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Venturing in spinach cultivation
By Dr
Ali Muhammad Khushk & Rifat Abro
Spinach is an
excellent source of beta cortene, vitamin C, E, and K,
potassium, iron, sulphur, sodium, folic acid and oxalic
acid. It contains more protein than most vegetables.
Spinach is one of the vegetables with the highest amount
of chlorophyll, a fat-soluble substance that stimulates
hemoglobin and red blood cell production.
Chlorophyll is known to have a chemical formula
remarkably similar to that of hemoglobin, and it is said
that the ingestion of chlorophyll will raise hemoglobin
in blood without increasing the formed elements.
In plants, chlorophyll carries carbon dioxide as food to
cells and oxygen back as waste to be discharged from the
system. In animals, hemoglobin carries oxygen as food to
cells and exchanges it for carbon dioxide which is then
discharged as waste from the system.
So plants like spinach that are high in chlorophyll
support the liver in detoxifying and cleansing the
blood. With spinach, the effect is reinforced by its
considerable amount of sulphur. Sulfur is an
acid-forming mineral that protects the protoplasm of the
cells, disinfects the blood and helps body resist
bacteria. Folic acid is needed to form red blood cells
and support the formation and function of white blood
cells.
The exceptionally high antioxidant property of spinach
is due to carotenoids, beta carotene and lutein, which
are three to four times higher than in broccoli, for
example. These naturally occurring fat-soluble pigments
are most effective when eaten with some fat. Spinach
also has plenty of potassium, which supports a healthy
nervous system, aids proper muscle contraction,
stabilises blood pressure, regulates the transfer of
nutrients through cell membranes and, together with
sodium, controls the water balance of the body.
While spinach is known for its high iron content, recent
studies have shown that the iron contained in spinach is
not easy for the body to assimilate and only a very low
percentage is used. The relatively high amount of oxalic
acid in spinach interferes with the absorption of iron
and calcium into the blood.
When eaten in large amounts, spinach could damage
already impaired kidneys: oxalic acid removes calcium
from the blood in the form of calcium oxalate, and
calcium oxalate obstructs the kidney tubules. The fairly
high concentrate of nitrogen compounds in spinach can be
reduced up to 70 per cent by blanching the vegetable.
Climate and soils: This is an important vegetable of
Rabi season and requires a cool and moist climate. Low
temperature and high humidity helps in the development
of succulent, tenders mild flavoured foliage and quick
growth. The plant prefers sunshine.
For seed development and maturity, plant requires long
and warm days. Spinach germinates best at soil
temperature below 10-12c. At high temperature, the seed
fails to germinate because they enter into a dormant
state which continues until the temperature again falls
below 10-12oc.
Spinach can be grown successfully on a variety of soils,
but a fertile sandy loam high in organic matter is
preferred. The use of cover crops and green manure crops
is recommended to maintain the soil organic matter. The
soil pH should range between 6.4 to 6.8. Spinach is very
sensitive to acid soils, thus a soil test prior to
planting this crop should be made. Low germination,
yellowing and browning of margins and tips of seedling
leaves, browning of roots, general slow growth and even
death of plants, may indicate that the soil is too acid.
If the pH is too high, leaves may have a yellow colour
referred to as chlorosis.
Land preparation: A well-prepared seedbed that is free
of large clods permits precision planting with rapid and
uniform emergence of spinach seedlings. Uniform depth of
seeding is critical when using pre-plant-incorporated
herbicides because if spinach seeds are planted too
deeply, seedlings may be killed by herbicide.
Well-prepared seedbeds also permit proper and accurate
incorporation of pre-plant-incorporated herbicides,
leading to improved weed control and reduced
phytotoxicity to seedlings. In situations where
cultivation can be used, uniform beds with level bed
tops are essential
Irrigation: Spinach requires abundant moisture to insure
a high quality product. An application of one inch of
water every seven to ten days, when rainfall is
inadequate, is recommended. Keep soil moist until
seedlings have emerged.
Time of sowing: Winter spinach is best when sown in
August. Summer spinach can be started in February and
needs lot of water
Seed rae and varieties: There are two varieties of
spinach in Pakistan. Local Sindhi and prickly heat.
Around eight to ten seed per acre is recommended. Seeds
are broadcasted on the flat beds or in ridges and are
mixed with fully prepared soil sans pressed with some
hard material immediately after sowing seed, irrigation
water is applied.
Fertilisers: Spinach requires a high level of fertility,
especially nitrogen. Early spring spinach may require
larger quantities of fertiliser than fall crops. Per
acre requirements on sands and sandy loams are 85 to 120
lb N; 75 to 85 lb P2O5; and 85 to 150 lb K2O. On heavier
clay soils, 50 lb/acre of each nutrient should be
adequate. Fertilizer is often broadcast and worked into
the soil prior to seeding. If the fertilizer is banded
at seeding, it should be placed along each side of the
rows 2 to 3 inches below the level of the seed .
Weed control: A healthy, vigorous crop provides
substantial competition that suppresses weed growth and
acts as part of the weed control programme. Therefore,
proper fertilisation, irrigation, and insect and disease
control measures promote good crop growth and compliment
other weed control measures.
Hand-weeding is an expensive component of crop
production budget. If a weeding crew is sent into a
field before the harvest when weeds are mature, weed
removal is typically slow and expensive. Ideally, good
cultural practices and careful use of herbicides will
result in minimal hand-weeding requirements.
After planting the crop, there are two periods in which
herbicides may need to be applied, depending on the weed
species present. Post plant treatments are applied after
planting but before the first irrigation and the
emergence of crop; post emergent treatments are applied
when spinach is in the seedling stage or older to the
side of the row; fertiliser should never come in contact
with the seed.
Insects: Spinach aphid and leaf miner are the two
predominant insect pests of spinach.
Diseases: Downy mildew (blue mold), bacterial soft rot,
fusarium wilt, cucumber mosaic virus, carpospores spot,
white rust and heterosporium spot can all be problems in
spinach production
Marketing and storage: Spinach is sold loose, in
pre-packaged bags, or frozen. Fresh spinach loses much
of its nutritional value with storage of more than a few
days. While refrigeration slows this effect to about
eight days, spinach will lose most of its folate and
carotenoid content, so for longer storage it is frozen,
cooked and frozen, or canned. Storage in the freezer can
be for up to eight months.
Harvesting and yield: The crop is ready for cutting with
in six to eight weeks after sowing. The cutting is done
2cm above the ground level when plants have put five to
six leaves. New foliage is cut later with three to four
cuttings.
Courtesy: The DAWN |
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Pakissan.com;
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