- Germinate seeds on moist filter paper in petri dishes at 20°C.
- Collect root tips when they are about 1-cm long and pretreat with ice water for 24-48 h.
- Fix in Carnoy's
- Squash in 45% acetic acid.
- Remove cover slips by placing on dry ice until frozen and air dry.
- Drop fixative onto the preparations and flame dry.
- Dissolve 1 g of silver nitrate (AgNO3) in 1 mL of 0.02
g sodium citrate (C6H5Na3O7·2
H2O) per 500 mL distilled water, adjusted to pH 3.0 with
- Add 1 or 2 drops of the above solution (needs to be prepared fresh each time) onto the slides and place a cover slip over the preparation.
- Incubate slides in a moist chamber at 55-60°C for 30 min to several h. Monitor the silver precipitation under the microscope.
- When chromosomes are stained brown to yellow and Ag-NOR-bands appear black, staining is complete. Rinse slides thoroughly in distilled water.
- Soak in xylene and mount in Depex.