Calendula (Calendula officinalis L.), or pot marigold, is an herbaceous annual or short-lived perennial (Mohammad and Kashani, 2012) that is widely naturalized and grown for ornamental and medicinal purposes throughout temperate zones. The species has been cultivated since antiquity for its purported general medicinal qualities. Recent work investigating calendula’s medicinal properties have reported antimicrobial (Mohammad and Kashani, 2012), antiviral (Kalvatchev et al., 1997), antitumor (Matic et al., 2013), and anti-inflammatory (Preethi and Kuttan, 2009; Preethi et al., 2009) effects. Pharmaceutically active compounds in calendula are commonly derived from the “essential oils” distilled from fully open flowers (Gazim et al., 2008; Khalid and Teixeira da Silva, 2010; Okoh et al., 2008). Essential oils, or “volatile oils” are complex mixtures of plant secondary compounds, whose quantity and quality may be affected by cultivar and growing environment (Jha et al., 2011; Khalid and Teixeira da Silva, 2010; Król, 2011; Ozturk et al., 2004).
Calendula varieties grown for ornamental and medicinal purposes both contain essential oils; however, the systems in which they grow may differ considerably. Ornamental cultivars are typically grown on a relatively small scale, often under irrigated and high nutrient input conditions (RezaeiNejad and KhosraviShakib, 2013). In contrast, calendula used for medicinal or oilseed purposes are grown on a relatively large scale, and may be in systems that are water and/or nutrient limited (Forcella et al., 2012).
Understanding how to optimize medicinal plant production under reduced input regimes (e.g., water and fertility) is key to the sustainable and profitable production of calendula and other medicinal plants in a variety of contexts. Calendula grown for essential oil is often produced in semiarid and arid regions where agricultural water is limited (e.g., Khalid and Teixeira da Silva, 2010; Maleki et al., 2014; Metwally et al., 2013). Production of medicinal plants has been suggested as an economic development activity in developing countries (Khalid and Teixeira da Silva, 2010; Srivastava et al., 1996), where access to conventional inputs may be limited (Srivastava et al., 1996). Sustainability-oriented production systems may be structured with similar constraints. Low external input farming systems seek to minimize purchased off-farm inputs, such as fertilizers and pesticides, and to increase the internal production and cycling of on-farm inputs (Parr et al., 1990). Similarly, organic farming systems often use fertility sources of biological origin (e.g., cover crops, crop residues, composts, and manures) and are based on minimal use of off-farm inputs (USDA NOSB, 1995). In all of these situations, nutrient availability and water limitation present management challenges and may have complex effects on essential oil production in medicinal plants.
Ensuring an adequate N supply is a key challenge to crop production in these systems (Parr et al., 1990), because the bulk of the N must be mineralized from the fertility source by microbial decomposition before plant uptake. Consequently, N availability may be difficult to predict (Gaskell, 2006; Gaskell and Smith, 2007; Hartz et al., 2010), leading to deficiencies that can reduce plant growth (Chand et al., 2011; Nourimand et al., 2012; Siddiqui et al., 2011). Although N stress is generally detrimental to plant growth, the effects on plant secondary compounds are somewhat more complex. Nitrogen deficiency may enhance synthesis of secondary chemicals including antioxidants of medicinal plants (Chand et al., 2011; Nourimand et al., 2012; Siddiqui et al., 2011). However, N fertilization has also been positively correlated with enhanced secondary compound synthesis and the ability to mitigate oil yield losses caused by drought (Rahmani et al., 2011).
Similarly, drought stress may reduce plant primary productivity, but the effects on secondary compounds are less straightforward. Drought can reduce plant biomass and simply increase the concentrations of secondary metabolites due to reduced fresh biomass in water-restricted plants (de Abreu and Mazzafera, 2005; Liu et al., 2011; Nogues et al., 1998; Selmar and Kleinwaechter, 2013). However, Selmar and Kleinwaechter (2013) opine that this is an oversimplification, and that drought stress may cause a plant to redirect carbon from growth to increased secondary compound production (Selmar, 2008; Selmar and Kleinwaechter, 2013). This may protect the plant from damage induced under stress conditions. For example, the medicinal plants Rosmarinus officinalis L. and Salvia officinalis L. produce more essential oils at higher concentrations when grown under drought stress conditions (Selmar and Kleinwaechter, 2013). The essential oils are effective antioxidants and thus protect the plant from reactive oxygen species that result when water-stressed plants are unable to dissipate surplus absorbed solar energy (Bozin et al., 2007; Selmar and Kleinwaechter, 2013).
The effects of both nutrient supply and water availability on medicinal plant growth and secondary compound production are important to understand singularly. However, in systems using biological sources of fertility, nutrient mineralization is mediated by soil microbial activity, which is highly influenced by moisture and temperature (Drinkwater and Snapp, 2007). As such, plant growth and secondary compound production in medicinal plants grown in these systems is a function of the interaction between the nutrient source and climatic factors. There has been little work examining the interaction of these factors on resource allocation in medicinal plant production, save a few notable exceptions (e.g., Jha et al., 2011; Król, 2011). Thus, improved understanding of how the interactions between plant growth, development, and secondary compound production are affected by nutrient dynamics and drought stress is important for the sustainable production of medicinal crops, such as calendula.
This work determined the influences of fertility source and water stress on N availability, plant growth, and essential oil production of four calendula cultivars in a greenhouse setting. Cultivars included herbal and ornamental varieties. Each cultivar was produced using four fertility treatments, including conventional, high-input organic, low external input organic, and no input treatments. Drought stress was induced in each combination of treatments.
de AbreuI.N.MazzaferaP.2005Effect of water and temperature stress on the content of active constituents of Hypericum brasiliense ChoisyPlant Physiol. Biochem.43241248
BerimavandiA.R.HashemabadiD.GhazianiM.V.F.KavianiB.2011Effects of plant density and sowing date on the growth, flowering and quantity of essential oil of Calendula officinalis LJ. Med. Plants Res.551105115
BozinB.Mimica-DukicN.SamojlikI.JovinE.2007Antimicrobial and antioxidant properties of rosemary and sage (Rosmarinus officinalis L. and Salvia officinalis L., Lamiaceae) essential oilsJ. Agr. Food Chem.5578797885
ChandS.PandeyA.AnwarM.PatraD.D.2011Influence of integrated supply of vermicompost, biofertilizer and inorganic fertilizer on productivity and quality of rose scented geranium (Pelargonium species)Indian J. of Nat. Prod. Resour.2375382
CrutchfieldJ.D.GroveJ.H.2011A new cadmium reduction device for the microplate determination of nitrate in water, soil, plant tissue, and physiological fluidsJ. AOAC Intl.9418961905
DrinkwaterL.E.LetourneauD.K.WorknehF.VanbruggenA.H.C.ShennanC.1995Fundamental differences between conventional and organic tomato agroecosystems in CaliforniaEcol. Appl.510981112
GazimZ.C.RezendeC.M.FragaS.R.Dias FilhoB.P.NakamuraC.V.CortezD.A.G.2008Analysis of the essential oils from Calendula officinalis growing in Brazil using three different extraction proceduresRevista Brasileira de Ciências Farmacêuticas44391395
GrayD.E.PallardyS.G.GarrettH.E.RottinghausG.E.2003Effect of acute drought stress and time of harvest on phytochemistry and dry weight of St. John’s wort leaves and flowersPlanta Med.6910241030
JhaP.RamM.KhanM.A.KiranU.MahmooduzzafarY.M.AbdinM.Z.2011Impact of organic manure and chemical fertilizers on artemisinin content and yield in Artemisia annua LInd. Crops Prod.33296301
KaskonieneV.KaskonasP.JalinskaiteM.MaruskaA.2011Chemical composition and chemometric analysis of variation in essential oils of Calendula officinalis L. during vegetation stagesChromatographia73S163S169
KhalidK.A.Teixeira da SilvaJ.A.2010Yield, essential oil and pigment content of Calendula officinalis L. flower heads cultivated under salt stress conditionsSci. Hort.126297305
KrólB.2011Yield and the chemical composition of flower heads of pot marigold (Calendula officinalis L. cv. Orange King) depending on nitrogen fertilizationActa Sci. Pol. Hortorum Cultus10235243
LiuH.Y.WangX.D.WangD.H.ZouZ.R.LiangZ.S.2011Effect of drought stress on growth and accumulation of active constituents in Salvia miltiorrhiza BungeInd. Crops Prod.338488
MalekiA.FeizolahiA.NaseriR.RezaeiK.HeydariM.M.2014Effects of different fertilizer sources on vegetative characteristics of pot marigold plant (Calendula officinalis L.)Intl. J. Biosci.5242249
MaticI.Z.JuranicZ.SavikinK.ZdunicG.NadvinskiN.GodevacD.2013Chamomile and marigold tea: Chemical characterization and evaluation of anticancer activityPhytother. Res.27852858
MetwallyS.A.KhalidK.A.Abou-LeilaB.H.2013Effect of water regime on growth, flower yield, essential oil and proline contents of Calendula officinalisNus. Biosci.56569
NoguesS.AllenD.J.MorisonJ.I.L.BakerN.R.1998Ultraviolet-B radiation effects on water relations, leaf development, and photosynthesis in droughted pea plantsPlant Physiol.117173181
NourimandM.MohsenzadehS.da SilvaJ.A.T.2012Physiological responses of fennel seedling to four environmental stresses. Iran J. Sci. Technol. Trans. (A1):37–46
OkohO.O.SadimenkoA.P.AsekunO.T.AfolayanA.J.2008The effects of drying on the chemical components of essential oils of Calendula officinalis LAfr. J. Biotechnol.715001502
OzturkA.UnlukaraA.IpekA.GurbuzB.2004Effects of salt stress and water deficit on plant growth and essential oil content of lemon balm (Melissa officinalis L.)Pak. J. Bot.36787792
ParrJ.F.PapendickR.I.YoungbergI.G.MeyerR.E.1990. Sustainable agriculture in the United States p. 50–67. In: C. Edwards R. Lal P. Madden R.H. Miller and G. House (eds.). Sustainable agriculture systems. Soil and Water Conservation Society Ankeny
PreethiK.C.KuttanG.KuttanR.2009Anti-inflammatory activity of flower extract of Calendula officinalis Linn. and its possible mechanism of actionIndian J. Exp. Biol.47113120
RahmaniN.DaneshianJ.FarahaniH.A.TaherkhaniT.2011Evaluation of nitrogenous fertilizer influence on oil variations of calendula (Calendula officinalis L.) under drought stress conditionsJ. Med. Plants Res.5696701
RezaeiNejadA.KhosraviShakibA.2013Ornamental value of Calendula officinalis “Yellow Gitana” as a result of nitrogen fertilizer and plant densityInter. Jour. Agric. Crop Sci.5362365
RiceC.W.SmithM.S.CrutchfieldJ.M.1984Inorganic-N analysis of soil extracts by automated and distillation proceduresCommun. Soil Sci. Plant Anal.15663672
RichterC.2007Commercial calendula cultivation. Richters herbs. 22 Feb. 2015. <www.richters.com/show.cgi?page=MagazineRack/Articles/CommercialCalendulaCultivation.html>.
SanchezE.S.RichardT.L.2009Using organic nutrient sources. Pennsylvania State University Extension Publication UJ256. 2 Mar. 2015. <http://pubs.cas.psu.edu/freepubs/pdfs/uj256.pdf>.
SelmarD.2008Potential of salt and drought stress to increase pharmaceutical significant secondary compounds in plantsLandbauforsch Volkenrode58139–144
SelmarD.KleinwaechterM.2013Influencing the product quality by deliberately applying drought stress during the cultivation of medicinal plantsInd. Crops Prod.42558566
SiddiquiY.IslamaT.M.NaiduY.MeonS.2011The conjunctive use of compost tea and inorganic fertiliser on the growth, yield and terpenoid content of Centella asiatica (L.) urbanSci. Hort.130289295
Sigal EscaladaV.ArchboldD.D.2009Preharvest aminoethoxyvinylglycine plus postharvest heat treatments influence apple fruit ripening after cold storageHortScience4416371640
SrivastavaJ.LambertJ.VietmeyerN.1996Medicinal plants: An expanding role in development. World Bank Technical Paper World Bank Washington DC
TaherkhaniT.RahmaniN.AghdamA.M.ZandiP.2011Assessment of nitrogen levels on flower yield of calendula grown under different water deficit stresses using drough tolerant indicesJ. Am. Sci.7591598
USDA NOSB1995As compiled by Gold MV Alternative Farming Systems Information Center. 1 Mar. 2015. <http://www.nal.usda.gov/afsic/pubs/ofp/ofp.shtml>.