Bio-Herbicidal Effects of Oregano and Rosemary Essential Oils on Chamomile (Matricaria chamomilla L.) Crop in Organic Farming System
Department of Agricultural, Food and Environmental Sciences, University of Foggia, 71122 Foggia, Italy
*
Author to whom correspondence should be addressed.
Agronomy 2019, 9(9), 475; https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy9090475
Submission received: 16 July 2019
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Revised: 6 August 2019
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Accepted: 13 August 2019
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Published: 21 August 2019
(This article belongs to the Special Issue Ecologically Sustainable Weed Management in Cropping Systems)
Abstract
:Chamomile (Matricaria chamomilla L.) is a well-known medicinal plant species in which the products requested from the market are those that are derived from the organic system. The study was conducted to assess the allelopathic effects, as natural herbicides, of two essential oils extracted from oregano (Origanum vulgare L.) and rosemary (Rosmarimum officinalis L.), with the objective of exploring the possibility of their utilization for future weed management. A field experiment was conducted over two seasons, when the infestation of 15 different weed species was detected. Each essential oil was applied at two different concentrations (50% diluted and undiluted), three times during the chamomile crop under an organic farm system. The results demonstrated that the germination of different weed species was affected differently by the type of essential oils and especially by their concentrations. The undiluted oils inhibited most of the germination of several weed species, highlighting a significantly higher percentage of Weed Control Efficiency (WCE) and suggesting the potential to be used as bio-herbicides. Bioherbicidal weed control methods could offer an advantage with respect to hand weeding, particularly from an economic point of view.
1. Introduction
Chamomile (Matricaria chamomilla L.) is a plant species from the Asteraceae family, often referred to as the “star among medicinal species” [1]. Nowadays, it is a highly favored and much used medicinal plant in folk and traditional medicine. Its multitherapeutic, cosmetic and nutritional values have been established through years of traditional and scientific use and research. Chamomile is an important crop grown in the organic farming system in Foggia province (Apulia region, Southern Italy). In recent years, compared to other medicinal crops, farmers showed more interest in Chamomile to diversify its agricultural production and consumers for its beneficial health quality. It is obvious that for the officinal plant product, intended for food and/or to benefit health, it is difficult to think that it may contain chemicals residues. In this sense, the market seems to have already oriented its choices by proposing products derived from certified organic agriculture. Prices in this sector are very much related to the quality of the product, and consumers require compliance with increasingly precise quality requirements, considering the only real possibility is to face the competition with goods available at very low prices from non-European countries. Moreover, it should be considered that in chamomile crops, weeds are the major problem because growers cannot use synthetic herbicides, and weed infestations result in severe crop losses [2,3]. Weed control in organic agriculture does not have simple or standard solutions. Hand weeding, performed several times during the chamomile crop cycle, is a major approach for weed control by organic farmers, but this technique is carried out with expensive manual labor in Italy. In this context, the search for alternative products with high efficiency, low cost and low environmental impact represents a challenge for a modern eco-sustainable agriculture. The alternative proposal includes physical methods (such flame weeding), which, however, require the use of expensive equipment in carrying out field operations. To challenge these problems, in the last years, research has increased its effort to find out alternative farming strategies. A feasible alternative could be the identification of natural substances with allelopathic effects for the realization of natural herbicides. In this direction, efforts to utilize natural plant products for effective weed management have been made [4,5,6,7]. The advantage in the utilization of such natural compounds is the quick breakdown process into the environment, and so the possible application in sustainable agriculture as the organic farming. [8,9,10].
Among natural plant products, volatile essential oils (EOs) and their constituents have attracted much attention because of their phytotoxicity (also providing allelopathic property) and relatively quicker degradation in the environment [6,11,12,13,14,15,16]. EOs must be obtained by distillation in the water vapor stream of the whole plant or part of it. This is in fact the only procedure that allows to obtain 100% natural extracts, without traces of chemical solvents. Most of the seed germination and plant-growth inhibitors are phenolic compounds or their derivatives: coumarins, flavonoids, alkaloids, cyanoglycosides, proteins, and amino acids [17]. To this list must be added the monoterpenoids that include the volatile terpenes which are the main components of the EOs obtained from aromatic plants [18]. Monoterpenoids such as camphor, 1,8-cineol and alpha-pinene have been shown to be inhibitors of germination and cell proliferation at root meristematic apices [19]. The richest botanical families of plants containing EOs are: Apiaceae, Asteraceae, Lamiaceae, Rutaceae, Liliacee, Magnoliacee, Cupressaceae, Pinaceae, Hypericaceae, Fabaceae, Malvaceae, Myrtaceae, and Oleaceae [20,21]. In particular, many aromatic species, such as rosemary and oregano, belonging to the Lamiaceae family, produce EOs that contain chemical components with potential herbicides [22,23,24,25]. The main EOs components of Rosemary are 1.8-Cineole (21.45%), Camphor (19.70%), Borneol (8.58%), and Linalool (5.88%); while for Oregano they are Carvacrol (57.01), γ-Terpinene (8.77%), Linalcool (8.39%), and p-Cymene (7.86%) [26].
Azirak et al. (2008) [26] have developed research on the allelopathic effects of Menthax piperita L. and Salvia officinalis L. against various weed species (Amaranthus retroflexus L., Centaurea salsotitialis L., Raphanus raphanistrum L., Sinapis arvensis L., Sonchus oleraceus L. and others). Although laboratory experiments provided substantial information [13,19,26], studies on the real biological activity of EOs in the field are needed to apply them in agriculture.
For this reason, the objective in this study was to evaluate in the field the effect of oregano and rosemary EOs, each one at two concentrations, as natural herbicides on chamomile crop, in an organic farming system, to control seed germination and weed plant growth of the most common Mediterranean’s weed species.
2. Results and Discussion
2.1. Climate of the Experimental Site
Apulia region is characterized by a Mediterranean climate with a humid mild winter and hot dry summer. The long-term mean annual rainfall is about 590 mm, which is mainly concentrated between October and April. The annual average temperature goes from 15 to 16 °C, with a maximum temperature of 35 °C recorded in July and a minimum one of 0 °C recorded in January [28]. In Table 1, the monthly mean climatic parameters, recorded during the 2011–2012 and 2012–2013 experimental seasons, are reported. The mean maximum temperatures were almost similar between the two seasons (16.3 and 16.9 °C respectively), whereas the mean minimum were lower in 2011–2012 (5.5 °C) than in 2012–2013 (7.0 °C). Also, the total rainfall was lower in the first season (503.2) than in the second one (547.9 mm). The total evaporation between the two seasons was somewhat similar (516.9 and 503.5 respectively).
2.2. Floristic Surveys
From the floristic surveys, carried out during the two experimental seasons, the most represented weeds were the following 15 species: Portulaca oleracea L., Amaranthus retroflexus L., Solanum nigrum L., Convolvulus arvensis L., Taraxacum officinale W., Beta vulgaris L., Eruca sativa L., Silybum marianum L., Lamium maculatum L., Lactuca virosa L., Avena spp. L., Veronica persica L., Glechoma hederacea L., Fumaria officinalis L., and Papaver rhoeas L.
Weed ground cover (WGC %).
In Table 2 and Table 3, the WGC % of different weeds for all treatments, recorded at the six surveys throughout 2011–2012 and 2012–2013 chamomile-growing seasons, respectively are reported. In both seasons, the manual weeding treatment (T5), at each assessment date, showed significantly lower values, ranging from 2.9 to 5.6%, with no differences among weed species. No significant differences of total WGC %, in each survey, were detected for the same EOs concentrations of both oregano and rosemary plants (namely between T1 and T2, and between T3 and T4 treatments). While significant lower, WGC % was detected more in the undiluted EOs treatments (T3 and T4) than in the 50% diluted ones (T1 and T2), whose last treatments showed very low weed reduction. Overall, all the aforementioned treatments, with the exception of the withdrawals of 6 March 2012 and 22 March 2013, showed total WGC % values lower than those of the untreated plot.
Within all the EOs treatments, in both years, a general increase in WGC % during the grown seasons was observed, with greater relative values, as expected, detected in the spring-summer period. Indeed, from April to June, the growth-limiting effect of EOs on weeds decreased and it was less important than it was in March (Table 2 and Table 3). This observation could lead us to assume that the persistence of essential oil active ingredient(s) in the soil is relatively short in such a way that it affects weed emergence and growth shortly after application, and then loses its potential with time.
In Figure 1, the 2011–2012 and 2012–2013 seasonal average values of WCE %, recorded in the six surveys of different treatments for each weed, are reported. In general, data showed very similar results in both experimental seasons. Among all compared treatments, the manual weeded (T5) always showed the significantly highest WCE %, whose values on the complex of all weed species, ranged from 70 to 90%. Significant differences were recorded among weed species and among EOs treatments.
Considering, as a whole, the T1, T2, T3 and T4 treatments, in both seasons, P. oleracea, A. retroflexus, C. arvensis, E. sativa and P. rhoeas weed species showed significantly higher WCE values, ranging from 50 and 86%, compared to S. nigrum, F. officinalis, B. vulgaris, L. maculatum, T. officinale, Avena spp. and V. persica weeds, whose values ranged from 29 to 39%. The lowest values, ranging from 8 to 20%, were obtained for S. marianum, L. virosa and G. hederacea (Figure 1).
Among the EOs treatments, WCE % differences within the weed species and sometimes even between seasons were noted. In both seasons, A. retroflexus, C. arvensis and P. rhoeas weeds showed no WCE differences within the same EOs concentrations (between T1 and T2, and T3 and T4). Whereas significantly higher WCE values in T3 and T4 treatments (ranged from 64 to 77%) than in T1 and T2 (ranged from 40 to 57%), were recorded. In particular, the C. arvensis is a perennial and creeping weed species that causes serious problems to the crops, as it forms stuffy carpets in cultivated land. Its characteristic of growing ‘twisting’ to the crops, in addition to the competition for water, light and nutrients such as other weeds, determines problems during harvesting for the need to clean the product, with a consequent increase in processing costs. Moreover, its propagation by creeping underground rhizomes, creates difficulty in its total elimination, even with manual tillage. As for P. rhoeas species, the same Figure 1 shows WCE values around 70%. This weed, that has recently shown a great resistance to traditional chemical herbicides, is very widespread in the agricultural area of the Foggia province, especially in wheat cultivation. Therefore, the good results obtained in both seasons on the application of T3 or T4 treatments, are to be considered very interesting.
Regarding P. oleracea, it differs from the above-mentioned weeds, as it showed significant differences in WCE between seasons. Indeed, only in the 2011–2012 season, higher WCE values were obtained in T3 and T4 (on average 63%) than in T1 and T2 (on average 54%) treatments, whereas no differences among all EOs treatments (on average 55%) were noted in 2012–2013. Finally, as for E. sativa, in the 2011–2012 season, no WCE differences were recorded among all EOs treatments (average value of 64%), while in 2012–2013, the T2 and T3 treatments were determined to have the highest WCE values (on average 51%) (Figure 1).
Just to briefly clarify the above results, in Table 4, the mean WCE % values of both diluted EOs (T1–T2), both undiluted ones (T3–T4) and manual weeded (T5) treatments, are reported. This table shows that in both seasons for A. retroflexus, C. arvensis and P. rhoeas, and only in 2011–2012 season for P. oleracea and L. maculatum, the weed inhibitory ability does not differ between the oregano and rosemary EOs types but increased with the increase of their concentrations. This finding is in accordance with the results obtained from other research [32]. As for the other weed species, the inhibitory effects, although variable among them, were not different between the EOs concentrations.
2.3. Crop Yield
In Table 5, the chamomile fresh flowers yield and EOs yield percentage of different treatments are reported. In both seasons, flower yields were highest in the manual weeded treatment (T5), followed by T3 and T4 treatments, which in turn were significantly higher than the T1 and T2. No indirect significant effects on EOs yield percentage were recorded.
3. Materials and Methods
3.1. Site Description and Plant Material Preparation for the Essential Oil Extraction
This study was carried out in two consecutive seasons (2012 and 2013) on chamomile (cv Ducan), grown in the open field of private “Bonomelli” s.r.l. farm, which produces and processes medicinal herbs. The experimental trial was carried out in an agricultural area of Foggia province (Apulia Region, Southern Italy, 41°27′30′′ N’;15°31′56′′ E), on the clay-loam soil (USDA classification) deep and vertisol of alluvional origin having the following characteristics: sand = 39.6%, loam = 23.4%, clay = 37,0%; total N (Kjeldahl) = 1.9‰, assimilable P2O5 (Olsen) = 68 ppm; exchangeable K2O (Schollemberger) = 559 ppm; Ca exchangeable = 3128 ppm; Mg exchangeable = 327 ppm; Na exchangeable = 35 ppm; ratio C/N = 5:2; electrical conductivity (ECe) = 0,43 dS cm−1; pH (in water) = 8.2; organic matter (Walkley and Black) = 1.5%.
The study was designed to assess the effects, as natural herbicides, of EOs extracted from oregano and rosemary plants, on chamomile crop. Oregano and rosemary were cultivated previously in an open field in the same “Bonomelli” farm. At harvest, fresh leaves of these aromatic plants were collected at full flowering stages, each one mixed for homogenization and used for EOs extractions by distillation for 2 hours in a current stream. EOs extraction were made directly after harvesting of the aromatic plants: on 19 July 2011 and 23 July 2012 for oregano and 11 June 2011 and 20 July 2012 for rosemary. The EOs were stored in hermetically-sealed dark-glass containers and kept in rooms at 5–6°C.
EOs were isolated by direct steam distillation using a 62 L steel extractor apparatus (Albrigi Luigi EO 131, Verona, Italy). With this type of steam distillation apparatus, the remaining water (a by-product), called floral water or hydrosol, can be recycled after condensation, thereby limiting the process duration.
3.2. Climate Conditions
Meteorological data (mean monthly maximum and minimum temperature, total rainfall and “Class A” pan evaporation) were collected during the 2011–2012 and 2012–2013 growing seasons of chamomile crop, at the nearest meteorological station, a few kilometers from the experimental area, and supplied by the Consorzio per la Bonifica della Capitanata.
3.3. Field Experimetal Treatments
Each oregano and rosemary EOs was applied in two different concentrations (50% diluted oil and undiluted one), compared with a manual weeding in experimental plots cultivated with chamomile. Consequently, the field experiment included five treatments: two doses of each type of EOs and manual weeding, named as reported here:
- T1 = 50% diluted oil of R. officinalis;
- T2= 50% diluted oil of O. vulgare;
- T3 = undiluted oil of R. officinalis;
- T4 = undiluted oil of O. vulgare;
- T5 = weeded manually (considered as weeded control).
Each EO was applied manually three times: directly after sowing of chamomile (on 16 October 2011 and 14 October 2012), 1 month and 2 months later. The manual weeded treatment was planned at the time when it is usually (last weeks of December, January and March) carried out in the farms, where chamomile is grown in the open field. Five millimeters of EOs plus adjuvant (nonionic surfactant, polyoxetylenestearyl-ether, 10 E0), at 0.2 (v/v) were sprayed on 5 m2 of soil surface, immediately followed by gently spraying with “minisprinkler” (Metafin), until water drained from the soil surface. Sprayer bottles with pumps were used in order to spray small liquid amounts.
The manual weeded were performed three times in December, January and March of each season, as normal practices adopted by the farmers. The five experimental treatments were arranged according to a complete randomized block design, with four replicates.
In addition to the aforementioned treatments, one untreated plot (T6) was taken at the border of each block, to which was given zero weed containment capacity. Consequently, each block was formed of six plots of 10.5 m2 (3.5 × 3.0 m) in which the chamomile crop was grown. While each sampling areas was 5 m2 (2.5 × 2.0) (with a border of 1 meter around it).
Chamomile was sown on 16 October 2011 and on 14 October 2012, in continuous rows 40 cm apart, with a quantity of seeds of 1.5 kg ha−1, mixed with inert matter. The planting density was 40 plants m−2. The harvests were made on 6 June 2012 and 13 June 2013, respectively. The EO was extracted from a sample of 10 g of dried flowers for each treatment by hydro distillation method for 3 h, using the Clevenger-type apparatus.
The agricultural management practices applied to the chamomile crop, during the experimental trials, were those adopted by the farmer in an organic system.
3.4. Weed Survey
The infestation of the different weed species, in each plot, was manifested by the weed ground cover percentage (WGC %) and the weed control efficiency percentage (WCE %).
The WGC % of associated weeds was visually estimated according to the Braun-Blanquet [33] cover abundance-dominance method (1964), by assigning to each species a value ranging from 1 to 5, based on the proportion of the plot area covered. Classes of presence and abundance were transformed in cover percentage using the following scale: 0 = absent; 1 = 1–4%; 2 = 5–24%; 3 = 25–49%; 4 = 50–74%; 5 = 75–100%.
Since weed growth in the autumn-winter period is much lower than that of spring-summer, weed assessment in each season was started on March and repeated about every 20 days until June. Therefore, during the chamomile growing cycles, the WGC % was rated visually for each weed species on 03/06, 03/22, 04/11, 05/02, 05/24 and 06/06 in 2012, and 03/06; 03/22; 04/11; 05/09; 05/30 and 06/13 in 2013.
The data obtained were processed to calculate the “weed control efficiency”, as the formula given below:
where X = % of weeds in untreated plot; Y = % of weeds in treated plot.
Weed control efficiency (WCE) = X − Y/X × 100
The WCE denotes the magnitude of weed reduction, due to weed control treatment.
3.5. Statistical Analysis
All data were analyzed by analysis of variance (ANOVA), followed by Tukey’s post-hoc test for significant mean values. Values of p ≤ 0.05 were considered as statistically significant. All of the analyses were performed using the JMP software 2008.
4. Conclusions
The manual removal of weeds gave better control of all types of weeds, with the average weed control efficiency (WCE) ranging between 70 and 90 %. Results of the oregano and rosemary essential oils (EOs), each one applied in two concentrations (50% diluted oil and undiluted one), similar to other previous studies, in general show phytotoxicity effect on seed germination, with differences in sensitivity of the various weed species. Indeed, the soil application of these EOs posseses an inhibitory ability especially on weed emergence and plant growth of Amaranthus retroflexus L., Portulaca oleracea L., Convolvulus arvensis L., Eruca sativa L. and Papaver rhoeas L, in which WCE ranged from 50 to 86%. Conversely, Solanum nigrum L., Fumaria officinalis L., Beta vulgaris L., Lamium maculatum L., Taraxacum officinale W., Avena spp. L., Veronica persica L., showed that the WCE ranged between 29 and 39%. The EOs inhibitory effect on Silybum marianum L., Lactuca virosa L. and Glechoma hederacea L. was less than 18%.
Furthermore, Amaranthus retroflexus L., Convolvulus arvensis and Papaver rhoeas L., showed, in both types of oils, a better WCE % at the undiluted oil concentration.
Moreover, especially in the last period of the chamomile grown cycle, a greater increase in weed growth cover (WGC %) was detected. This is due to the short persistence of EOs in the soil after their application.
Further field research is necessary to develop an appropriate technology as well the optimization of the use of essential oil application for inhibiting weed seed germination. For example, it is possible that essential oil could be followed by other tools to manage weeds, as well as only one handing weed application during the chamomile crop cycle. In this regard, an economic and environment analysis would also be needed in future research.
Author Contributions
L.F., G.D. have contributed in developing the research ideas, conducting the research, analyzing the data, and writing the manuscript. A.T. and F.P. provided efforts on field research, lab analysis and manuscript writing. All authors read and approved the final manuscript.
Funding
This research received no external funding.
Acknowledgments
The work was carried out within the projet: “Promozione di processi ECO-_ sostenibili per la valorizzazione delle produzioni agroalimentari Pugliesi (ECO_ P4)”: PON02_ 00186_2866121.
Conflicts of Interest
The authors declare no conflict of interest.
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Figure 1.
Mean weed control efficiency of different treatments on different weeds. Values within each weed species that have the same letters are not significantly different (p ≤ 0.5, Tukey’s test).
Figure 1.
Mean weed control efficiency of different treatments on different weeds. Values within each weed species that have the same letters are not significantly different (p ≤ 0.5, Tukey’s test).
Table 1.
Mean monthly climatic parameters recorded during the 2011–2012 and 2012–2013 growing seasons of the chamomile crop.
Table 1.
Mean monthly climatic parameters recorded during the 2011–2012 and 2012–2013 growing seasons of the chamomile crop.
| 2011–2012 | 2012–2013 | |||||||
|---|---|---|---|---|---|---|---|---|
| Month | Tmax | Tmin | P | EV | Tmax | Tmin | P | V |
| (°C) | (°C) | (mm) | (mm) | (°C) | (°C) | (mm) | (mm) | |
| October | 18.7 | 10.6 | 11.2 | 32.3 | 22.1 | 10.5 | 63.0 | 46.8 |
| November | 15.3 | 5.5 | 64.5 | 18.8 | 16.0 | 8.7 | 110.5 | 19.2 |
| December | 14.1 | 2.7 | 60.2 | 23.4 | 10.4 | 3.0 | 105.0 | 14.7 |
| January | 10.9 | 0.1 | 92.2 | 26.9 | 10.8 | 2.4 | 64.7 | 12.9 |
| February | 7.3 | -0.4 | 68.2 | 25.2 | 9.4 | 1.7 | 83.5 | 45.6 |
| March | 16.4 | 4.5 | 39.5 | 60.7 | 13.8 | 4.5 | 53.0 | 44.5 |
| April | 18.6 | 6.4 | 76.0 | 69.8 | 19.3 | 7.1 | 15.5 | 76.9 |
| May | 23.0 | 9.6 | 28.2 | 113.0 | 22.7 | 10.4 | 32.7 | 104.0 |
| June | 22.1 | 10.5 | 63.0 | 146.8 | 27.9 | 14.3 | 20.0 | 138.8 |
| Mean | 16.3 | 5.5 | 16.9 | 7.0 | ||||
| Total | 503.2 | 516.9 | 547.9 | 503.5 | ||||
Tmax, Tmin, monthly maximum, minimum air temperature; P, total rainfall; Ev, total “Class A” Pan evaporation.
Table 2.
Effect of treatments on weed ground cover percentage (WGC %) at different surveys during the 2011–2012 season.
Table 2.
Effect of treatments on weed ground cover percentage (WGC %) at different surveys during the 2011–2012 season.
| Treatment | Portulaca oleracea L. | Amaranthus retroflexus L. | Solanum nigrum L. | Convolvulus arvensis L. | Taraxacum officinale W. | Beta vulgaris L. | Eruca sativa L. | Silybum marianum L. | Lamium maculatum L. | Lactuca virosa L. | Avena spp L. | Veronica persica L. | Glechoma hederacea L. | Fumaria officinalis L. | Papaver rhoeas L. | Total % |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6 March | ||||||||||||||||
| T1 | 9.4 | 3.6 | 6.5 | 9.4 | 2.0 | 8.6 | 3.4 | 12.4 | 2.6 | 10.4 | 0.2 | 8.6 | 6.4 | 10.4 | 8.4 | 102.3a |
| T2 | 10.4 | 12.4 | 6.5 | 12.4 | 15.0 | 12.4 | 9.4 | 10.4 | 2.6 | 11.5 | 0.1 | 12.4 | 10.4 | 12.4 | 10.4 | 148.7a |
| T3 | 0.1 | 0.1 | 6.5 | 0.7 | 1.6 | 3.6 | 0.1 | 6.5 | 9.4 | 8.4 | 2.6 | 8.5 | 8.4 | 8.5 | 0.1 | 65.1b |
| T4 | 0.2 | 0.1 | 2.6 | 0.1 | 6.5 | 6.5 | 0.1 | 9.4 | 9.4 | 6.5 | 0.1 | 3.6 | 0.1 | 8.4 | 0.1 | 53.7b |
| T5 | 0.1 | 0.3 | 0.5 | 0.1 | 0.3 | 0.3 | 0.5 | 0.1 | 0.5 | 0.5 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 3.7c |
| T6 | 12.8 | 11.6 | 7.7 | 13.9 | 12.2 | 9.6 | 9.7 | 11.6 | 3.2 | 11.3 | 0.3 | 12.6 | 9.2 | 12.9 | 11.2 | 149.8a |
| 22 March | ||||||||||||||||
| T1 | 12.6 | 4.5 | 2.6 | 12.4 | 9.4 | 14.5 | 1.4 | 14.5 | 1.4 | 10.5 | 1.4 | 3.6 | 9.4 | 8.4 | 8.2 | 114.8a |
| T2 | 10.4 | 12.4 | 6.5 | 12.4 | 1.5 | 9.4 | 11.4 | 8.4 | 9.4 | 14.5 | 0.1 | 12.4 | 10.4 | 14.5 | 10.4 | 144.1a |
| T3 | 0.1 | 0.1 | 6.5 | 0.1 | 2.6 | 2.0 | 1.7 | 6.0 | 9.4 | 12.4 | 2.6 | 11.5 | 8.4 | 8.4 | 0.4 | 72.2b |
| T4 | 1.4 | 0.1 | 4.5 | 0.1 | 2.6 | 14.5 | 9.4 | 9.4 | 9.4 | 6.5 | 0.1 | 9.4 | 12.4 | 8.4 | 0.1 | 88.3b |
| T5 | 0.1 | 0.3 | 0.5 | 0.2 | 0.4 | 0.3 | 0.5 | 0.1 | 0.5 | 0.5 | 0.1 | 0.1 | 0.2 | 0.1 | 0.2 | 4.1c |
| T6 | 14.9 | 10.9 | 5.5 | 14.0 | 6.5 | 15.5 | 8.2 | 12.4 | 6.5 | 13.7 | 1.8 | 12.6 | 10.9 | 13.7 | 12.1 | 159.2a |
| 11 April | ||||||||||||||||
| T1 | 13.4 | 12.4 | 6.5 | 12.4 | 12.4 | 12.4 | 2.6 | 14.5 | 4.4 | 1.4 | 14.5 | 10.4 | 9.4 | 8.4 | 11.6 | 146.7b |
| T2 | 12.0 | 12.4 | 9.4 | 10.4 | 2.0 | 10.4 | 13.4 | 8.4 | 2.0 | 9.4 | 3.6 | 11.9 | 8.4 | 14.5 | 12.4 | 117.7b |
| T3 | 2.0 | 0.1 | 9.4 | 9.4 | 10.4 | 12.1 | 3.4 | 3.6 | 10.4 | 14.5 | 2.6 | 11.5 | 3.6 | 4.0 | 0.2 | 97.2c |
| T4 | 3.1 | 1.4 | 3.6 | 3 | 3.4 | 11.4 | 9.4 | 10.1 | 10.4 | 8.4 | 3.4 | 11.4 | 11.4 | 8.4 | 1.6 | 100.4c |
| T5 | 0.2 | 0.3 | 0.6 | 0.3 | 0.4 | 0.3 | 0.5 | 0.2 | 0.5 | 0.5 | 0.2 | 0.1 | 0.3 | 0.2 | 0.2 | 4.8d |
| T6 | 16.1 | 15.2 | 8.4 | 14.8 | 9.6 | 14.8 | 9.6 | 7.5 | 12.4 | 13.9 | 3.6 | 13.8 | 9.8 | 14.7 | 15.6 | 179.8a |
| 2 May | ||||||||||||||||
| T1 | 10.4 | 20.2 | 12.4 | 12.4 | 11.4 | 11.4 | 1.4 | 12.4 | 9.4 | 12.4 | 14.5 | 10.4 | 9.4 | 15.7 | 12.0 | 175.8b |
| T2 | 21.5 | 15.4 | 9.4 | 10.4 | 2.0 | 9.4 | 13.0 | 15.0 | 21.5 | 14.4 | 3.6 | 14.5 | 10.4 | 12.4 | 12.4 | 185.3b |
| T3 | 9.4 | 2.6 | 12.4 | 9.4 | 12.4 | 11.0 | 3.6 | 10.4 | 9.4 | 14.5 | 2.6 | 12.5 | 3.6 | 6.0 | 16.0 | 135.8c |
| T4 | 2.6 | 9.4 | 8.4 | 7.1 | 9.4 | 14.5 | 0.4 | 14.5 | 14.5 | 16.5 | 14.5 | 9.4 | 9.4 | 14.5 | 3.6 | 148.7c |
| T5 | 0.2 | 0.3 | 0.5 | 0.3 | 0.4 | 0.5 | 0.5 | 0.2 | 0.5 | 0.5 | 0.2 | 0.1 | 0.4 | 0.3 | 0.3 | 5.2d |
| T6 | 20.1 | 23.1 | 13.4 | 14.2 | 9.7 | 13.5 | 10.0 | 15.4 | 18.5 | 14.7 | 10.8 | 14.9 | 10.9 | 16.8 | 15.9 | 221.9° |
| 24 May | ||||||||||||||||
| T1 | 13.5 | 21.5 | 24.0 | 26.5 | 12.4 | 12.5 | 2.6 | 24.0 | 16.5 | 14.0 | 21.5 | 16.5 | 16.5 | 14.0 | 12.0 | 248.0a |
| T2 | 21.5 | 14.4 | 21.5 | 10.4 | 25.5 | 14.5 | 24.0 | 21.5 | 25.5 | 21.5 | 25.0 | 11.5 | 24.4 | 16.5 | 16.5 | 294.2a |
| T3 | 14.5 | 12.4 | 11.5 | 11.0 | 11.9 | 12.1 | 11.5 | 9.4 | 13.5 | 11.5 | 6.5 | 12.4 | 8.0 | 9.0 | 14.0 | 169.2b |
| T4 | 6.5 | 13.4 | 3.6 | 7.0 | 9.4 | 13.4 | 6.5 | 9.1 | 11.5 | 16.5 | 10.4 | 12.4 | 12.4 | 21.5 | 4.2 | 157.8b |
| T5 | 0.2 | 0.3 | 0.6 | 0.3 | 0.5 | 0.4 | 0.6 | 0.2 | 0.5 | 0.6 | 0.2 | 0.2 | 0.3 | 0.3 | 0.2 | 5.4d |
| T6 | 22.7 | 23.3 | 27.3 | 23.9 | 22.7 | 17.5 | 16.3 | 25.0 | 25.2 | 19.5 | 27.9 | 16.8 | 22.5 | 18.3 | 18.5 | 327.4a |
| 6 June | ||||||||||||||||
| T1 | 12.4 | 26.5 | 26.5 | 21.5 | 14.4 | 14.0 | 12.4 | 27.0 | 21.5 | 12.0 | 20.5 | 14.5 | 16.5 | 14.0 | 14.5 | 268.2b |
| T2 | 14.5 | 12.4 | 21.5 | 12.4 | 21.5 | 12.4 | 19.4 | 24.0 | 9.4 | 21.5 | 24.0 | 12.4 | 24.0 | 12.4 | 12.4 | 254.2b |
| T3 | 21.5 | 12.6 | 12.4 | 12.4 | 6.5 | 9.6 | 11.5 | 9.4 | 12.4 | 12.5 | 9.4 | 14.5 | 12.4 | 8.4 | 8.4 | 173.9c |
| T4 | 9.4 | 5.4 | 9.4 | 1.4 | 9.4 | 12.4 | 10.6 | 9.4 | 16.5 | 12.4 | 6.5 | 6.5 | 9.4 | 9.4 | 2.6 | 130.7c |
| T5 | 0.2 | 0.3 | 0.6 | 0.3 | 0.4 | 0.6 | 0.5 | 0.3 | 0.5 | 0.5 | 0.3 | 0.1 | 0.4 | 0.3 | 0.3 | 5.6d |
| T6 | 20.4 | 25.2 | 23.3 | 22.0 | 21.5 | 17.2 | 19.0 | 28.1 | 18.5 | 18.4 | 26.7 | 16.1 | 22.3 | 15.8 | 17.5 | 312.0a |
Table 3.
Effect of treatments on weed ground cover percentage (WGC %) at different surveys during the 2012–2013 season.
Table 3.
Effect of treatments on weed ground cover percentage (WGC %) at different surveys during the 2012–2013 season.
| Treatment | Portulaca oleracea L. | Amaranthus retroflexus L. | Solanum nigrum L. | Convolvulus arvensis L. | Taraxacum officinale W. | Beta vulgaris L. | Eruca sativa L. | Silybum marianum L. | Lamium maculatum L. | Lactuca virosa L. | Avena spp L. | Veronica persica L. | Glechoma hederacea L. | Fumaria officinalis L. | Papaver rhoeas L. | Total % |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6 March | ||||||||||||||||
| T1 | 2.6 | 3.6 | 4.5 | 1.5 | 2.0 | 3.4 | 1.4 | 12.4 | 2.6 | 0.9 | 6.5 | 3.6 | 12.4 | 9.4 | 6.5 | 73.3a |
| T2 | 1.4 | 2.0 | 3.6 | 2.4 | 0.2 | 1.4 | 2.6 | 12.4 | 2.6 | 8.1 | 3.6 | 9.4 | 9.4 | 9.4 | 2.4 | 70.9a |
| T3 | 0.1 | 0.2 | 1.4 | 1.8 | 2.0 | 3.6 | 2.0 | 2.6 | 3.6 | 3.6 | 6.5 | 2.0 | 8.4 | 2.6 | 0.1 | 40.5b |
| T4 | 0.2 | 2.0 | 2.4 | 0.2 | 2.4 | 6.5 | 0.1 | 8.4 | 2.6 | 3.6 | 4.2 | 0.2 | 10.4 | 7.4 | 0.1 | 44.2b |
| T5 | 0.1 | 0.1 | 0.1 | 0.2 | 0.1 | 6.5 | 0.2 | 0.0 | 1.4 | 0.1 | 0.2 | 0.1 | 0.1 | 0.1 | 0.1 | 2.9c |
| T6 | 3.5 | 4.0 | 4.9 | 2.8 | 1.4 | 3.7 | 2.8 | 13.6 | 3.1 | 6.0 | 6.6 | 7.8 | 8.3 | 11.0 | 5.8 | 85.3a |
| 22 March | ||||||||||||||||
| T1 | 12.4 | 2.4 | 2.6 | 2.4 | 2.0 | 9.4 | 0.2 | 14.5 | 4.4 | 3.6 | 12.4 | 2.6 | 12.4 | 6.5 | 2.6 | 90.4a |
| T2 | 10.4 | 0.2 | 12.4 | 2.4 | 0.2 | 2.4 | 8.4 | 12.4 | 12.4 | 6.5 | 1.5 | 12.4 | 6.4 | 6.4 | 6.5 | 100.9a |
| T3 | 0.1 | 3.6 | 2.6 | 1.6 | 3.6 | 1.4 | 0.2 | 2.6 | 8.4 | 3.6 | 12.4 | 2.4 | 12.4 | 2.0 | 0.1 | 57.0b |
| T4 | 3.6 | 1.0 | 2.6 | 3.4 | 2.6 | 8.4 | 2.6 | 8.4 | 2.6 | 4.5 | 8.4 | 2.6 | 12.4 | 8.4 | 0.2 | 71.7b |
| T5 | 0.1 | 0.0 | 0.1 | 0.2 | 0.2 | 0.2 | 0.1 | 0.1 | 2.6 | 0.1 | 0.7 | 0.1 | 0.1 | 0.1 | 0.7 | 5.4c |
| T6 | 10.0 | 2.0 | 9.0 | 3.1 | 2.0 | 7.6 | 5.2 | 14.8 | 10.1 | 5.5 | 8.3 | 9.0 | 8.1 | 7.6 | 6.0 | 108.3a |
| 18 April | ||||||||||||||||
| T1 | 10.4 | 6.6 | 2.2 | 2.4 | 2.6 | 9.4 | 2.6 | 14.5 | 6.6 | 4.0 | 14.8 | 2.6 | 14.4 | 6.7 | 4.5 | 104.3b |
| T2 | 9.4 | 11.5 | 9.4 | 1.2 | 0.8 | 9.4 | 4.5 | 6.6 | 8.4 | 12.5 | 12.2 | 12.6 | 14.6 | 3.6 | 9.1 | 125.8b |
| T3 | 10.4 | 6.5 | 2.6 | 3.6 | 2.6 | 8.4 | 1.4 | 2.0 | 12.6 | 1.4 | 11.4 | 2.8 | 12.4 | 9.4 | 0.1 | 86.2c |
| T4 | 3.0 | 2.0 | 10.4 | 13.4 | 2.6 | 12.4 | 1.4 | 2.6 | 2.6 | 4.5 | 11.5 | 3.6 | 3.6 | 2.6 | 0.1 | 76.3c |
| T5 | 0.2 | 0.1 | 0.1 | 0.4 | 0.1 | 0.2 | 0.2 | 2.6 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 4.7d |
| T6 | 12.0 | 11.7 | 8.9 | 2.8 | 2.1 | 11.3 | 5.2 | 16.7 | 8.9 | 10.0 | 15.8 | 10.3 | 15.1 | 7.8 | 8.8 | 147.4a |
| 9 May | ||||||||||||||||
| T1 | 10.0 | 6.5 | 6.5 | 1.5 | 8.6 | 12.4 | 2.6 | 20.5 | 9.5 | 1.5 | 9.6 | 2.6 | 11.4 | 12.4 | 6.5 | 122.1b |
| T2 | 12.4 | 12.4 | 14.5 | 1.3 | 14.0 | 8.4 | 9.8 | 26.5 | 12.4 | 14.4 | 14.2 | 9.4 | 21.5 | 14.6 | 12.1 | 197.9b |
| T3 | 8.4 | 10.4 | 8.4 | 2.4 | 1.4 | 12.4 | 2.4 | 6.6 | 11.6 | 2.6 | 9.6 | 3.6 | 16.5 | 6.5 | 0.2 | 103.0c |
| T4 | 2.7 | 2.2 | 8.2 | 15.0 | 3.6 | 11.8 | 0.8 | 4.6 | 8.4 | 10.1 | 11.2 | 2.1 | 2.5 | 11.6 | 0.1 | 94.9c |
| T5 | 0.1 | 0.1 | 0.1 | 0.2 | 0.1 | 6.5 | 0.2 | 0.0 | 1.4 | 0.1 | 0.2 | 0.1 | 0.1 | 0.1 | 0.1 | 2.9d |
| T6 | 14.1 | 12.2 | 15.6 | 1.8 | 15.0 | 13.1 | 9.9 | 27.9 | 13.7 | 10.7 | 15.8 | 11.0 | 22.3 | 15.9 | 14.1 | 213.1a |
| 30 May | ||||||||||||||||
| T1 | 10.5 | 8.2 | 14.2 | 7.0 | 9.2 | 14.4 | 3.6 | 26.6 | 10.2 | 9.0 | 8.2 | 19.0 | 15.4 | 17.2 | 9.6 | 182.3b |
| T2 | 10.6 | 10.8 | 9.2 | 1.2 | 14.0 | 17.4 | 10.2 | 28.4 | 9.5 | 13.2 | 27.2 | 20.4 | 10.6 | 16.6 | 19.4 | 218.7b |
| T3 | 9.8 | 9.8 | 7.6 | 2.0 | 4.6 | 14.4 | 0.2 | 7.6 | 10.4 | 11.4 | 18.2 | 12.4 | 12.6 | 9.0 | 6.6 | 136.6c |
| T4 | 1.4 | 1.4 | 3.2 | 15.0 | 1.4 | 11.5 | 0.2 | 9.4 | 10.6 | 11.2 | 11.2 | 4.6 | 6.6 | 10.0 | 9.4 | 107.1c |
| T5 | 0.2 | 0.1 | 0.1 | 0.4 | 0.1 | 0.2 | 0.2 | 2.6 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 4.7d |
| T6 | 13.1 | 12.3 | 15.2 | 5.3 | 14.1 | 18.1 | 10.1 | 29.8 | 11.0 | 13.4 | 20.1 | 19.0 | 14.9 | 16.1 | 18.8 | 231.3a |
| 13 June | ||||||||||||||||
| T1 | 10.2 | 11.6 | 13.2 | 8.2 | 10.2 | 14.5 | 1.4 | 29.6 | 11.0 | 18.6 | 16.6 | 18.0 | 14.6 | 19.2 | 2.8 | 199.7b |
| T2 | 11.8 | 9.6 | 4.6 | 2.6 | 14.4 | 15.4 | 3.6 | 24.2 | 9.1 | 11.2 | 26.0 | 11.4 | 17.4 | 12.6 | 9.4 | 183.3b |
| T3 | 8.8 | 11.4 | 4.5 | 4.2 | 9.4 | 9.2 | 0.2 | 8.2 | 11.6 | 11.6 | 16.6 | 14.8 | 9.5 | 9.1 | 6.8 | 135.9c |
| T4 | 1.1 | 11.4 | 11.5 | 5.6 | 0.2 | 11.0 | 0.2 | 9.0 | 11.8 | 11.2 | 14.0 | 4.5 | 4.0 | 10.4 | 4.6 | 110.5c |
| T5 | 0.2 | 0.4 | 0.2 | 0.4 | 0.1 | 0.2 | 0.3 | 2.6 | 0.1 | 0.1 | 0.1 | 0.2 | 0.2 | 0.3 | 0.2 | 5.6d |
| T6 | 14.3 | 13.7 | 12.0 | 7.2 | 15.0 | 19.4 | 8.0 | 29.6 | 14.9 | 15.3 | 16.4 | 25.0 | 17.5 | 18.9 | 15.0 | 242a |
Table 4.
Mean Weed Control Efficiency (WCE) percentage of the 50 diluted oils (T1–T2), undiluted ones (T3–T4) and manual weeding (T5) treatments of different weed species (2011–2012 and 2012–2013 seasons).
Table 4.
Mean Weed Control Efficiency (WCE) percentage of the 50 diluted oils (T1–T2), undiluted ones (T3–T4) and manual weeding (T5) treatments of different weed species (2011–2012 and 2012–2013 seasons).
| 2011–2012 | 2012–2013 | |||||
|---|---|---|---|---|---|---|
| T1–T2 | T3–T4 | T5 | T1–T2 | T3–T4 | T5 | |
| Portulaca oleracea L. | 54 c | 63 b | 82 a | 51 b | 58 b | 83 a |
| Amaranthus retroflexus L. | 55 c | 65 b | 80 a | 52 c | 68 b | 82 a |
| Solanum nigrum L. | 29 b | 33 b | 84 a | 28 b | 30 b | 83 a |
| Convolvulus arvensis L. | 55 c | 75 b | 84 a | 48 c | 71 b | 82 a |
| Taraxacum officinale W. | 25 b | 28 b | 74 a | 28 b | 25 b | 78 a |
| Beta vulgaris L. | 25 b | 32 b | 88 a | 29 b | 25 b | 79 a |
| Eruca sativa L. | 65 b | 63 b | 70 a | 51 b | 58 b | 78 a |
| Silybum marianum L. | 18 b | 18 b | 80 a | 15 b | 17 b | 78 a |
| Lamium maculatum L. | 29 c | 36 b | 72 a | 32 b | 39 b | 77 a |
| Lactuca virosa L. | 11 b | 12 b | 86 a | 14 b | 9 bc | 82 a |
| Avena spp. L. | 24 b | 28 b | 82 a | 25 b | 29 b | 85 a |
| Veronica persica L. | 31 b | 34 b | 74 a | 34 b | 38 b | 78 a |
| Glechoma hederacea L. | 11 b | 13 b | 90 a | 14 b | 16 b | 90 a |
| Fumaria officinalis L. | 28 b | 21 b | 82 a | 23 b | 23 b | 80 a |
| Papaver rhoeas L. | 45 c | 73 b | 75 a | 42 c | 71 b | 87 a |
Data for T1–T2 and T3–T4 are means of 48 values (two essential oil concentrations x six sampling dates x four replicates. Data of T5 are means of 24 values (six sampling dates x four replicates). Means followed by the same letters in each line of each season are not significantly different (p ≤ 0.5; Turkey’s test). For the abbreviations, see main test.
Table 5.
Effect of treatments on fresh flower yield and essential oil percentage of chamomile crop in 2011–2012 and 2012–2013 seasons.
Table 5.
Effect of treatments on fresh flower yield and essential oil percentage of chamomile crop in 2011–2012 and 2012–2013 seasons.
| Seasons | |||||
|---|---|---|---|---|---|
| Treatments | 2011–2012 | 2012–2013 | |||
| Flower | Oil | Flower | Oil | ||
| (kg ha −1) | (%) | (kg ha −1) | (%) | ||
| T1 | 2008 | c | 0.40 | 1950 c | 0.39 |
| T2 | 2000 | c | 0.38 | 1900 c | 0.37 |
| T3 | 2110 | b | 0.38 | 2130 b | 0.37 |
| T4 | 2100 | b | 0.37 | 2220 b | 0.38 |
| T5 | 2150 | a | 0.35 | 2200 a | 0.36 |
Means followed by the different letters in each colon of each season are significantly different (p ≤ 0.5; Turkey’s test). For the abbreviations, see main test.
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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MDPI and ACS Style
Frabboni, L.; Tarantino, A.; Petruzzi, F.; Disciglio, G. Bio-Herbicidal Effects of Oregano and Rosemary Essential Oils on Chamomile (Matricaria chamomilla L.) Crop in Organic Farming System. Agronomy 2019, 9, 475. https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy9090475
AMA Style
Frabboni L, Tarantino A, Petruzzi F, Disciglio G. Bio-Herbicidal Effects of Oregano and Rosemary Essential Oils on Chamomile (Matricaria chamomilla L.) Crop in Organic Farming System. Agronomy. 2019; 9(9):475. https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy9090475
Chicago/Turabian StyleFrabboni, Laura, Annalisa Tarantino, Fiorenza Petruzzi, and Grazia Disciglio. 2019. "Bio-Herbicidal Effects of Oregano and Rosemary Essential Oils on Chamomile (Matricaria chamomilla L.) Crop in Organic Farming System" Agronomy 9, no. 9: 475. https://0-doi-org.brum.beds.ac.uk/10.3390/agronomy9090475
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