The aromatic plant Melissa officinalis and effects of its aqueous extracts on summer annual and invasive weed species
Kokkuvõte
The effects of aqueous extracts of the aromatic plant Melissa
officinalis were studied on the seed germination and early seedlings growth
of ten summer annual species in Petri dish bioassays and pot experiments.
The in vitro experiments on the aqueous extracts from M. officinalis on seed
germination shows that the extracts of 5 and 10% were the most active
inhibitors for all the studied weed species. Seed germination reduction by
the aqueous extracts was up to 54% of the untreated seed lot for each species.
On the contrary, the concentration of 1% resulted in germination reduction
ranging from 1 to 11%, while in some of the weed species (P. minor, S.
nigrum, P. angulata and C. albida) the effect was rather stimulatory. This
finding is in full agreement with “novel weapons hypothesis” and supports
that native plants compared with invasive (like C. albida and P. angulata)
are affected more due to the absence of tolerance or resistance to the
allelochemicals. The allelopathy RI of aqueous extracts of lemon balm was
negative in most cases, while in the case of 10% concentration, emergence
was reduced by 58, 54, 48, 46 and 43% for X. strumarium, C. album, S.
faberi, C. canadensis and C. bonariensis, respectively. The allelopathic
activity of M. officinalis could be exploited in future studies, to identify and
isolate the allelochemicals, as models for future herbicides for integrated
weed management.