Relationship between seed bank and actual weed flora as influenced by soil tillage and chemical control [Triticum aestivum L. - Emilia-Romagna]
2000
Baldoni, G. | Catizone, P. | Viggiani, P (Bologna Univ. (Italy). Dipartimento di Agronomia)
To optimise weed management practices, decision models require the knowledge of how soil tillage and chemical control influence weed population. Their effects on weed emergence and infestation from a known seedbank were studied in this research. 25 cm ploughing, 10 cm disking and no-tillage were compared on winter wheat with and without herbicides. At crop planting, weed seeds in the 0-12 cm layer of soil were counted. Seedling emergence from February to June was monitored in permanent areas kept free of wheat interference. Weed density was also assessed in treated and untreated crop. Density and composition of seedlings emerged without crop interference was correlated with seedbank. Aboveground flora in untreated wheat was less than this potential population and showed a different specific composition. Although tillage was confirmed as favouring emergence, there were more weeds in sod seeding. This could be ascribed both to a denser seedbank and lower herbicide efficacy. The poor chemical control was also due to delayed emergence in no tillage, which allowed more weeds to escape post-emergence treatment. Crop has a major importance in regulating the pattern and magnitude of weed emergence. In no-tillage, soil conditions are anfavourable to weed emergence, however a reduced herbicide efficacy encourages a higher chemical input. This efficacy can be improved by taking into account weed emergence
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