© Benaki Phytopathological Institute
Gitsopoulos
et al.
50
ity of summer savory (Gulluce
et al.,
2003).
Concerning the herbicidal activity of savory,
Tworkoski (2002) reported that the essential
oil of
S. hortensis
was phytotoxic and caused
electrolyte leakage resulting in cell death
when applied to detached leaves of dande-
lion
Taraxacum officinale
F. H. Wigg (Aster-
aceae) in the laboratory. Moreover, Angelini
et al
. (2003) showed that the essential oil of
S. montana
completely inhibited germina-
tion both of three crops [
Raphanus sativus
,
Capsicum annuum
L.
(Solanaceae),
Lactu-
ca sativa
] and three different annual weeds
[
Chenopodium album
L.
(Amaranthaceae),
Portulaca oleracea
L.
(Portulacaceae),
Echi-
nochloa crus-galli
L. Beauv
.
(Poaceae)]. Up to
now there is limited information about the
effect of the essential oil of
S. hortenis
and
M. officinalis
on grass weed species. The ob-
jective of this study was to evaluate in labo-
ratory conditions the allelopathic activity of
S. hortensis
and
M. officinalis
essential oils on
germination and root elongation of annual
ryegrass [
Lollium rigidum
L. (Poaceae)] and
short spiked canarygrass [
Phalaris brachys-
tachys
L.
(Poaceae)].
Materials and methods
Essential oils isolation
The plant material, aerial parts of
M. of-
ficinalis
and
S. hortensis,
was collected at
bloom stage from experimental plots of Me-
dicinal and Aromatic Plants Department of
the National Agricultural Research Founda-
tion (NAGREF) in Thessaloniki, Greece (40°
32´ 16.32´´ B, 23° 00´ 00.65´´ E).
Dried upper leaves, 100g and 30 g of
M.
officinalis
and
S. hortensis,
respectively, were
hydrodistilled for two hours with a distillation
rate of 3 to 3.5 mL/min by using a Clevenger–
type apparatus (Chatzopoulou
et al.,
2006).
Essential oil analyses
The essential oil samples were ana-
lyzed by Gas Chromatograph Hewlett Pack-
ard 5890 Series II connected to a chromato-
graphic integrator (Hewlett Packard 3396
Series II Dual Channel). Two fused silica col-
umns of different polarity were used: Dura-
bond-DB 1 and DB-Wax. Temperature pro-
gram: 45 to 220°C at 3.5°C/min, carrier gas
nitrogen: 140Kpa, injection temperature:
220°C, detector temperature 300°C. Sam-
ple injection: 0.2–0.3μl of a 10% essential
oil solution in pentane; split 1:20. The per-
centage compositions were computed after
3 GC runs of each sample from the peak ar-
eas without correction factors. The GC/MS
analysis was performed on a fused silica col-
umn DB-5, using a Gas Chromatograph 17A
Ver. 3 interfaced with a Mass Spectrome-
ter Shimadzu QP-5050A supported by the
Class 5000 software. Injection temperature:
260°C, interface heating: 300°C, ion source
heating: 200°C, EI mode: 70eV, scan range:
41-450 amu, and scan time 0.50s. Oven tem-
perature programs: a) 55-120°C (3°C/min),
120-200°C (4°C/min), 200-220°C (6°C/min)
and 220°C for 5min and b) 60-240°C at 3°C/
min, carrier gas He, 54.8kPa, split ratio 1:30.
Identification of the essential oils com-
ponents
The identification of the constituents
was based on comparison of their Kovats
indices (RI) relative to n-alkanes with corre-
sponding literature data, as far as by match-
ing a) their spectra with those from MS li-
braries (NIST 98) (Adams, 1995) and b) the RT
of co-eluting reference compounds – peak
enrichment technique (authentic samples
by Roth and Sigma Aldrich).
Petri dish bioassay
Petri dish bioassay was performed to
compare the germination and the radical
length of annual ryegrass and shortspiked
canarygrass treated with different concen-
trations of essential oils obtained from
S.
hortensis
and
M. officinalis
. Twenty seeds
of each species were placed separately at
the bottom of 10cm glass Petri dishes and
were covered with 5g of perlite. Deionized
water (12ml) was added in each Petri dish.
Each essential oil was loaded on a piece of
filter paper, which was attached to the in-
ner side of a small aluminum cup placed in
the centre of each Petri dish, at 0, 8, 16, 32
1,2,3 5,6,7,8,9,10,11,12,13,14,...43