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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<strong>crop</strong>s, some species including Poa annua showed an intermediate behaviour in both studies,<br />
and only few species showed inconsistent reactions between the studies (see Fig. 21 for<br />
<strong>de</strong>tails). This result is remarkable, as the two studies differed in several aspects. While the<br />
Chizé study compared perennial alfalfa <strong>crop</strong>s <strong>with</strong> six different annual <strong>crop</strong>s (<strong>with</strong> various<br />
sowing dates) inserted in various <strong>crop</strong> <strong>rotations</strong> <strong>with</strong> a big variability in <strong>crop</strong> management<br />
practices (herbici<strong>de</strong>s, soil tillage, sowing and cutting dates…) and in natural conditions in the<br />
region, the Epoisses experiment compared only one succession of annual cereal <strong>crop</strong>s <strong>with</strong><br />
two PFC species, alfalfa and cocksfoot, <strong>with</strong> different management practices (but all <strong>with</strong>out<br />
herbici<strong>de</strong>s) and a rather homogeneous weed species pool (weed seed adding at the beginning).<br />
For instance, the high frequencies of Echinochloa crus-galli (ECHCG) and A. retroflexus<br />
(AMARE) in perennial <strong>crop</strong>s of the Epoisses experiment (Fig. 21) occurred only in the springsown<br />
and never in the autumn-sown perennial <strong>crop</strong>s. Such weed species would probably find<br />
good emergence and growing conditions in summer-sown annual <strong>crop</strong>s which were not<br />
inclu<strong>de</strong>d in the Epoisses experiment. Alopecurus myosuroi<strong>de</strong>s (AMOMY) was clearly<br />
associated <strong>with</strong> the annual cereal <strong>crop</strong>s in the Epoisses experiment. In the Chizé surveys, this<br />
species appeared <strong>with</strong> equal frequencies in annual and perennial <strong>crop</strong>s. Its frequency in annual<br />
<strong>crop</strong>s was probably lowered due to the fact that the six annual <strong>crop</strong>s of the large-scale study<br />
inclu<strong>de</strong>d also 3 spring/summer-sown <strong>crop</strong>s, where this species rarely grows. However, the<br />
reason why Veronica persica (VERPE) was associated <strong>with</strong> alfalfa in Chizé and <strong>with</strong> annual<br />
<strong>crop</strong>s in the Epoisses experiment is still unclear.<br />
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