Experiment:-2
Germination Test
The germination
capacity is one of the most desirable quality characteristic of a seed-lot.
Germination test is most widely used seed quality test. Germination of a seed
is defined as the emergence and development of the seedling to a stage where
the aspects of its essential structures indicate whether or not it is able to
develop further into a satisfactory plant under favorable conditions in soil. The
germination test is carried out with the following objectives:-
1)
To determine the maximum potential of a
seed lot.
2)
To obtain an indication of the field planting
value of a seed lot.
3)
To provide results that can be used to compare
the quality of seed lots.
Requirements
for germination
All the seeds need certain
conditions for normal germination. For a viable, non dormant seed to germinate
some factors viz. water, air, temperature, light and substratum are required. Germination
test in the laboratory should be performed under ideal conditions to get
maximum potential. This necessitates proper substrate, controlled temperature and
relative humidity. Currently paper and sand substrate, the following methods
are commonly used for testing purpose.
a) Top of paper (TP)
b) Between paper (BP)
c) In sand (S)
Equipment and materials:- Seed germinator, counting boards,
germination paper, blotters, wax paper, sterilized sand, plastic trays and boxes.
Between
Paper (BP) Method:-
1)
Take a random sample of seed from the pure
seed fraction of the purity analysis.
2)
Cut the towel (germination) papers and
wax papers to a convenient size to hold one replication of the seeds.
3)
Soak the towel papers for at least 20-30
minutes in a tray before use.
4)
Put the wax paper sheet on the table and
label it on the rough side with laboratory test number, replication and date of
start of the test with marker pen/pencil.
5)
Put one sheet of moist towel paper on
the wax paper.
6)
Arrange the seeds at regular intervals
on the paper by using counting board and bearing at least two centimeters space
clear from the edges all round.
7)
Cover the seeds with another sheet of
paper and fold in the edges to prevent the seeds from falling out.
8)
Roll the towel paper loosely towards the
end with label.
9)
Place the rolled papers in an upright position
in ventilated wire baskets or plastic boxes.
10)
Then keep these wire baskets or plastic
boxes in the seed germinator operating at required temperature.
Top
of Paper (TP) Method:-
a)
Take a random sample of seeds from the
pure seed fraction.
b)
Cut the absorbent paper to the size and
shape of the petri dishes.
c)
Place a layer of paper in each dish, if
the paper is too thin use a double layer.
d)
Label the paper or top and bottom at
each dish with laboratory test number, number of the replicate and date of the
start of the test.
e)
Moist the paper with water using wash bottle.
f)
Arrange the seeds in a regular
equidistant pattern on the surface of the paper.
g)
Cover the dish with lid and keep the dishes
in the seed germinator operating at required temperature.
Sand
(S) Method:-
1)
Take a random sample of required number
of seeds from the pure seed fraction.
2)
Pack clear sterile sand into boxes or
trays.
3)
Water the sand until it is moist, do not
excess water.
4)
Make holes in a regular equidistant
pattern at about the same depth as the size of seeds for each replication.
5)
Fill seeds from each replicate into the
holes and cover with sand.
6)
Either prepare a label and place it in
each tray or write down on the tray.
7)
Water the sand again, if needed, to
cover the seeds but don’t make it too wet.
Duration
of test:- The duration of test for individual species ranged
between 7-28 days.
Evaluation
of Germination Test:- At the end of germination test, the
samples are taken out and evaluated and classified in to the following:
Normal seedling:-
Seedlings which show the potential for continued development into satisfactory
plants, when grown under favorable conditions. These can be one of the following
categories: Intact seedlings:- Seedlings
with all their essential structures well developed, complete in proportion and
healthy.
Abnormal seedling:-
Seedling which do not show the potential to develop in to a normal plant when
grown under favorable conditions. Following type of seedlings are classified as
abnormal seedlings- damaged seedlings,
deformed seedlings and decayed seedlings.
Un-germinated seeds:- Seeds
which have not germinated by the end of the test period are classified as:
a)
Hard
seeds:- seeds remain hard at
the end of the test period, because they have not absorbed water due to
an impermeable seed coat. Eg. Leguminosae, Malvaceae.
b)
Fresh
seed:- seeds other than hard seed, which remain clean, firm
and apparently viable at the end of test period.
c)
Dead
seeds:- seeds which are neither hard nor fresh and have not
produced any part of seedling at the end of test period.
Calculation and reporting of
results:
Calculations:-
Example:
Calculate the germination percentages of the samples of wheat var. WH-147 and Mungbean
var. Asha tested in the seed-testing laboratory and recorded the following
observations (Averages):
Solution:-
a)
Wheat (50 seeds/application)
Normal
seedling = 43, abnormal seedling = 04
Fresh
seeds = 01, dead seeds = 02
Germination
(%) = 43/50 x 100 = 86%
b)
Mungbean (50 seeds/application)
Normal
seedlings = 39, abnormal seedlings = 06
Hard
seed = 02, dead seed = 03
Germination
(%) = 39+2/50 x 100 =
82%
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