Resumo -O objetivo deste trabalho foi avaliar o desempenho agronômico das culturas do milho e do capim-xaraés (Urochloa brizantha 'Xaraés') em consórcio, cultivadas em plantio direto e convencional, em sistema agrossilvipastoril, com a aplicação de diferentes doses de nitrogênio em cobertura. O experimento foi conduzido em área de cultivo de milho com a espécie florestal mulateiro (Calycophyllum spruceanum). Utilizou-se o delineamento experimental de blocos ao acaso, com arranjo em parcelas subdivididas, com dois sistemas de manejo do solo (plantio direto e convencional com grade pesada) alocados nas parcelas e com cinco doses de adubação nitrogenada em cobertura (0, 50, 100, 150 e 200 kg ha -1 de N), nas subparcelas, o que totalizou dez tratamentos. A produtividade de grãos de milho respondeu linearmente à aplicação de N em área de plantio convencional. Em área de plantio direto, a dose de 165 kg ha -1 de N em cobertura foi necessária para a obtenção de produtividades satisfatórias. A adubação nitrogenada em cobertura na cultura do milho, até a dose de 200 kg ha -1 de N, não influencia o rendimento do capim-xaraés em consórcio nas entrelinhas, após a colheita do milho.Termos para indexação: Brachiaria brizantha, Zea mays, adubação de cobertura, consórcio, integração lavoura-pecuária, manejo do solo. Nitrogen fertilization in maize and xaraés palisade grass under no-tillage and conventional tillage in an agrosilvopastoral systemAbstract -The objective of this work was to evaluate the agronomic performance of the maize and xaraés palisade grass (Urochloa brizantha 'Xaraés') crops in intercropping, grown in no-tillage and conventional tillage, in an agrosilvopastoral system, with the application of different nitrogen topdressing rates. The experiment was conducted in a maize crop area with the forest species "mulateiro" (Calycophyllum spruceanum). The experimental design was randomized complete blocks, in a split-plot arrangement with two systems of soil management (no-tillage and conventional tillage with heavy disk) allocated to the plots and five rates of nitrogen topdressing (0, 50, 100, 150, and 200 kg ha -1 N) to the subplots, totaling ten treatments. Maize grain yield responded linearly to N application in area of conventional tillage. In no-tillage area, the dose of 165 kg ha -1 N topdressing was necessary to obtain satisfactory yields. Nitrogen topdressing in maize crop until the dose of 200 kg ha -1 N does not influence xaraés palisade grass yield when intercropped between the lines, after maize harvest.
Abstract:The soil preparation in horticulture, including organic, is characterized by intense soil tillage, which increases energy costs and unbalanced the environment. The organic system in onion cultivation has shown satisfactory results, however the soil covering use tends to improve the cultivation environment and may result in higher yields. The objective of this work was to evaluate the performance of onion cultivars in organic cultivation under different soil coverages. The experiment was conducted in the period of April to October of 2009, under protected cropping, in the experimental area of the horticulture sector of the Universidade Federal do Acre (UFAC), in Rio Branco, Acre, Brazil. A randomized block design was adopted, in a split-plot arrangement, the plots being comprised of soil coverings: coffee bean husks, grass straw (Brachiaria decumbens); dessicated bamboo leaves (Bambusa spp.) and uncovered soil (control treatment), and the subplots comprised of three onion cultivars (IPA 10, IPA 11 and IPA 12), with four repetitions. The variables analyzed were total bulb yield (t ha -1 ), marketable bulb yield (t ha -1 ), fresh mass of the bulb (g bulb -1 ), classification of the bulbs and loss of mass as a function of storage time. There was no interaction effect between the soil coverings and the cultivars. Cultivars IPA 10 and IPA 11 showed greater agronomic performance of the studied variables. The soil coverings did not affect the yield and average mass of the bulbs under organic cultivation. The three cultivars presented more than approximately 70% of the bulbs in class 2 and a maximum of 5% of unmarketable bulbs. The loss of mass after 49 days of storage was 10% independent of the cultivar or soil covering.Key words: Allium cepa. Organic agriculture. Sustainability.Resumo: O preparo do solo na olericultura, incluindo a orgânica, caracteriza-se por intenso revolvimento do solo, o que aumenta os gastos com energia e desequilibra o ambiente. O cultivo de cebola em sistema orgânico tem mostrado resultados satisfatórios, todavia o uso de cobertura do solo tende a melhorar o ambiente de cultivo, podendo resultar em maior produtividade. O objetivo deste trabalho foi avaliar o desempenho de cultivares de cebola em cultivo orgânico sob diferentes coberturas do solo. O experimento foi conduzido no período de abril a outubro de 2009, em cultivo protegido, na área experimental do setor de olericultura da Universidade Federal do Acre (UFAC), em Rio Branco, Acre, Brasil. Adotou-se delineamento experimental em blocos casualizados, com arranjo em parcelas subdivididas, sendo as parcelas constituídas pelas coberturas de solo: casca de café, palha de gramínea (Brachiaria decumbens); folha de bambu dessecada (Bambusa spp.) e solo descoberto (tratamento controle), e as subparcelas constituídas pelas três cultivares de cebola (IPA 10, IPA 11 e IPA 12), com quatro repetições. As variáveis analisadas foram produtividade total de bulbos (t ha -1 ), produtividade comercial dos bulbos (t ha -1 ), massa fresca do bulbo (g b...
The tuberous roots of some oriental species of Aconitum (Ranunculaceae) have been used as one of the most important drugs in Chinese medicine as an analgesic in the treatment of rheumatism and neuralgia (1,2). It is well known that hypogeous organs of aconites contain diterpene alkaloids like aconitine, mesaconitine, and so on; remarkable qualitative and quantitative variations occur in the alkaloid content in relation with the plant species and some exogenous factors. Some years ago we have undertaken an extensive analysis of the secondary metabolites of the italian species of Aconitum (3,4,5).In this investigation, we studied the alkaloid content in samples, harvested during a one year period, of A. napellus ssp. tauricum (Wulfen) Gayer (Ranuneulaceae) growing in Cansigho (TV), in order to determine the influence of seasonal factors on such content. Plant material was extracted as described elsewhere (4); analytical HPLC was performed as reported in (5).In the examined population, the major alkaloid is represented by aconitine. The highest content of aconitine appears during summer, when the plant is flowering; the richest organs are the threadlike roots (0.44 % d. w.) and the aerial parts (leaves 0.46% and flowers 0.47% d. w.). The aconitine is also present in other parts of the plant, in particular, in the parent and in daughter roots. In the parent tuberous roots, which bear the aerial stem, the content is maximum (0.36 % d. w.) during the vegetative growth period and it decreases gradually during the year reaching the minimum (0.11% d. w.) in the quiescency. In the daughter tuberous roots, which bear the apical bud, it remains almost constant (about 0.2 % d. w.) during the year. In the fruiting stage also the seeds have a noteworthy content of aconitine.Other alkaloidsmesaconitine, N-deethylaconitine and two compounds with relative molecular messes of 629 and 688have been detected, but their content is always far less remarkable in all parts of the plant and all over the year (never greater than 0.04% d/w.).Root cultures of S. vulgaris efficiently incorporate biosynthetic precursors such as [t4Cj-labelled arginine, ornithine, putrescine, and spermidine into the pyrrolizidine alkaloid senecionine N-oxide (1). u-Difluoromethylarginine, a suicide inhibitor of arginine decarboxylase, completely prevented the incorporation of radioactivity from [t4q-arginine and [14C]-ornithine into spermidine and senecionine N-oxide. In contrast, ct-difluoromethylornithine, a specific inhibitor of ornithine decarboxylase, had no effect on the flow of radioactivity from labelled ornithine and arginine into polyamines and alkaloids. Thus, putrescine, the common precursor of polyamines and pyrrolizidine alkaloids, is exclusively derived via the arginineagmatine route. Ornithine is rapidly transformed into arginine. Recycling of the guanido moiety of agmatine back to ornithine as known from Lathyrus sativus (2) could be excluded. The enzymes catalyzing the conversion of arginine into putrescine were characterized: arginine decarbo...
Cultivo consorciado de olerícolas em sistema agroecológico Viability of the intercropping of vegetables using an agro-ecological system RESUMO: A agricultura brasileira vem passando por um período de reflexão (desde pesquisadores até produtores rurais), com vistas à necessidade de mudar o sistema produtivo atualmente adotado para um modelo de maior sustentabilidade. Nesse sentido, objetivou-se avaliar o desempenho agronômico da alface "Crespa Repolhuda", da cebola "Texas Grano 502 PRR" e da cenoura "Brasília" em sistemas de cultivo solteiro e seus respectivos consórcios, em sistema Agroecológico. O experimento foi conduzido no campo experimental
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