| 1. |
- Fogelfors, Håkan
(författare)
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Seasonal restrictions of bud growth on roots of Cirsium arvense and Sonchus arvensis and rhizomes of Elymus repens
- 2010
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 50, s. 102-109
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Tidskriftsartikel (refereegranskat)abstract
- P>The success of weed management aimed at depleting the regenerative structures of perennial weeds depends largely on the sprouting activity of rhizome and root buds. Seasonal variation in sprouting of these buds on Cirsium arvense, Sonchus arvensis and Elymus repens was studied for plants collected from Denmark, Finland, Norway and Sweden. At 2-week intervals from July to October, 5-cm fragments of roots or rhizomes were cut from plants grown in buckets and planted into soil in pots, half of which were placed immediately into growth chambers at 18 degrees C for 4 weeks. The other half of the pots were initially placed in a dark room at 2 degrees C for 4 weeks before being transferred to the same growth chamber, also for 4 weeks. During the growth chamber period, the numbers of emerged shoots in each pot were counted weekly. The sprouting activity of C. arvense and E. repens was relatively uniform during this period and bud dormancy was not apparent. In all ecotypes of S. arvensis, innate bud dormancy developed during the latter part of the growing season. For all three species, differences in sprouting readiness were found among ecotypes. The results imply that C. arvense and E. repens are more likely to be controlled by mechanical measures in autumn than S. arvensis.
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| 2. |
- Karlsson, Laila, et al.
(författare)
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Seed dormancy and germination in the summer annual Galeopsis speciosa
- 2006
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Ingår i: Weed research (Print). - : Institutionen för fysik, kemi och biologi. - 0043-1737 .- 1365-3180. ; 46:5, s. 353-361
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Tidskriftsartikel (refereegranskat)abstract
- This study examined germination and dormancy in Galeopsis speciosa (Lamiaceae), a common summer annual weed in cold-temperate areas. Seeds collected in southern Sweden were subjected to several experiments. The seeds were dormant at maturity. Seeds sown outdoors after collection produced a small number of seedlings, that emerged early in the spring. After long cold stratification or stratification outdoors over two winters, the maximum germination was 40 to 50%; germination occurring over a wide range of temperatures. Warm stratification preceding cold stratification had no effect on germination, but repeated warm and cold periods seemed to promote germination. Gibberellic acid (GA) stimulated germination but full germination was only achieved after more than two months of incubation at the most suitable temperature regime tested. Excised embryos grew and developed into normal seedlings. With these results, the species does not fit into the currently used system for seed dormancy classifications. The response to GA and the growth of excised embryos indicate non-deep or intermediate physiological dormancy, but dormancy alleviation by stratification was not in line with the guiding principles for these classifications. Galeopsis speciosa has a strong dormancy that is sufficiently alleviated during the winter to allow germination of only part of a seed batch each year, hence a stepwise germination pattern occurs over a period of several years.
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| 3. |
- Karlsson, Laila, et al.
(författare)
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Comparing after-ripening response and germination requirements of Conyza canadensis and C. bonariensis (Asteraceae) through logistic functions
- 2007
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Ingår i: Weed research (Print). - : Blackwell. - 0043-1737 .- 1365-3180. ; 47:5, s. 433-441
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Tidskriftsartikel (refereegranskat)abstract
- Germination requirements and after-ripening effects during one year of dry storage at 15/5 and 25/15°C (day/night) were compared for Conyza bonariensis and C. canadensis (Asteraceae). A logistic function was fitted to the results from tests over time in various incubation conditions, using three populations of each species as replicates. Time required for response to dry storage was measured by using a new method; the third derivative of the logistic function. Therefore, a point when major germination was achieved could be detected, without having to rely on maximum germination (which is uncertain), individual data points or any subjectively chosen limit. Fresh seeds of both species were dependent on light for germination and after-ripening was mainly manifested by increasing germination in darkness. Low dormancy status and light requirement might indicate that soil cultivations should rapidly reduce the seed banks of these species, although fecundity and wind dispersal will affect population levels. The species differed in their germination response, with C. bonariensis germinating at lower temperatures than C. canadensis. This seemingly counter-intuitive result may explain the prevention of fatal germination of C. canadensis in cold conditions and its behaviour as a summer annual in northern climates, while C. bonariensis is restricted to warmer parts of the world.
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| 4. |
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| 5. |
- Anbari, Saghi, et al.
(författare)
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Sprouting and shoot development of Sonchus arvensis in relation to initial root size
- 2011
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 51, s. 142-150
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Tidskriftsartikel (refereegranskat)abstract
- To assess the effects of initial root size of Sonchus arvensis on sprouting and shoot development, an outdoor box experiment was performed in Sweden in 2008. Shoot emergence time, shoot numbers, rosette size and flower production were quantified as functions of root length and weight. Emergence of the first shoot per root and of later cohorts was delayed with decreasing root length and weight. Number of shoots per root increased with root length and weight, but per unit root length and weight, short roots produced more shoots. The first emerging rosettes were, for rosettes of a given age, larger for longer roots. Total rosette area per root 5 weeks after planting increased with increasing root length and weight. The number of flowers and production of mature seeds were positively related to root length and weight, because of delayed sprouting of short and light roots. The proportion of flowers leading to mature seeds declined with shoot emergence time. By clarifying relationships between root size and growth parameters, this study showed that fragmenting of S. arvensis roots delays phenological development and hampers reproduction by seeds. The information may be used to refine mechanical weed control strategies for S. arvensis.
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| 6. |
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| 7. |
- Andersson, Lars, et al.
(författare)
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Seasonal changes in seed dormancy of Solanum nigrum and Solanum physalifolium
- 2009
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 49, s. 90-97
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Tidskriftsartikel (refereegranskat)abstract
- The seed dormancy cycle in Solanum nigrum and S. physalifolium was studied in relation to seasonal temperature. Seed lots of both species were buried in pots outdoors in a randomized complete block design with four replicates from November 2004 to November 2006. At regular intervals, samples of the seeds were randomly exhumed and tested for germination in incubators at three temperatures and light/darkness regimes. For both species low winter temperature weakened dormancy and high temperature strengthened it. Dormancy induction mainly occurred from August to October in both species after experiencing warm temperatures. An exception from the general pattern of seed dormancy was however observed when seed germination percentages were temporarily reduced in early spring followed by a peak in germination before the main period of strong dormancy in S. nigrum. The same phenomenon was observed in S. physalifolium during June in the first year. This short-lived dormancy induction might explain the late emergence of the species. Seed dormancy enables the species to maximize its chance of survival by regulating germination timing to favourable conditions. Therefore, information on the dormancy cycle can be used to predict seedling emergence and optimize weed control operations
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| 8. |
- Andersson, Lars, et al.
(författare)
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Variation in seed dormancy and light sensitivity in Alopecurus myosuroides and Apera spica-venti
- 2009
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 49, s. 261-270
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Tidskriftsartikel (refereegranskat)abstract
- Variation in seed dormancy and light sensitivity was studied in Alopecurus myosuroides and Apera spica-venti. Seeds were collected from different populations, at different dates and from plants emerging in autumn or spring, and used in four experiments. In the first experiment, initial dormancy was investigated in light and darkness. In Expt 2, buried seeds were exhumed on 16 occasions, from September 1997 to March 2000, and germinated in light, in darkness and after a 5-s light exposure. In Expt 3, emergence was recorded for seeds sown in pots outdoors. In Expt 4, stratified seeds of A. myosuroides only were exposed to photon irradiance ranging from 0.1 to 25 600 mu mol m(-2). Variation was high among seed collections, but both species showed winter annual dormancy patterns. Apera spica-venti germinated to high percentages in autumn but negligibly in spring. Alopecurus myosuroides germinated less in spring when tested in darkness and after a short light exposure and emerged poorly in spring, which reflected photo-desensitisation during cold stratification. We conclude that the peak of emergence in A. myosuroides, and to some extent in A. spica-venti, is largely regulated by exposure to light interacting with low-level dormancy. This offers valuable information regarding optimal timing of weed control measures.
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| 9. |
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| 10. |
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| 11. |
- Bergkvist, Göran, et al.
(författare)
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Red fescue undersown in winter wheat suppresses Elytrigia repens
- 2010
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 50, s. 447-455
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Tidskriftsartikel (refereegranskat)abstract
- P>Elytrigia repens (syn. Elymus repens) is a perennial grass weed that is controlled by herbicides or by tillage. Both methods are expensive and may have negative effects on the environment. Therefore, alternative methods of weed control, such as using competition from under-sown perennial forage crops, are of interest. Red fescue can be sown together with winter wheat as a non-flowering understorey crop that has its main growth during late summer and autumn. This study quantified the effect of red fescue and E. repens on wheat biomass and tested the hypothesis that under-sown red fescue reduces the amount of E. repens rhizomes and thus the need for herbicides or tillage. Two field experiments in which winter wheat, red fescue and E. repens were grown in all possible combinations were conducted between 2003 and 2005. Elytrigia repens reduced wheat biomass by 8%, while red fescue had no significant effect on wheat biomass. Red fescue reduced late autumn biomass of E. repens rhizomes by 40%. The results suggest that red fescue sown with winter wheat can reduce propagation of E. repens during summer and autumn, without a significant reduction in wheat biomass.
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| 12. |
- Bertholdsson, Nils-Ove
(författare)
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Breeding spring wheat for improved allelopathic potential
- 2010
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 50, s. 49-57
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Tidskriftsartikel (refereegranskat)abstract
- P>It is becoming apparent that allelopathy plays a significant role in the competitive ability of cereals against weeds; barley, wheat and rice cultivars with high allelopathic activity have been identified. However, direct breeding efforts to improve allelopathy have to date only been reported in rice. In this study, a breeding programme in spring wheat (Triticum aestivum) was evaluated to determine the efficiency of selection of allelopathy and the ability of breeding lines to suppress weeds in the field. The material used originated from a cross between a Swedish cultivar with low allelopathic activity and a Tunisian cultivar with high allelopathic activity. Allelopathic activity was measured as growth inhibition of perennial ryegrass (Lolium perenne) roots when grown together with the wheat cultivars on agar. For screening of F(2) populations, a single plant bioassay was used for the first time. In the F(6) and F(7) generations, three breeding lines with an average improved allelopathy of 20% and one line with an unimproved allelopathy activity, but with the same phenotype as the high allelopathic lines, were tested together with the low allelopathic Swedish parent. The main result from the field study was a 19% average reduction of weed biomass for the high allelopathic lines, but no significant reduction of the low allelopathic breeding line. Early shoot length and early crop biomass (stages 37-39, Zadoks scale) and straw length of the high allelopathic lines were not significantly different from the Swedish parent. A negative effect was that grain yield was reduced by 9% in the high allelopathic lines. It is suggested that the reduced biomass of weeds in plots planted with the highly allelopathic wheat lines is related to differences in allelopathic activity and not differences in plant growth.
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| 13. |
- Bertholdsson, Nils-Ove
(författare)
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Use of multivariate statistics to separate allelopathic and competitive factors influencing weed suppression ability in winter wheat
- 2011
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 51, s. 273-283
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Tidskriftsartikel (refereegranskat)abstract
- P>There is an increasing interest in an integrated, less herbicide-dependent approach to weed management, based on combinations of cultivation practices and competitive crops. More competitive cultivars are essential to this approach and breeders need to know how to breed such. It is known that early vigour and extensive early season vegetative growth are important traits. The questions are, which is most efficient to use in breeding and if allelopathy should be bred for? Weed suppressive ability (WSA) of 12 winter wheat, two rye and two triticale cultivars was studied in a 2-year field trial with natural weeds and under-sown Apera spica-venti and rapeseed (Brassica napus). Crop biomass, shoot length, straw length and plantlet root length and root weight were analysed. Biomass growth in autumn and spring was studied in weed-free plots using multispectral analysis. Grain yield, winter hardiness and maturity data were collected from official variety tests in Sweden. Allelopathic activity was assessed with use of a bioassay. Factor analysis showed that early season crop biomass and allelopathy were two traits explaining most of the variance in weed biomass. It was predicted by partial least square regression models that weed biomass could be reduced by 60%, if both crop biomass and allelopathy are improved to the levels of triticale. An improvement of allelopathy alone should reduce weed biomass by 18-28%. The factor analysis and multivariate models showed that WSA could be improved without a negative trade-off in grain yield or winter hardiness.
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| 14. |
- Hansson, David
(författare)
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Weed occurrence on pavements in five North European towns
- 2009
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 49, s. 516-525
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Tidskriftsartikel (refereegranskat)abstract
- Weeds on pavements in urban areas are unwanted mainly because they cause an untidy appearance or sometimes structural damage. Glyphosate has been the principal weed control method for years, but policies in several European towns have changed to lower dependence on herbicides. Instead, less effective and more species-dependent non-chemical methods are used, but little is known about the pavement flora. Consequently, we surveyed the flora on pavements in five North European towns [Braunschweig (DE), Malmo (SE), Naestved (DK), Royal Leamington Spa (UK) and Wageningen (NL)] by recording weed species and their coverage in 56 recording points randomly placed in each town. Weeds were recorded at several dates in 2005 and 2006 and no weed control was applied apart from sweeping. Weed coverage increased during the survey (averaging 1.4% in late 2006) and was highest in the towns having the strictest policies limiting herbicide use. Most coverage (averaging 2%) was found along the pavement edge away from the road. Poa annua was the most frequently recorded species, followed by bryophytes (mainly mosses), Sagina procumbens and perennial grasses. Grasses and some other species frequently found, notably Taraxacum officinale, should receive particular attention when planning a non-chemical weed control campaign on pavements.
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| 15. |
- Jung, L. S., et al.
(författare)
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Above- and below-ground nutrient and alkaloid dynamics in Colchicum autumnale : optimal mowing dates for population control or low hay toxicity
- 2012
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 52:4, s. 348-357
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Tidskriftsartikel (refereegranskat)abstract
- Jung LS, Eckstein RL, Otte A & Donath TW (2012). Above- and below-ground nutrient and alkaloid dynamics in Colchicum autumnale: indications for optimal mowing dates for population control or low hay toxicity. Weed Research52, 348-357. Summary In some Central European regions, the conservation of seminatural grasslands is jeopardised by management intensification or abandonment, caused by high densities of the toxic weed Colchicum autumnale. We investigated two possibilities to deal with C. autumnale: (i) reducing population densities by mowing when nutrient contents are high in leaves and capsules and low in the storage organs, that is, when the ratio between both is highest, or (ii) reducing alkaloid content in hay by mowing when alkaloid content of leaves and capsules of C. autumnale is low. To identify the optimal mowing point, we analysed the dynamics of nutrients, starch and alkaloids of naturally grown plants in two biogeographical regions. In the colder region, the maximum nutrient ratio between above-ground and storage organs, as well as alkaloid content in leaves and capsules, occurred significantly later. Compared with the common first mowing date (15 June), alkaloid content decreased significantly until 5 July in both regions. On both dates, it was on average 1.8 times higher in the colder region. Our results suggest the following time for the two management options: (i) mowing at about 25 cm plant height (late April/early May) to reduce C. autumnale densities or (ii) delayed mowing in late June/early July when the plant has turned brown and dry and alkaloid content has declined.
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| 16. |
- Liew, Josefine, et al.
(författare)
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Influence of temperature and photoperiod on sprouting capacity of Cirsium arvense and Sonchus arvensis root buds
- 2012
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 52:5, s. 449-457
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Tidskriftsartikel (refereegranskat)abstract
- Influence of temperature and photoperiod on sprouting capacity of Cirsium arvense and Sonchus arvensis root buds. Weed Research.52, 449-457. Summary Timing of treatment is a key to successful and sustainable weed management. For perennial weeds, highly energy-demanding, repeated stubble cultivation or tillage is a common strategy in organic agriculture. The fragmentation of underground material stimulates root buds to grow and, if repeated, significantly reduces the energy and nutrient resources of the roots. However, the effect might differ depending on variation in sprouting over the season and among species. Here, we studied the impact of different photoperiods and temperatures on sprouting capacity of root buds of Cirsium arvense and Sonchus arvensis in a climate chamber experiment. Two populations of each species, collected in northern and southern Sweden, were used. Plants were exposed to long (18 h), short (12 h) or decreasing (from 18 to 8 h) photoperiods in combinations with high (18/12 degrees C for 16/8 h), low (12/6 degrees C), decreasing (from 21 to 5 degrees C in 4 weeks) or constant high (16 degrees C) temperatures. Sprouting capacity was evaluated based on the proportion of sprouting buds from short root fragments. Neither temperature nor photoperiod affected root bud sprouting in C. arvense, while in S. arvensis, photoperiod seemed to regulate sprouting capacity. The proportion of sprouted buds decreased in short photoperiods, especially if combined with high temperature. In northern conditions, this suggests that weeding strategies based on fragmentation of the root system of S. arvensis will have low efficiency if the autumns are warm.
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| 17. |
- Lundkvist, Anneli
(författare)
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Effects of pre- and post-emergence weed harrowing on annual weeds in peas and spring cereals
- 2009
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 49, s. 409-416
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Tidskriftsartikel (refereegranskat)abstract
- P>To assess the effects of timing and frequency of weed harrowing on weed abundance and crop yield, different pre- and post-emergence weed harrowing sequences were applied to spring cereals and peas in field experiments performed during 2003 and 2004 in Sweden. Post-emergence harrowing was performed at crop growth stages 2-3 and 5-6 true leaves respectively. The best weed control was obtained by a combination of pre- and post-emergence harrowing, but these treatments also caused yield losses of 12-14% in spring cereals, while no yield losses were observed in peas. Pre-emergence weed harrowing treatments alone or combined with weed harrowing shortly after crop emergence proved to be most effective against the early emerging annual weed species Sinapis arvensis and Galeopsis spp. Post-emergence harrowing alone in peas had no effect on S. arvensis. The late emerging annual weed species Chenopodium album and Polygonum lapathifolium were most effectively controlled when pre-emergence weed harrowing was combined with one or two weed harrowing treatments after crop emergence.
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| 18. |
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| 19. |
- Taab, Alireza, et al.
(författare)
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Seed dormancy dynamics and germination characteristics of Solanum nigrum
- 2009
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 49, s. 490-498
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Tidskriftsartikel (refereegranskat)abstract
- Four experiments were conducted to study seed dormancy and germination requirements in Solanum nigrum. In Expt 1, seeds were stratified at different constant and stepwise rising temperatures and their germinability was tested at three germination regimes at weekly intervals. In Expts 2-4, seeds dry stored at 4 degrees C and stratified at 5 and 15 degrees C were tested at constant temperatures, as well as fluctuating temperatures with constant and increasing amplitudes. Results suggest that the rate of dormancy release increased with increasing temperatures ranging from 4.5 to 18.6 degrees C. However, prolonged strati. cation at higher temperatures caused subsequent induction of dormancy. When tested at constant temperatures, stratified seeds germinated between 18 and 34 degrees C, with the optimum between 26 and 30 degrees C, while dry-stored seeds showed no germination. Fluctuating temperatures, with amplitudes ranging from 5 to 15 degrees C, promoted germination of seeds from all treatments. The dormancy dynamics and germination characteristics of the species will have implications for its survival and establishment. This information can be used to predict time of emergence and, thus, improve control of the species in weed management systems.
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| 20. |
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| 21. |
- Van Der Weide, R.Y., et al.
(författare)
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Innovation in mechanical weed control in crop rows
- 2008
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 48:3, s. 215-224
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Tidskriftsartikel (refereegranskat)abstract
- Weed control within crop rows is one of the main problems in organic farming. For centuries, different weed removal tools have been used to reduce weeds in the crop rows. Stimulated by the demand from organic farmers, research in several European countries over the last decade has focused on mechanisation using harrowing, torsion finger weeding and weeding with compressed air (Pneumat). Intelligent weeders are now being developed which offer more advanced ways to control weeds, including larger ones and to leave the crop plants unharmed. One of the first commercially available intelligent weeders, the Sarl Radis from France, has a simple crop detection system based on light interception, which guides a hoe in and out of the crop row, around the crop plants. The inclusion of innovative technologies, including advanced sensing and robotics, in combination with new cropping systems, might lead to a breakthrough in physical weed control in row crops leading to significant reductions, or even elimination, of the need for hand weeding. © 2008 The Authors.
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| 22. |
- Albertsson, Johannes, et al.
(författare)
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Site-related set-back by weeds on the establishment of 12 biomass willow clones
- 2014
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 54, s. 398-407
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Tidskriftsartikel (refereegranskat)abstract
- Ten commercial clones of willow and two breeding clones were studied for their ability to compete with weeds during the establishment year at three different sites in southern Sweden. Cuttings were planted according to commercial practice in April, and the two treatments, 'Weeded' and 'Unweeded', were laid out in a strip-plot design. Weeds in the 'Weeded' treatment were removed mechanically and by hand hoeing. Willow plant shoot weight and plant mortality were measured after the first growing season to evaluate the initial effect of weeds. In addition, weed flora, weed aboveground biomass, soil properties, shoot damage and soil moisture were assessed during the growing season. Plant mortality was <1% in the 'Weeded' treatment at the three study sites, while in 'Unweeded' it was significantly higher, 2.7%, 24.6% and 37.4%. Weeds reduced willow plant shoot weight by 93.4%, 94.0% and 96.1% at the three sites. Only one site showed clonal differences in shoot growth reduction, as well as in plant mortality. These results show the importance of weed control in willow plantations, as growth of all clones tested were dramatically hampered by weeds during the first growing season, regardless of trial site conditions. Moreover, conditions at certain sites, such as soil properties in combination with weed cover, may cause high plant mortality during the establishment year in this perennial biomass crop.
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| 23. |
- Andersson, Lars
(författare)
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An investigation to enhance understanding of the stimulation of weed seedling emergence by soil disturbance
- 2014
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 54, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Enhanced understanding of soil disturbance effects on weed seedling recruitment will help guide improved management approaches. Field experiments were conducted at 16 site-years at 10 research farms across Europe and North America to (i) quantify superficial soil disturbance (SSD) effects on Chenopodium album emergence and (ii) clarify adaptive emergence behaviour in frequently disturbed environments. Each site-year contained factorial combinations of two seed populations (local and common, with the common population studied at all site-years) and six SSD timings [0, 50, 100, 150, 200day-degrees (d degrees C, base temperature 3 degrees C) after first emergence from undisturbed soil]. Analytical units in this study were emergence flushes. Flush magnitudes (maximum weekly emergence per countflush) and flush frequencies (flushesyear(-1)) were compared between disturbed and undisturbed seedbanks. One year after burial, SSD promoted seedling emergence relative to undisturbed seedbanks by increasing flush magnitude rather than increasing flush frequency. Two years after burial, SSD promoted emergence through increased flush magnitude and flush frequency. The promotional effects of SSD on emergence were strongest within 500d degrees C following SSD; however, low levels of SSD-induced emergence were detected as late as 3000d degrees C following SSD. Accordingly, stale seedbed practices that eliminate weed seedlings should occur within 500d degrees C of disturbance, because few seedlings emerge after this time. However, implementation of stale seedbed practices will probably cause slight increases in weed population densities throughout the year. Compared with the common population, local populations exhibited reduced variance in total emergence measured within sites and across SSD treatments, suggesting that C.album adaptation to local pedo-climatic conditions involves increased consistency in SSD-induced emergence.
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| 24. |
- Andersson, Lars
(författare)
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Comparing the emergence of Echinochloa crus-galli populations in different locations. Part I: Variations in emergence timing and behaviour of two populations
- 2022
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 62, s. 192-202
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Tidskriftsartikel (refereegranskat)abstract
- Echinochloa crus-galli (L.) P. Beauv. is one of the most important weeds. It is distributed worldwide and has adapted to diverse habitats and climatic conditions. This study aimed to compare the emergence patterns of two populations of E. crus-galli from different environments at 11 locations across Europe and the Middle East. Seeds of the two populations were collected from maize in Italy and from spring barley in Norway and were then buried in soil in autumn 2015. In the spring of 2016, the soil was disturbed around the usual seedbed preparation date in each location and emergence was recorded. The soil was again disturbed a year later and emergence was recorded for a second season. Total emergence, the times of onset, end and to 50% emergence and the period between 25% and 75% of emergence were analysed by two-way ANOVA and principal components analysis. The Italian population showed a higher emergence than the Norwegian population in Southern locations, while the ranking was reversed in Northern locations. In almost all locations, a tendency to emerge earlier was recorded for the Norwegian population, but the periods from 25% to 75% emergence were similar for both populations. Total emergence, and the times of onset and end of emergence seemed to be mainly under genotypic (plus maternal) control, suggesting there were different temperature thresholds for seedling emergence in each population. Conversely, the duration of emergence seemed to be mainly under environmental control. This research confirms the high variability between populations and suggests the need to continue identifying key characteristics for the development of efficient models for seedling emergence in specific climates and/or latitudes.
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| 25. |
- Andersson, Lars
(författare)
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Comparing the emergence of Echinochloa crus-galli populations in different locations. Part II: similarities and threshold parameters
- 2022
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 62, s. 203-214
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Tidskriftsartikel (refereegranskat)abstract
- The variability in the emergence process of different populations was confirmed for two Echinochloa crus-galli populations, one from Italy (IT) and the second from Norway (NO). Seeds were sown in 12 localities over Europe and the Middle East, and the emergence patterns of IT and NO were compared with those of several local populations at each location. Seeds of each population were sown in pots buried to the ground level. The base temperature (T-b) for emergence was estimated by (1) analysing logistic models applied to the field emergence of IT and NO, and (2) a germination assay set in winter 2020 at constant temperatures (8, 11, 14, 17, 20, 26, 29 degrees C) with newly collected seeds in 2019 from the same fields where IT and NO had previously been harvested in 2015. The logistic models developed for IT and NO in each location showed that the emergence pattern of IT was similar to that of the local populations in Poland, Italy, Spain, Turkey South and Iran, while NO fitted better to those in Sweden and Latvia. No germination was obtained for IT in a germination chamber, but the estimated T-b with the logistic model was 11.2 degrees C. For NO, the estimated T-b was 8.8 degrees C in the germination chamber and 8.1 degrees C in the field. Results suggest that adaptation to local environmental conditions has led to inter-population differences in T-b and parameter estimates of thermal-time models to predict the emergence of E. crus-galli should only be used for populations with similar climatic and habitat conditions.
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| 26. |
- Andersson, Lars, et al.
(författare)
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Sprouting capacity from intact root systems of Cirsium arvense and Sonchus arvensis decrease in autumn
- 2013
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 53:3, s. 183-191
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Tidskriftsartikel (refereegranskat)abstract
- Perennial weeds are often controlled by mechanical means, which aim at stimulating axillary and adventitious buds to sprout. This happens when the apical dominance of the main shoot is removed by defoliation or when the underground system is fragmented. By repeating the measures, the result is a depletion of storage compounds, which weakens the plants and reduces their capacity to grow and reproduce. However, timing is critical. Earlier research has indicated that emergence from fragments of Sonchus arvensis cease during a period in autumn, while the seasonal pattern of sprouting in Cirsium arvense appears to be inconsistent. We studied the emergence pattern of defoliated plants with undisturbed root systems, from late summer to early spring. Potted plants grown outdoors were exhumed at regular intervals, put under forcing conditions for 4weeks, after which shoots above and below soil level were counted and weighed together with the remaining root systems. In both species, the number and weight of emerged shoots decreased during a period in the autumn. In C.arvense, underground shoots were constantly produced during the same period, while fewer underground shoots were present in S.arvensis. For the latter species, apical dominance does not fully explain the effect; thus, endodormancy might be involved. Root weight increased until withering and did not explain the lack of emergence. Our results suggest an impaired sprouting capacity of undisturbed root systems of C.arvense and S.arvensis during SeptemberOctober, which has implications for the timing and method of control of these species.
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| 27. |
- Bergkvist, Göran, et al.
(författare)
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Control of Elymus repens by rhizome fragmentation and repeated mowing in a newly established white clover sward
- 2017
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Ingår i: Weed research (Print). - : Blackwell Publishing Ltd. - 0043-1737 .- 1365-3180. ; 57:3, s. 172-181
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Tidskriftsartikel (refereegranskat)abstract
- Control of perennial weeds, such as Elymus repens, generally requires herbicides or intensive tillage. Alternative methods, such as mowing and competition from subsidiary crops, provide less efficient control. Fragmenting the rhizomes, with minimal soil disturbance and damage to the main crop, could potentially increase the efficacy and consistency of such control methods. This study's aim was to investigate whether fragmenting the rhizomes and mowing enhance the control of E. repens in a white clover sward. Six field experiments were conducted in 2012 and 2013 in Uppsala, Sweden, and Ås, Norway. The effect of cutting slits in the soil using a flat spade in a 10 × 10 cm or 20 × 20 cm grid and the effect of repeated mowing were investigated. Treatments were performed either during summer in a spring-sown white clover sward (three experiments) or during autumn, post-cereal harvest, in an under-sown white clover sward (three experiments). When performed in autumn, rhizome fragmentation and mowing reduced E. repens shoot biomass, but not rhizome biomass or shoot number. In contrast, when performed in early summer, rhizome fragmentation also reduced the E. repens rhizome biomass by up to 60%, and repeated mowing reduced it by up to 95%. The combination of the two factors appeared to be additive. Seasonal differences in treatment effects may be due to rhizomes having fewer stored resources in spring than in early autumn. We conclude that rhizome fragmentation in a growing white clover sward could reduce the amount of E. repens rhizomes and that repeated mowing is an effective control method, but that great seasonal variation exists. © 2017 The Authors.
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| 28. |
- Boström, Ullalena, et al.
(författare)
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Seasonal variation in sprouting capacity from intact rhizome systems of three perennial weeds.
- 2013
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 53:5, s. 387-398
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Tidskriftsartikel (refereegranskat)abstract
- The three rhizomatous perennials Elytrigia repens, Equisetum arvense and Tussilago farfara are all problematic in Scandinavian agriculture, due to their low susceptibility to soil cultivation. While repeated soil tillage is a fundamental part of the integrated control of these species, it is highly energy consuming and inefficient during periods when little sprout regrowth occurs. Substituting cultivation with mowing will reduce the environmental impact and labour costs, but its efficiency will still depend on the capacity of plants to sprout. Therefore, we studied the seasonal pattern in emergence and rhizome biomass allocation from July to April in six populations for each of the species. Plants were grown outdoors in pots buried in soil and exhumed at regular intervals in a two-year experiment. In all three species, biomass allocation to rhizomes continued until late in the autumn. Emergence was severely impaired in E.arvense and T.farfara in September-October, while in E.repens, there was no such reduction in the number of emerged shoots. However, in the latter species, the shoot/rhizome ratio decreased and remained low until the plants had been exposed to a period of low temperatures. The increase in shoot/rhizome ratio for E.repens coincided with the resumed capacity to emerge for E.arvense and T.farfara. These results imply that there is no need to repeat a defoliation of E.arvense and T.farfara, if carried out in September-October. However, removal of the aerial plant parts early in the autumn is important to interrupt the upload of storage compounds to the rhizome systems of all species.
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| 29. |
- Dalbato, Abitew Lagibo, et al.
(författare)
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Effect of rhizome fragment length and burial depth on emergence of Tussilago farfara
- 2014
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 54:4, s. 347-355
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical control of Tussilago farfara is carried out mainly by soil cultivation. The aim is to deplete the energy stored in the rhizomes. The treatment includes cutting the rhizomes, to stimulate increased shooting, followed by renewed soil cultivation to destroy the shoots and incorporate them into the soil. Factors generally regarded as important in the control of perennial weeds are extent of fragmentation and burial depth. In this study, the importance of these two factors on T. farfara emergence was studied in detail in two pot experiments. Rhizomes were cut into different lengths (5-25 cm) and buried at various depths (1-42 cm) in pots filled with peat soil or clay loam. Shoot germination, emergence and early plant performance were studied. Intensive fragmentation and deep burial (possible to achieve using conventional tillage) are not enough to completely hinder emergence of T. farfara; 6-cm fragments emerged and developed normal leaves from 42 cm depth, regardless of soil type. However, there were higher total emergence and emergence rates in peat soil than in clay soil. Burial depth was correlated with time to emergence; burying rhizome fragments, not longer than 25 cm, to at least 20 cm depth gave a time to emergence of at least 20 days. The delay of weed emergence should allow good establishment of a crop and ensure a significant competitive effect against T. farfara.
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| 30. |
- Menegat, Alexander
(författare)
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Minimal soil disturbance combined with spring cropping can halt soil seedbank accumulation of Alopecurus myosuroides
- 2023
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 63, s. 115-122
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Tidskriftsartikel (refereegranskat)abstract
- The basic mechanism of soil inversion tillage for control of annual weeds is based on the vertical translocation of weed seeds from the soil surface to deeper soil layers. Buried weed seeds either remain dormant in the soil seedbank and are exposed to biological and chemical decay mechanisms, or they germinate but the seedlings cannot reach the soil surface (fatal germination). However, depending on the seed biology of the respective target species, frequent inversion tillage can lead to a build-up of the soil seedbank. For soil seedbank depletion based on available knowledge of the biology of Alopecurus myosuroides seeds, soil inversion tillage is suggested to be reduced to every third or fourth year with reduced or even no-tillage (direct seeding) in between (rotational inversion tillage systems). Including spring crops in the crop rotation could further help dampening the population growth and hence the seed return into the seedbank. This study investigated the effect of rotational inversion tillage in combination with reduced tillage or direct seeding on the soil seedbank and population development of A. myosuroides. In a long-term field trial, set up in 2012, these tillage strategies were compared with continuous inversion tillage in a 3-year crop rotation with two consecutive years of winter wheat (Triticum aestivum) followed by spring barley (Hordeum vulgare). The results showed a significant decline in the soil seedbank following the spring crop, irrespective of the tillage system. The continuous inversion tillage system and inversion tillage before spring cropping with reduced tillage (shallow tillage with a disc harrow) before winter wheat both led to accumulation of seeds in the soil seedbank. In contrast, inversion tillage before spring cropping with direct seeding of winter wheat depleted the soil seedbank significantly after only one crop rotation. Although only covering one intensively studied field site, these findings highlight the need for diversified cropping systems and indicate potential avenues for reducing soil tillage while controlling economically important weeds.
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| 31. |
- Neve, Paul, et al.
(författare)
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Current and future glyphosate use in European agriculture
- 2024
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Ingår i: Weed research (Print). - : John Wiley & Sons, Ltd. - 0043-1737 .- 1365-3180. ; 64:3, s. 181-
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Tidskriftsartikel (refereegranskat)abstract
- Abstract There has been a longstanding and contentious debate about the future of glyphosate use in the European Union (EU). In November 2023, the European Commission approved the renewal of the use registration for glyphosate for a further 10?years. Nevertheless, the EU Farm to Fork strategy calls for a 50% reduction in pesticide use by 2030. In November 2022, the European Weed Research Society organised a 2 day workshop to identify critical glyphosate uses in current EU cropping systems and to review the availability of glyphosate alternatives. Workshop participants identified four current, critical uses in EU cropping systems; control and management of perennial weeds, weed control in conservation agriculture, vegetation management in tree and vine crops and herbicide resistance management. There are few herbicide alternatives that provide effective, economic, broad-spectrum control of weeds, particularly perennial weeds. Mechanical weed control, and in particular, soil cultivation is the most obvious glyphosate alternative. However, this is not possible in conservation agriculture systems and, in general, increased soil cultivation has negative impacts for soil health. Emerging technologies for precision weed control can enable more targeted use of glyphosate, greatly reducing use rates. These technologies also facilitate the use and development of alternative targeted physical weed control (e.g. tillage, lasers, electricity), reducing the energy and environmental costs of these approaches. In tree crops, the use of organic and inorganic mulches can reduce the need for glyphosate use. In general, reduced use of glyphosate will require an even greater focus on integrated weed management to reduce weed establishment in agroecosystems, increase weed management diversity and limit the use of alternative resistance-prone herbicides.
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| 32. |
- Ringselle, Björn, et al.
(författare)
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Dry weight minimum in the underground storage and proliferation organs of six creeping perennial weeds
- 2021
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Ingår i: Weed research (Print). - : John Wiley & Sons, Ltd. - 0043-1737 .- 1365-3180. ; 61:3, s. 231-241
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Tidskriftsartikel (refereegranskat)abstract
- Many herbaceous perennial plant species gain significant competitive advantages from their underground creeping storage and proliferation organs (CR), making them more likely to become successful weeds or invasive plants. To develop efficient control methods against such invasive or weedy creeping perennial plants, it is necessary to identify when the dry weight minimum of their CR (CR DWmin) occurs. Moreover, it is of interest to determine how the timing of CR DWmin differs in species with different light requirements at different light levels. The CR DWmin of Aegopodium podagraria, Elymus repens and Sonchus arvensis were studied in climate chambers under two light levels (100 and 250 ?mol m?2 s?1), and Reynoutria japonica, R. sachaliensis and R. ? bohemica under one light level (250 ?mol m?2 s?1). Under 250 ?mol m?2 s?1, the CR DWmin occurred before one fully developed leaf in R. sachaliensis, around 1?2 leaves in A. podagraria and E. repens and around four leaves in S. arvensis, R. japonica and R. ? bohemica. In addition to reducing growth in all species, less light resulted in a higher shoot mass fraction in E. repens and S. arvensis, but not A. podagraria; and it delayed the CR DWmin in E. repens, but not S. arvensis. Only 65% of planted A. podagragra rhizomes produced shoots. Beyond the CR DWmin, Reynoutria spp. reinvested in their old CR, while the other species primarily produced new CR. We conclude that A. podagraria, R. sachaliensis and E. repens are vulnerable to control efforts at an earlier developmental stage than S. arvensis, R. japonica and R. bohemica.
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| 33. |
- Ringselle, Björn, et al.
(författare)
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Importance of timing and repetition of stubble cultivation for post-harvest control of Elymus repens
- 2016
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Ingår i: Weed research (Print). - : Blackwell Publishing Ltd. - 0043-1737 .- 1365-3180. ; 56:1, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- Without herbicides, the control of Elymus repens relies on intensive tillage, often in the form of repeated post-harvest stubble cultivations followed by ploughing. This is costly and time-consuming and also increases the risk of nitrogen leaching. Our aim was to quantify the controlling effect on E. repens of single and repeated cultivation and differing time of cultivation in relation to spring cereal harvest. A 2-year experiment was conducted at two sites in the south and east of Sweden in 2011-2012 and 2012-2013. We compared no, single and repeated tine cultivation followed by mouldboard ploughing; the single cultivation was performed directly after harvest or 20 days after harvest; when repeated, the first cultivation was performed immediately or 5 days after harvest, followed by a second cultivation 20 days after harvest. Tine cultivation in combination with mouldboard ploughing resulted in 50-70% lower rhizome biomass, and increased average subsequent cereal yields by 0-130% compared with ploughing alone. Large E. repens populations appeared to be more efficiently reduced by tine cultivation than smaller populations. A single tine cultivation 20 days after harvest tended to result in a higher E. repens shoot density and more rhizome biomass in the subsequent year than tine cultivation directly after harvest. Additional cultivation 20 days after harvest did not improve control of E. repens or the subsequent cereal grain yield, compared with a single cultivation conducted directly after harvest. In conclusion, preventing the growth of E. repens during the early part of the post-harvest autumn period was more important than starving rhizomes with repeated cultivations. Weed Research
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| 34. |
- Ringselle, Björn, et al.
(författare)
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Under-sown cover crops and post-harvest mowing as measures to control Elymus repens
- 2015
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 55:3, s. 309-319
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Tidskriftsartikel (refereegranskat)abstract
- Two potential control methods for Elymus repens, which do not disturb the soil, are post-harvest mowing and competition from under-sown cover crops. Our aim was to quantify the effect of cover crop competition and mowing on E. repens and to evaluate the potential for combining the two methods. We present a two-factorial split-plot experiment conducted at three locations in Sweden, in two experimental rounds conducted in 2011-2012 and 2012-2013. A spring cereal crop was under-sown with perennial ryegrass, red clover or a mixture of the two (subplots). Under-sown crops were either not mowed, or mowed once or twice post-harvest (main plots). This was followed by ploughing and a new spring cereal crop the next year. Mowing twice reduced autumn shoot biomass by up to 66% for E. repens and 50% for cover crops compared with the control, twice as much as mowing once. Pure ryegrass and mixture treatments reduced E. repens shoot biomass by up to 40% compared with the control. Mowing twice reduced rhizome biomass in the subsequent year by 35% compared with the control, while the pure red clover treatment increased it by 20-30%. Mowing twice and treatments including red clover resulted in higher subsequent grain yields. We concluded that repeated mowing has the potential to control E. repens, but a low-yielding cover crop has insufficient effect on rhizome biomass. Clover-grass mixtures are of interest as cover crops, because they have the potential to increase subsequent crop yield and even at low levels they reduce E. repens above-ground autumn growth.
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| 35. |
- Taab, Alireza, et al.
(författare)
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Modelling the sprouting capacity from underground buds of the perennial weed Sonchus arvensis
- 2018
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 58, s. 348-356
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Tidskriftsartikel (refereegranskat)abstract
- Sonchus arvensis is a problematic perennial weed species causing problems in many crops. Control measures often rely on soil tillage or mowing; both methods are used to exhaust the root system. This approach fails during periods of restrictions in sprouting capacity or shoot regrowth. The aim of this study was to develop a simulation model for prediction of shoot sprouting capacity in underground buds of S.arvensis. We hypothesised restricted regrowth to be induced as a function of photoperiod and temperature sum and released as a function of cold temperature sum. The model was parameterised and calibrated against observations of shoot regrowth from an experiment on intact roots of S.arvensis. Subsequently, it was validated against observations of regrowth from another experiment on intact roots and sprouting from fragmented roots from a third experiment. Restriction in regrowth was attributed to reduction in the photoperiod, observed when the day length decreased below a threshold of 16.5h, but also to a daily mean temperature below 16.8 degrees C. Resumed regrowth occurred in late autumn at a daily mean temperature threshold of 4.7 degrees C. The pattern of changes over time in shoot regrowth from an intact root system was well predicted by the model. The temporal change in sprouting capacity from buds on fragmented roots followed the same pattern, but with a quantitative difference between the model prediction and the observed sprouting capacity. We conclude that the model can be used to predict the pattern over time of sprouting capacity in intact roots of S.arvensis.
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| 36. |
- Tavaziva, Varwi Jacob, et al.
(författare)
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Effects of selective cutting and timing of herbicide application on growth and development of Cirsium arvense in spring barley
- 2019
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 59, s. 349-356
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Tidskriftsartikel (refereegranskat)abstract
- Recently, a new implement for controlling weeds in cereals (CombCut) has been developed. It cuts weeds in growing cereals without damaging them by using the physical differences (in height, stem thickness, straw stiffness and branching pattern) between crops and weeds. To evaluate and compare the effects of selective cutting with different timings of herbicide application on Cirsium arvense in spring barley, a randomised block experiment was conducted in Sweden in 2015-2017, in a field with a naturally occurring C. arvense population. Treatments consisted of control (C), herbicide application at 4-5-leaf stage of C. arvense (H1), herbicide application at 8-10-leaf stage (H2) and selective cutting at 10-leaf stage (S). The treatments were performed in 2015 and repeated in 2016 in the same plots, and a final evaluation was performed in 2017. Compared to the control, S, H1 and H2 were equally efficient in reducing above-ground biomass production of C. arvense and increasing spring barley grain yield per unit area. The number of C. arvense shoots per area was, however, higher in S compared to H1 and H2. No differences in control effects on shoot number were observed between H1 and H2. Our study indicates that (i) selective cutting (S) reduces C. arvense equally efficient as herbicide application and (ii) early herbicide spraying is as efficient as spraying later in the season.
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| 37. |
- Verwijst, Theo, et al.
(författare)
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Assessment of the compensation point of Cirsium arvense and effects of competition, root weight and burial depth on below-ground dry weight - leaf stage trajectories
- 2018
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 58, s. 292-303
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Tidskriftsartikel (refereegranskat)abstract
- Farmers are recommended to employ mechanical control when Cirsium arvense is most sensitive to disturbance. Earlier studies suggest that this occurs at a stage of minimum below-ground dry weight, coinciding with three to seven or seven to ten leaves per shoot, depending on the definition of below-ground dry weight. However, some farmers notice better effects when mechanical control is performed at earlier leaf stages. To estimate the compensation point (CP), defined as the minimum weight of the entire below-ground structure of C.arvense and to further understand links between initial root weight, planting depth and crop competition, three outdoor pot experiments were performed in Sweden in 2013-2014. We hypothesised that (i) CP likely occurs before C.arvense has developed three leaves, (ii) relative depletion of the below-ground system at CP is less at lower initial root weight compared with higher weight, and (iii) methodological variations in CP estimations have minor impact on the results. We found that the CP for C.arvense in all treatments occurred before shoots had developed three leaves and that treatment effects were minor (<0.5 leaf stages). Leaf and leaf stage definitions, choice of leaf range and model also had minor effects on CP estimates. Depletion of planted root fragments ceased around leaf stages 3-4, and their partial replenishment also constitutes evidence for a CP at early leaf stages. For agronomy, our results imply that mechanical control of C.arvense should be performed earlier than previously recommended, probably before reaching an average of three to four leaves per shoot.
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| 38. |
- Verwijst, Theo, et al.
(författare)
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Weight loss in overwintering below-ground parts of Sonchus arvensis under current and temperature-elevated climate scenarios in Sweden
- 2013
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 53, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- Weight loss in overwintering below-ground parts of perennial weeds has been attributed to respiration, but neither its temperature dependence nor its relevance for biomass dynamics under changing climate conditions have been investigated. In two experiments, we quantified weight loss of the perennial weed Sonchus arvensis, by measuring weight changes over time of sprouting roots in dark rooms at temperatures of 4, 8 and 18 degrees C. Dry weight loss rates were 0.47, 0.64 and 1.47% day-1 at 4, 8 and 18 degrees C, respectively, giving a half-life time of 149, 110 and 47 days, respectively. A factor by which weight loss rates increase for every 10 degrees rise in temperature (Q10) was equal to about 2.3. Cumulative weight loss may comprise >40% of the below-ground biomass during overwintering periods. Applying weight loss rates and Q10 to elevated soil temperature projections showed that losses during winter seasons in central Sweden will remain basically constant, the effect of increased weight loss at higher temperatures being balanced by shorter winters. This implies that need for control of S. arvensis in a changing climate will persist, but that shorter winter seasons will provide a longer time window for control of S. arvensis prior to sowing crops.
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| 39. |
- Wu, A. P., et al.
(författare)
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Rapid nitrogen and phosphorus homeostasis transformation in Eupatorium adenophorum during invasion
- 2019
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 59:5, s. 387-395
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Tidskriftsartikel (refereegranskat)abstract
- Exotic plants can compete well with native species because many invasive species are considered better nutrient users in both low- and high-resource environments. However, whether invasive plants can outperform native plants at all stages of invasion is not very clear. We investigated the nitrogen (N), phosphorus (P) and N:P homeostasis of an invasive Eupatorium adenophorum and a co-occurring native plant Artemisia argyi in an area across the five invasion stages of E. adenophorum. The N homeostasis (HN) of E. adenophorum was higher than that of A. argyi, whereas the P and N:P homeostasis (HP and HN/P) were higher for A. argyi. For E. adenophorum, HN decreased, but HP and HN /P increased with the invasion time. For A. argyi, HN /P increased, HP and HN remained stable with the invasion time. The results demonstrated that E. adenophorum could maintain higher HN during invasion stages when N was limited and could maintain higher HN and HP at invasion stages when P was more limited. This rapid nitrogen and phosphorus homeostasis transformation of invasive E. adenophorum during its invasion stages guarantees its stronger competitive ability over native species and promotes its invasion success.
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| 40. |
- Wiklund, Lena
(författare)
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Existential aspects of living with addiction - Part II: caring needs. : A hermeneutic expansion of qualitative findings
- 2008
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Ingår i: Journal of Clinical Nursing. - : Wiley. - 0962-1067 .- 1365-2702. ; 17:18, s. 2435-2443
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Tidskriftsartikel (refereegranskat)abstract
- AIM: This paper aims to describe caring needs associated with existential aspects of living with addiction. BACKGROUND: Spirituality is considered a driving force within and the concept relates to self, others and God and the relationships between them. The spiritual dimension is of great importance in both the addiction itself as well as in recovery and addressing caring needs relating to spirituality is important in nursing. DESIGN: Hermeneutic inquiry was used to explore caring needs related to peoples experiences of living with addiction. METHOD: This paper is a hermeneutic expansion of findings presented in Part I. Existential themes in the form of spiritual challenges and caring needs are reflected upon as a process between figure and background. RESULTS: The themes presented are: meaning - meaninglessness, connectedness - loneliness, life - death, freedom - adjustment, responsibility - guilt, control - chaos. Caring needs associated with them are identified as; the need to create a new frame of reference for interpreting of life, the need to experience coherence in life, a restored dignity as well as the need for a sense of community and attachment, confirmation and acceptance. The caring need for forgiveness and reconciliation is also identified as well as the need for continuity, comprehensibility and manageability. CONCLUSIONS: When caring for patients suffering from addiction nurses should address patients' spirituality. The caring communion is vital, as it is the foundation for meeting the patients' needs. Intervention by nurses should focus on aspects that will help patients feel alive and in communion with others. RELEVANCE TO CLINICAL PRACTICE: Understanding and being able to identify patients' caring needs associated with existential aspects of living with addiction will enable nurses to provide professional care and promote patient's recovery.
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