Synthetic Media for Growing Duckweeds
Duckweeds in nature
Hoagland E-Medium
Schenk and Hildebrandt Medium
Other Media

Before preparing any duckweed medium, read the section on troublshooting.  Adjusting the pH of the medium is important.

Duckweeds in nature

Before deciding on a growth medium for the laboratory, it is useful to understand how duckweeds grow in nature.

Elias Landolt did extensive investigtions of duckweed ecology.  He found that duckweeds grow under a wide variety of conditions.  However, he did find some generalities.  Duckweeds generally are not found in oligotrophic water (water in which nutrients are in low supply).  They also are rare on lakes drained by granitic soils and limestone and on very old soils that are poor in most nutrients.  "Exceptions are waters heavily contaminated by waste water.  On the other hand extensive eutrophication may lead to the disappearance of more sensitive species, e.g. L. trisulca in Finland (Toivonen, 1985) or Wolffiella species in California (own observations)." (Landolt, 1986, p149).

The Table below shows the range of minerals found in waters supporting the natural growth of duckweeds.
Range of nutrient content in waters with Lemnaceae 

(chemical elements in mg/l, conductivity in uS/cm)

range of 95% of
  the samples
absolute range
range of 95% of
the samples
pH

conductivity

Ca
Mg
Na
K
N
p
HCO3
Cl
S

3.5—10.4

10 — 10900

0.1 — 365
0.1—230
l.3—>l000
0.5—100
0.003—43
0.000—56
8—500
0.1—4650
0.03—350

5.0—9.5 

50 — 2000

1.0 — 80 
0.5—50 
2.5—300 
1.0—30 
0.02—10 
0.003—2 
10—200
1—2000
1—200

Table reproduced from Landolt, 1986, p 150, summarizing data from various sources.
 
Lowest yearly mean of some nutrients in waters of Central Europe with Lemnaceae species

46 waters were investigated for three years. The Lemnaceae cover of the water was noted and the water analyzed from March to October once each month. In addition, 33 waters were observed less intensively. The number of occurrences of each species are as follows: S. polyrrhiza 18 times, L. gibba 16 times, L. minor 59 times, L. trisulca 15 times, and L. mi- nuscula 28 times.

nutrients in mg/L
Spirodela polyrrhiza
Lemna gibba
Lemna minor
Lemna trisulca
Lemna minuscula
P
N
K
Ca
Mg
0.007
0.04
1.3
18.8
1.1
0.027
0.22
2.6
23.7
4.5
0.006
0.04
0.9
11.6
1.1
0.01
0.04
2
40
4.6
0.012
0.18
1.5
18.6
1.1
Data above from Lueoend, 1983, V. Geobot. Inst. ETH, Stiftun Rubel, 80:116 pp., cited in Landolt, 1986, p. 150.
 

Hoagland's E-Medium

The most-commonly recommended medium is Hoagland's E-Medium.  There are different formulations of Hoagland's medium in the literature.  It was originally developed for hydroponic growth of terrestrial plants, not for the growth of duckweeds.

UTCC Formulation of Hoagland's E-Medium Additions per Liter of Final Medium
 
COMPOSITION STOCK SOLUTION Use 
mL/L
1. MgSO4·7H2O 24.6 g/100mL 1.0 mL
2. Ca(NO3)2·4H2O 23.6 g/100mL 2.3 mL
3. KH2PO4 13.6 g/100mL 0.5 mL
4. KNO3 10.1 g/100mL 2.5 mL
5. Micronutrients Micronutrient Solution (see below) 0.5 mL
6. Fe·EDTA  Fe·EDTA Solution (added last, see below)  20.0 mL
Preparation of Micronutrient Solution
 
ADDITION STOCK SOLUTION
1. H3BO3 2.86 g/L
2. MnCl2·4H2O 1.82 g/L
3. ZnSO4·7H2O 0.22 g/L
4. Na2MoO4·2H2O 0.09 g/L
5. CuSO4·5H2O 0.09 g/L

Preparation of Fe·EDTA Solution
 

ADDITION STOCK SOLUTION
1. FeCl3·6H20 0.121 g/250 mL
2. EDTA 0.375 g/250 mL
Cleland and Briggs Formulation of Hoagland's Medium

Reference:  Cowgill, U.M. and Milazzo, D.P. "The culturing and testing of two species of duckweed," Aquatic Toxicology and Hazard Assessment: 12th Volume, ASTM STP 1027, U.M. Cowgill and L.R. Williams, Eds. American Society for Testing and materials, Phila. 1989, pp. 379-391.  This article references Cleland and Briggs for this revision.  Cowgill and Milazzo also recommend addition of traces of Se, Co, Sn and V for optimal growth of one or more Lemna species.  In many cases, these trace elements are likely supplied by impurities in the other mineral components of these media, in the water used in their preparation, or leached from the glass walls of culture vessels.

TABLE 2-Chemical composition of Hoagland's E+ medium.
 

Substance
Stock Solution,
g L-1
Growth Medium,
mL L-1
A. Ca(NO3)2·4H2O
   KNO3
   KH2PO4
   6 mL 6N HCl
59.00
75.76
34.00
20
B. Tartaric acid
3.0
1.0
C. FeCl3·6H20
5.4
1.0
D. EDTA
   8 mL 6N KOH
9.0
1.0
E. MgSO4·7H2O
50.0
10.0
F. H3BO3
   ZnSO4·7H2O
   Na2MoO4·2H2O
   CuSO4·5H2O
   MnCl2·4H2O
2.86
0.22
0.12
0.08
3.62
1.0
G. Sucrose
10.00 g
H. Yeast extract
0.10 g
I. Bactotryptone
0.60 g


Schenk and Hildebrandt Medium

Reference:  Schenk, R. U. and A. C. Hildebrandt, 1972, Medium and Techniques for Induction and Growth of Monocotyledonous and Dicotyledonous Plant Cell Cultures, Can. J. Bot. 50:199-204.
 
 

SH Stock Solutions

COMPOSITION STOCK SOLUTION Use 
mL/L
1. CaC12 (100X) To 100mL of distilled water add: 
CaC12·2H2O  2.0 g
10 mL
2. Major Elements 
   (100X)
To 80 mL of distilled water add: 
KNO3           25 g
MgSO4·7H2O      4 g
(NH4)H2PO4      3 g
Stir until dissolved. Then bring to a final volume of 100 mL.
10 mL
3. Minor Elements
   (100X)
To 100 mL of distilled water add:
MnSO4·H2O      0.1 g 
H3BO3          0.05 g 
ZnSO4·7H2O     0.01 g 
KI            0.01 g 
CuSO4·5H2O    0.002 g 
Na2MoO4·2H2O  0.001 g 
CoCl2·6H20    0.001 g
10 mL
4. Fe·EDTA (100X) 1. Dissolve in 50 mL distilled water:  0.15 g FeSO4·7H2O
2. Dissolve in 50 mL distilled water:  0.2 g Na2EDTA
3. Mix the two solutions with constant stirring.
10 mL
5. Organics
   (100X)
To 100 mL distilled water add: 
Myo-Inositol   10. g
Thiamine·HCl    0.05 g
Nicotinic acid  0.05 g
Pyridoxine·HCl  0.005 g
10 mL
6. Sucrose 10. g

Composition of Final Medium

Component mg/L
Major Elements
  KNO3 2500

MgSO4·7H2O 400

(NH4)H2PO4 300

CaC12·2H2O 200
Minor Elements

MnSO4·H2O 10.0

H3BO3 5.0

ZnSO4·7H2O 1.0

KI 1.0

CuSO4·5H2O 0.2

Na2MoO4·2H2O 0.1

CoCl2·6H20 0.1
Iron

FeSO4·7H2O 15.

Fe·EDTA 20.
Organics

Myo-Inositol 1000

Thiamine·HCl 5.0

Nicotinic acid 5.0

Pyridoxine·HCl 0.5

Sucrose 10
pH 5.6

Other Media

Regulatory agencies require specific defined media for phytotoxicity testing in Lemna.   The LemnaTec company details several of these formations (Steinberg, OECD, and ASTM media) on their website.

Wayne Armstrong recommends using 20% Hutner's solution solidified with agar for growth of duckweeds on a gelled medium.  There are several patents using duckweeds [ available on-line ], that reference synthetic media, including Nickell's Medium, and various commercial formulations, such as Nutricol No. 3 (Fertilizers and Chemical, Haifa, Israel) and Solu-Spray (Leffingwell Chemical Company).  These advantages of these, if any, are unclear.  The pH of these media should be adjusted, as for any medium.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Last revised:  August 13, 2013