The aimof this work was to study the changes during 15 days in the monoterpene emission rates of the Mediterranean
shrub rosemary (Rosmarinus officinalis L.), in response to increasing drought stress and fertilisation using
two different composts derived fromlivestock anaerobic digestates (cattle and pig slurry). Drought stress considerably
reduced photosynthetic rates, stomatal conductance and isoprenoid emissions and also induced a change
in blend composition. In the drought stressed rosemary plants, a positive relationship of non-oxygenated monoterpene
emissions and a negative relationship of oxygenated monoterpene with photosynthesis were observed,
indicating a different control mechanism over theemissions of the twotypes of isoprenoids. The emission of nonoxygenated
monoterpenes seemed to depend more on photosynthesis and “de novo” synthesis, whereas emission
of oxygenate monoterpenes was more dependent on volatilisation from storage, mainly driven by cumulative
temperatures. In the short term, the addition of composted organic materials to the soil did not induce a
significant effect on isoprenoid emission rates in the rosemary plants. However, the effect of the interaction
between fertilisation and seasonality on isoprenoid emission rates was influenced by the amendment origin.
Also, we emphasized changes in potential isoprenoid emission factors throughout the experiment, probably indicating
changes in the leaf developmental stage