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

Future studies must determine the shapes of these different relationships and the validity for a
bigger number of species. For simplicity in the model, linear negative relationships with plant
age may be assumed. However, the start of flowering or seed production might also cause
somewhat abrupt decreases in the regrowth abilities for some species (illustrated in Fig. 23)
which should be tested in future by comparing the regrowth capacity of a bigger variety of
plant ages and stages.
B
Species 1
Species 2
↓ Flowering
Plant age
Fig. 23: Possible relations between the plant age and the plant’s regrowth ability after cutting determined by the
‘quantity of carbohydrate resources that can be remobilized for regrowth’ (B) [g d°day -1
].
C, the ‘presence of intact buds/meristems for regrowth’, depends equally on the cutting height
and the plant morphology (vertical distribution of buds in this case). As for ‘A’, the plant
morphology would depend on the species (functional group), plant age at cutting date and the
general growth conditions. While FLORSYS simulates the plant height and the vertical
distribution of leaf area for each individual plant, the position of buds is currently not included
in the model and rarely investigated by experimental studies. Concerning the interspecific
variation, botanists and weed scientists might categorize most of the frequent weed species
into ‘functional groups’ according to their morphology which may give first approximations
for the vertical position of buds for different species. It is clear that the meristems of all grass
species (from the Poaceae family) lie always near to (or below) the soil surface and are thus a
priori not affected by hay cuttings. In contrast, buds of broadleaved species with an upright or
climbing morphology may be partly or totally destroyed by cuttings (see e.g. the fate of
Chenopodium album and Amarantus retroflexus after cutting in the greenhouse experiments)
while broadleaved species with rosettes, a creeping morphology, a small size or many
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↓ Seed production