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Technology
Following
is a brief description of the techniques that would
be taught to the trainees:
Production
of seedlings Producing ready-to-transplant
seedlings is currently common only for vegetables.
But in the case of other crops such as cotton, castor,
arhar, sugarcane or even cereals like rice, bajra
and jowar, one can raise seedlings in a nursery
and transplant them at the right time.
For woody dicots like cotton, arhar and castor,
the seedlings could be produced in plastic bags,
while seedlings for most vegetables and cereals
can be produced on a bed of soil or sand laid on
a plastic film. For optimum results, the soil should
have pH of about 6.5. In peninsular India, red (lateritic)
soil generally satisfies this condition. If the
soil is clayey, it should be mixed with sand or
compost, in order to ensure good drainage. The soil
is initially drenched with a fungicide solution,
to kill pathogenic fungi. Since drenching also causes
any weed seeds in the soil to germinate, these should
be removed before sowing the crop seed. Incorporating
inoculum of Trichoderma viridae also protects the
seedlings from soil-borne fungal pathogens. The
seed is sown in rows, about 7 to 10 cm apart. The
space between the rows is covered by strips pf black
plastic film (plastic mulch), which prevents excessive
evaporation of water, checks growth of weeds between
the rows and, in winter, keeps the soil warm to
accelerate germination. The seedlings are fertilized
and watered as usual.
Surroundings
the seedbed with a continuous skirting of transparent
colourless plastic film, about 1 m high, prevents
dissipation of the carbon dioxide generated by the
plants during the night and enables itsassimilation
by the plants during the following day. The growth
of the seedlings is also accelerated because of
the additional carbon dioxide. The plastic skirting
around the beds is later removed so that the plants
are exposed to dry air and wind, which hardens them
in readiness for sale.
Vegetative
Propagation through rooted cuttings Shoot
cuttings of most tropical dicot species are capable
of producing roots if they are properly treated.
Such rooted cuttings have the same genetic constitution,
and therefore the same characteristics, as the mother
plant. Cuttings of most vines, lianas and herbs,
and also those taken from young saplings of trees,
root more easily than cuttings from adult tress
(i.e. trees that are already producing flowers/fruits).
In general, softwood cuttings (i.e. twigs having
green bark) root more easily than hardwood cuttings
(cut-tings having brown bark). Hormonal treatment
of the basal part of the cutting increases the percentage
of rooting. The treatment consists of dipping the
basal 1 or 2 cm of the cutting for about 10 sec
in 4000 ppm solution of indole butyric acid (IBA)
or naphthalene acetic acid (NAA) and planting such
cuttings in moist sand.
High
Humidity Chamber Cuttings placed for rooting
can lose moisture of the weather is dry. This can
be avoided by keeping the cuttings in an atmosphere
having more than 70% relative humidity. If the rooting
is conducted in coastal regions, normal atmospheric
humidity is itself generally high enough but in
inland regions atmospheric humidity can be very
low. In such cases, the beds in which the cuttings
are planed are covered by a transparent plastic
film supported by wire arches forming an enclosed
chamber. The atmosphere within this space is very
soon saturated by water vapour, indicated by droplets
of water condensing on the inner surface of the
plastic film. Twigs planted in this chamber remain
turgid and fresh for even up to 8 weeks. Using a
low-cost humidity chamber of this type dramatically
increases the percentage of rooting. For commercial-scale
production, the size of the chamber can be increased
as required. The only precaution required is to
place it in the shade because, if the humidity chamber
gets exposed to direct sunlight, it would get so
heated up that the twigs would die of heat shock.
Potting
Medium Sand-soil mixture is generally quite
adequate as potting medium. Sand serves primarily
to increase porosity of the soil, therefore the
proportion of its use depends upon the clay content
of the soil. In black cotton soil, which is extremely
clayey, ratio of sand to soil should be 1:1, but
if the soil is sandy, there is no need to add sand
to the medium. Leaf litter (semi-decomposed leaves)
can also be used instead of sand. It is light in
weight, has good porosity and, while it decomposes,
also provides the saplings with nutrients. If it
is plentifully available, the pots may be filled
with just the leaf litter. Another substance commonly
used nowadays is coconut peat, which however, is
quite costly. A similar product can also be obtained
by controlled decomposition of dry sugarcane leaves,
wheat straw or any other agro-waste, which is locally
available.
Peat
substitute from agro-waste A silo-like structure
about 1m wide and 2 m tall is made by wrapping a
black plastic sheet around four vertical bamboo
poles. This silo is filled with the target biomass,
which has been thoroughly soaked in slurry of cattle
dung. The entire mass is kept wet by periodically
sprinkling water on it so as to maintain the process
of decomposition, which takes place only if the
material is moist. Covering the top also with black
plastic sheeting helps to conserve the moisture
in the pile. As the biomass decomposes, it subsides
and therefore requires to be topped up periodically
with more biomass treated with cattle dung slurry.
Depending on the nature of the agro-waste, the composting
process can take anywhere from two to four months.
A square hole of about 50 cm side is cut near the
bottom of the silo and the composted material removed
through this exit port. After each removal, fresh
biomass (always treated with cattle dung) should
be added to the silo from the top. Once the method
has been standardized, the plastic sheet can be
replaced by a permanent brick structure or by a
large diameter cement pipe.
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