The effect of water deficit stress on the growth, yield and composition of essential oils of parsley

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/248478000 The effect of water deficit stress on the growth, yield and composition of essential oils of parsley Article in Scientia Horticulturae · February 2008 DOI: 10.1016/j.scienta.2007.10.008 CITATIONS READS 81 481 4 authors, including: Spyridon Alexandros Petropoulos Dimitra Daferera 81 PUBLICATIONS 222 CITATIONS 62 PUBLICATIONS 4,851 CITATIONS University of Thessaly SEE PROFILE Agricultural University of Athens SEE PROFILE Some of the authors of this publication are also working on these related projects: Evaluation of chemical composition and nutritional value of Greek okra cultivars View project Chemical composition and nutritional value evaluation of Greek artichokes View project All content following this page was uploaded by Spyridon Alexandros Petropoulos on 10 January 2017. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. Available online at www.sciencedirect.com Scientia Horticulturae 115 (2008) 393–397 www.elsevier.com/locate/scihorti The effect of water deficit stress on the growth, yield and composition of essential oils of parsley S.A. Petropoulos a, Dimitra Daferera b, M.G. Polissiou b, H.C. Passam a,* a Agricultural University of Athens, Laboratory of Vegetable Production, 75 Iera Odos, 11855 Athens, Greece Agricultural University of Athens, Laboratory of General Chemistry, 75 Iera Odos, 11855 Athens, Greece b Received 6 July 2007; received in revised form 21 September 2007; accepted 4 October 2007 Abstract Three parsley cultivars (plain-leafed, curly-leafed and turnip-rooted) were grown under conditions of 35–40% and 45–60% water deficit in order to evaluate the effect of this form of stress on plant growth, essential oil yield and composition. Plant growth (foliage and root weight, leaf number) was significantly reduced by water stress, even at 30–45% deficit. Water stress increased the yield of essential oil (on a fresh weight basis) from the leaves of plain-leafed and curly-leafed, but not turnip-rooted, parsley. However, on a m2 basis foliage oil yield increased significantly only in curly-leafed parsley. Water stress also caused changes in the relative contribution of certain aroma constituents of the essential oils (principally 1,3,8-p-menthatriene, myristicin, terpinolene + p-cymenene), but these changes varied between cultivars. The oil yield of roots was low and water deficit stress had relatively little effect on the root oil composition. It is concluded that because the biomass of plants subjected to water deficit is reduced, it is possible to increase the plant density of plain-leafed or curly-leafed parsley, thereby further increasing the yield of oil per m2. However, the application of water deficit stress to parsley essential oil production must also take into account likely changes in oil composition, which in turn relate to the cultivar. # 2007 Elsevier B.V. All rights reserved. Keywords: Plain-leafed; Curly-leafed; Turnip-rooted parsley; Drought 1. Introduction Parsley (Petroselinum crispum [Mill.] Nym. ex A.W. Hill) is cultivated both as a herb for consumption in the fresh and dried state and as a source of essential oils. Whereas plain-leafed and curly-leafed parsley are cultivated for their foliage, turniprooted or ‘‘Hamburg type’’ parsley, is cultivated for its enlarged, fleshy, edible roots (Petropoulos et al., 2006). The optimisation of irrigation for the production of fresh leaves and roots of parsley is essential since, as in other horticultural crops, water is a major component of the fresh produce and significantly affects both weight and quality (Jones and Tardieu, 1998). Water deficit in plants may lead to physiological disorders, such as a reduction in photosynthesis and transpiration (Sarker et al., 2005), and in the case of aromatic crops may cause significant changes in the yield and composition of essential oils. For example, water deficit * Corresponding author. Tel.: +30 10 5294535; fax: +30 10 5294504. E-mail address: passam@aua.gr (H.C. Passam). 0304-4238/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2007.10.008 decreased the oil yield of rosemary (Rosmarinus officinalis L.) and anise (Pimpinella anisum L.) (Singh and Ramesh, 2000; Zehtab-Salmasi et al., 2001). By contrast, water stress had a positive effect on pepper (Capsicum annuum L. var. annuum) by increasing the phenolic capsaicinoids (capsaicin and dihydrocapsaicin) and thereby increasing pungency (Estrada et al., 1999). Moreover, although water stress caused a significant reduction in the growth and oil yield of citronella grass (Cymbopogon winterianus Jowitt.) per acre, oil yield expressed on the basis of plant fresh weight increased, with the severity of the water stress response varying with cultivar and plant density (Fatima et al., 2000). Plain-leafed parsley is widely grown throughout the Mediterranean region, usually under irrigation, whereas the turnip-rooted form has been proposed as a suitable alternative crop within the framework of the European common agricultural policy (Petropoulos et al., 2006). In Greece, the principal areas of cultivation are situated close to large urban markets, such as Athens and Thessaloniki. Because of the relatively hot, dry climate, plants are susceptible to water stress, especially during late spring and early summer; hence, the 394 S.A. Petropoulos et al. / Scientia Horticulturae 115 (2008) 393–397 application of a precise irrigation schedule is of major importance. Since the effect of such stress on parsley growth and essential oil composition has not been previously reported, the experiments described in the present paper were undertaken. 2. Materials and methods Three parsley cultivars were used: (a) Petroselinum crispum (Mill) Nym. ex A.W. Hill ssp. neapolitanum Danert cv. plainleafed (Geniki Fytotechniki, Greece), (b) P. crispum ssp. crispum (L.) cv. curly-leafed (Geniki Fytotechniki, Greece) and (c) P. crispum ssp. tuberosum (Bernh.) Crov., turnip-rooted cv. Fakir (Bejo Zaden b.v., Holland). Seeds were sown in trays containing a compost of peat (KTS2, Klasmann-Deilman Gmbh, Geeste, Germany) and washed, riverbed sand in a ratio of 2:1 (v/v) on 12 January (year 1) and 17 January (year 2). At the 2–3 leaf stage, plants were transplanted to 10 l plastic pots (3 plants per pot  8 pots per treatment) containing the same compost and placed in rows so as to achieve a plant density of 27 plants per m2. The pots were retained in an unheated greenhouse until early spring, when they were transferred outdoors. The substrate contained 150 g superphosphate (0–46–0), 90 g potassium nitrate and 900 g marble dust per m3. Pots were irrigated with 0.3 l water for the first 2 weeks, increasing gradually to 1.5 l by the end of the growth cycle, regardless of treatment. Irrigation was applied once a week during the early stage of growth increasing to up to three times a week during the stages prior to harvest. Soluble fertilizer (1.25 g l 1 of 20N-20P-20K) was dissolved in the irrigation water once every 2 weeks throughout the cultivation. Water deficit was achieved by withholding irrigation in relation to the control until soil moisture reached the desired level. Two levels of water deficit were maintained with the aid of tension meters (Irrometer-Moisture Indicator, Irrometer, Riverside, CA), in which irrigation was applied at soil water potentials of 30–45% (level 1) and 45–60% (level 2), whereas the control was held at 0–10% (field capacity). These percent levels are those indicated in terms of centibars by the tension meters, where 0% represents soil at field capacity and 100% dry soil. Plants of all treatments were hand-harvested at the stage of market acceptability on 21–22 May (year 1) and 25 May (year 2). At the time when water stress was applied, mean air temperature was 16.0 and 20.8 8C, mean air temperaturemax was 20.1 and 25.2 8C, mean temperaturemin was 11.2 and 15.9 8C and relative humidity was 51 and 65% (years 1 and 2, respectively). In year 2, leaves and roots were separated and sliced into small pieces immediately after harvest, placed in sealed, airtight plastic food-bags and stored at 10 8C, in order to determine the yield and composition of the essential oil. Because the yield of oil from parsley is rather low, Clevenger distillers, with 1000 ml round, heating flasks were used. Samples of 100–150 g of sliced frozen leaves or roots were boiled in distilled water in the flasks heated by thermo-mantles (Barnstead Electrothermal EMV 1000, Barnstead International, Southend, U.K.) for 3 h from the start of boiling. The volume of the oil phase from each distillation was measured and the product put into 30 ml glass bottles, sealed with parafilm and stored at 20 8C until analyzed. In order to remove any traces of water in the samples before gas chromatography analysis, the essential oil was extracted from the water phase in 10 ml diethyl ether, with a 50 ml extraction funnel. Since only small quantities of oil were required for composition analysis, oil samples for this purpose were more conveniently obtained by micro-steam distillation in a Likens– Nickerson apparatus, which requires a shorter boiling time. Samples of 10–12 g of sliced frozen leaves were boiled in distilled water in 100 ml round flasks, heated by thermomantles (Barnstead Electrothermal EMV 250), with 5 ml diethyl ether for extraction. The process was carried out for 1 h from the start of vapor condensation on the condenser walls. The organic phase (containing the essential oil) was put into 30 ml glass bottles, sealed with parafilm and stored at 20 8C until analyzed. Essential oils extracted with hydro-distillation were analyzed by gas chromatography using a Hewlett Packard 5890 II GC (Hewlett Packard, Waldbronn, Germany) equipped with a FID detector and HP-5MS capillary column (30 m  0.25 mm, film thickness 0.25 mm). Injector and detector temperatures were set at 220 and 290 8C, respectively. Column temperature was initially kept at 50 8C for 5 min, then gradually increased to 200 8C at a rate of 4 8C/min and maintained for 5 min. The flow rate of helium was 1 ml/min. Quantitative data were obtained electronically from FID area percent data without the use of correction factors. Each extraction was replicated three times and the compound percentages are the means of the three replicates. Gas chromatography/mass spectrometry (GC/MS) analysis was applied for the samples obtained with micro-steam distillation and performed under the same conditions as GCFID (column, oven temperature, flow rate of the carrier gas) using a Hewlett Packard 5890 II GC equipped with a Hewlett Packard 5792 mass selective detector (Hewlett Packard, Waldbronn, Germany) in the electron impact mode (70 eV). Injector and MS transfer line temperatures were set at 220 and 290 8C, respectively. The identification of components was based on the comparison of their GC retention time and mass spectra with authentic standards when possible. Additionally, tentative identification was based on the comparison of their relative retention time and mass spectra with those of the NBS75K library data of the GC/MS system and literature data (Adams, 2001; Petropoulos et al., 2004). Leaf and root yields were subjected to analysis of variance and means compared by the least significance difference test using the statistical packages Statgraphics Plus 5.1 and JMP 4.0.2 v. Oil yield and composition statistics were carried out with Microsoft Excel. 3. Results Exposure of parsley plants to increasing levels of water deficit caused a progressive decrease in the fresh weight of 395 S.A. Petropoulos et al. / Scientia Horticulturae 115 (2008) 393–397 Table 1 The effect of water deficit stress on the fresh weight of foliage and roots and the number of leaves per plant of three parsley cultivars Cultivar Level of water deficit Year 1 Year 2 Foliage (g) Root (g) Leaf number Foliage (g) Root (g) Leaf number Plain-leafed Control (0–10%) Level 1 (30–45%) Level 2 (45–60%) 62.3 a 32.8 b 29.6 b 17.8 a 11.3 b 7.3 c 8.2 a 5.9 b 5.9 b 80.7 a 55.6 b 49.7 b 27.8 a 24.9 ab 21.1 b 9.1 a 7.0 b 6.4 b Curly-leafed Control (0–10%) Level 1 (30–45%) Level 2 (45–60%) 52.6 a 28.7 b 24.4 c 14.8 a 9.0 b 5.8 c 6.5 a 4.5 c 5.3 b 86.3 a 58.1 b 46.3 c 14.3 14.5 14.1 6.7 6.5 6.0 Turnip-rooted Control (0–10%) Level 1 (30–45%) Level 2 (45–60%) 52.2 a 33.7 b 29.5 c 42.3 a 27.8 b 20.8 b 6.9 a 5.1 b 4.9 b 62.2 a 43.7 b 35.5 c 44.4 a 41.4 a 25.8 b 6.7 a 5.7 b 4.8 c Means for each cultivar within the columns that are not followed by a letter or are followed by the same letter are not significantly different at P = 0.05. foliage of curly-leafed and turnip-rooted parsley, whereas the foliage weight of plain-leafed parsley decreased greatly when plants were subjected to the lower level of water deficit (30– 45%) but not further at the higher water deficit level (45–60%). The number of leaves per plant also decreased under the influence of water stress (except curly-leafed parsley in year 2), as did root fresh weight in year 1. In year 2, root fresh weight was only reduced in plants of plain-leafed and turnip-rooted parsley exposed to the higher level of water deficit (45–60%), whereas the root weight of the curly-leafed cultivar was not affected (Table 1). The effect of water deficit stress on the yield of essential oils extracted from parsley leaves (expressed as ml per 100 g fresh weight) was variable. Thus, oil yield was higher in the leaves of plants of plain-leafed and curly-leafed parsley subjected to water stress, but not in the leaves of the turnip-rooted cultivar. Overall, the yield of oil from the roots was lower than that of the leaves and was not affected by water deficit stress, irrespective of cultivar (Table 2). When expressed on an area basis (ml per m2) oil yield of the leaves was found to be higher in curly-leafed parsley subjected to water deficit stress, but not in the other two cultivars. Water stress did not significantly affect the oil yield of the roots on a fresh weight basis, and even decreased oil yield on a m2 basis in the plain-leafed cultivar (Table 2). Water deficit stress affected the relative composition of the essential oils of the leaves (Table 3). In plain-leafed parsley, both levels of water stress caused a reduction in the relative concentration of 1,3,8-p-menthatriene, but an increase in myristicin. In this cultivar too, the percent concentration of terpinolene + p-cymenene decreased at the higher stress level. In the leaves of curly-leafed parsley, increasing water stress caused a progressive decrease in the percentage of myristicin which was offset by increases in a- and b-phellandrene, terpinolene + p-cymenene. In contrast, the composition of the essential oil extracted from the leaves of turnip-rooted parsley was only marginally affected by water stress. In this cultivar, a small, but significant decrease in the relative concentration of b-myrcene coincided with a small increase in apiole (Table 3). Water stress had relatively little effect on the composition of the essential oil extracted from the roots of turnip-rooted parsley. A decrease in myristicin was observed at the higher level of water deficit, as was a slight decline in the percentage of terpinolene + p-cymenene at both levels of stress (Table 4). Water stress did not appear to affect the relative composition of the essential oil from curly-leafed or plain-leafed parsley, except for a relative decrease in the apiole content of the latter, coinciding with a small increase in b-pinene (data not shown). 4. Discussion Essential oils derived from parsley are of value to the cosmetic industry as well as for the synthesis of medicinal Table 2 The effect of water deficit stress on the essential oil yield of parley leaves and roots expressed as ml of essential oil per 100 g fresh plant material and ml per m2 Level of water deficit ml per m2a ml per 100 g fresh weight Plain-leafed Curly-leafed Turnip-rooted Plain-leafed Curly-leafed Turnip-rooted Leaves Control (0–10%) Level 1 (30–45%) Level 2 (45–60%) 0.04 b 0.06 a 0.07 a 0.05 b 0.07 b 0.11 a 0.04 0.05 0.05 0.87 0.90 0.94 1.17 b 1.09 b 1.38 a 0.67 0.59 0.48 Roots Control (0–10%) Level 1 (30–45%) Level 2 (45–60%) 0.05 0.04 0.04 0.03 0.02 0.02 0.02 0.01 0.02 0.38 a 0.27 b 0.23 b 0.12 0.08 0.08 0.24 0.11 0.14 Means for each year within the columns that are not followed by a letter or are followed by the same letter are not significantly different at P = 0.05. a Plant density = 27 plants m 2. 396 S.A. Petropoulos et al. / Scientia Horticulturae 115 (2008) 393–397 Table 3 The effect of water deficit stress on the relative concentrations of the principal components of the essential oil extracted from parsley leaves Component Relative concentration (%) of essential oil components in the leaves of Plain-leafed parsley a-Pinene b-Pinene b-Myrcene a-Phellandrene p-Cymene b-Phellandrene Terpinolene + p-cymenene 1,3,8-p-Menthatriene b-Elemene Myristicin Apiole Total Curly-leafed parsley Turnip-rooted parsley Control Level 1 Level 2 Control Level 1 Level 2 Control Level 1 Level 2 4.11 3.35 6.76 1.07 nd a 25.07 10.77 a 5.49 a 0.77 28.63 b 2.91 88.93 3.98 3.36 5.76 0.96 nd 23.63 10.23 a 2.63 b 0.78 33.43 a 1.90 86.66 4.32 3.50 4.28 0.99 0.6 21.97 6.79 b 1.95 b 0.96 33.35 a 6.35 85.06 1.17 1.04 6.35 0.29 0.28 9.66 2.62 0.15 3.52 61.09 2.96 89.13 1.13 0.99 6.54 0.61 0.44 18.66 3.86 0.34 4.50 48.19 3.04 88.30 1.86 1.95 a 7.91 0.83 a nd 20.96 a 5.77 a 3.18 3.32 41.20 c 2.95 89.63 5.36 4.69 26.94 a 0.97 a 1.02 26.73 18.69 a 3.16 0.66 a 0.43 nd 88.65 5.75 5.28 24.44 b 0.37 b 0.97 25.41 21.28 a nd 0.45 b 1.34 0.10 b 85.39 7.6 6.7 22.0 b 1.1 a 1.0 29.7 16.4 b 3.5 0.3 c 1.0 2.7 a 92.00 b c b c a b b a b b Means for each cultivar within the rows that are not followed by a letter or are followed by the same letter are not significantly different at P = 0.05. a nd: not detected. products. Oils are extracted mainly from the foliage or the seeds, but yields are rather low in comparison with other aromatic species, e.g. dill (Anethum graveolens L.) (Callan et al., 2007). When grown in warm climates such as those of the Mediterranean Basin, especially in late spring and summer, parsley may easily be exposed to stress due to water deficit. As shown in the present paper, such stress causes a reduction in biomass, as expressed by mean foliage and root weight, as well as leaf number per plant (Table 1), and probably results from a disruption of photosynthesis, transpiration and other metabolic processes (Jones and Tardieu, 1998; Sarker et al., 2005). Water deficit stress does not reduce the essential oil yield of parsley foliage on a fresh weight basis. Indeed, the oil yield of both the plain-leafed and the curly-leafed cultivars increased significantly under stress conditions (Table 2), thus compensating for the reduction in fresh biomass. This result contrasts with those of Zehtab-Salmasi et al. (2001), who reported that water stress reduced oil yields from rosemary. Singh and Ramesh Table 4 The effect of water deficit stress on the relative concentrations of the principal components of the essential oil extracted from the roots of turnip-rooted parsley Component Relative concentration (%) of essential oil in roots from Control Level 1 Level 2 a-Pinene b-Pinene b-Myrcene a-Phellandrene p-Cymene b-Phellandrene Terpinolene + p-cymenene 1,3,8-p-Menthatriene b-Elemene Myristicin Apiole nd 16.43 a 9.88 a 1.53 1.72 a 20.95 a 3.04 a nd 1.05 13.55 a 23.59 b nd 12.97 b 5.67 b 1.35 1.25 b 14.37 b 2.31 b nd 1.1 16.05 a 33.92 a 1.1 21.0 a 7.7 ab 1.6 1.1 b 19.8 a 2.5 b nd 1.5 7.7 b 25.7 b Total 91.74 88.99 89.7 Means within the rows that are not followed by a letter or are followed by the same letter are not significantly different at P = 0.05. nd: not detected. (2000) also reported that water deficit stress reduced the oil yield of rosemary on a hectare basis, but oil yield on a plant fresh weight basis did not appear to be affected. In curly-leafed parsley water deficit stress may be considered beneficial since the oil yield of the foliage increases with stress on an area (m2) basis. Indeed, this effect may be further enhanced if planting occurs at a higher density, which is permitted thanks to the smaller plant size under stress conditions (Petropoulos, 2006; Table 1). The value of higher plant densities under stress conditions has been noted for citronella grass (Fatima et al., 2000). Theoretically, by increasing the plant density of curly-leafed and plain-leafed parsley from 27 to 36 plants per m2, an increase in net foliage oil yield of 44 and 57%, respectively at a water deficit level of 45–60% may be achieved in comparison with unstressed plants at the lower plant density, but the corresponding foliage oil yield of turnip-rooted parsley is still 5% less than that of unstressed plants. The value of increasing the plant population, however, requires field testing since the increase in plant density might further increase plant water stress. The effects of water stress are not only confined to plant growth and essential oil yield, but also extend to the quality of the oil. Parsley aroma appears to be due primarily to 1,3,8-pmenthatriene (Jung et al., 1992; Masanetz and Grosch, 1998). Consequently, the reduction in the relative concentration of 1,3, 8-p-menthatriene in the oil extracted from plain-leafed parsley subjected to water stress (Table 3) can be considered detrimental to oil quality, even though this was partly offset by an increase in myristicin, another important aromatic constituent (Simon and Quinn, 1988). In curly-leafed parsley, the progressive decrease in the percentage of myristicin due to increasing water stress may be ameliorated by the increase in b-phellandrene, terpinolene and p-cymenene, which also contribute to parsley aroma (Kasting et al., 1972; Freeman et al., 1975). Changes in the composition of essential oils as a result of exposing plants to water stress have also been reported for citronella grass (Fatima et al., 2000), but in rosemary soil moisture levels had no effect on oil quality (Singh and Ramesh, 2000). S.A. Petropoulos et al. / Scientia Horticulturae 115 (2008) 393–397 Turnip-rooted parsley is the only one of the three parsley types that is cultivated for its roots, which are fleshy tap roots as opposed to the branching adventitious root systems of the plainleafed and curly-leafed cultivars (Petropoulos, 2006). Because of the low yield of essential oil from parsley roots, only turniprooted parsley may be considered for root oil production. Even so, the yield is appreciably less than that of the foliage on a fresh weight basis (Table 2). Although water deficit stress may affect the quality of oil from the roots of turnip-rooted parsley, since the percentage of myristicin was slightly reduced under stress conditions, the main effect of water stress here is a reduction in oil yield on a plant or m2 basis. Even when applying higher plant densities, the net root oil yield under stress conditions is similar to the oil yield under normal conditions and plant densities, rendering this practice of no practical value. In conclusion, although water deficit stress reduces plant biomass, in the case of curly-leafed parsley this is offset by an increase in the essential oil yield per 100 g fresh tissue. Although it may be possible to increase oil yield of both curlyleafed and plain-leafed parsley per m2 by exploiting the reduction in plant size to use higher plant densities, the feasibility of such a practice must first be evaluated in terms of changes in oil quality, which are also related to the cultivar. Acknowledgements We thank Bejo Zaden (Holland) for kindly providing the seeds of turnip-rooted parsley, and S. Colovos, V. Tsagaraki and V. Petroulea for technical assistance. The financial support of the Greek National Foundation of Scholarships is gratefully acknowledged. 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