Materials and Reagents

1. Solanum lycopersicum seeds
   
2. Agar
   
3. Sodium hypochlorite (NaClO)
   
4. Potassium nitrate (KNO₃)
   
5. Ammonium nitrate (NH₄NO₃)
   
6. Calcium nitrate [Ca(NO₃)₂^.4H₂O]
   
7. Magnesium sulphate (MgSO₄^.7H₂O)
   
8. Ethylene diamine-N, N bis (2hydroxyphenylacetic acid) Ferric sodium complex (Fe-EDDHA)
   
9. Boric acid (H₃BO₃)
   
10. Manganese chloride (MnCl₂.4H₂O)
    
11. Zinc sulphate (ZnSO₄^.7H₂O )
    
12. Copper sulphate (CuSO₄^.5H₂O)
    
13. Sodium molybdate (Na₂MoO₄^.2H₂O)
    
14. Sodium chloride (NaCl)
    
15. Sodium sulphate (Na₂SO₄)*
    
16. Magnesium chloride (MgCl₂)*
    
17. Magnesium sulphate (MgSO₄)*
    *Note: These salts are necessary only if they have to be assayed. The standard assay is performed with NaCl.
    
18. Non-saline nutrient solution (see Recipes)
    
19. Salt stock solutions (see Recipes)
    

Equipment

1. Eppendorf-type tubes (1.5 ml)
   Note: Caps are removed and the tube end is cut with scissors (Figure 1A). Tubes are placed in a tube rack (with a sealed bottom, Figure 1B) and filled with 0.6% agar in tap water (melted in a microwave) using a 50 ml syringe (Figure 1C-D).
   
   
   Figure 1. Preparation of the tubes to hold plantlets. A) Cut tube, B) Racks with a sealed bottom, C) Filling tubes with agar in the rack and D) Tube filled with agar.
   
   
2. Opaque 10 L containers with cover
   Polyethylene containers (40 cm long x 30 cm wide x 12 cm high) are used. Covers are bored with a drill to allow the placement of the Eppendorf-type tubes (Figure 2).
   
   
   Figure 2. Example of a container with a bored cover to hold Eppendorf-type tubes
   
   
3. Petri dishes
   
4. 50 ml syringe
   
5. Growth chamber
   
6. ‘Aquarium’-type air pumps
   
7. Timer control
   
8. Microwave oven
   
9. Pasteur pipettes
   
10. Racks for Eppendorf-type tubes with a sealed bottom
    
11. Plastic trays with humidity domes
    
12. Precision balance (± 0.001)
    

Procedure