COMPARING BASIL (OCIMUM BASILICUM) PRODUCTION IN HYDROPONIC AND AQUAPONIC SYSTEMS

Lauren Wilson1 | Nathan Duncan, Ph.D. 2 | D. Andrew Crain, Ph.D. 1

Maryville College, Maryville, TN., USA1Department of Biology, 2Department of Chemistry

Abstract:

Introduction:

Soilless farming, though it has been around for over two millennia, is becoming more prevalent in modern food production as it not only saves water and space but also provides an effective option for indoor urban farming. There are currently two major models of soilless farming—hydroponics and aquaponics. While both systems are effective, very few studies compare the two. The objective of this study was to compare the water quality, basil (Ocimum basilicum) productivity, and basil essential oil profiles from plants grown in a hydroponic and newly established aquaponic system. Basil plants from two age groups (young plants and old plants) were measured before, during, and after a four-week growth period in either a hydroponic or aquaponic system. Water quality was also analyzed before, during, and after the growth period, and essential oils were evaluated from harvested basil. Whereas older aquaponics plants seemed to grow better initially (p=0.0002 for leaf number and p=0.0036 for leaf density), at the end of the growth period it was younger hydroponic plants that had increased leaf number (p=0.0013) and stem height (p=0.0041). Both water quality and essential oils differed between the systems as well, with the aquaponics system having more stable nutrient supply and lower concentrations of essential oils. These data show that aquaponic and hydroponic systems show differences in water quality, basil productivity, and basil-leaf essential oil profiles.

Ø Human population growth necessitates more sustainable means of food production1. Ø Soilless farming saves water and space and also provides an effective option for indoor urban farming. Ø Two soilless farming methods:• Hydroponic farming delivers nutrients directly to plants without soil, which is replaced by nutrient-

rich water2,3.• Aquaponic farming is a combination of hydroponics and aquaculture, where fish waste is fixed by

bacteria and provides nutrients needed by plants that act as bio-filters and maintain a clean environment for the fish4-6.

Ø Question: Are quantity and quality of crops different when using hydroponic verses aquaponictechniques?

Ø Objective: In a hydroponic and newly established aquaponic system, compare:• Water quality• Basil (Ocimum basilicum) productivity• Essential oil profiles from basil

Methods:

Results:

Discussion:Experimental Design

Water Quality

Hydroponic system(with plants added)

Aquaponic system(before fish and plants added)

Basil Production Analysis

• Leaf density was calculated as number of leaves/stem height

• A t-test assuming equal variance (with α = 0.05) was performed for each measurement (number of leaves, stem height, and leaf density).

hydroponicaquaponic

Cl- NO3- PO4

-3 SO2-4

A

hydroponicaquaponic

Na+ K+ Ca+2 Mg+2

B

Literature Cited:1. de Carvalho RO, Weymar Jr LCN, Zanovello CB, da Luz MLG, Gadotti GI, da Luz CAS, Gomes MC. 2015.

Hydroponic lettuce production and minimally processed lettuce. Agric. Eng. Int. CIGR J.:290–294.2. Giurgiu RM, Morar GA, Dumitras A, Boanca P, Duda BM, Moldovan C. 2014. Study regarding the suitability

of cultivating medicinal plants in hydroponic systems in controlled environment. Res. J. Agric. Sci. 46:84–93.3. Schafer ED. 2014. Hydroponics. In: Salem Press Encyclopedia of Science.4. Elia E, Popa DC, Nicolae CG. 2014. Startup stages of a low-tech aquaponic system. Sci. Pap. Ser. D, Anim.

Sci. 42:263–269.5. Moya EAE, Sahagún CAA, Carrillo JMM, Alpuche PJA, Álvarez-González CA, Martínez-Yáñez R. 2014.

Herbaceous plants as part of biological filter for aquaponics system. Aquac. Res. 47:1716–1726.6. Tomlinson L. 2015. Indoor aquaponics in abandoned biuldings: a potential solution to food deserts. Sustain.

Dev. Law Policy XVI:16–24.7. Joshi RK. 2014. Chemical composition and antimicrobial activity of the essential oil of Ocimum basilicum L.

(sweet basil) from Western Ghats of North West Karnataka, India. Anc Sci. Life 33: 151-156.8. Wilson, G. 2005. Greenhouse aquaponics proves superior to inorganic hydroponics. Aquaponics Journal 39:

14-17.

1 2 3 4Leaves extracted with anhydrous diethyl ether for

three days

Extract filtered

Extract dried using anhydrous

magnesium sulfate

Extract evaporated

using a rotary evaporator

Essential Oil Extraction

Essential Oil Analysis• Total extract (see below) was

diluted to 10 mg/ml.• One ml extracts were

analyzed by GCMS by Cornerstone Analytics (Maryville, TN) using an Agilent 6890 GC with a 5972 MS (temperature program 40-300 C with a 60 min run at 2 µl injection).

Basil Production.

Essential Oils

Conclusions:Ø Aquaponics provided a more constant supply of nutrients to plants when compared to hydroponics.Ø Leaf number and plant height differed in the two systems, dependent on age of the plants when introduced.• “Old” aquaponic plants were more dense after 2 weeks.• “Young” hydroponic plants were taller after 4 weeks.

Ø Essential oil composition is different in basil grown in the two systems.• Hydroponic plants had higher concentrations of the identified essential oils.• Higher concentrations of oils such as eugenol may be an indicator of stress.7

Areas for Future Research:Ø Comparison of morphometric data after a full growing season/after aquaponics system has become more established (~ >6 months)8

Ø Full water quality analyses from samples collected every weekØ Full essential oil profile analyses for individual plantsØ Role of essential oils in stress and antibacterial defenseØ Aphid/pest damage differences between the systems (potential causes and solutions)2-week (”young”) and 4-week (“old”)

basil plants added

Water quality analysis Basil

production

Essential oil analysis

4 weeks of growth

Acknowledgements:Funding was provided by the Coyote Fund at Maryville College.In addition, we would like to thank:• Diane Kim at University of Southern California• Claire Snyder• Kent Davis and Maria Laughlin at Special Growers• Adam Latham at MC Steam Plant• Dave Flynn with Perennial Ponds• Mike Goodrich at Cornerstone Analytical Laboratories• James Spalvins at Innovative Hydroponic Supply

p = 0.0013 p = 0.0002

p = 0.0036P = 0.0041

Figure 1: Anions (A) and cations (B) in water sample from Day 28. Data from other days available upon request. Hydroponic water had much more variation in anions and cations.

Figure 2: Significant differences in young (A and C) and old (B and D) mean plant measurements of basil grown in either an aquaponic or hydroponic system after 2 weeks and 4 weeks of growth. * = significant

Figure 3: GCMS chromatogram of volatile basil extract from basil leaves. Leaves from the hydroponic system have more essential oils.

Water Analysis• Four ml samples were

collected from both systems on Days 11, 17, 24, and 28.

• Samples were analyzed by Cornerstone Analytics(Maryville, TN) by ion chromatography.