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perennial crop treatments showed rather high weed biomasses (Fig. 18). For both spring-sown perennial crops and for the autumn sown cocksfoot crops, weed biomasses exceeded crop biomasses during the first months after crop sowing, while they were lower in both autumn sown alfalfa crops, which showed a quicker and more homogeneous initial crop establishment. After the first hay cutting, the proportion of weed biomass decreased strongly in nearly all perennial crop treatments. After 2-3 cutting operations, weeds accounted for no more than 1- 20% of total biomass and decreased further to 0% in most treatments and replicate plots (Fig. 18). These decreases tended to be quicker (a) for all plots with the higher cutting frequency (5 cuts/year) and (b) in the three cocksfoot crop treatments, where weed biomass decreased often to 0% already during the first year (2007) and stayed that low until the end of the experiment. In contrast, substantial weed biomasses re-appeared in some alfalfa plots during the second year (2008), especially in those with the low cutting frequency (3 cuts/year). In general, all weed species showed a higher mortality and a much weaker regrowth capacity after cuttings than both perennial crop species. However, the biomass of broad-leafed weeds often decreased more quickly than the biomass of grasses. Until the first cut in 2008, grasses (mainly B. sterilis and A. myosuroides) accounted for 20 to 60% of the biomass in alfalfa with a low cutting frequency. Most of these grass plants germinated already in autumn 2007, survived the winter but disappeared at the first cutting in 2008. This ‘problem’ did not appear in any cocksfoot crop treatment nor in the spring and autumn sown alfalfa with the higher cutting frequency, where weed densities accounted for only 0-15% of the total biomass in 2008 and decreased further with time ( Fig. 18). While all perennial crops showed decreasing weed biomass during the experiment, the opposite was true for annual crops, where broad-leaved weed species including Galium aparine, Polygonum sp., and Sinapis arvensis as well as grasses such as A. myosuroides showed increasing biomass during the two years ( Fig. 17, Fig. 18). In the first year (2007), most of the winter wheat plots showed much lower weed biomasses than the perennial crops, weeds accounted for 0-20% of total biomass. This proportion was much higher in 2008, where mainly dicotyledonous weeds accounted for up to 40% of the total aboveground biomass (Fig. 17, Fig. 18). 91
Cumulated BM production (g m -2 ) 1400 1200 1000 800 600 400 200 0 2007 2008 2007 2008 2007 2008 2007 2008 92 2007 2008 2007 2008 2007 2008 T2 T4 T5 T6 T7 T8 T9 Treatments & Years Fig. 17: Cumulated crop and weed biomass production in 2007 and 2008 in different crop treatments. Crop BROST ALOMY LOLMU Other grasses VERPE STEME SON SINAR POL GERDI GALAP CHEAL AMARE Other dicots T2-T5, perennial alfalfa crop; T6-T8, perennial cocksfoot crop; T9, annual cereal crops (winter wheat in 2006- 2007, spring barley in 2008). See Table 6 for details on the crop treatments. Weed biomass is separated to grasses (striped, above) and dicotyledonous species (not striped, below), 12 important weed species/genera are separated with a colour code, all other species with lower biomasses are grouped as ‘other Grasses’ and ‘other Dicots’.
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Diversifying crop rotations with te
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In Chizé, I am indebted to all the
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Talks . ...........................
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C.II.4.1 Differences between crop t
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INDEX OF FIGURES Fig. 1: Population
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ABSTRACTS (ENGLISH, FRENCH & GERMAN
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Extended summary in English Résum
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Extended summary in English Résum
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CONTEXT AND FUNDING This thesis is
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THESIS ORGANISATION This thesis ent
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8) Meiss, H., Lagadec, L. L., Munie
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Posters . 1) Meiss, H., Waldhardt,
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2007). Agriculture is increasingly
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term considerations (Munier-Jolain
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problematic for the production of d
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Newton, 2004). Several bird species
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A.III APPROACHES TO ALLEVIATE THE
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and higher production costs or even
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competitive yield loss (Cousens, 19
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2006; Makowski et al., 2007). Moreo
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Table 3: Four strategies for combin
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otations is thus an obvious approac
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iv) the availability of cheap and e
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Clay & Aguilar (1998) compared the
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Heggenstaller & Liebman (2006) comp
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growth of any (crop or weed) plant
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A.V DIVERSIFIED CROPPING SYSTEM CON
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crops will thus probably show rathe
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annual crops while increasing organ
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• Which species are suppressed, w
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B OVERWIEW OF THE MATERIALS & METHO
Page 63 and 64: A) France B) Study site ~1000 km Pe
Page 65 and 66: perennial crops with different mana
Page 67 and 68: B.III.2.4 Cutting height In 2008, t
Page 69 and 70: B.IV.3 Design of the seed predation
Page 71 and 72: Agron. Sustain. Dev. 30 (2010) 657-
Page 73 and 74: Contrasting weed species compositio
Page 79 and 80: Mean frequency in perennial lucerne
Page 81 and 82: C.I.2 Article 2: Meiss, H., Médiè
Page 83 and 84: 332 H Meiss et al. communities (Boo
Page 85 and 86: 334 H Meiss et al. functional group
Page 87 and 88: 336 H Meiss et al. Table 3 Indicato
Page 89 and 90: 338 H Meiss et al. Relative frequen
Page 91 and 92: 340 H Meiss et al. MEISS H, MUNIER-
Page 93 and 94: perennial crop treatments, differen
Page 95 and 96: PFCs might inhibit the successful g
Page 97 and 98: during winter), T10 without soil ti
Page 99 and 100: The viability and germination abili
Page 101 and 102: Table 8: Organic carbon and total n
Page 103 and 104: The development of weed species ric
Page 105 and 106: C.II.3.1.2 Dynamics of weed communi
Page 107 and 108: C.II.3.1.3 Dynamics of individual w
Page 109 and 110: Time Fig. 14: Temporal development
Page 111 and 112: At the end of the experiment in spr
Page 113: Difference sown - unsown (plants m
Page 117 and 118: Weed biomass (g m -2 ) 500 400 300
Page 119 and 120: Table 12: Factors differing between
Page 121 and 122: However, some differences in densit
Page 123 and 124: Table 13: Mechanisms causing the im
Page 125 and 126: 2007 and 2008, while big numbers of
Page 127 and 128: • Weed biomasses decreased in sum
Page 129 and 130: Our results show that different mec
Page 131 and 132: including exotic species (Palmer an
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Page 141 and 142: XIII ème COLLOQUE INTERNATIONAL SU
Page 143 and 144: irradiation,…), and (ii) biotic i
Page 145 and 146: Table I: Species included in the ex
Page 147 and 148: Fig. 2: Mean biomass (harvestable d
Page 149 and 150: When both treatments were combined,
Page 151 and 152: C.IV WEED SEED PREDATION C.IV.1 Art
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Page 159 and 160: XIII ème COLLOQUE INTERNATIONAL SU
Page 161 and 162: produites restent à la surface du
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Insectes prédateurs Les principaux
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C.IV.3 Article 8: Meiss, H., Lagade
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Table 1 Studies investigating the i
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Table 2 Overview showing (i) mean s
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higher weed seed losses (e.g., Mena
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D GENERAL DISCUSSION Data from weed
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The first two limits could be addre
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composition that may be compared to
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Frequency in field experiment (Epoi
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crops (Clay and Aguilar, 1998; Card
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Such diversified crop rotations cou
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the leaves (needed for photosynthes
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field margin strips (compare Articl
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1) The absence of soil tillage and
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D.III.2 Predicting weed regrowth af
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Future studies must determine the s
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(illustrated in Fig. 24). Later, re
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D.III.3 Factors determining weed se
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governing the presence and abundanc
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natural conditions, weed species po
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This PhD research project documente
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area needed for crop production. Gl
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seed characteristics, tillage and s
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Fried G., S. Petit, F. Dessaint, X.
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at the Eastern base of the Meissner
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Lindegarth M., L. Gamfeldt. (2005)
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Murphy S.D., D.R. Clements, S. Bela
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affected by experimental substrate.
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Vincent G., M. Ahmim. (1985) Note o
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ANNEXES ANNEXE 1: KEY WORDS IN ENGL
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genetically modified crop varieties
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ANNEXE 3: WEED SPECIES OF THE LARGE
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Name of species /genera Code Freq.
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Name of species /genera Code Freq.
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ERKLÄRUNG (DECLARATION FOR THE GIE
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