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