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Eragrostis tenuifolia is a weed species that is gaining ground in Brazil. This weed occurs in pastures, grasslands, crop fields, and roadsides. The objective of this study was to examine the effects of different environmental factors on E. tenuifolia seed germination and seedling emergence. The optimum constant temperature for germination was around 35–30°C. It was also found that 85% of seeds germinated under a 30/20°C alternate temperature regime. Light appears to have a positive effect on seed germination. No seedlings emerged when seeds were buried 3 cm or deeper. The results suggested that E. tenuifolia has the potential to spread into pastures and in no-tillage crop systems in Brazil. Measures such as the use of cover crops and/or soil cultivation can be used to limit germination and seedling emergence, respectively.
In the present paper, results of a study on the effect of a reduction in the number of ploughings in a crop rotation on the seed weed bank in the soil are presented. The study was carried out in the second and fourth year of a crop rotation (potato– spring wheat– pea– winter wheat). A reduction in the number of ploughings to three in the crop rotation decreased weed infestation of the plough layer, whereas when only one ploughing was made there was clearly more weed diaspores in the soil than after plough tillage. In the fi rst period of the study, the mineral fertilisation level did not differentiate the weed seed bank in the soil, whereas after the end of the rotation its signifi cant increase was noted as a result of more intensive fertilisation. In all the experimental treatments, diaspores of Chenopodium album, Viola arvensis, Galinsoga sp. and Apera spica-venti occurred in greatest numbers.
A strictly controlled field experiment on traditional and reduced tillage systems as well as herbicide treatment was conducted at the Agricultural Experimental Station of Uhrusk in the years 2007-2011. In the last year of the experiment, the effect of different tillage systems on the level of weed infestation and biodiversity of weeds was determined in all the plots for the crop of common spring wheat Triticum aestivum L., spring durum wheat Triticum durum Desf., and oat Avena sativa L. at two growth stages: tillering (23/24 on BBCH scale) and dough stage (83/85). A higher number and higher air-dry weight of weeds were determined at tillering than at the dough stage. Long-term reduced tillage increased the number of weeds per 1m2 at the tillering stage, contrary to herbicide treatment. At the dough stage, a higher number of weeds was observed in the herbicide treatment and reduced tillage plots compared to traditional tillage. The air-dry weight of weeds at the tillering and dough stages of cereals was significantly higher in the case of herbicide treatment than under the traditional and reduced tillage systems. Weed communities in spring wheat, durum wheat and oat included mostly annual weeds. A higher number of weed species was determined in the plot with long-term herbicide treatment than in the plots with reduced and traditional tillage systems.
Field studies were conducted in 2007–2009 at the Research Station Brody of Poznań University of Life Sciences. The aim of this study was to determine weed community in pea as affected by tillage systems (conventional and direct drilling). Between tillage systems, conventional tillage plots had the highest level of weed biomass and density in 2007, while in 2009 weed infestation was greatest under direct drilling. In 2008 and mean of three years levels of weed infestation was not affected by the tillage systems. The dominant weed species according to weed density were Viola arvensis in each tillage system. Chenopodium album had the highest biomass under direct drilling, while conventional tillage enhanced Veronica hederifolia biomass.
Acta Agrobotanica
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2002
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tom 55
|
nr 2
209-220
In a strict field experiment we have studied the influence of different weed control method on the species composition and the number on weeds occurring in a field of four potato cultivars. The application of herbicides decreased the number of weeds, as compared with the number obtained for mechanical control by 1,9 - 5,1 times at the beginning of the vegetation and by 1,5 - 3,7 times prior to tubers harvest. The herbicides considerably reduced the composition of weed species, moreover.
A field experiment was conducted in 2007 to 2009 at Experimental Station Brody of Poznań University of Life Sciences to determine the effect of tillage, including strip tillage, conventional tillage and no tillage on weed pressure in corn. Strip tillage implementation included coulter, shank, covering disks and rolling basket. Cultivated straps were 35 cm wide and 20 cm deep at fall and spring strip tillage, 35 cm wide and 10 cm deep at shallow spring strip tillage and about 10–15 cm wide and 20 cm deep at narrow spring strip tillage. Conventional tillage was performed in the fall or spring with moldboard plow at a depth of 20 cm. Weed density for individual species was recorded prior postemergence herbicide application. Weed emergence was over eight times lower in strip tillage compared with conventional tillage with emergence patterns in strip tillage generally similar to the no tillage. Main weed species were Chenopodium album and Echinochloa crus-galli and this weeds density the most depended on tillage.
This paper presents the results of investigations on the weed infestation and vertical distribution of weed seed bank in rendzina under spring cereals cultivation in crop rotations and monoculture. Used herbicides (MCPA and fenoxaprop-P-etylu) decreased the number of weeds and species composition in comparison with harrowing. In the soil layer of 0-25 cm used in the monoculture there was found about 22,9% weed seeds more than in crop rotation. In the canopy of spring cereals the following weeds dominated: in crop rotation - Chenopodium album, Echinochloa crus-galli and Veronica persica; and in monoculture - Stellaria media, Galium aparine and Chenopodium album. In the soil layer of 0-25 cm used in crop rotation and monoculture the following weed seeds dominated : Amaranthus retroflexus, Chenopodium album and Stellaria media.
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