3,098 research outputs found

    Organic production of strawberries

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    Organic fruit and vegetable growing is increasing world-wide, but knowledge concerning best practice is generally empirical rather than field-based. This thesis extends knowledge concerning best practice in Swedish organic strawberry (Fragaria x ananassa (Duch)) production, which is usually based on a two-year crop. A series of four field experiments were conducted at Rånna Experimental Station (58°27’N, 13°51’E) on the strawberry cultivars ‘Honeoye’, ‘Cavendish’ and ‘Korona’. Specific objectives were to investigate: the effects of different organic fertilisers combined with degradable plastic mulch on plant establishment, yield and nitrogen mineralisation in soil; the efficiency of biological pest control using a predatory mite against strawberry mites (Phytonemus pallidus); innate within-field dispersal capacity of strawberry mite; the effects of pyrethrum combined with fleece covering on damage by strawberry blossom weevil (Anthonomus rubi). Plant establishment measured as fruit yield was improved by 60% when degradable plastic mulch was used, probably through more flowers being initiated. Additional applications of organic fertiliser during the cropping period had little effect on yield. Biological control using the predatory mite Neoseiulus cucumeris reduced strawberry mite populations by up to 50% but there was no increase in yield. It was difficult to draw clear conclusions from the strawberry mite dispersal pilot study, but mites tended to move more easily along planted rows than between rows. Pyrethrum alone had no visible effect on flower bud damage by strawberry blossom weevil but when combined with fleece covering it reduced the number of ‘Honeoye’ buds damaged by weevils by approximately 10%. This was followed by a corresponding increase in cultivar yield. Similar effects were not recorded in the other cultivar examined. The study identified the following practical consequences for organic strawberry production: • Choice of pest-resistant cultivars is extremely important for success. • Use of clean plants and an efficient predatory species is essential in controlling mite infestations. • Use of degradable plastic mulching is recommended. • Fleece covering is recommended for protecting some cultivars against strawberry blossom weevils. • Only an initial starter fertilisation is required. • Use of pyrethrum is not recommended

    Kinetics of Particles Adsorption Processes Driven by Diffusion

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    The kinetics of the deposition of colloidal particles onto a solid surface is analytically studied. We take into account both the diffusion of particles from the bulk as well as the geometrical aspects of the layer of adsorbed particles. We derive the first kinetic equation for the coverage of the surface (a generalized Langmuir equation) whose predictions are in agreement with recent simulation results where diffusion of particles from the bulk is explicitly considered.Comment: 4 page

    Quasiperiodic time dependent current in driven superlattices: distorted Poincare maps and strange attractors

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    Intriguing routes to chaos have been experimentally observed in semiconductor superlattices driven by an ac field. In this work, a theoretical model of time dependent transport in ac driven superlattices is numerically solved. In agreement with experiments, distorted Poincare maps in the quasiperiodic regime are found. They indicate the appearance of very complex attractors and routes to chaos as the amplitude of the AC signal increases. Distorted maps are caused by the discrete well-to-well jump motion of a domain wall during spiky high-frequency self-sustained oscillations of the current.Comment: 10 pages, 4 figure

    First record of Isia alcumena, Spodoptera cosmioides and S. eridania (LEPIDOPTERA: NOCTUOIDEA) attacking Passion Fruit (Passiflora edulis Sims) in Brazil.

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    RESUMO: O Brasil é considerado o centro de origem e de diversidade das passifloras, que apresentam importância, tanto para o consumo in natura, industrialização, uso medicinal e também como plantas ornamentais. As diferentes espécies de Passiflora hospedam uma grande diversidade de artrópodes que, ocasionando injúrias, podem causar danos econômicos e morte da planta. Dentre os artrópodes, as lagartas-desfolhadoras são consideradas as pragas mais frequentes e severas nas principais regiões produtoras de maracujá. Assim, o objetivo foi informar o primeiro registro da ocorrência das espécies Isia alcumena, Spodoptera cosmioides e S. eridania atacando maracujazeiros no Distrito Federal, Brasil. As lagartas de S. cosmioides e S. eridania foram coletadas enquanto consumiam folhas de híbridos intraespecíficos de Passiflora edulis cultivado no banco ativo de germoplasma ?Flor da Paixão? da Embrapa Cerrados. Já as lagartas de I. alcumena foram coletadas em folhas da cultivar BRS Rubi do Cerrado, na Unidade de Apoio da Fruticultura da Embrapa Cerrados. Após a coleta, as lagartas foram individualizadas em sistema de criação com folhas das plantas hospedeiras. O desenvolvimento das lagartas foi acompanhado até à emergência dos adultos, que foram identificados e fixados em alfinetes entomológicos para preservação permanente, a seco. ABSTRACT: Brazil is considered the center of origin and diversity of passifloras. These species have a great importance to in natura fruits consumption, industrialization, medicinal use and also as ornamental plants. The different Passiflora speciesare host of a great diversity of arthropods that can cause injuries, economic damages and, in some situations, the plant death. Among the arthropods, leafhopper caterpillars are considered frequent and severe pests in the main passion fruit producing regions. The present work is an occurrence report of Isia alcumena and Spodoptera cosmioides attacking passion fruit plants (Passiflora edulis Sims) in the Federal District, Brazil. The S. cosmioides and S. eridania caterpillars were collected while consuming leaves of Passiflora edulis intra-specific hybrid located in the Germplasm Active Bank ?Flor da Paixão? at Embrapa Cerrados. The caterpillars of I. alcumena were collected on leaves of the Passiflora edulis cv. BRS Rubi do Cerrado at the Agricultural Support Unit, Embrapa Cerrados. After collected, the caterpillars were individualized in a breeding system with leaves of the host plants. The development of the caterpillar was accompanied until the emergence of the adults, which were identified and fixed in entomological pins for permanent dry preservation.Título em português: Primeiro registro de Isia alcumena, Spodoptera cosmioides e Spodoptera eridania (LEPIDOPTERA: NOCTUOIDEA) em maracujazeiro (Passiflora edulis Sims) no Brasil

    Availability of floral resources in yellow passion fruit cultivars

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    The reproductive strategies and resources available in the flower are characteristics that stimulate research studies on the genetic improvement and fruit yield of commercial cultivars. In this sense, this study aimed to study the floral biology aspects of passion fruit cultivars in Tangará da Serra region, Mato Grosso State, Brazil at different evaluation times. The experiment was carried out with eight cultivars of yellow passion fruit from an ex situ germplasm bank of the State University of Mato Grosso. The floral resources (pollen and nectar) were evaluated in a completely randomized, factorial arrangement (8 cultivars x 5 evaluation times), with five replications. Throughout anthesis, the pollen viability, stigma receptivity, and sugar volume and concentration in the nectar were evaluated. The evaluations were carried out in 1-h intervals, between 1:30 and 5:30 p.m. The highest nectar volume production was at 2:30 p.m., decreasing gradually thereafter at the later evaluation times, for all cultivars. Pollen viability increased from the first to the second evaluation time and then decreased gradually until the last evaluation. Stigma receptivity was higher than 90% in all cultivars, at all evaluation times. BRS Rubi do Cerrado and FB 200 were the most promising cultivars for nectar volume and concentration, pollen viability, and stigma receptivity characteristics.The reproductive strategies and resources available in the flower are characteristics that stimulate research studies on the genetic improvement and fruit yield of commercial cultivars. In this sense, this study aimed to study the floral biology aspects of passion fruit cultivars in Tangará da Serra region, Mato Grosso State, Brazil at different evaluation times. The experiment was carried out with eight cultivars of yellow passion fruit from an ex situ germplasm bank of the State University of Mato Grosso. The floral resources (pollen and nectar) were evaluated in a completely randomized, factorial arrangement (8 cultivars x 5 evaluation times), with five replications. Throughout anthesis, the pollen viability, stigma receptivity, and sugar volume and concentration in the nectar were evaluated. The evaluations were carried out in 1-h intervals, between 1:30 and 5:30 p.m. The highest nectar volume production was at 2:30 p.m., decreasing gradually thereafter at the later evaluation times, for all cultivars. Pollen viability increased from the first to the second evaluation time and then decreased gradually until the last evaluation. Stigma receptivity was higher than 90% in all cultivars, at all evaluation times. BRS Rubi do Cerrado and FB 200 were the most promising cultivars for nectar volume and concentration, pollen viability, and stigma receptivity characteristics

    Qualidade do café arábica em diferentes altitudes no Espírito Santo.

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    Este trabalho teve como objetivo avaliar a influência de diferentes altitudes na qualidade do café arabica, avaliada pela análise sensorial. Para tanto, foram avaliados grãos de três cultivares de café arábica colhidos em três ambientes com altitudes diferentes, ou seja, a 700 m, 950 m e 1100 m, nos municípios de Venda Nova do Imigrante, Domingos Martins e Santa Maria do Jetiba, respectivamente. Os cafés foram secos em terreiro suspenso coberto até que alcançassem 12% de umidade. A classificação sensorial foi realizada por um provador especializado, sem prévio conhecimento das amostras. Verificou-se que cafés cultivados em maiores altitudes originaram melhores bebidas. Não houve diferença significativa entre as cultivares Rubi, Catuai Vermelho IAC 44 e Catuai Vermelho IAC 81 para a qualidade da bebida

    Primeiro registro de Isia alcumena, Spodoptera cosmioides e Spodoptera eridania (Lepidoptera: Noctuoidea) em maracujazeiro (Passiflora edulis Sims) no Brasil

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    O Brasil é considerado o centro de origem e de diversidade das passifloras, que apresentam importância, tanto para o consumo in natura, industrialização, uso medicinal e também como plantas ornamentais. As diferentes espécies de Passiflora hospedam uma grande diversidade de artrópodes que, ocasionando injúrias, podem causar danos econômicos e morte da planta. Dentre os artrópodes, as lagartas-desfolhadoras são consideradas as pragas mais frequentes e severas nas principais regiões produtoras de maracujá. Assim, o objetivo foi informar o primeiro registro da ocorrência das espécies Isia alcumena, Spodoptera cosmioides e S. eridania atacando maracujazeiros no Distrito Federal, Brasil. As lagartas de S. cosmioides e S. eridania foram coletadas enquanto consumiam folhas de híbridos intraespecíficos de Passiflora edulis cultivado no banco ativo de germoplasma “Flor da Paixão” da Embrapa Cerrados. Já as lagartas de I. alcumena foram coletadas em folhas da cultivar BRS Rubi do Cerrado, na Unidade de Apoio da Fruticultura da Embrapa Cerrados. Após a coleta, as lagartas foram individualizadas em sistema de criação com folhas das plantas hospedeiras. O desenvolvimento das lagartas foi acompanhado até à emergência dos adultos, que foram identificados e fixados em alfinetes entomológicos para preservação permanente, a seco.Brazil is considered the center of origin and diversity of passifloras. These species have a great importance to in natura fruits consumption, industrialization, medicinal use and also as ornamental plants. The different Passiflora speciesare host of a great diversity of arthropods that can cause injuries, economic damages and, in some situations, the plant death. Among the arthropods, leafhopper caterpillars are considered frequent and severe pests in the main passion fruit producing regions. The present work is an occurrence report of Isia alcumena and Spodoptera cosmioides attacking passion fruit plants (Passiflora edulis Sims) in the Federal District, Brazil. The S. cosmioides and S. eridania caterpillars were collected while consuming leaves of Passiflora edulis intra-specific hybrid located in the Germplasm Active Bank ‘Flor da Paixão’ at Embrapa Cerrados. The caterpillars of I. alcumena were collected on leaves of the Passiflora edulis cv. BRS Rubi do Cerrado at the Agricultural Support Unit, Embrapa Cerrados. After collected, the caterpillars were individualized in a breeding system with leaves of the host plants. The development of the caterpillar was accompanied until the emergence of the adults, which were identified and fixed in entomological pins for permanent dry preservation

    Combining 1,4-dimethoxybenzene, the major flower volatile of wild strawberry Fragaria vesca, with the aggregation pheromone of the strawberry blossom weevil Anthonomus rubi improves attraction

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    The aggregation pheromone of strawberry blossom weevil [Anthonomus rubi Herbst (Col.: Curculionidae)], a 1:4:1 blend of Grandlure I, II and racemic lavadulol, has been available for pest monitoring for several years but shows low attractancy. Attempts to control A. rubi using the pheromone alone were also unsuccessful. This paper reports the finding that addition of the major flower volatile from wild strawberry flowers [Fragaria vesca L. (Rosaceae)], 1,4-dimethoxybenzene (comprising 98% of the volatiles emitted from wild strawberry flowers), to the aggregation pheromone increased trap catches by over two fold compared to the pheromone alone. There was no significant difference between the response of overwintered or summer emerged adults. Field trials in 2007-2008 in central and southern Norway, Denmark and southern England used green funnel traps with white cross vanes for the evaluations. (-)-Germacrene D, previously shown to be emitted by plants in increased amounts in the presence of pheromone producing weevils, did not improve trap catches. Thus, the combined use of the aggregation pheromone and 1,4-dimethoxybenzene is promising for improved monitoring and possibly control of this important pest of strawberry
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