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

D.III.2 Predicting weed regrowth after cutting
According to the experimental results and discussions in Articles 4 and 5, the regrowth
capacity of a given plant would depend on four main factors:
A) the green area remaining after cutting, determining the photosynthesis activity immediately
after cutting,
B) the carbohydrate resources that can be remobilized from roots and stubbles for regrowth (to
substitute the lack of resources and energy derived from photosynthesis due to the suppression
of leaves),
C) the presence of intact buds/meristems where regrowth can start, and
D) the general growth conditions (see Table 1 and references in Article 4).
The probability of plant survival and the regrowth speed after cutting (‘regrowth index’ R)
would thus be a (complex) function of these four factors. The simplest function might have the
following form:
R = (A + B) * C * D
Three cases might lead to R = 0 (no regrowth, plant dies):
v) A+B = 0 (no leaf area remaining for photosynthesis and no carbohydrate resources
available for remobilisation),
vi) C = 0 (no buds remaining for regrowth), or
vii) D = 0 (too bad general growth conditions).
In a simulation model, these four basic factors (A-D) would be determined by various
underlying variables including i) the plant species (functional group), ii) the individual plant
size (biomass), morphology (position of leafs and buds), and age (stage) at cutting date, iii) the
cutting height, cutting dates and frequency, and iv) abiotic and biotic conditions determined
by soil and climate variables, competition, parasitism, symbioses, crop and weed management.
Most of these variables affect several of the four basic factors simultaneously (summarized in
Table 1 of Article 4). Preliminary propositions how the four factors (A-D) might be simulated
in a model are detailed in the following four paragraphs:
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