Maize Genetics
Cooperation Newsletter vol 85 2009
Strategies to Produce
Farmers Own Seed of Open Pollinated Varieties (OPVs) of Maize
A. G. Rather, Shafiq A. Wani, S. Najeeb, F. A. Sheikh and M. A. Ahangar*
High Altitude Maize Research Sub-Station, Sagam
Sher-e-Kashmir University of Agricultural
Sciences & Technology of Kashmir, India.
*E-mail: [email protected]
Maize
varieties may be either hybrids or open pollinated. While hybrids are
inherently high yielding, OPVs have the advantage of stable performance than hybrid
in low yielding and stress environments. Moreover, the seed of the OPVs can be
saved for next planting. Maize being a highly cross pollinated crop, standards
for minimum isolation have been developed for seed production depending on
class of seed and size of the field.
In Kashmir maize is second most important crop after rice
occupying about 01 lakh hectares. The crop is largely
cultivated under rainfed conditions using OPVs. Among many factors responsible
for low productivity of the crop, seed has been recognized one of the crucial
elements. It is well documented that good quality seed alone can enhance
productivity up to 20%. Due to unorganized seed sector and underdeveloped
infrastructure more than 85% farmers use their own saved seed. Since the maize grown in contiguous plots, the production of
quality seed under prescribed minimum isolation distance becomes difficult
rather impossible. However, owing to straightforward nature of seed
production in OPVs farmers can use their own saved seed for several seasons without
substantial loss of yield potential or good agronomic characters provided some
precautionary measures as described below are undertaken;
Choice of cultivar: Broadly speaking two types of
cultivars are available suited to two different agro-ecological situations
(valley/high altitude) of Kashmir. Farmers should choose the cultivars
according to their ecological requirements.
Seed: Initially certified seed of
particular cultivar should be used to produce farmers
own saved seed.
Cultural practices:
Agronomic practices are, in general similar to used in producing a grain crop.
However careful consideration must be given to land preparation and
fertilizer/manure application to produce the uniform growing conditions in seed
production plot. This would facilitate the identification of off-types during
rouging operation. Seed rate: Plant 10-15% more seed than desired at the harvesting time to
compensate for reduced germination and seedling mortality caused by pest
attacks (cutworms etc).
Irrigation: If there is a provision of
irrigation two irrigations may be given at tasseling and grain filling stage.
Field layout to produce farmers own saved
seed for 8 kanals (1 acre*): In one acre of land plant 9-10 kg seed of the
desired OPVs uniformally in lines**
drawn 60 cm apart. At four leaf stage thin out excess plants maintaining a
plant to plant distance of 20 cm. Emphasis should be given to the removal of
plants that do not resemble the variety based on colour of leaves/stem, height,
vigour etc. In the middle of the field select 150 sq m (15 x 10 m) area where
slightly wider spacing (25 cm) is maintained between plants. Thus there will be
25 rows of 10 m length, each row having 40 plants to accommodate about 100
plants. The wider spacing will ensure good seed set and development. This will
also allow full expression of plant type to aid in the identification of
off-types. When a hill is missing allow two plants to grow in the next hill. In
the selected area detassel plants, before pollen shed, not confirming to the
varietal description because 90% of the pollen comes from plants in the
vicinity. In the central 17 rows excluding 5 plants from each side of row (500
plants), henceforth called seed plot, detassel 40% (200) plants before pollen
shed which are considered atypical. Selection criteria used will include plant
and ear height, leaf/ stem colour, pubescence, disease/insect damage etc. Very
tall and very dwarf plants as well as plants falling outside the range of
maturity are rejected. Allow the crop to mature.
Harvesting: Harvesting the crop when seed
moisture is between 16-20% (dry husk stage). Harvesting should be done
carefully by hand. Harvest seed plot first to avoid any chances of mixture.
Only those plants (300) are harvested for seed which
had been lift with their tassels on in the seed plot whereas the rejected
plants are detassled. Spread these 300 ears on a tarpaulin or on a dry and
clean concrete surface and check for ear and grain characteristics (ear size
and kernel colour/ texture) after dehusking. Select 250-275 true type ears free
from disease and insect damage.
Drying of ears: Sundry selected ears on a clean and dry surface. Do not heap
ears while sun drying. Turn ears frequently for uniform drying. Shelling is
done when grain moisture comes down to 14% level. A simple test can be applied
to check whether seed has reached 14% moisture content. Shell an ear and mix
100 kernels with one gram of common salt. If the salt feels moist after five
minutes, ears need to be dried further but if salt remains dry shelling can
begin.
Drying of seed: Sundry the seed to 12% moisture
level (when seed under teeth is broken with a sharp sound) for safe storage.
Low seed moisture increases the viability and storability of the seed. While
sun drying ensure that seed is turned frequently to prevent �sun burn� damage
to the embryo.
Cleaning: The shelled seed may be cleaned
(winnowed) and any chipped and diseased seed be removed by hand. A quantity of
18-20 kg seed will be obtained from selected ears.
Treating: Treat the seed with Thiram @ 2g/kg
of seed. Ensure that seed is uniformally treated. When treating with chemical
observe safety recommendations given on the container. Treated seed must never
be used for human or animal consumption.
Storage: Store in gunny bags in a cool and
dry place away from rodents.
During the next season half of the seed is sown and next half
is retained to meet any eventuality. The process is repeated for three seasons
before procuring fresh certified seed.
The package of seed production described above briefly
mentions the maintenance and seed multiplication of maize OPVs but provide plenty
of information to the resource poor farmers who are ignorant about the
importance of quality seed. The necessary infrastructure for the production and
marketing of superior hybrids are still not available under our temperate
conditions. Hence maize is generally grown on marginal lands as rain fed crop
with least inputs and whose economic production is highly dependent on input
based technologies. Thus rules out the possible role of single cross hybrids in
improving the economy of the farmers. The OPVs resolves the problem in the form
of genetic and population buffering, besides are easier to develop than
hybrids. The seed production is relatively simple and inexpensive and resource
poor farmers who grow them can save their own seed for planting 2-3 subsequent
seasons. Also the management technologies presented in the article can be
undertaken without involving any special operation and cost except some minor
manipulations and adjustments together will create plenty of employment
opportunities.
References:
Anonymous, 1994. World Maize Facts and Trends. Maize Seed Industries, Emerging Role of Public and Private Sectors,
CIMMYT, Mexico.
Anonymous, 1988. Quality Protein
Maize, National Academy Press, Washington, D. C.
Hallauer, A. R. and Miranda, J. B.1988. Quantative
genetics in maize breeding. 2nd ed. Iowa
State University Press, Ames.
Please Note: Notes submitted to the Maize Genetics Cooperation
Newsletter may be cited only with consent of authors.