Improved method for raising rice nursery
By Dr Shahzad M. A. Basra, Dr M.
Farooq & Hafeez ur Rehman
is grown here under diverse climatic and edaphic conditions.
Basmati predominates in traditional rice tracts of Punjab.
Temperate Japonica rice is grown in Swat at high altitude in
the mountainous valleys. IRRI type long grain heat-tolerant
variety of tropical rice is grown in the south of NWFP,
Sindh and Balochistan.
Transplanting is the major method of growing rice. In this
method rice is grown in a nursery, pulled and transplanted
into well puddle and prepared field. Rice seedlings can
either be transplanted manually or by mechanically. In
transplanted rice, spacing between hills varies with variety
and seedling age. A spacing of 20 x 20 cm is recommended. A
hill should be transplanted with two healthy seedlings.
For transplanted seedlings, age is a major factor in
determining yield. Transplanting shock, this is a setback to
growth due to uprooting and replanting of seedling,
increases with increased age of seedling. In general, the
effect of transplanting on yield increases with the
decreasing age. Seedling age also varies with environmental
conditions and the type of nursery. The physical and
bio-chemical factors set a minimum and maximum age for a
particular nursery. Minimum age of a seedling for
transplanting is about 15-20 days. However, ideal seedling
age is about 30 days; tilling capacity is reduced if older
seedlings are transplanted.
Nursery seedlings: Rice which is to be transplanted into
puddle soil must first be nursed on seed beds. The main
reason for rising nursery is to provide seedlings a
substantial head-start on weeds. Rice nursery is raised by
four methods in world, viz. the wet-bed nursery, the dry-bed
nursery, the dapog and mat type in trays. Each has its
advantages and disadvantages. Dapog method originated in the
Philippines and is now fairly common in South East Asia, but
not practised in Pakistan. Mat type is being introduced in
the country. Wet-bed and dry-bed methods are common here
depending on the soil and water availability.
The wet-bed method is popular worldwide. It is used in areas
where water is adequate. In our country, it is commonly
followed in Punjab and the NWFP. The area selected for
nursery is watered for about 30 days before sowing. It helps
in eradication weeds. When weeds germinate after a week, the
field is thoroughly puddled and levelled. Clean seed is
shifted into gunny bags and soaked in water for 24 hours.
After soaking it is placed under shade and covered with
gunny bags. Water is sprinkled over seed after intervals and
turned with hands about three times in a day for proper
aeration and avoiding damage by heat due to suffocation.
After about 36-48 hours, the seed sprouts and is ready for
sowing. Pre-germinated seeds are then broadcast in seedbed.
Once the seedlings are established, the nursery is impounded
with water. Water level is then raised gradually. Some
decomposed organic manures and small amount of inorganic
fertiliser as basal dose may also be added in the nursery.
Remember to flood the beds while uprooting. Uproot seedlings
by holding at a few times between thumb and forefinger at
the base of culms and pulling sideway.
The dry-bed method of nursery is practised in dry soil
conditions. The fields are prepared under dry conditions.
Seeds beds of convenient dimensions are prepared by raising
soil to a height of about 5-10 cm. A thin layer of farmyard
manure or half burnt paddy husk could be spread over nursery
bed mainly to facilitate uprooting. In this method, soaked
seed are spread over seedbed and then irrigated. In some
areas of Punjab rab method of nursery raising is also
Nursery raised by soaking seeds and then broadcasting
pre-germinated seeds may be ready for transplanting within
40-45 days under both system of nursery growing. For
decades, our farmers are using pre-germinated seeds for rice
nursery raising that result in poor and delayed germination.
Not only it is very difficult to handle the pre-germinated
seeds but it also makes the nursery sowing a tedious job.
Nursery seedlings thus raised can be transplanted when they
are 40-45 days old, while, 30-day-old seedlings are
considered ideal for transplanting. Older seedlings result
in lower tilling capacity thus reducing the final yield.
Sub-optimum plant population and uneven crop stand resulting
from poor nursery seedlings are the most important yield
limiting factors in the traditional rice production system
which ultimately results in low paddy yield. Success in
raising healthy rice seedlings depends mainly on planting
high quality seeds with increased vigour. Seeds with
enhanced vigour have high percentages for germination and
vigorous seedling growth than seeds low in vigour generally
produce weak seedlings that are susceptible to environmental
stresses. Seeds high in vigour generally provide for early
and uniform stands that give seedlings a competitive
advantage against environmental stresses. Improved seed
invigoration techniques like seed priming are being used to
reduce the germination time, to get synchronised
germination, improve germination rate, and better seedling
stand in many field crops like wheat, maize including rice.
These seed priming techniques including hydro priming, osmo-conditioning,
osmo-hardening and hardening has been successfully employed
for earlier and better nursery stand establishment, which
result in improved performance of traditional rice
Recently, after a series of trials at farmerís field of
districts of Sialkot, Sheikhupura and Faisalabad,
researchers at the Department of Crop Physiology, University
of Agriculture, Faisalabad, have successfully established an
improved method of nursery raising by using primed seeds
instead of pre-germinated seeds as in case of traditional
method of nursery raising. The seed priming techniques like
osmo-hardening with CaCl2, followed by hardening and osmo-hardening
KCl are found the most effective and promising seed priming
techniques in both coarse and fine rice varieties for
raising healthy and vigorous nursery seedlings growth.
These seed priming techniques not only improve nursery
seedlings and performance of improved nursery seedlings,
increased growth, yield and quality of transplanted rice
production system are also reported. Rapid and more uniform
germination and seedling growth, younger seedlings are able
to be transplanted after 25-30 days which result in higher
tilling that ultimately lead to improved kernel yield of the
Transplanted rice raised by improved nursery method is also
resistant to lodging due to natural calamities such as
windstorm having healthy and vigorous seedling growth of
main culms and secondary branches and deeper, more vigorous
and fibrous root system development.
It should always be kept in mind that it is really very easy
to raise healthy seedlings by primed seeds if one is
prepared to take enough time to do the job properly. Success
in raising healthy rice seedlings depends mainly on the
constant supervision and proper management.
Courtesy: The Dawn