Resumo -A dificuldade de controle das plantas daninhas tem sido considerada como um dos principais entraves ao sucesso dos projetos de recuperação da vegetação em áreas degradadas. O presente trabalho teve o objetivo de avaliar o efeito de diferentes herbicidas pré-emergentes sobre a emergência, sobrevivência e desenvolvimento inicial de plantas das espécies nativas amendoim bravo (Platypodium elegans), mutamba (Guazuma ulmifolia), carobinha (Jacaranda micrantha) e angico cuiabano (Anadenanthera colubrina). O experimento foi desenvolvido em casa de vegetação no delineamento experimental inteiramente casualizado, com cinco repetições. Os tratamentos foram constituídos pela aplicação em pré-emergência dos seguintes herbicidas e doses: isoxaflutole (75, 150 e 300 g i.a. ha -1 ), pendimenthalin (500, 1000 e 2000 g i.a. ha -1 ), trifluralin (600, 1200 e 2400 g i.a. ha -1 ) e uma testemunha padrão sem a aplicação de herbicidas. O efeito dos herbicidas foi avaliado quanto ao número de plântulas emergidas, número de folhas por plântula, altura de plântulas, diâmetro de plântulas na altura do coleto e matéria seca de raiz e folhas aos 35 dias após a germinação. Com os resultados obtidos foi possível afirmar que todos os herbicidas e doses utilizadas não prejudicaram a emergência e o desenvolvimento inicial das espécies P. elegans e J. micrantha. As doses de 150 e 300 g i.a. ha -1 do herbicida isoxaflutole foram não seletivas para a espécie arbórea G. ulmifolia. Apenas a dose de 600 g i.a. ha -1 do herbicida trifluralin apresentou seletividade para a espécie A. colubrina.Abstract -The weed control difficulties has been considered one of the most obstacles to success of forest recovery projects at degraded areas. This experiment aimed to evaluate the different pre-emergent herbicides effect on seed emergence, seedling survival and initial development of Brazilian native tree species Platypodium elegans, Guazuma ulmifolia, Anadenanthera colubrine and Jacaranda micrantha. The experiment was conducted under greenhouse conditions in a completely randomized design with five replications. The treatments were constituted by the pre-emergence application of the following herbicides and doses: isoxaflutole (75, 150 and 300 g a.i. ha -1 ), pendimenthalin (500, 1000 and 2000 g a.i. ha -1 ), trifluralin (600, 1200 and 2400 g a.i. ha -1 ) and untreated herbicide as a check control. The effect of the herbicides was evaluated for the number of seedlings emerged, number of leaves per seedlings, height of seedlings, diameter of stem and dry matter of root and leaves at 35 days after germination. With the results obtained it was possible to affirm that all herbicides and their respective rates were safe to P. elegans and G. ulmifolia trees. Isoxaflutol at 150 and 300 g a.i. ha -1 was not selective to G. ulmifolia specie. Only trifluralin at 600 and 1200 g a.i. ha -1 sowed selectivity to A. colubrina specie.
A recuperação de áreas de pastagens degradadas baseia-se na utilização eficiente da gramínea forrageira visando minimizar a interferência das plantas daninhas. Objetivou-se avaliar o efeito de densidades de semeadura na variação populacional de plantas daninhas sob condição de reforma de pastagem cultivada de Urochloa brizantha cv. Marandu. Adotou-se o delineamento experimental em blocos casualizados, com quatro repetições e os tratamentos constituídos de cinco densidades de semeadura: 0%, 25%, 50%, 75% e 100% estabelecidas em função da recomendação de uso do capim-marandu (15 kg ha-1) baseado no valor cultural (60% de pureza e 60% de germinação). A identificação e quantificação das plantas daninhas foram realizadas aos 7, 14, 21, 28, 35, 42 e 49 dias após a emergência (DAE). A matéria seca das plantas daninhas foi obtida aos 49 DAE e as parcelas foram avaliadas quanto as características estruturais e produtivas da forrageira. Com os dados de matéria seca das plantas daninhas determinou-se a importância relativa pelo índice de valor de importância das espécies do estudo. Os resultados foram submetidos a análise de variância, e quando significativos realizou-se análise de regressão. Verificou-se redução gradativa no número total de indivíduos m-2 da comunidade infestante de acordo com o aumento na densidade de semeadura, chegando à 55% de redução na densidade de semeadura de 75% aos 42 DAE. A competição entre as espécies estabelece-se logo no período inicial de convivência e contribui para a baixa produção de matéria seca do capim-marandu semeado à 25% da recomendação de uso.
The presence of weeds as a consequence of pasture degradation is one of the main problems facing livestock worldwide. Thus, knowing the interference aspects and the appropriate time for weed management is essential for applying a particular control measure. This research aimed to study the weed interference on the morphostructural and nutritional quality of the Marandu palisade grass in conditions of renewal or maintenance of pasture. The experiments were conducted in a randomized block design, with four replicates and treatments consisted of eight growth periods of coexistence between Marandu palisade grass and weeds (0, 15, 30, 45, 60, 75, 90, and 120 days). Forage grass was characterized at the end of the experimental period, corresponding to 120 days of coexistence, and the main morphostructural and nutritional components were determined. Under the renewal or maintenance process, the weeds interfere in the morphostructural and nutritional quality of pasture areas with Marandu palisade grass. In vitro organic matter digestibility of Marandu palisade grass is negatively influenced by weeds, suggesting that control measures for renewal or maintenance areas should be adopted within 24 and 18 days of coexistence, respectively.
The growing demand for food, bioenergy, and forest products requires solutions that encourage socioeconomic development without compromising the sustainability of natural resources. It is in this scenario that the integration strategy has been pointed as an alternative to reconcile conflicts of interest. This study evaluates possible changes in nodulation, photosynthetic efficiency, and yield of soybean grown in a Crop-Forest Integration system with eucalyptus as a tree component. The experiment was conducted in a randomized complete block design with four replications. Treatments were arranged in a 3x5 factorial scheme, corresponding to three sowing conditions (near eucalyptus stands; 3.0 meters away from the stands, in a clean seedbed; and 3.0 m away from the stands, among the vegetation) and five points of distance between soybean and the stands, represented by planting rows, namely: 1 st , 2 nd , 3 rd , 11 th , and 21 st row. We evaluated morphophysiological and productive variables of soybean plants. Soybean cultivation near eucalyptus stands does not affect the number and dry matter of soybean nodules, but reduces yield in the first two rows. The presence of weeds in the range between eucalyptus stands and soybean plants impaired the photochemical apparatus and the chlorophyll α fluorescence of soybean crop, decreasing the shoot dry matter accumulation, number and dry matter of nodules, and yield of plants present in the first planting rows.
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