Baličević Renata, Ravlić Marija, Lucić Ivana *
,
Marić Katarina *
, Nikolić Marina
*
, Bule Sanjin
*
,
Topić Ivan *
Faculty of Agriculture in Osijek, Kralja Petra Svačića 1d, 31000 Osijek, Croatia (mravlic@pfos.hr)
*
Student, Graduate study
Abstract
The aim of the study was to determine allelopathic effect of chamomile ( Matricaria chamomilla L.) on germination and initial growth of weed species hoary cress ( Cardaria draba (L.) Desv.). Two experiments were conducted under laboratory conditions to determine effect of cogermination of chamomile and hoary cress seeds and effect of chamomile water extracts. Water extracts from fresh and dry chamomile biomass in concentrations of 5 and
10% (50 and 100 g of biomass per litre) were investigated. Chamomile seeds in cogermination with hoary cress showed inhibitory effect on weed seeds germination, up to 10.8%, while no significant effect on growth parameters was observed. Extracts from fresh and dry chamomile biomass showed inhibitory effect on germination, root and shoot length and fresh weight of hoary cress. With the increase of concentration, the measured parameters proportionately decreased. Extract from dry chamomile biomass in 10% concentration had the highest effect, completely inhibiting (100%) weed fresh weight and root and shoot length. On average, extracts from dry biomass had higher allelopathic potential compared to extracts from fresh chamomile biomass.
Key words: allelopathy, chamomile ( Matricaria chamomilla L.), hoary cress ( Cardaria draba
(L.) Desv.), cogermination, water extracts
Introduction
Excessive use of chemical herbicides leads to various problems in weed control (weed resistance, herbicides residues), environmental pollution and adverse effects on human and animal health (Singh et al., 2003, Baretto et al., 2000). Such problems could be minimized and overcome with the use of alternative measures, such as allelopathy. Allelopathy is defined as any direct or indirect harmful or beneficial effect of one plant, fungus or microorganism on the other ones through production of allelochemicals that escape into the environment (Rice,
1984).
Allelopathically active crops can be utilized in different ways and currently aromatic and medicinal plants are investigated as potential allelochemical crops in weed supression as i.e. water extracts, essential oils, soil incorporated green manure (Đikić 2005b, Dudai et al.,
1999, Dhima et al., 2009).
The aim of the study was to determine allelopathic potential of chamomile ( Matricaria chamomilla ) on weed species hoary cress ( Cardaria draba (L.) Desv.) through cogermination and use of water extracts.
Materials and methods
Two experiments were conducted in 2013 in the Laboratory of Phytopharmacy at the Faculty of Agriculture in Osijek.

Seeds of chamomile were purchased from seed company and weed seeds of hoary cress were collected during 2013 from agricultural fields in Osijek-Baranja County. The weed seeds were surface-sterilized for 20 min with 1% NaOCl (4% NaOCl commercial bleach), then rinsed three times with distilled water (Siddiqui et al., 2009). Chamomile plants were in full flowering stage corresponding to phenological stage 6/65 (Hack et al., 1992.). Fresh biomass was shade dried, cut into small pieces and ground with electronic grinder into fine powder.
In the first experiment the effect of cogermination of chamomile and weed seeds was investigated according to Đikić (2005a). Thirty seeds of both chamomile and hoary cress were placed in Petri dishes (9 cm diameter) on top of filter paper soaked in distilled water. Control treatment consisted of 30 weed seeds per dish.
In the second experiment the effect of chamomile water extracts on hoary cress was evaluated.
The extracts were prepared according to Norsworthy (2003) from fresh and dry aboveground mass of chamomile. One hundred grams of fresh or dry biomass was mixed with 1000 ml of distilled water and kept for 24 h at room temperature. The mixtures were filtered through muslin cloth to remove debris and after that through filter paper. The obtained extracts were diluted with distilled water to give final concentrations 5 and 10% (50 and 100 g of biomass per litre). Thirty seeds were placed in sterilized Petri dishes (9 cm in diameter) on top of filter paper. In each Petri dish the equal amount of certain extract was added, while distilled water was used in control.
In both experiments Petri dishes were kept at room temperature (22 °C ± 2) for 9 days. All treatments had four replications and experiments were conducted twice. Allelopathic effect was evaluated at the end of experiments through number, length of root and shoot (cm) and fresh weight (g) of weed seedlings. Germination percentage was calculated for each replication using the formula: G = (Germinated seed/Total seed) x 100. The collected data were analysed statistically with ANOVA and differences between treatment means were compared using the LSD-test at probability level of 0.05.
Results and discussion
Chamomile seeds showed allelopathic effect on germination and growth parameters of hoary cress (Table 1). Germination of hoary cress was significantly decreased, for 10.8%, compared to the control. Both root and shoot length of weed were reduced, but not significantly.
Contrary, fresh weight of hoary cress was slightly stimulated, for 7.1%.
Table 1. Effect of cogermination on germination, seedling length and fresh weight of hoary cress
Treatment Germination (%) Root length (cm) Shoot length (cm) Fresh weight (g)
Control 77.5 a 2.72 a 1.89 a 0.014 a
Cogermination
(chamomile + 69.1 b 2.40 a 1.81 a 0.015 a hoary cress)
Means followed by the same letter within the column are not significantly different at P<0.05.
Cogermination of seeds of aromatic and medicinal plant and weeds can have both negative
(inhibitory) and positive (stimulatory) effect on weeds. The effect depends on crop and weed

species (Đikić, 2005a). According to Ravlić et al. (2013b) other aromatic plants in cogermination have potential to reduce germination of hoary cress, such as basil coriander and lovage, but have no significant effect on other growth parameters.
Table 2.
Effect of chamomile water extracts on germination, seedling length and fresh weight of hoary cress
Chamomile biomass in water, g/l
0
50
100
Average
Germination (%)
Fresh biomass
75.8 a
67.9 ab
61.6 b
68.4 A
Dry biomass
75.8 a
9.90 b
9.10 b
31.6 B
Fresh weight (g)
Fresh biomass
0.029 a
0.015 b
0.008 b
0.017 A
Dry biomass
0.029 a
0.003 b
0.000 b
0.011 B
Chamomile biomass in water, g/l
0
50
100
Root length (cm)
Fresh biomass
2.44 a
2.29 a
1.10 b
Dry biomass
2.44 a
0.19 b
0.00 b
Shoot length (cm)
Fresh biomass
2.48 a
2.57 a
1.32 b
Dry biomass
2.48 a
0.40 b
0.00 c
Average 1.94 A 0.88 B 2.13 A 0.96 B
Means followed by the same letter within the column (lower case letters) or in rows (capital letters) are not significantly different at P<0.05.
Water extracts from fresh and dry chamomile biomass showed negative allelopathic effect on hoary cress (Table 2). Germination was inhibited from 10.4 to 87.9%. Both extracts and concentrations showed significant decrease of fresh weight of hoary cress compared to the control. The highest concentration of dry biomass extract reduced root and shoot length for
100%. Higher concentrations of fresh biomass extracts reduced root and shoot length for 54.9 and 46.8%, respectively. Extract from fresh biomass in 5% concentration slightly stimulated shoot growth of weed seedlings. Đikić (2005b) also reported that water extracts from fresh chamomile biomass have inhibitory effects on germination and seedlings weight of Galinsoga parviflora and Echinochloa crus-galli .
Regardless of concentration, extracts from fresh chamomile biomass showed statistically lower inhibitory effect (around 50%) on hoary cress. Differences among extracts prepared from fresh or dry biomass were also observed by Marinov-Serafimov (2010) and Ravlić et al.
(2013a).
Conclusions
The results showed that chamomile had certain allelopatic effect, inhibitory and stimulatory, on weed species hoary cress. Cogermination affected only weed seed germination. Water extract had greater impact on germination and seedling growth. Higher concentrations of

chamomile biomass had the greatest inhibitory effect. Extracts from fresh and dry chamomile biomass differed in their inhibitory potential. Since the experiments were conducted in Petri dishes, further studies in pots and under filed conditions are necessary to fully determine chamomile allelopathic effect.
References
1.
Barreto, R., Charudattan, R., Pomella, A., Hanada, R. (2000): Biological control of neotropical aquatic weeds with fungi. Crop Protection, 19: 697–703.
2.
Dhima, K.V., Vasilakoglou, I.B., Gatsis, Th.D., Panou-Pholotheou, E.,
Eleftherohorinos, I.G. (2009): Effects of aromatic plants incorporated as green manure on weed and maize development. Field Crops Research, 110: 235-241.
3.
Dudai, N., Poljakoff-Mayber, A., Mayer, A.M., Putievski, E., Lerner, H.R. (1999):
Essential oils as allelochemicals and their potential use as bioherbicides. Journal of
Chemical Ecology, 25(5): 1079-1089.
4.
Đikić, M. (2005a): Allelopathic effect of cogermination of aromatic and medicinal plants and weed seeds. Herbologia, 6(1): 15-24.
5.
Đikić, M. (2005b): Allelopathic effect of aromatic and medicinal plants on the seed germination of Galinsoga parviflora, Echinochloa crus-galli and Galium molugo .
Herbologia, 6(3): 51-57.
6.
Hack, H., Bleiholder, H., Buhr, L., Meier, U., Schnock-Fricke, U., Weber, E.,
Witzenberger, A. (1992): Einheitliche Codierung der phänologischen
Entwicklungsstadien mono- und dikotyler Pflanzen – Erweiterte BBCH-Skala,
Allgemein. Nachrichtenbl. Deut. Pflanzenschutzd., 44: 265-270.
7.
Marinov-Serafimov, P. (2010): Determination of Allelopathic Effect of Some Invasive
Weed Species on Germination and Initial Development of Grain Legume Crops.
Pesticides and Phytomedicine, 25(3): 251-259.
8.
Norsworthy, J.K. (2003): Allelopathic Potential of Wild Radish ( Raphanus raphanistrum ). Weed Technology, 17: 307-313.
9.
Ravlić, M., Baličević, R., Knežević, M., Ravlić, J. (2013a): Allelopathic effect of creeping thistle ( Cirsium arvense (L.) Scop.) on germination and early growth of winter wheat and winter barley. Proceedings of 48th Croatian & 8th International
Symposium on Agriculture. Poljoprivredni fakultet Sveučilišta J. J. Strossmayera u
Osijeku, Osijek. pp. 97-100.
10.
Ravlić, M., Baličević, R., Pejić, T., Pećar, N. (2013b): Allelopathic effect of cogermination of some aromatic plants and weed seeds. Proceedings & abstracts, the
6th international scientific/professional conference Agriculture in nature and environment protection, Glas Slavonije d.d. Osijek, pp. 104-108.
11.
Rice, E.L. (1984): Allelopathy. 2 nd
edition. Academic Press, Orlando, Florida.
12.
Siddiqui, S., Bhardwaj, S., Khan, S.S., Meghvanshi, M.K. (2009): Allelopathic Effect of Different Concentration of Water Extract of Prosopsis Juliflora Leaf on Seed
Germination and Radicle Length of Wheat ( Triticum aestivum Var-Lok-1). American-
Eurasian Journal of Scientific Research, 4(2): 81-84.
13.
Singh, H.P., Batish, D.R., Kohli, R.K. (2003): Allelopathic interactions and allelochemicals: New possibilities for sustainable weed management. Critical Reviews in Plant Sciences, 22: 239-311.

Sažetak
Alelopatski utjecaj kamilice (Matricaria chamomilla L.) na strjeličastu grbicu (Cardaria
draba (L.) Desv.)
Cilj istraživanja bio je ispitati alelopatski utjecaj kamilice ( Matricaria chamomilla L.) na klijavost i početni rast korovne vrste strjeličaste grbice (
Cardaria draba (L.) Desv.).
Provedena su dva pokusa u laboratorijskim uvjetima kako bi se utvrdio utjecaj zajedničkog klijanja sjemena kamilice i strjeličaste grbice, te utjecaj vodenih ekstrakata kamilice. Ispitivani su vodeni ekstrakti od svježe i suhe mase kamilice u koncentracijama od 5 i 10% (50 i 100 g biljne mase na litru vode). Sjeme kamilice pri zajedničkom klijanju sa sjemenom grbice pokazalo je inhibitorni učinak na klijavost grbice, do 10,8%, no nije bilo utjecaja na rast klijanaca. Ekstrakti kamilice od svježe i suhe mase pokazali su negativan učinak na klijavost, duljinu korijena i izdanka te svježu masu klijanaca grbice. S povećanjem koncentracije biomase kamilice u ekstraktima, mjereni parametri su se proporcionalno smanjivali. Ekstrakt suhe mase kamilice u koncentraciji od 10% imao je najveći učinak, te potpuno inhibirao
(100%) svježu masu te duljinu korijena i izdanka grbice. U prosjeku, alelopatski učinak ekstrakata suhe mase bio je veći od ekstrakata svježe mase.
Ključne riječi: alelopatija, kamilica ( Matricaria chamomilla L.), strjeličasta grbica ( Cardaria draba
(L.) Desv.), zajedničko klijanje, vodeni ekstrakti