Seasonal growth of "algodão-bravo" (Ipomoea carnea spp. fistulosa)

Ipomoea carnea spp. fistulosa, a native woody perennial, is capable of spreading rapidly over seasonally flooded grassland in the Brazilian Pantanal, South America's largest wetland, thus conflicting with the local cattle ranching. I. carnea is controlled by mowing at the onset of the rainy season, as close as possible before the seasonal flooding. Often, however, flooding begins after the plant has had enough time to re-sprout enabling it to survive. The objective of this study was to verify if Ipomoea carnea plant's production follows a seasonal cycle, and, if so, at which point in this cycle, the plant is most vulnerable to mechanical control measures. Seasonal dynamics of stem and leaf production of I. carnea were studied. The results showed that growth of I. carnea is fastest at the onset of the rainy season in November/December. Production declines when seasonal flooding commences in January/February and almost ceases towards the begin of the dry season in May/June. This leads to the proposal that I. carnea could be controlled more effectively if the weed were mown in the early dry season when its production and its capability to re-sprout is lowest, and if any new sprouts were cut by hand when the seasonal flooding starts.

Seasonal changes of leaf Nitrogen content in trees of Amazonian floodplains

In Amazonian floodplains the trees are exposed to extreme flooding of up to 230 days a year. Waterlogging of the roots and stems affects growth and metabolic activity of the trees. An increased leaf fall in the aquatic period and annual increment rings in the wood indicate periodical growth reductions. The present study aims at documenting seasonal changes of metabolism and vitality of adult trees in the annual cycle as expressed by changes of leaf nitrogen content. Leaves of six tree species common in floodplains in Central Amazonia and typical representants of different growth strategies were collected every month between May 1994 and June 1995 in the vicinity of Manaus, Brazil. Mean leaf nitrogen content varied between 1.3% and 3.2% in the non-flooded trees. Three species showed significantly lower Ν content in the flooded period (p=0.05, 0.001, 0.001), the difference ranging 20-25% lower than in the non-flooded period. Two species showed no significant difference while Nectandra amazonum showed 32% more Ν in the flooded season (p=0.001). Leaf nitrogen content was generally high when new leaves were flushed (in the flooded period) and decreased continuously thereafter in all species. Three species showed an additional peak of nitrogen during the first month of the terrestrial phase, in leaves which had flushed earlier, indicating that flooding may disturb nitrogen uptake.

Seasonal effects and antifungal activity from bark chemical constituents of Sterculia apetala (Malvaceae) at Pantanal of Miranda, Mato Grosso do Sul, Brazil

In the Southern Pantanal, the hyacinth macaw (Anodorhynchus hyacinthinus), an endangered species, often chooses the manduvi tree (Sterculia apetala) as a nesting site, because of its physical properties. In addition, the chemical composition of the wood may also contribute to a nesting selection by the hyacinth macaws. The objective of this study was to determine the main chemical components of S. apetala bark for two seasons, and evaluate its fungicidal potential. Bark samples from S. apetala trees with and without nests of A. hyacinthinus were collected in January (wet season) and August (dry season) of 2012. The inhibition of mycelium growth (MGI) from tree samples with and without nests were assessed using a phytochemical analysis to evaluate their antifungal activity against Trichoderma sp. Phytochemical analysis confirmed the presence of phenolic compounds and flavonoids. In both seasons, samples obtained from nested trees had higher content of total phenols than those collected from non-nested trees. The average content of total flavonoids was higher in January for samples with nest and in August for samples without nest. All selected samples showed antifungal activity, and those with nest collected in August (peak of hyacinth macaw breeding) resulted in an MGI of 51.3%. Therefore, this percentage, related to the content of flavonoids and the presence of coumarins, may influence the reproductive success of hyacinth macaws and other species of birds, in this region. This is the first chemical study report with the stem bark of S. apetala.

Seasonal abundance of the shipworm Neoteredo reynei (Bivalvia, Teredinidae) in mangrove driftwood from a northern Brazilian beach

Shipworms are important decomposers of wood, especially in mangrove forests where productivity is high. However, little emphasis has been given to the activity of shipworms in relation to the export of nutrients from mangroves to adjacent coastal areas. As a first step to obtaining such information, the frequency of colonized mangrove driftwood as well as shipworm density and length were studied by collecting washed up logs during a year at Ajuruteua beach, state of Pará, northern Brazil. A single species, Neoteredo reynei (Bartsch, 1920), was found colonizing driftwood. Although large colonized logs were most common on the beach, shipworm density was higher in small logs, especially during the dry season. In general, however, density was higher during the wet season (January to April) and lowest in July. Overall shipworm mean length was 9.66cm. In large logs, mean length increased between the wet and dry seasons. However, there was no difference in length among log size categories. Mean shipworm length was similar throughout most of the year but tended to be greater in July. Although salinity varied between 10.9 and 40 during the year, no relationship was found between salinity and density or length. The results suggest that shipworm activity in driftwood logs is relatively constant throughout the year. Increased air humidity and rainfall may promote survival during the wet season. Large logs may take longer to colonize and thus have lower densities than small ones which are scarce probably because they are destroyed rapidly by shipworm activity. However, data on the disintegration of logs would be necessary to test this hypothesis. Larger size of shipworms in the dry season may be related to growth after an earlier recruitment period. Shipworms in large logs during the dry season may be better protected from dessication and high temperatures by the insulating properties of the larger volume of wood.

Potato crop growth as affected by nitrogen and plant density

Growth and development variables and dry matter characteristics were studied for cultivar Snowden of potato (Solanum tuberosum L.) to evaluate nitrogen and plant density influence. Disregarding ending of season plant stress, the average number of actives haulms per plant was five and it was not affected by plant spacing. However, seasonal and final number of active haulms per plant were increased at 200 kg/ha of nitrogen. Maximum stem elongation was reached quickly with double density and had the tendency to keep constant at the highest and lowest nitrogen levels after 70 days after planting. Specific stem mass defined as mass per unit stem length was established as an indirect measure of stem thickness and load capacity. Specific leaf mass position in plant was higher at upper stem leaves, increased as plant density increased and did not vary markedly over time throughout the season. The rate of leaf appearance increased drastically due to more branching caused by high nitrogen level, and increased above ground dry matter per plant. Canopy growth and development influenced main tuber yield components. The number of active tubers per haulm decreased after 60 days after planting showing that tuberization is reversible. Tuber growth functions were established allowing the estimate of dry biomass partitioning coefficients for each plant organ.

Seasonal variation in the composition of volatile oils from Schinus terebinthifolius raddi

Essential oils from leaves, ripe and unripe fruits of Schinus terebinthifolius growing in Brazil were investigated. Oil content from either ripe or unripe fruits was similar (4.65% and 3.98%, respectively). Sesquiterpenes (from 78.0% to 90.4%) dominated the oil content of both leaves and unripe fruit. The essential oils were tested in vitro for their allelopathic activity on germination and radicle growth of Lactuca sativa and Cucumis sativus at 1,000 and 10,000 µg mL-1concentrations. The three samples tested were more active in inhibiting the radicle growth for L. sativa (88.6-92.4%) than for C. sativus (50.5-84.5%) at 10,000 µg mL-1 concentration.

Growth, leaf and stomatal traits of crabwood (Carapa guianensis Aubl.) in central Amazonia

Crabwood (Carapa guianensis Aubl.) is a fast growing tree species with many uses among Amazonian local communities. The main objective of this study was to assess the effect of seasonal rainfall pattern on growth rates, and seasonal and diurnal changes in leaf gas exchange and leaf water potential (ΨL) in crabwood. To assess the effect of rainfall seasonality on growth and physiological leaf traits an experiment was conducted in Manaus, AM (03º 05' 30" S, 59º 59' 35" S). In this experiment, six 6-m tall plants were used to assess photosynthetic traits and ΨL. In a second experiment the effect of growth irradiance on stomatal density (S D), size (S S) and leaf thickness was assessed in 0.8-m tall saplings. Stomatal conductance (g s) and light-saturated photosynthesis (Amax) were higher in the wet season, and between 09:00 and 15:00 h. However, no effect of rainfall seasonality was found on ΨL and potential photosynthesis (CO2-saturated). ΨL declined from -0.3 MPa early in the morning to -0.75 MPa after midday. It increased in the afternoon but did not reach full recovery at sunset. Growth rates of crabwood were high, and similar in both seasons (2 mm month-1). Leaf thickness and S D were 19% and 47% higher in sun than in shade plants, whereas the opposite was true for S S. We conclude that ΨL greatly affects carbon assimilation of crabwood by reducing g s at noon, although this effect is not reflected on growth rates indicating that other factors offset the effect of g s on Amax.

The seasonal and ovarian status effects on in vitro production of domestic cat embryos between Equator and Tropic of Capricorn

From the Tropic of Capricorn to Equator, the seasonality of domestic cat is known to be absent, i.e., these animals are considered non-seasonal breeders at these regions. We hypothesized that this particularity might have some influence on in vitro embryo production. The aim of this experiment was to determine the percentage of cleavage and morulae and blastocyst formation produced from oocytes recovered from queen ovaries of three distinct status - follicular, luteal or inactive - during two different reproductive seasons experienced by cats in southeast of Brazil (22°53'09" S and 48°26'42" W) - non breeding season (NBS), comprehending January to March; and breeding season (BS), August to October. Thirty queens were neutered. Ovaries were classified according to their status and were sliced in PBS for cumulus oocyte complex (COC) releasing. Grade I COC were washed three times in H-MEM supplemented with BSA, glutamine, sodium pyruvate, cysteine, streptomycin and penicillin. Oocytes were incubated in groups of 20-30 in 400µL of DMEM supplemented with FSH, LH, estradiol, IGF-I and basic fibroblast growth factor under mineral oil for 30 or 36 hours at 38°C in humidified environment of 5% de O2, 5% CO2 and 90% N2. COC were fertilized in Ham's F-10 medium supplemented with BSA, cysteine, pyruvate and streptomycin/penicillin (culture medium) with fresh semen selected through swim up technique. Eighteen hours later, the presumptive zygotes were denuded, the percentage of cleavage was determined and every 10 zygotes were transferred to 100mL drops of culture medium for culture during three days. After 72 hours of culture the percentage of morulae formation was evaluated and these structures were transferred to drops of the same culture medium. At the eighth day of culture blastocyst formation was analyzed. During NBS, from a total of 272 (inactive), 162 (luteal) and 134 (follicular) fertilized oocytes, the percentage of cleaved zygotes, morulae and blastocysts derived from inactive ovaries were 24.63, 16.54 and 8.09 respectively; for those derived from luteal ovaries, the percentage was 21.6, 12.96 and 8.64, and for those from follicular ovaries, they were 24.62, 16.41 and 8.21. Considering BS, from a total of 102 (inactive), 198 (luteal) and 86 (follicular) fertilized oocytes, the relative frequency (%) of cleaved zygotes, morulae and blastocysts derived from inactive ovaries were 64.7, 41.17 and 23.53 respectively; for those derived from luteal ovaries, the percentage was 64.14, 40.41 and 23.73, and for those from follicular ovaries, they were 63.95, 39.54 and 24.41. The results of this experiment demonstrate that no statistically significant difference (P<0.05) was verified in the frequency of cleaved embryos and morulae and blastocyst formation when comparing the three ovarian conditions in the same season. However the breeding season presented better results considering cleavage and morulae and blastocyst formation.

Growth and leaf demography of two Cecropia species

Allometry, growth and leaf demography of two Cecropia species, one with ant mutualist (C. glazioui) and another without it (C. hololeuca), were studied in an Atlantic Rain Forest area in the State of Rio de Janeiro, SE Brazil. Stem diameter was allometrically related to height in both species. Cecropia glazioui showed higher annual growth rates and longer internodes than C. hololeuca. Leaf phenology showed a seasonal pattern in both species, but the number of leaves on each plant was more variable along the year in C. hololeuca than in C. glazioui. Survivorship curves for leaves were intermediate between Deevey's Type I and Type II curves, with young leaves of C. glazioui showing a greater survival rate and life expectancy than those of C. hololeuca. Low variability in leaf production throughout the year and high survival rate for young leaves of C. glazioui may be characteristics related to its association with ants.

Phenology, litterfall, growth, and root biomass in a tidal floodplain forest in the Amazon estuary

The dynamics of forests subject to inundation appears to be strongly influenced by the frequency and intensity of natural disturbances such as flooding. In a late successional tidal floodplain forest near the Amazon port of Belém, Brazil, we tested this prediction by measuring seasonal patterns of phenology and litterfall in relation to two key variables: rainfall and tide levels. In addition, we estimated the root biomass and the annual growth of the forest community by measuring stem increments over time. Our results showed high correlations between phenological events (flowering and fruiting) and rainfall and tide levels, while correlations between litterfall and these variations were generally weaker. Contrary to our prediction, root biomass to 1 m depth showed no significant differences along the topographic gradient, and the root biomass at all topographic levels was low to intermediate compared with other neotropical forests. Both litterfall and total stem increment were high compared to other tropical forest, indicating the high productivity of this ecosystem.

Structure and dynamics of a woody plant community of a tropical semi-deciduous seasonal forest in the "Estação Ecológica do Panga", municipality of Uberlândia, Minas Gerais, Brazil

Studies of plant community dynamics are essential in understanding the demographic patterns of species since changes in demographic rates can affect the floristic composition and future structure. The purpose of the present study was to analyze the changes in the community structure and floristic composition of woody plants in a tropical semi-deciduous forest in Uberlândia in central Brazil, during a 10-years period. The data were collected in 1989 and in 2000 in 50 quadrats (10 m x 10 m) where all trees with a minimum circumference at breast height of 10 cm were sampled. In 1989, 93 species and 1103 individuals were registered. Over a period of 10 years, seven new species were added to the community, although eight disappeared. The main change that occurred during this period in the floristic composition was the replacement of savannah species occurring in forest gaps by those from the forest understory.

The influence of light spectra, UV-A, and growth regulators on the in vitro seed germination of Senecio cineraria DC.

This study was carried out to investigate the effects of light spectra, additional UV-A, and different growth regulators on the in vitro germination of Senecio cineraria DC. Seeds were surface-sterilized and inoculated in MS medium to evaluate the following light spectra: white, white plus UV-A, blue, green, red or darkness. The maximum germinability was obtained using MS0 medium under white light (30%) and MS + 0.3 mg L-1 GA3 in the absence of light (30.5%). S. cineraria seeds were indifferent to light. Blue and green lights inhibited germination. Different concentrations of gibberellic acid (GA3) (0.1; 0.4; 0.6; 0.8; 1.0 and 2.0 mg L-1) and indole-3-acetic acid IAA (0.1; 0.3 and 1.0 mg L-1) were evaluated under white light and darkness. No concentration of GA3 enhanced seed germination percentage under white light. However, when the seeds were maintained in darkness, GA3 improved germination responses in all tested concentrations, except at 1.0 mg L-1. Under white light, these concentrations also increased the germination time and reduced germination rate. Germination rate, under light or darkness, was lower using IAA compared with GA3.

Slow-release and organic fertilizers on early growth of Rangpur lime

Slow-release and organic fertilizers are promising alternatives to conventional fertilizers, as both reduce losses by leaching, volatilization and problems of toxicity and/or salinity to plants. The objective of this work was to evaluate the effect of different rates of the organic fertilizer Humato-Macota® compared with the slow-release fertilizer Osmocote® on the growth and nitrogen content in the dry matter of Rangpur lime. A field experiment was conducted in a factorial completely randomized design with an additional treatment (4 x 4 +1). The first factor consisted of four Humato­Macota® rates (0, 1, 2, and 3%) applied to the substrate; the second factor consisted of the same Humato-Macota® concentrations, but applied as fortnightly foliar sprays; the additional treatment consisted of application of 5 kgm-3 Osmocote® 18-05-09. Means of all growth characteristics (plant height, total dry matter, root/shoot ratio and leaf area) and the potential quantum yield of photosystem II (Fv/Fm) were higher when plants were fertilized with the slow-release fertilizer. The organic fertilizer applied alone did not meet the N requirement of Rangpur lime.

Root growth of Arabidopsis thaliana (L.) Heynh. treated with humic acids isolated from typical soils of Rio de Janeiro state, Brazil

Humic substances isolated from soil organic matter had been used as stimulators of plant metabolism. Arabidopsis thaliana (L.) Heynh. with only five chromosomes, short cycle and size, is an important model to evaluate the physiological effects of these substances, which are qualitatively and quantitatively influenced by morphogenesis, mineralogy and chemistry of soils. The objective of this study was to evaluate the ambience effects on bioactivity of humic acids. A and B horizons of four typical soils of the North Fluminense were sampled. After isolation and purification, humic acids were applied to plants in increasing concentrations. The number and length of lateral roots and main root length were evaluated and, subsequently, the concentrations of maximum stimulation were determined by dose-response curves and regression equations. The results showed that more stable humic acids isolated from soil in less advanced stages of weathering, high activity clay and high base saturation resulted in better physiological stimulants for Arabidopsis.

Initial growth of maize in response to application of rock phosphate, vermicompost and endophytic bacteria

Due to the high energy requirement and demand for non-renewable resources for the production of chemical fertilizers, added also to the environmental impact caused by the use of such products, it is important to intensify research on bio-based agricultural inputs. The use of nitrogen-fixing endophytic and phosphate solubilizing bacteria can provide these nutrients to the plants from the air and poorly soluble phosphorus sources, such as phosphate rock. The objective of this study was to evaluate the nutrition and initial growth of maize (Zea mays L.) in response to the inoculation of nitrogen-fixing and rock phosphate solubilizing endophytic bacteria, in single or mixed formulation, applied with vermicompost. The treatments containing bacteria, both diazotrophic and phosphate solubilizing, when compared to controls, showed higher levels of leaf nitrogen and phosphorus in maize, as well as higher growth characteristics. The application of vermicompost showed synergistic effect when combined with endophytic bacteria. Thus, the innovation of the combination of the studied factors may contribute to the early development of maize.