Diversifying crop rotations with temporary grasslands - Université de ...

2001), field margin strips (De Cauwer et al., 2005), permanent grasslands (Magda et al.,
2003), in-row mowing for weed control in annual row crops (Donald, 2000; , 2007) or
vineyards and mowing of cereal crops at harvest. Weed shoots may also be destroyed by
grazing, which is sometimes specifically used for weed control (Gill and Holmes, 1997), but
grazing is generally less homogeneous concerning the height, space and time of the
disturbance than mowing. Despite this variety of situations, the regrowth capacity of weed
plants has rarely been studied and the factors determining plant survival, growth and
reproduction after cutting are not well known.
B.III.2 Design of the greenhouse experiments
From the list of hypothetical variables (see introduction and Tab. 1 of Article 4), the impacts
of (1) weed species, (2) plant size, (3) plant age, (4) cutting height, and (5) interactions
between cutting and competition on the regrowth ability of weed (and crop) plants were
investigated by specific experiments conducted in 2007 (Article 4) and 2008 (Article 5 and
Bonnot, 2008, master I thesis co-supervised by the present author).
B.III.2.1 Differences between species
In 2007, the regrowth capacity was compared between 10 plants species (containing grasses
and broadleaved species, annual and perennial species, crops and weeds, see Article 4 for
details). In 2008, 16 species representing the same functional groups were compared in the
same way (Bonnot, 2008).
B.III.2.2 Plant biomass
The impact of plant biomass before cutting was assessed for 10 species in 2007 (Article 4) and
for 4 species in 2008. To increase the intraspecific variability in plant biomass before cutting,
parts of the plants were placed in partial shadow (Article 4).
B.III.2.3 Plant age
The effect of plant age was tested for 2 species in 2007 and for 4 species in 2008. In 2007,
plants sown at three dates (differing by 3 weeks each) were cut at the same date (Article 4). In
2008, plants sown at the same date were cut at 4 dates (differing by 4 weeks) (Bonnot, 2008).
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