排序方式： 共有6条查询结果，搜索用时 218 毫秒
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J C Streibig J Rasmussen D Andújar C Andreasen T W Berge D Chachalis T Dittmann R Gerhards T M Giselsson P Hamouz C Jaeger‐Hansen K Jensen R N Jørgensen M Keller M Laursen H S Midtiby J Nielsen S Müller H Nordmeyer G Peteinatos A Papadopoulos J Svensgaard M Weis S Christensen 《Weed Research》2014,54(3):223-233
Non‐destructive assessment of herbicide effects may be able to support integrated weed management. To test whether effects of herbicides on canopy variables could be detected by sensors, two crops were used as models and treated with herbicides at BBCH 20 using a logarithmic sprayer. Twelve days after spraying at BBCH 25 and 42 days after sowing, nine sensor systems scanned a spring barley and an oilseed rape field experiment sown at different densities and sprayed with increasing field rates of glyphosate and tribenuron‐methyl. The objective was to compare ED50s for crops and weeds derived by the different sensors in relation to crop density and herbicides. Although sensors were not directly developed to detect herbicide symptoms, they all detected changes in canopy colours or height and crop density. Generally ED50s showed the same pattern in response to crop density within herbicide, but there were marked differences between barley and oilseed rape. We suggest that the results of comparing the various sensor outputs could become a stepping stone to future standardisation for the benefit of the research and development of sensors that will detect herbicide effect on crops and weeds, particularly at the most vulnerable stages of development of the canopy. 相似文献
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Ghadir Mohammadi Ebrahim M. Khah Demosthenis Chachalis 《Journal of plant nutrition》2018,41(6):702-715
The effect of nitrogen (N) application rate and sowing date on seed quality and pod production of four cultivars of okra (Abelmoschus esculentus L.) were examined. Seeds of four okra cultivars (cv. ‘Boyatiou’, ‘Veloudo’, ‘Clemson’, and ‘Pylaias’) were sown on 13 May (1st sowing) and 2 June (2nd sowing). Plants were subjected to three N levels: F1, F2, and F3 (150, 300, and 450 mg N L?1). The 2nd sowing improved flower induction and pod set, without however affecting pod size. The number of seeds per pod was not affected by sowing time, but the mean 100 seed weight was generally lower in the 2nd sowing. In all cultivars, except cv. ‘Veloudo’ germination increased in the 2nd sowing mainly as a result of lower seed hardness. Germination was also improved by increasing N levels, or by seed storage, acid scarification, or seed priming. 相似文献
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Hairy fleabane is a weed found increasingly in agronomic crops and rural areas. Although glyphosate resistance is now widespread in this species, the ecological fitness of glyphosate-resistant (GR) and glyphosate-susceptible (GS) populations has not been compared. When seeds of both biotypes were subjected to different alternating temperature, germination occurring and seedling vigor did not differ between the biotypes with maximum germination at 10/20 and 15/25 °C. Under noncompetitive conditions, growth and seed production of the GR and GS biotypes were similar. The competitive ability of the two biotypes, as determined by a replacement series experiment, was also similar. Initially, the relative crowding coefficient (RCC) between the biotypes was close to one. However, the RCC values for each characteristic increased with time indicating that the GR had a small competitive advantage as plants matured. Overall, there was no apparent fitness penalty associated to glyphosate resistance. Therefore, the GR populations are likely to persist unless effective management strategies are adopted. 相似文献
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Ghadir Mohammadi Ebrahim M. Khah Demosthenis Chachalis 《Journal of plant nutrition》2016,39(13):1899-1905
Four okra cultivars [Abelmoschus esculentus (L.) Moench] were cultivated for two growing periods at nitrogen (N) application rates of 150, 300 and 450 mg N L?1. There was no effect of N on pod size (length and diameter) or on the number of seeds per pod and seed size (mean 1000 seed weight), all these characteristics of which related to the genotype. High N application (450 mg N L?1), increased the seed yield of the cultivar with the lowest flower induction (Boyiatiou), but only in experiment 2. In Veloudo, seed yield was highest at 300 mg N L?1, whereas in Pylaias and Clemson 450 mg N L?1 reduced seed yield. In all cultivars, seeds produced at an N rate of 450 mg N L?1 exhibited a significantly higher percent germination N, possibly by reducing the incidence of seed hardness. 相似文献
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