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

B.III.2.4 Cutting height
In 2008, the effect of cutting height was tested for four species (containing crops and weeds,
grasses and broadleaved species). Seven treatments were compared varying by the cutting
height and the quantity of leaves and buds remaining after cutting (Bonnot, 2008).
B.III.2.5 Interactions between cutting and competition
In 2008, interactions between cutting and competition were analyzed for plants of 12 weed
species grown in small experimental plant communities. Cutting and competition treatments
were crossed using a 2x2 factorial design where the potential interactions could be analyzed
(Article 5).
B.III.3 Cutting treatment and data collection
In all experiments except the tests of cutting height, plants were manually cut at a standardized
height (about 5 cm above soil surface) using a pair of scissors. As a control, 4 supplementary
plants of each species were left uncut to compare their productivity with the cumulated
productivity of cut plants (see details in Article 4). In some experiments, the cutting treatments
were repeated several times, i.e. regrown shoots were repeatedly cut at the same height to
analyze long-term effects. For each species and experimental modality, at least 4 replicate
plants were used, in some experiments up to 12.
Weed regrowth was characterized by measuring the aboveground biomass production until the
next cutting. Moreover, non-destructive measurements of the plant height and the leaf area
were used in some experiments to record regrowth dynamics between the cuttings. The leaf
area was determined by image analysis of plant photos in collaboration with two master
students co-supervised by the present author, Frederic Henriot (2007), and Rémi Bonnot
(2008), see also Article 4 for details.
B.IV FIELD EXPERIMENTS ANALYZING WEED SEED PREDATION
B.IV.1 Rationale
Unlike most annual crops, PFCs are characterized by the complete absence of soil tillage as
well as permanent vegetation during several years. Both characteristics may have various
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