Crop and density effects on weed beet growth and reproduction |
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| Authors: | M Sester M Delanoy N Colbach & H Darmency |
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| Institution: | Institut National de la Recherche Agronomique, U.M.R. Biologie et Gestion des Adventices, 17 rue Sully, BP 86510, 21065 Dijon Cedex, France |
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| Abstract: | Weed beet populations growing in each crop of the arable rotation could be a relay for the gene flow from adjacent transgenic herbicide‐resistant sugarbeet. In this study, weed beet growth and reproduction were assessed under several conditions which could be found in the rotation: various weed beet densities (ranging from 1 to 120 plants m?2) and various crops (winter wheat, spring barley, spring pea, sugarbeet, maize, ryegrass). Measurements were carried out both on life‐cycle dynamics (bolting time, time to flowering onset, dynamics of flower opening) and on other quantitative data (survival rate, bolting rate and pollen, flower and seed production). Increasing weed beet density resulted in decreases in bolting rate and flower and seed production per plant. In cereals, weed beet establishment and reproduction were strongly reduced, compared with bare ground as a control situation. In pea, there was no effect on establishment, but the early harvest limited seed set. In the other crops, flower and seed production were reduced to a lesser extent. Parameters of the fitted equations on the bolting and flowering progress were modified by the weed beet density and by the crop. Our data may be used in a model predicting weed beet demographic evolution according to cropping system, and in assessing gene flow. |
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| Keywords: | weed beet gene flow competition density rotation sugarbeet seed production model transgenic crop risk assessment |
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