and decreased to 61.5% at acidic medium (pH 4) and to 11% at alkaline medium (pH 9). Maximum seedling emergence of Velvetleaf and Barnyardgrass occurred when the seeds were placed on the surface of the soil or at a depth of 1 cm.

Factors affecting Cyperus difformis seed germination and seedling emergence

Specific knowledge about the dormancy, germination, and emergence patterns of weed species aids the development of integrated management strategies. Laboratory studies were conducted to determine the effect of several environmental factors on seed germination and seedling emergence of Cyperus difformis. Germination of freshly harvested seeds was inhibited by darkness; however, when seeds were subsequently transferred to complete light they germinated readily. Our results showed that 2 wk of cold stratification overcome the light requirement for germination. Seeds of C. difformis were able to germinate over a broad range of temperatures (25/15, 30/20, 35/25, and 40/30 ºC day/night). The response of germination rate to temperature was described as a non-linear function. Based on model outputs, the base, the optimum and the ceiling temperatures were estimated as 14.81, 37.72 and 45 ºC, respectively. A temperature of 120 ºC for a 5 min was required to inhibit 50% of maximum germination. The osmotic potential and salinity required for 50% inhibition of maximum germination were -0.47 MPa and 135.57 mM, respectively. High percentage of seed germination (89%) was observed at pH=6 and decreased to 12% at alkaline medium (pH 9) pH. Seeds sown on the soil surface gave the greatest percentage of seedling emergence, and no seedlings emerged from seeds buried in soil at depths of 1 cm.

Effect of plant density and seed position on mother plant on physiological characteristic of cocklebur (Xanthium strumarium) seeds

Experiments were conducted in 2010 to determine the influence of plant density and seed position on the mother plant on seed physiological characteristics of cocklebur (Xanthium strumarium). Cocklebur burs were collected in fall of 2010 from Research Farm of University of Agricultural Sciences and Natural Resources of Gorgan, Iran. The experiment was established as factorial arrangement using a completely randomized design with three replications. The factors included different densities of cocklebur (0, 2, 4, 6 and 8 plant m-2) and the top and bottom parts of the canopy. Non dormant seeds were used for determining cardinal temperatures and tolerance to salinity and drought stresses. Base, optimum and ceiling germination temperatures were estimated between 7.09 to 12.33, 32 to 35 and 44 to 45 respectively in different treatments. Salinity stress up to 300 Mm and osmotic potential 8 bar inhibited the germination completely. Comparison of base temperatures and sigmoid equation coefficients showed that seeds produced in the top had higher germination than those that produced at the bottom of the mother plant. It seems plant densities through seed position on the mother plant affect seed quality. Likewise changes of light quality and quantity in shade environment increased seed dormancy in matured seeds. Shade environment affect seed germination on mother plant that increased dormancy of seeds maturing under shade be an adaptive response that reduces the probability of germination of offspring under unfavorable (shade, competitive) conditions.

Fructan variation in the rhizophores of Vernonia herbacea (Vell.) Rusby, as influenced by temperature

The influence of climatic variations on fructan content in tropical regions is not well known. The present study deals with the effects of temperature on fructan contents in rhizophores of plants of Vernonia herbacea, a native species from the Brazilian cerrado vegetation. Intact plants and fragmented rhizophores were subjected to different temperatures under natural and controlled environmental conditions. Rhizophores of plants in pre-dormant stage (aerial parts showing some yellowish leaves) presented higher fructan content at 5oC than those kept at 25oC, whereas in dormant plants (aerial parts absent) temperature treatments did not affect fructan contents. Fragmented rhizophores obtained from dormant plants presented higher levels of fructo-polysaccharides at the end of the experiment than at the beginning of the treatment, regardless of the temperature they were stored, whereas fragments obtained from vegetative plants showed a decrease in fructan content under the same treatments. It was concluded that variations observed in fructan contents are related to the phenological state of the plants prior to the treatment rather than to extraneous temperatures they are subjected to during this stage.

Effect of light and temperature on germination and early growth of Vochysia tucanorum Mart., Vochysiaceae, in cerrado and forest soil under different radiation levels

Vochysia tucanorum Mart. (Vochysiaceae) is a very widely distributed species in the cerrado and forests in Brazil, from the State of Bahia to Paraná. Its seed germination was analysed under eight treatments using different conditions of light and temperature. Up to 73 days, at least ca. 93% of the seeds germinated in all treatments, except under alternating temperatures of 35°/10°C (62%). Light enhanced germination, except under constant temperature of 25°C when seeds are not photoblastic. At this temperature, the highest percentage of germination was found. Initial vegetative growth was analysed by comparing the effects of shading, by means of different percentages of full daylight (100%, 45%, 10.6%, 4.8%), and soils from cerrado and forest. During 123 days, no mortality was recorded and cotyledons persisted on the seedlings of all treatments. In general, the seedlings of V. tucanorum were found to be more or less indifferent to the soil from cerrado or forest and shading seems to promote height increment. However, total dry mass was larger under a radiation of 45% full daylight and smaller under extreme conditions (100% or 4.8% full daylight).

Effects of moisture content and temperature during storage on germination of the achenes of Bidens gardneri Baker

Bidens gardneri is a herbaceous species of the cerrados, whose seeds are light sensitive at 25 °C, but they become indifferent to light when stored in soil. In this work the effects of moisture content, temperature and light (during storage) upon light sensitivity during germination were studied. Ripe achenes were collected in the cerrados of Itirapina and Moji Guaçu, State of São Paulo, Brazil. The storage conditions of the achenes varied in each experiment. Achenes were stored in darkness or light, in closed bottles, at 4 °C, 20/30 °C or 25 °C. Achenes were imbibed for 24 h at 4 °C, 25 °C or 20/30 °C (in darkness) and then stored for 1, 10, 20, 30 and 40 days (40 days only for 4 °C and 25 °C). Germination tests were conducted at 25 °C and 20/30 °C. The achenes not previously imbibed showed sensitivity to light during germination. High moisture content did not affect light sensitivity of the achenes during germination but high moisture content together with storage temperatures of 25 °C and 20/30 °C had a deleterious effect upon the longevity of the achenes. Alternate temperatures during germination did not change the light sensitivity of newly collected achenes from Itirapina but changed the light sensitivity of the achenes stored imbibed at 4 °C in darkness. Alternate temperatures during storage of achenes with low moisture content did not change their photoblastism when germination was carried out at 25 °C. Alternate temperatures during storage of achenes with high moisture content followed by alternate temperatures during germination changed the light sensitivity of the achenes.

High irradiance and temperature inhibit the germination of spores of the fern Rumohra adiantiformis (Forst.) Ching (Dryopteridaceae)

Rumohra adiantiformis (Forst.) Ching is a fern (Dryopteridaceae) which is used to compose floral arrangements. Fertile fronds were harvested in the "Permanently Protected Area" of Ilha Comprida, São Paulo, Brazil. Sterilized spores were germinated in Mohr liquid medium modified by Dyer. The effect of 72%, 54%, 17% and 9% of total irradiance on germination under field conditions, was analyzed. Experiments were carried out in March (I), April (II) and August of 2000 (III). Under 54% and 72% of total irradiance in Experiment I (March) the germination was completely inhibited and partially inhibited under 72% of total irradiance in Experiment II (April). The lowest mean germination time () was observed under 9% of total irradiance in Experiments II (11.62 days) and III (8.80 days) respectively, followed by 17% in Experiment III (10.12 days) and 9% of total irradiance in the Experiment I (11.62 days ). The effect of temperatures of 15 ± 1, 20 ± 1, 25 ± 1 and 30 ± 1 ºC on germination was also analyzed. The lowest mean germination time (7.93 days) was observed at 25 ± 1 °C followed by 20 ± 1 °C. The highest mean germination time was observed at 15 ± 1 °C (12.10 days) followed by 30 ± 1 °C (10.63 days), which inhibited germination. The germination of R. adiantiformis was photoinhibited by high irradiance and partially inhibited by the highest temperature tested.

In vitro culture at low temperature and ex vitro acclimatization of Vriesea inflata an ornamental bromeliad

(In vitro culture at low temperature and ex vitro acclimatization of Vriesea inflata an ornamental bromeliad). In vitro culture by seeds is a technique for preservation of threatened species because it may provide a large number of plants with genetic diversity. The bromeliad Vriesea inflata (Wawra) Wawra, an ornamental bromeliad, is extensively and illegally collected from the nature and must be preserved. It is possible to form plant threatened collections in vitro by reducing the temperature of culture, while occupying little space, with the consequent reduction of maintenance costs. This work evaluated the influence of temperature on in vitro growth and morphology of plants of V. inflata, with the aim of establishing a slow growth-rate and analyzing the ex vitro acclimatization. Seeds were germinated in vitro in Murashige and Skoog (MS) medium, with macronutrients reduced to 50% (MS/2). After three months the plants were transferred to flasks of new same medium and kept in two germination chambers with the temperature adjusted to 15 °C and to 28 °C. After 24 months the plants were subject to biometric, photosynthetic pigments content and anatomical analyses. Results showed that plants maintained at 15 °C were smaller than those at 28 °C. Nevertheless, there were no alterations in pigments content, anatomy. In both treatments there was a survival rate of 100%. This work showed that plants of this species can be kept in vitro at 15 °C with the aim of forming a slow-growth collection, thereby seeking its preservation, and can be transferred to growth at ex vitro condition to achieved 100% survival rate.

Influence of air temperature on proteinase activity and beverage quality in Coffea arabica

Fruits were collected from trees of Coffea arabica cv. Obatã grown at Mococa and Adamantina in São Paulo State, Brazil, which are regions with marked differences in air temperature that produce coffee with distinct qualities. Mococa is a cooler location that produces high-quality coffee, whereas coffee from Adamantina is of lower quality. The amino acid and protein contents, amino acid profile, and proteinase activity and type in endosperm protein extracts were analysed. Proteinase genes were identified, and their expression was assayed. All results indicate that temperature plays a role in controlling proteinase activity in coffee endosperm. Proteinase activity was higher in the endosperm of immature fruits from Adamantina, which was correlated with higher amino acid content, changes in the amino acid profile, and increased gene expression. Cysteine proteinases were the main class of proteinases in the protein extracts. These data suggest that temperature plays an important role in coffee quality by altering nitrogen compound composition.

Cardiovascular, respiratory and metabolic responses to temperature and hypoxia of the winter frog Rana catesbeiana

The objective of the present study was to determine the effects of hypoxia and temperature on the cardiovascular and respiratory systems and plasma glucose levels of the winter bullfrog Rana catesbeiana. Body temperature was maintained at 10, 15, 25 and 35oC for measurements of breathing frequency, heart rate, arterial blood pressure, metabolic rate, plasma glucose levels, blood gases and acid-base status. Reducing body temperature from 35 to 10oC decreased (P<0.001) heart rate (bpm) from 64.0 ± 3.1 (N = 5) to 12.5 ± 2.5 (N = 6) and blood pressure (mmHg) (P<0.05) from 41.9 ± 2.1 (N = 5) to 33.1 ± 2.1 (N = 6), whereas no significant changes were observed under hypoxia. Hypoxia-induced changes in breathing frequency and acid-base status were proportional to body temperature, being pronounced at 25oC, less so at 15oC, and absent at 10oC. Hypoxia at 35oC was lethal. Under normoxia, plasma glucose concentration (mg/dl) decreased (P<0.01) from 53.0 ± 3.4 (N = 6) to 35.9 ± 1.7 (N = 6) at body temperatures of 35 and 10oC, respectively. Hypoxia had no significant effect on plasma glucose concentration at 10 and 15oC, but at 25oC there was a significant increase under conditions of 3% inspired O2. The arterial PO2 and pH values were similar to those reported in previous studies on non-estivating Rana catesbeiana, but PaCO2 (37.5 ± 1.9 mmHg, N = 5) was 3-fold higher, indicating increased plasma bicarbonate levels. The estivating bullfrog may be exposed not only to low temperatures but also to hypoxia. These animals show temperature-dependent responses that may be beneficial since during low body temperatures the sensitivity of most physiological systems to hypoxia is reduced

Evaluation of the addition of ascorbic acid to the ration of cultivated Piaractus mesopotamicus (Characidae) on the infrapopulation of Anacanthorus penilabiatus (Monogenea)

Sixty Piaractus mesopotamicus Holmberg, 1887 (pacu) fry fed a diet containing 0, 50, 100 and 200 mg ascorbic acid/kg dry feed were studied to evaluate the effect on parasitic infestation by the monogenean Anacanthorus penilabiatus Boeger, Husak and Martins, 1995 (Monogenea: Dactylogyridae) for a period of 24 weeks. The temperature of the aquaria was measured daily and remained between 28 and 31oC. At the beginning of the experiment, fish showed 6.15 ± 0.33 cm standard length and 8.64 ± 1.62 g average body weight. A sample of fish was examined and showed 43 ± 17 monogeneans per fish. At the end of the experiment, the gills of control and vitamin C-treated fish were collected for parasite counts. Control fish had 42.5 parasites per fish, a significantly higher number (P<0.05) when compared with fish fed vitamin C, that showed 16.5 parasites per fish. Ascorbic acid fortification in the food promoted an increase in fish resistance to parasites. It is suggested that an optimum level of 139 mg/kg vitamin C supplementation either elicited better nutritional conditions by stimulating the appetite of the fish or improved the immune response.

Purification and partial characterization of Phaseolus vulgaris seed aminopeptidase

The aminopeptidase activity of Phaseolus vulgaris seeds was measured using L-Leu-p-nitroanilide and the L-aminoacyl-ß-naphthylamides of Leu, Ala, Arg and Met. A single peak of aminopeptidase activity on Leu-ß-naphthylamide was eluted at 750 µS after gradient elution chromatography on DEAE-cellulose of the supernatant of a crude seed extract. The effluent containing enzyme activity was applied to a Superdex 200 column and only one peak of aminopeptidase activity was obtained. SDS-polyacrylamide gel electrophoresis (10%) presented only one protein band with molecular mass of 31 kDa under reducing and nonreducing conditions. The aminopeptidase has an optimum pH of 7.0 for activity on all substrates tested and the highest Vmax/KM ratio for L-Leu-ß-naphthylamide. The enzyme activity was increased 40% by 0.15 M NaCl, inhibited 94% by 2.0 mM Zn2+, inhibited 91% by sodium p-hydroxymercuribenzoate and inhibited 45% by 0.7 mM o-phenanthroline and 30 µM EDTA. Mercaptoethanol (3.3 mM), dithioerythritol (1.7 mM), Ala, Arg, Leu and Met (70 µM), p-nitroaniline (0.25 mM) and ß-naphthylamine (0.53 mM) had no effect on enzyme activity when assayed with 0.56 mM of substrate. Bestatin (20 µM) inhibited 18% the enzyme activity. The aminopeptidase activity in the seeds decayed 50% after two months when stored at 4oC and room temperature. The enzyme is leucyl aminopeptidase metal- and thiol group-dependent.

A moderate decrease in temperature inhibits the calcium signaling mechanism(s) of the regulatory volume decrease in chick embryo cardiomyocytes

Chick cardiomyocytes, when submitted to hyposmotic swelling, exhibit a partial regulatory volume decrease (RVD). A Ca2+ influx by stretch-activated channels signals a taurine efflux and the RVD at 37°C. We evaluated the cell's performance at room temperature. Cardiomyocytes isolated and cultured from 11-day-old chick embryos were submitted to a hyposmotic solution (180 mOsm/kg H2O) at 37°C and at room temperature (26°C). Under these conditions we measured the changes in cell volume as well as the intracellular free Ca2+ (using fura-2). During hyposmotic swelling, cells at 37°C displayed a peak relative volume of 1.61 ± 0.03 and recovery to 1.22 ± 0.04 (N = 14), while cells at 26°C presented a peak swell relative volume of 1.74 ± 0.06 and did not recover (1.59 ± 0.09, N = 9). Transient increases in intracellular Ca2+, which are characteristic of the normal RVD, were observed at both temperatures (29.1 ± 4.5% (N = 8) and 115.2 ± 42.8% (N = 5) increase at 37° and 26°C (P<0.05), respectively). A delay in the Ca2+ transient increase was also observed when the cells were at 26°C (109 ± 34 s compared to 38 ± 9 s at 37°C, P<0.05). At room temperature the RVD does not occur because the calcium transient increase, which is an early event in the signaling of the RVD, is delayed. Also, free calcium is not cleared as in the 37°C RVD. In the normal RVD the free calcium returns to baseline levels. The very high and persistent free calcium levels seen at room temperature can lead to unregulated enzyme activities and may promote irreversible injury and cell death.

Track of HSMS Sophia tracing the extent of navigable water along the main northern ice between Spitzbergen and Greenland September 1868 : also showing the nature of the ice and temperature and depth of the sea

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Temperature, air pollution, and mortality from myocardial infarction in São Paulo, Brazil

An increase in daily mortality from myocardial infarction has been observed in association with meteorological factors and air pollution in several cities in the world, mainly in the northern hemisphere. The objective of the present study was to analyze the independent effects of environmental variables on daily counts of death from myocardial infarction in a subtropical region in South America. We used the robust Poisson regression to investigate associations between weather (temperature, humidity and barometric pressure), air pollution (sulfur dioxide, carbon monoxide, and inhalable particulate), and the daily death counts attributed to myocardial infarction in the city of São Paulo in Brazil, where 12,007 fatal events were observed from 1996 to 1998. The model was adjusted in a linear fashion for relative humidity and day-of-week, while nonparametric smoothing factors were used for seasonal trend and temperature. We found a significant association of daily temperature with deaths due to myocardial infarction (P < 0.001), with the lowest mortality being observed at temperatures between 21.6 and 22.6ºC. Relative humidity appeared to exert a protective effect. Sulfur dioxide concentrations correlated linearly with myocardial infarction deaths, increasing the number of fatal events by 3.4% (relative risk of 1.03; 95% confidence interval = 1.02-1.05) for each 10 µg/m³ increase. In conclusion, this study provides evidence of important associations between daily temperature and air pollution and mortality from myocardial infarction in a subtropical region, even after a comprehensive control for confounding factors.