A manual of rice seed health testing - IRRI books - International Rice ...

Sieve method (Fig. 8.1)
Procedure: 1. The setup consists of a
sieve and a plastic dish.
The sieve, made from nylon
cloth mesh, is stretched
over a polyvinyl chloride
(PVC) drain pipe rim (15 x
15 mm) that has 3 legs.
Place sieve in a plastic
dish.
2. Place seeds over the mesh.
Fill dish with enough water
to submerge seeds. Leave
at 25±2 °C for at least 2 d.
3. After 48 h, gently remove
the sieve from the dish and
collect the water in a
beaker. Wash the dish 2 to
3 times to ensure that all
nematodes are transferred
to the beaker.
4. Allow beaker to stand for
1 h or so to allow nematodes
to settle down. Pipette
out excess water.
Count nematodes on a De
Griss counting dish under a
stereobinocular microscope.
This method is efficient
for seeds with or without
hulls and can detect
nematodes even after 24 h.
Identification
Parasitic plant nematodes have
stylets, which are not present in
nonparasitic nematodes. To see the
stylets, view the nematode under a
stereobinocular microscope with the
light source coming from below.
A. besseyi is described on p, 65.
Manual dehulling method
Procedure: 1. Soak seeds in water for
24 h.
2. Using a scalpel and needle,
dehull seeds while they are
soaking.
3. Transfer contents (kernels,
hulls, and water) either to a
Baermann funnel or a
sieve. Recover and count
nematodes after 48-72 h.
When dehulled grains are
used, more nematodes are
recovered through the sieve
method than the Baermann
funnel method.
Nematode count increases
as seeds soak
longer, but seeds putrify
after about 72 h.
48 Rice seed health testing manual