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| Rasmussen, Jesper; Mathiasen, Helle; Bibby, Bo Martin. |
| The timing of post-emergence weed harrowing was evaluated for two years in spring barley with crop-weed selectivity and crop recovery as the key parameters measured. selectivity describes the relationship between weed control and crop soil cover immediately after harrowing, with crop soil cover as the percentage of the crop that has been covered by soil due to harrowing. Crop recovery describes the relationship between crop yield loss and crop soil cover in the absence of weeds. Neither selectivity nor crop recovery was affected by timing within a period of two weeks in the early growth stages of spring barley. Selectivity was unaffected by year and 80% weed control was associated with crop soil cover in the range of 23–33%, for all combinations of year... |
| Tipo: Journal paper |
Palavras-chave: Weed management. |
| Ano: 2010 |
URL: http://orgprints.org/17844/4/17844.pdf |
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| Rasmussen, Jesper; Bibby, Bo Martin; Schou, Anders P.. |
| In six field experiments it was investigated whether row spacing, timing, direction and orientation of post-emergence weed harrowing in spring barley influenced the selectivity and whether it is important that increasing intensities of harrowing are generated either by increasing number of passes or increasing driving speed. Selectivity was defined as the relationship between crop burial in soil immediately after treatment and weed control. To estimate crop burial, digital image analysis was used in order to make the estimations objective. The study showed that narrow row spacing decreased selectivity in a late growth stage (21) whereas row spacing in the range of 5.3 cm to 24 cm had no effects in an early growth stage (12). Harrowing across rows decreased... |
| Tipo: Journal paper |
Palavras-chave: Weed management; Technology transfer. |
| Ano: 2008 |
URL: http://orgprints.org/14987/1/14987.pdf |
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| Rasmussen, Jesper; Nørremark, Michael; Bibby, Bo Martin. |
| A web-based digital image analysis tool (IMAGING Crop Response Analyser) has been developed, tested and made public (www.imaging-crops.dk). This new technology makes possible objective estimations of crop-soil cover (i.e. how much crop is buried with soil) associated with post-emergence weed control with spring tine harrows, rotary hoes and other weeders. Objective estimation of crop-soil cover offers new possibilities to improve decision support of physical weed control practises with low selectivity because trade-offs between weed control and resulting injury to the associated crop now may be quantified, communicated and incorporated into models. The objective of this resentation is to suggest key parameters and research priorities for future research... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Weed management; Technology assessment. |
| Ano: 2008 |
URL: http://orgprints.org/13688/1/13688.pdf |
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| Rasmussen, Jesper; Nørremark, Michael; Bibby, Bo Martin. |
| Objective assessment of crop soil cover, defined as the percentage of leaf cover that has been buried in soil due to weed harrowing, is crucial to further progress in post-emergence weed harrowing research. Up to now, crop soil cover has been assessed by visual scores, which are biased and context dependent. The aim of this study was to investigate whether digital image analysis is a feasible method to estimate crop soil cover in the early growth stages of cereals. Two main questions were examined: (1) how to capture suitable digital images under field conditions with a standard high-resolution digital camera and (2) how to analyse the images with an automated digital image analysis procedure. The importance of light conditions, camera angle, size of... |
| Tipo: Journal paper |
Palavras-chave: Weed management. |
| Ano: 2007 |
URL: http://orgprints.org/11007/1/11007.pdf |
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