973 resultados para juvenility of plants
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Climatic factors directly influence growth and productivity of plants inside greenhouses, where temperature can be considered one of the major parameter in this context. Thus, the aim of this research was to develop a low cost device for thermal sensing and data acquisition, and use it in data collection and analysis of spatial variability of temperature inside a greenhouse with tropical climate. The developed equipment for thermal measurements showed a high degree of accuracy and fast responses in measurements, proving its efficiency. The data analysis interpretations were made from the elaborations of variograms and of tridimensional maps generated by a geostatistical software. The processed data analysis presented that a greenhouse without thermal control has spatial variations of air temperature, both in the sampled horizontals layers as in the three analyzed vertical columns, presenting variations of up to 3.6 ºC in certain times.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Sclerotia of Sclerotinia sclerotiorum (Ss) can survive for long time in soil and are the main inoculum source of the white mold disease. An alternative for reducing this inoculum is the use of parasites, such as Coniothyrium minitans (Cm). We evaluated the potential of Cm isolates for the biological control of Ss in beans. The effect of the temperature on the growth of 15 isolated of Cm was evaluated in vitro. The hyperparasitism ability of Cm was evaluated in soil infested with sclerotia and conditioned in pots. The infested soil was treated with conidia suspension of the antagonists, fluazinan or sterile distilled water. After seven days at 20°C, the sclerotia were removed from soil and placed inside Petri dishes over bean leaves previously disinfested. The germination and parasitism of sclerotia were evaluated after 7 to 10 days. To evaluate the apothecia emission, soil infested with sclerotia of Ss and treated as described was maintained at 18°C and the number of emerged apothecia was counted up to 84 days after inoculation. The emergence of bean plants in soil infested with sclerotia and mycelium of the pathogen and treated as described was evaluated in greenhouse. The ideal temperature for growth of Cm isolates varied from 18 to 19°C and at 30-35°C they were complete inhibited. The isolates of Cm promoted less than 10% of reduction in viability of the sclerotia, but they significantly reduced the emission of apothecia. Two isolates increased the emergence of plants in relation to the inoculated check, but was significantly lower than the non-inoculated check. Field tests will be conduct to confirm the potential of the selected isolates to reduce the inoculum source of the pathogen.
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Insect pollination is an essential ecosystem service, and bees are the principal pollinators of wild and cultivated plants. Habitat management and enhancement are a proven way to encourage wild bee populations, providing them with food and nesting resources. I examined bee diversity and abundance in plots managed by The Nature Conservancy near Wood River, NE. The plots were seeded with 2 seed mixes at 2 seeding rates: high diversity mix at the recommended rate, high diversity mix double the recommended rate, Natural Resources Conservation Service (NRCS) conservation planting (CP) 25 mix at one-half the recommended rate, and NRCS CP25 mix at the recommended rate. I measured wild bee abundance and diversity, and established a database of wild bees associated with the plots. I also compared genus richness and abundance among the plots using and aerial net and blue vane traps to collect bees. Significant differences were not observed in genus richness and diversity among the plots; however, plot size and the ability of blue vane traps to draw bees from a long distance may have influenced my results. In 2008, 15 genera and 95 individual bees were collected using an aerial net and in 2009, 32 genera and 6,103 individual bees were collected using blue vane traps. I also studied the beneficial insects associated with native Nebraska flora. Seventeen species of native, perennial flora were established in 3 separate plots located in eastern Nebraska. I transplanted four plants of each species in randomized 0.61 m x 0.61 m squares of a 3.05 m x 9.14 m plot. Arthropods were sampled using a modified leaf blower/vacuum. Insects and other arthropods were identified to family and organized into groups of predators, parasites, pollinators, herbivores, and miscellaneous. Associations between plant species and families of beneficial arthropods (predators, parasites, and pollinators) were made. Pycnanthemum flexuosum Walter attracted significantly more beneficial arthropod families than 7 other species of plants tested. Dalea purpurea Vent and Liatris punctata Hook also attracted significantly fewer beneficial arthropod families than 4 other species of plants tested. In total, 31 predator, 11 parasitic, 4 pollinator, 31 herbivore, and 10 miscellaneous families of arthropods were recorded.
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The fig (Ficus carica L.) is a fruit tree of great world importance and, therefore, the genetic improvement becomes an important field of research for better crops, being necessary to gather information on this species, mainly regarding its genetic variability so that appropriate propagation projects and management are made. The improvement programs of fig trees using conventional procedures in order to obtain new cultivars are rare in many countries, such as Brazil, especially due to the little genetic variability and to the difficulties in obtaining plants from gamete fusion once the wasp Blastophaga psenes, responsible for the natural pollinating, is not found in Brazil. In this way, the mutagenic genetic improvement becomes a solution of it. For this reason, in an experiment conducted earlier, fig plants formed by cuttings treated with gamma ray were selected based on their agronomic characteristics of interest. We determined the genetic variability in these fig tree selections, using RAPD and AFLP molecular markers, comparing them to each other and to the Roxo-de-Valinhos, used as the standard. For the reactions of DNA amplification, 140 RAPD primers and 12 primer combinations for AFLP analysis were used. The selections did not differ genetically between themselves and between them and the Roxo-de-Valinhos cultivar. Techniques that can detect polymorphism between treatments, such as DNA sequencing, must be tested. The phenotypic variation of plants may be due to epigenetic variation, necessitating the use of techniques with methylation-sensitive restriction enzymes.
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Pollen analysis in honey can be used as an alternative method to research into flowers visited by bees in an area. This study aimed to indentify the main floral families in honey from apiaries in the Atlantic Forest and Sergipe state coast. Honey samples from these apiaries were studied, as well as plants that grow around them, which can be used as a source of foraging for bees. The palynological technique was used to compare the pollen content of honey samples with the pollen grains from leaves of plants found in the vicinity of the apiaries to assess whether they had been visited by bees. The results of studies in both sites were similar in terms of incompatibility of families found in the apiary vicinity and honey. Thus, it was possible to observe that in honey samples from the coast and in the remaining Atlantic forest, the number of families was greater than the number of families found in the apiary vicinity, which highlights the diversity of plants visited by bees and a possible expansion of the visited area for food search. This diversity suggests an adaptive foraging behavior to plant resources available in the environment, which may facilitate the pollination of these botanical families and consequently improve their genetic quality.
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The euglossine bee Eulaema nigrita plays an important role for the pollination of native and economically important plants, such as the sweet passion-fruit Passiflora alata. E. nigrita uniquely collects the nectar from the flowers of P alata, nevertheless, it needs to visit other plants to collect pollen, nectar and other resources for its survival. There are two methods to identify the species of plants used by bees in their diet: by direct observation of the bees in the flowers, and through identification of pollen grains present in brood cells, feces, or in the bees' body. In order to identify the other plants that E. nigrita visits, we analyzed samples of pollen grains removed from the bee's body in the course of the flowering period of P alata. Among our results, the flora visited by E. nigrita comprised 40 species from 32 genera and 19 families, some of them used as a pollen source or just nectar. In spite of being a polyletic species, E. nigrita exhibited preference for some plant species with poricidal anthers. P alata which has high sugar concentration nectar was the main source of nectar for this bee in the studied area. Nonetheless, the pollinic analysis indicated that others nectariferous plant species are necessary to keep the populations of E. nigrita. Studies such as this one are important since they indicate supplementary pollen-nectar sources which must be used for the conservation of the populations of E. nigrita in crops neighbouring areas. In the absence of pollinators, growers are forced to pay for hand pollination, which increases production costs; keeping pollinators in cultivated areas is still more feasible to ensure sweet passion fruit production. Rev. Biol. Trop. 60 (4): 1553-1565. Epub 2012 December 01.
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Mangrove forests encompass a group of trees species that inhabit the intertidal zones, where soil is characterized by the high salinity and low availability of oxygen. The phyllosphere of these trees represent the habitat provided on the aboveground parts of plants, supporting in a global scale, a large and complex microbial community. The structure of phyllosphere communities reflects immigration, survival and growth of microbial colonizers, which is influenced by numerous environmental factors in addition to leaf physical and chemical properties. Here, a combination of culture-base methods with PCR-DGGE was applied to test whether local or plant specific factors shape the bacterial community of the phyllosphere from three plant species (Avicenia shaueriana, Laguncularia racemosa and Rhizophora mangle), found in two mangroves. The number of bacteria in the phyllosphere of these plants varied between 3.62 x 10(4) in A. schaeriana and 6.26 x 10(3) in R. mangle. The results obtained by PCR-DGGE and isolation approaches were congruent and demonstrated that each plant species harbor specific bacterial communities in their leaves surfaces. Moreover, the ordination of environmental factors (mangrove and plant species), by redundancy analysis (RDA), also indicated that the selection exerted by plant species is higher than mangrove location on bacterial communities at phyllosphere.
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Lia Goncalves, Claudia Ines da Silva, and Maria Luisa Tunes Buschini (2012) Collection of pollen grains by Centris (Hemisiella) tarsata Smith (Apidae: Centridini): Is C. tarsata an oligolectic or polylectic species? Zoological Studies 51(2): 195-203. Among pollinator species, bees play a prominent role in maintaining biodiversity because they are responsible, on average, for 80% of angiosperm pollination in tropical regions. The species richness of the bee genus Centris is high in South America. In Brazil, these bees occur in many types of ecosystems. Centris tarsata is an endemic species occurring only in Brazil. No previous studies considered interactions between plants and this bee species in southern Brazil, where it is the most abundant trap-nesting bee. Accordingly, the goals of this study were to investigate plants used by this species for its larval food supply and determine if this bee is polylectic or oligolectic in this region. This work was conducted in the Parque Municipal das Araucarias, Guarapuava (PR), southern Brazil, from Mar. 2002 to Dec. 2003. Samples of pollen were collected from nests of these bees and from flowering plants in grassland and swamp areas where the nests were built. All of the samples were treated with acetolysis to obtain permanent slides. The family Solanaceae was visited most often (71%). Solanum americanum Mill. (28.6%) and Sol. variabile Mart. (42.4%) were the primary pollen sources for C. tarsata in the study area. We found that although C. tarsata visited 20 species of plants, it preferred Solanum species with poricidal anthers and pollen grains with high protein levels. This selective behavior by females of C. tarsata indicates that these bees are oligolectic in their larval provisioning in this region of southern Brazil. http://zoolstud.sinica.edu.tw/Journals/51.2/195.pdf
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Products based on botanical insecticides and entomopathogenic fungi have been widely used in organic farming, especially in southern Brazil. Thus, this study investigated, in vitro, the effect of aqueous extracts and commercial formulations of plants with insecticidal activity on Beauveria bassiana. The treatments comprised the botanical insecticides Neempro (azadiractin +3-tigloylazadirachtol), at the concentrations of 0.25, 0.5, 0.75, and 1.0% (v/v), and DalNeem (neem oil emulsifiable), at 0.5, 1.0, 1.5, and 2.0% (v/v) (both commercial formulations of Azadirachta indica (neem)), and the aqueous extracts, at the concentrations of 2.5, 5.0, 7.5, and 10.0% (w/v), of neem seeds, tobacco powder (Nicotiana tabacum), and catigua leaves (Trichilia clausenii). In potato, dextrose, and agar culture medium, the effects of each product on the mycelial growth and the production and viability of conidia of B. bassiana were estimated. According to the adopted compatibility index, the aqueous extracts of neem seeds and leaves catigua, depending on the concentration used, and the botanical insecticide Neempro, were classified as compatible with the entomopathogen, becoming important alternatives to integrate programmes of integrated pest management, especially in organic farming systems.
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Centrifugal spreaders dominate the application of solid materials in agriculture offering expressive operational field capacity and extended range of applied rates. Field tests for characterization of theirperformance are conducted without any physical obstacles (such as the presence of plants) during the parabolic trajectory of the falling particles of fertilizer to the soil. The purpose of this study was to comparatively evaluate the transverse distribution of solid fertilizers applied on cropped corn, soybeans and cotton. Evaluations of the spreaders were designed according to ASAE S341.3/99 Standard. Tests consisted in aligning side by side collectors in-between the cropped rows and weighting the material deposited. The results showed that transverse distribution of solid fertilizers applied over the cotton and corn crops is affected by the crop height, interfering directly on the effective width of the spreader application, which was not observedin the soybean crop, once the fertilizer application is done when the crop was still below the collector's height. The results suggest that evaluation of effective width of the spreaders application need to be done under real crop environment.
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This study extends the current knowledge regarding the use of plants for the passive accumulation of anthropogenic PAHs that are present in the atmospheric total suspended particles (TSP) in the tropics and sub-tropics. It is of major relevance because the anthropic emissions of TSP containing PAHs are significant in these regions, but their monitoring is still scarce. We compared the biomonitor efficiency of Lolium multiflorum 'Lema' and tropical tree species (Tibouchina pukka and Psidium guajava 'Paluma') that were growing in an intensely TSP-polluted site in Cubatao (SE Brazil), and established the species with the highest potential for alternative monitoring of PAHs. PAHs present in the TSP indicated that the region is impacted by various emission sources. L. multiflorum showed a greater efficiency for the accumulation of PAH compounds on their leaves than the tropical trees. The linear regression between the logBCF and logKoa revealed that L. multiflorum is an efficient biomonitor of the profile of light and heavy PAHs present in the particulate phase of the atmosphere during dry weather and mild temperatures. The grass should be used only for indicating the PAHs with higher molecular weight in warmer and wetter periods. (C) 2012 Elsevier Inc. All rights reserved.
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Sodium monofluoroacetate was first identified in Dichapetalum cymosum, a South African plant that can cause livestock poisoning and death. After, several other plants also showed to contain this toxin, which leads to the "sudden death". Mascagnia rigida, a well identified poisonous plant, commonly found in northeast of Brazil also cause sudden death in cattle, which shows clinical signs similar to those produced by the ingestion of plants that contain monofluoroacetate. Our aim was to identify the toxic compound present in the aqueous extract of M. rigida. For this purpose, the dried and milled plant was extracted; the extract was lyophilized and submitted to successive chromatographic process, until the desired purity of the active compound was achieved. The study of this material by planar chromatography and by infrared spectrometry indicated that the toxin can be a mixture of mono, di and trifluoroacetate. (C) 2012 Elsevier Ltd. All rights reserved.
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Lectins are carbohydrate-binding proteins of non-imune origin. This group of proteins is distributed widely in nature and they have been found in viruses, microorganisms, plants and animals. Lectins of plants have been isolated and characterized according to their chemical, physical-chemical, structural and biological properties. Among their biological activities, we can stress its fungicidal action. It has been previously described the effect of the lectins Dviol, DRL, ConBr and LSL obtained from the seeds of leguminous plants on the growth of yeasts isolated from vaginal secretions. In the present work the experiments were carried out in microtiter plates and the results interpreted by both methods: visual observations and a microplate reader at 530nm. The lectin concentrations varied from 0.5 to 256 mu g/mL, and the inoculum was established between 65-70% of trammitance. All yeast samples isolated from vaginal secretion were evaluated taxonomically, where were observed macroscopic and microscopic characteristics to each species. The LSL lectin did not demonstrate any antifungal activity to any isolate studied. The other lectins DRL, ConBr and DvioL, showed antifungal potential against yeast isolated from vaginal secretion. These findings offering offer a promising field of investigation to develop new therapeutic strategies against vaginal yeast infections, collaborating to improve women's health.
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Banana is one of the most economically important fruit, explored almost exclusively by small producers as a continuous source of food and income. Although Brazil is one of the main banana producers, the national banana production is undergoing serious problems especially in the phases of production and post-harvest limiting its participation in the international market. One of the main factors leading to great production losses is the toppling over due to the tall height of plants of main commercial cultivars. A strategy to solve this problem is reducing height by inducing mutation. The objective of the present work was to characterize irradiated Prata type banana mutants (cvs. Pacovan and Preciosa) during two production cycles in order to select short plants in height with good agronomic characteristics. In vitro plants of both cultivars were irradiated with gamma rays in the doses of 20 Gy ('Pacovan', 200 plants) and 30 Gy ( 'Preciosa', 200 plants) subcultivated four times and afterwards evaluated in the field during two production cycles. Four possible mutants were selected from each cultivar with height smaller than the average height of the controls after two evaluation cycles. It was observed that some of these mutants presented greater precocity and bunch weight compared to the controls. From the results obtained it is possible to select mutant plants with superior agronomic characteristics for 'Pacovan' as well as 'Preciosa' submitted to gamma radiation.