Abstract
The study was conducted in the Department of Agronomy,
Bangladesh Agricultural University, Mymensingh from Novembe
1983 through August 1987 with the objectives of determining
the effect of growing conditions of seed crop on the quality
and performance of seed, to determine the effect of duration
of pre - storage drying of seed on their quality and
performance; and to characterise environments of commonly
used storage containers and their effects on the quality and
perfor mance of wheat seed.
The study included the following activities :
(i) Characterization of storage environments
The storage containers has been characterised based upon
their Moisture Reciprocation Index of seed (MRI M1
D1 tennunt Mn/Dn, where Mi# per cent seed moisture at
first observation, Di# duration of seed storage at first
observation, Mn# per cent of seed moisture at last
observation, Dn= duration of seed storage at last
observation ), Humidity Reciprocation Index of container H
RI X1/Y1t.. + Xn/Ym, where X1= per cent humidity at
first observation, Yi duration of seed storage at first
observation, Xn per cent of humidity at last observation
and Xn= duration of seed storage at last obsevation),
moisture permeability of the environment, levels of seedmoisture content, temperature and relative humidity
with the ambient temperature and relative humidity.
along
The nine storage environments were designated as E1(duli or
bamboo basket), E2(duli, seeds dried at monthly
intervals), E3 (duli with 0.12 mm thick polythene bag
inside), E4 (duli mixed with bishkatali leaves), E5(duli
coated with two coatings of coaltar ), E6 (hessian bag),
E7 (earthen pitcher coated with two coats of coal tar), E8
(kerosene tin with air tight lid) and E9 (polythene bag, 0.12
mm thick). The farmer's practice of storing seed containers
along with improved ones were included in the study.
i) Growing of wheat seed crops ( cultivar Sonalika
In addition to eleven field experiments, three seed crops
such as Seed crop I ( Grown at 100, 110, 120, 130 and 140 kg
seed /ha), Seed crop II ( Grown at 45, 90 and 135 kg N/ha )
and Seed crop III ( Harvested at three stages of maturity,
:
immature, mature and over mature i.e. harvested 4, & and 8
weeks after anthesis ) were grown for using them as seed
materials for the laboratory as well as field experiments.
(iii) Presevation of seed in nine storage environments
Seeds collected from each of the three seed crop werre
separately sun dried for 27 hours ( three days ) and stored
in nine environments for three sets of laboratory
experiments. In addition, a part of the mature seeds of seed
crop II was sun dried for 9,18,36 and 54 hours and stored in
nine storage environments. Before storing the seeds, theN content and 1000 - grain weight of Seed crop I and II were
determined.
(iv) Evaluation of seed quality and field perforamnce of the
seeds
Seeds of different storage environments were evaluated at.
monthiy intervals in respect of their moisture, germinat.ion
and insect infestatior. Storage environments were studied
with respect to seed temperature and seed humidity. The
seeds having germination above 80% at the end of the storage
period were tried in the field to see their performance.
Results from the ten laboratory experiments revealed that
duration of storage, seed moisture content and relative
humidity of the storage environment always and seed
temperature in certain environments significantly influenced
the retention of seed viability. Initial seed moisture
content could not play any significant role in the retention
of seed viability. Correlation co-efficient between moisture
perrmeability of the storage environment and the per cent of
seed mortality was estimated (r= + 0.926 ) for the nine
storage environments. There was a strong positive
correlation between them. Correlation co-effient between MRI
and per cent of seed mortality ( r= + 0.980 ) and also
between HRI and per cent of seed mortality ( r= + 0.979 )
were also determined for nine storage environments, both of
which had stong positive correlations.
Based on the ability of viability retention capacity of the
seeds, the storage environments E3, E8 and E9 were found to
be efficient and the seeds maintained over 80% germination
at the end of storage.
Results from all the twenty one experiments conducted in
field and also in laboratory condition clearly indicated
that lower seed rate of the seed crop ( 100 to 120 kg/ha
),its higher level of N application ( 135 kg N/ ha ) and
harvesting them in a maturity stage of 8 weeks afte
anthesis ensured production of high quality seed. And the
seeds again yielded better in the following generation under
field conditions, when they were sun dried for a longer
period between 36 to 54 hours and stored in suitable storage
enviroments such as E3, EB and E9. E8 ( which was almost
impermeable with 0.99% MRI and 10.2% HRI ), and E9 ( which
was almost impermeable with 0.95% MRI and 9.1 % HRI ) may be
suggested for small:scale storage. EZ ( which was almost
impermeable with 1.31 % MRI and 16.5% HRI ) may be suggested
for bulk storage.