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C.II.3.1.4 Effect of weed seed addition During the first month of the experiment, field emergence rates were always much lower than the densities of viable seeds added to the soil at the beginning of the experiment. However, this ratio showed considerable differences between the weed species, separating three groups of species (Fig. 15). Field emergence densities were about 2-5 times lower than sowing densities for a first group of species including G. aparine, V. persica, G. dissectum, S. media, A. myosuroides, and L. multiflorum. For a second group including C. bursa-pastoris, F. convolvulus, and B. sterilis, emergence rates were about 10 times lower (thus 10-15% emergence). For a third group containing the remaining 8 sown species, only 1-5% of the sown viable seeds emerged during the 8 first month of the experiment (Fig. 15). Emergence density (seedlings m -2 ) 10 8 6 4 2 0 GALAP 1:1 1:2 PAPRH GERDI ALOMY 0 10 20 30 40 Sowing density (viable seeds m -2 ) Fig. 15: Relation between weed sowing density and field emergence densities of 17 weed species. See Table 7 for species codes. Field emergence are means (±SD) of maximum seedling densities on sown microplots during the first 8 month of the field experiment. SD of sowing density corresponds to the variability of seed viability tested in Petri dishes (cf. Table 7). Comparisons of weed emergence densities on sown and unsown micro-plots showed that weed seed addition increased the plant densities of all sown weed species (except C. bursapastoris) during the first month of the experiment ( Fig. 16). The initial positive effect of sowing increased with time for three species (group 1 in Fig. 16 including A. myosuroides, B. sterilis, and G. aparine, thus the species that showed strong population increases in the annual crops). The positive effect of seed addition remained more or less stable for four species (group 2 in Fig. 16 including V. persica, S. arvensis, L. multiflorum and P. rhoeas) and 89 VERPE LOLMU POLCO BROST CAPBP VIOAR SINAR LAMPU CHEAL STEME POAAN ANGAR 1 st group 2 nd group 3 rd group AMARE 1:5 1:10 1:40
Difference sown - unsown (plants m -2 ) 60 40 20 0 -20 decreased with time for eight species (group 3, see Fig. 16 for species names). For most species, the variances of the differences increased with time, probably reflecting the contrasted growth conditions in the nine crop treatments, which were pooled in the analysis shown in Fig. 16. 80 Veronica persica (2) 150 Sinapis arvensis (2) 80 Alopecurus myosuroides (1) 60 40 20 0 100 50 100 0 -50 50 -100 0 29 10 42 0 20 -10 10 -20 0 -30 -10 45 10 5 0 -5 (3) Chenopodium album 15 Amaranthus retroflexus (3) 39 52 63 80 178 204 227 260 297 323 346 374 396 429 512 561 578 609 646 689 764 777 959 Bromus sterilis (1) 30 Anagallis arvensis (3) 40 30 20 10 0 Papaver rhoeas (2) 39 52 63 80 178 204 227 260 297 323 346 374 396 429 512 561 578 609 646 689 764 777 959 200 Galium aparine (1) 150 100 50 0 -20 -40 -60 -80 0 60 40 20 20 15 10 5 0 -5 -10 30 5 0 -5 -10 -15 90 (3) Stellaria media (3) Geranium dissectum (3) Viola arvensis 39 52 63 80 178 204 227 260 297 323 346 374 396 429 512 561 578 609 646 689 764 777 959 33 20 0 -20 -40 40 20 0 -20 34 20 0 -20 -40 -60 (3) Fallopia convolvulus Lolium multiflorum (2) (0) Capsella bursa-pastoris 8 Poa annua (3) 2006 2007 2008 2009 Time (days after sowing) 2006 2007 2008 2009 Fig. 16: Effect of weed seed addition on plant density of 16 weed species during the 2-years experiment. The graphs show absolute differences of plant densities between adjacent sown and unsown plots; N varies between 15 and 24 for each date, double zeros are not plotted. Positive differences indicate that the sown plots had higher weed densities. Arrows () indicate the total density of seeds sown at the beginning of the experiment (Table 7). Species are sorted by their frequency of occurrence (Veronica persica, most frequent; Poa annua, least frequent, Lamium purpureum germinated only very rarely and is not shown). C.II.3.1.5 Dynamics of weed and crop biomass 32 6 4 2 0 -2 -4 -6 39 52 63 80 178 204 227 260 297 323 346 374 396 429 512 561 578 609 646 689 764 777 959 During the 2.5-years experiment, absolute and relative weed biomass decreased in the perennial crop treatments and increased in the annual crop treatments (Fig. 17 and Fig. 18). During the first month after perennial crop sowing (autumn 2006 or spring 2007), all 6
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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
Page 61 and 62: 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: At the end of the experiment in spr
Page 115 and 116: Cumulated BM production (g m -2 ) 1
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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Tableau 1 : Liste des espèces adve
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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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