Deep ploughing is necessary to break up compacted layers
and allow unrestricted root development.
Since sunflower seeds vary considerably in size, those used
for mechanical planting should preferably be graded to produce
an even sample.
This will ensure a free flow in the seeders with no blockages
or crushed seeds to cause gappy stands.
Germination will also be more even, allowing more efficient weed
and pest control.
The achievement of optimum plant population is essential for profitable
yield, since sunflower with its single head is less able to compensate
for gross variation in plant number than, for instance, soya or rape
Combine drills, maize or cotton planters with suitable sunflower seed
plates can be used.
Uniform spacing ensures uniform growth, and thus ease of working
for cultivators and harvesters. When using electronically controlled
seeder units, depth of planting and seed rate are very even and grading
of seed may be unnecessary.
Although seed grading is not essential, since large or small seeds
of equal quality produce similar plants at maturity ,clean bold seeds
should be selected since they germinate evenly and produce vigorous
seedlings.
Whenever possible new seeds should be sown, Since sunflower seed
rapidly loses viability when improperly stored.
As a field guide to final stand, most modern cultivars have 80-85
percent emergence 2-5 days after first seedlings appear.
Seed should be dressed with a fungicide; Captan, Carboxin, Quintozene
and Thiram are suitable, and preferably an insecticide, or a combination
may be used, i.e. a standard groundnut or maize seed dressing.
Dressing the seed some months before planting helps to retain
viability and reduce fungal infection.
Seed should normally be planted 3-8 cm deep, depending mainly
on the variety and moisture in the seed-bed.
Soil in the vicinity of the seed must remain moist throughout
germination, and there should be no danger of frost.
On light soils a press wheel should be set to give a firm seed-bed,
since this will ensure that the soil does not dry out too quickly
and the small furrow made will stop soil blowing off the seed.
This technique should also be used in areas of low rainfall to
assist moisture penetration and absorption.
Below 15 degrees C generally retards germination and
below 10 degrees C inhibits many varieties.
High oil-content seed is more susceptible to low temperature damage
than low oil-content seed especially when germination has commenced.
When using standard planters with 75 cm row-width, seed rates
will vary from 3 to 8 kg/ha depending on seed size, to achieve a final
spacing of approximately 30 cm between plants.
Seed rates can be calculated from the following formula
(b) Seed required, kg=seed number/ha X area to be sown
(ha)/seed number/kg
(c) Number of seeds=seed number/ha X row-width (mm)/required/10
m of row 1,000,000
The practice of sowing sunflower on lands which remain unplanted
to maize or wheat is economically unsound, since the yield tends to
fall significantly and quickly outside the optimum period.
Correct time of planting affects not only yield, but also the
kernel-husk ratio.
Seed weight tends to decrease with delay in sowing, and the greatest
loss is in the kernel.
However, sowing outside the optimum period to obtain a high seed
yield may be necessary in some areas to avoid flowering at periods
of high temperature, in order to obtain a particular grade of oil
Within the optimum sowing period, plant population can vary within
reasonable limits since plants tend to produce larger heads at wider
spacing .
However, large heads also tend to have more pops, and yield of
oil per hectare may be significantly reduced.
Seed size may also be affected, and thus the kernel-husk ratio.
Thus the optimum plant population must be determined in terms
of the product required, oil or bold seed, and not solely by final
seed yield.
Population in the range 30,000 - 40,000 plants/ha at harvest is
acceptable for the tall varieties and 35,000 - 60,000 for hybrids
in areas where annual rainfall of 500 mm or above is normal.
Population can be 25-50 percent higher under irrigation in the
same area, but the possibility of increased loss form lodging must
be considered.
Under dry-land farming conditions, the plant population which
can be sustained is usually between 12,000 and 15,000 plants/ha, mainly
dependent on the rainfall expected during crop growth.
Ikisan - Seed treatment and crop unformity in Sunflower
Seed Treatment And Crop Uniformity
The seed should be planted at 4 cm deep in the plough for getting
highest percentage of germination.
Sunflower can stand a little deeper sowings than other oil
seeds. Hence depth of sowing should be adjusted according to the
soil moisture.
Dibbling of seed at proper distance and depth is also a common method
of sowing sunflower seed. Initially 2-3 soaked (12 hours) seed per hill
should be planted and with in 15-20 days of germination, the additional
one to two weak plant should be thinned out.
Gap if any , should be filled at 10 days after sowing .
In heavy soils, the crop can be grown on ridges and furrows as to
avoid water stagnation.
Seed dormancy and Viability
The sunflower seeds (achenes) remain dormant upto 40-45 days of harvesting
however, the dehusked seeds may germinate from 10th day after
harvest.
Exogenous application of ethrel, benzyl adenine and Gibberlic acid
promotes germination of achenes.
Pre-soaking of dormant seeds with ethrel solution (25 ppm) equivalent
to 40% by volume of seeds has been found to be optimum.
The soaking period may vary from 6 hours to 24 hours.
The achenes should be dried in shade and then may be sown directly.
Usually sunflower seeds remain viable for 10-12 months but under hot
humid conditions the seeds lose viability quickly.
At 50 to 85% relative humidity, seeds lose viability within 40-60
days.
Pre-soaking seeds with water or protein (10-5 M concentration)
before storing increases viability even under high humidity conditions.
Seed treatment
Seeds must be treated with a fungicides to control the seed
borne disease.
For this , the seed should be treated with Captan or Thiram
or Mancozeb 75 W.P @ 3 gm. per kg of seed before sowing.
For getting good result, the sunflower seed should be soaked in water
twelve hours and shade dried before sowing.
This will avoid ill filled grains and for quick and uniform-germination.
After fungicide treatment, the seed can be treated with Azospirillum
which helps in N-fixation (or) apply one kg or Azospirillum to soil
after mixing with powdered FYM.
Seed rate
Straight varieties - Rainfed 8-10 Kg/ha/ ID 6-8 Kg/ha
Hybrids - Rainfed 6-7 Kg/ha/ ID 5-6 Kg/ha
Spacing
The seed should be sown in lines 60 cm. apart (row to row) and in
rows with a plant spacing of 30 cm.
For a good crop, row to row spacing of 80 cm, and plant to plant
spacing of 20 cm must be kept .
Root development is affected in Narrow spaced plantings.
Development of numerous small roots and spreading of root system into
deeper layers is more in wide spaced plantings.
Spacing in different soils
Soils
Spacing(cm)
Optimum population/ha
Light
45 x 20
1,11,000
Medium
45 x 30
74,000
Heavy
60 x 30
55,000
Usually for long duration varieties or hybrids adopt a spacing of
60 x 30cm.
In regions where the amount and distribution of rainfall is good adopt
a spacing of 45 x 30cm.
For short duration straight varieties like Mordern adopt a spacing
of 45 x 20 cm.
For rainfed sunflower keep more spacing between the rows and less
spacing within the row which facilitates better root development.
In fertile heavy soils adopt closer spacing while in light red soil
adopt wider spacing.
Under I.D conditions maintain more population which control weeds,
avoids lodging and give higher yields.
Immediately after seeding cover the seed with soil by running a blade
harrow.
Care should be exercised upto 7-10 days after sowing against bird,
rat and squirrel damage.
Time of planting affects not only yield, but also the kernel-husk
ratio.
Seed weight tends to decrease with delay in sowing, and the greatest
loss is in the kernel.
Sowing outside the optimum period to obtain a high seed yield may
be necessary in some areas to avoid flowering at periods of high temperature,
in order to obtain a particular grade of oil.
Within the optimum sowing period, plant population can vary within
reasonable limits since plants tend to produce larger heads at wider
spacing .