C.V. Hanson1, E.A. Oelke2, D.H. Putnam2, and E.S.
1Center for Alternative Plant and Animal Products, University of Minnesota,
St. Paul, MN 55108.
2Department of Agronomy, and Plant Genetics, University of Minnesota,
St. Paul, MN 55108.
3Department of Agronomy, College of Agricultural and Life Sciences and
Cooperative Extension Service, University of Wisconsin-Madison, WI 53706.
June 1, 1992.
Psyllium is the common name used for several members of the plant genus Plantago
whose seeds are used commercially for the production of mucilage. The genus Plantago
contains over 200 species. P. ovata and P. psyllium are produced commercially
in several European countries, the former Soviet Union, Pakistan, and India. Plantago
seed known commercially as black, French or Spanish psyllium is obtained from P.
psyllium and P. arenaria. Seed produced from P. ovata is known
in trading circles as white or blonde psyllium, Indian Plantago or Isabgol. Isabgol,
the common name in India for P. ovata, comes from the Persian words "isap"
and "ghol" that mean horse ear, which is descriptive of the shape of the seed. India
dominates the world market in the production and export of psyllium. Psyllium research
and field trials in the U.S. have been conducted mainly in Arizona and also in Washington.
Recent interest in psyllium has arisen primarily due to its use in high fiber breakfast
cereals and from claims that these high fiber cereals containing psyllium are effective
in reducing cholesterol. Several studies point to a cholesterol reduction attributed
to a diet that includes dietary fiber such as psyllium. Research reported in The
American Journal of Clinical Nutrition concludes that the use of soluble-fiber cereals
is an effective and well tolerated part of a prudent diet for the treatment of mild
to moderate hypercholesterolemia. Research also indicates that psyllium incorporated
into food products is more effective at reducing blood glucose response than use
of a soluble fiber supplement that is separate from the food. Although the cholesterol
reducing properties and glycemic response properties of psyllium containing foods
are fairly well documented, the effect of long term inclusion of psyllium in the
diet has not been determined. Cases of allergic reaction to psyllium containing
cereal have been documented.
Psyllium is produced mainly for its mucilage content, which is highest in P. ovata.
Mucilage describes a group of clear, colorless, gelling agents derived from plants.
The mucilage obtained from psyllium comes from the seed coat. Mucilage is obtained
by mechanical milling/grinding of the outer layer of the seed. Mucilage yield amounts
to approximately 25% or more (by weight) of the total seed yield. Plantago
seed mucilage is often referred to as husk or psyllium husk. The milled seed mucilage
is a white fibrous material that is hydrophilic (water-loving). Upon absorbing water
the clear colorless mucilaginous gel that forms increases in volume by ten-fold
or more. Psyllium is mainly used as a dietary fiber, which is not digested by action
in the small intestine. The purely mechanical action of psyllium mucilage absorbs
excess water while stimulating normal bowel elimination. Although its main use has
been as a laxative, it is more appropriately termed a true dietary fiber.
The United States is the world's largest importer of psyllium "husk" with over 60%
of total imports going to pharmaceutical firms for use in products such as "Metamucil",
"Effersyllium" and "Fiberall". Psyllium mucilage is also used as a natural dietary
fiber for animals. The dehusked seed that remains after the seed coat is milled
off is rich in starch and fatty acids and is used in India as chicken feed and as
Psyllium mucilage possesses several other desirable properties. As a thickener,
it has been used in ice cream and frozen deserts. A 1.5% weight/volume ratio of
psyllium mucilage exhibits binding properties that are superior to a 10% weight/volume
ratio of starch mucilage. The viscosity of psyllium mucilage dispersions are relatively
unaffected between temperatures of 68 to 122o F, by pH from 2 to 10 and
by salt (sodium chloride) concentrations up to 0.15 M. These properties in combination
with psyllium's natural fiber characteristic may lead to increased use by the food
processing industry. Technical grade psyllium has been used as a hydrocolloidal
agent to improve water retention for newly seeded grass areas and to improve transplanting
success with woody plants.
III. Growth Habit:
Plantago ovata is an annual herb that grows to a height of 12 to 18 in. Leaves
are opposite, linear or linear lanceolate (0.4 x 7.5 in.) The root system has a
well developed tap root with few fibrous secondary roots. A large number of flowering
shoots arise from the base of the plant. Flowers are numerous, small, and white.
Plants flower about 60 days after planting. The seeds are enclosed in capsules that
open at maturity.
IV. Environmental Requirements:
P. ovata is a 119 to 130 day crop that responds well to cool, dry weather.
In India, P. ovata is cultivated mainly in North Gujarat as a "Rabi"
or post rainy season crop (October to March). During this season, which follows
the monsoons, average temperatures range between 60 to 85o F and moisture
is deficient. Isabgol (P. ovata) which has a moderate water requirement,
is given 5 to 6 light irrigations. A very important environmental requirement of
this crop is clear, sunny and dry
weather preceding harvest. High night temperature and cloudy wet weather close to
harvest have a large negative impact on yield. Rainfall on the mature crop may result
in shattering and therefore major field losses. The growing season in Wisconsin
and Minnesota is not likely to be suitable for production of psyllium.
Isabgol grows best on light, well drained, sandy loams. The nutrient requirements
of the crop are low. In North Gujarat, the soil tends to be low in nitrogen and
phosphorus and high in potash with a pH between 7.2 and 7.9. Nitrogen trials under
these conditions have shown a maximum seed yield response with the addition of 20
lb/acre of nitrogen.
C. Seed Preparation and Germination:
P. ovata has small seeds, 1000 seeds weigh less than 2 grams. Under ideal
conditions of adequate moisture and low temperature (50 to 68o F) 30%
of the seed germinates in 5 to 8 days. The seed shows some innate dormancy (3 months)
following harvest. Various treatments including wet and dry heat, cold, scarification,
ethylene and CO2 do not eliminate this dormancy period. Post-dormancy
seeds show reliable germination in excess of 90% at 84o F and lower rates
of germination as temperature is increased.
V. Cultural Practices:
The fields are generally irrigated prior to seeding to achieve ideal soil moisture,
to enhance seed soil contact, and to avoid burying the seed too deeply as a result
of later irrigations or rainfall. Maximum germination occurs at a seeding depth
of 1/4 in. Emerging seedlings are frost sensitive, therefore planting should be
delayed until conditions are expected to remain frost free. Seed is broadcast at
5 to 7.5 lb/acre in India. In Arizona trials, seeding rates of 20 to 25 lb/acre
resulted in stands of 1 plant/in. in 6 in. rows produced excellent yields. Weed
control is normally achieved by one or two hand weedings early in the growing season.
Control of weeds by pre-plant irrigation that germinates weed seeds followed by
shallow tillage may be effective on fields with minimal weed pressure. Psyllium
is a poor competitor with most weed species.
Plantago wilt Fusarium oxyspirum and downy mildew are the major diseases
of Isabgol. White grubs and aphids are the major insect pests.
The flower spikes turn reddish brown at ripening, the lower leaves dry and the upper
leaves yellow. The crop is harvested in the morning after the dew is gone to minimize
shattering and field losses. In India, mature plants are cut 6 in. above the ground
and then bound, left for a few days to dry, thrashed, and winnowed.
Harvested seed must be dried below 12% moisture to allow for cleaning, milling,
and storage. Seed stored for future crops has shown a significant loss in viability
after 2 years in storage.
VI. Yield Potential and Performance Results:
The contract price for 95% purity psyllium husk set by the Indian Basic Chemical,
Pharmaceutical and Cosmetic Export Promotion Council for April of 1988 was $1.65/lb
F.O.B. This price is up from $1.14/lb set in 1985. The average seed yield of P. ovata
in India often exceeds 1000 lb/acre. Net yield of 95% purity husk after milling
would be 250 lb/acre. Average gross revenue from milled product at 1988 prices would
be $412/acre. The costs of production and milling in the U.S. are unknown but would
certainly need to be determined in order to analyze the potential profitability
of a commercial psyllium venture.
VII. Economics of Production and Markets:
The U.S. currently imports and consumes approximately 8,000 metric tons of psyllium
annually. A continued expansion of this market seems likely due to the high level
of interest in natural dietary fibers. No variety has been tested in the Upper Midwest
but it would seem that the varieties that are grown in India would
not be suited to production in this area. A major cultural problem limiting
psyllium production in this area is the shattering characteristic of the mature
crop. Some success has been achieved by cross-breeding high yielding Indian varieties
with varieties that are more shatter resistant. Until shatter resistant varieties
are available, production of Isabgol is likely to be restricted to environments
that consistently provide a cool dry harvest season.
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Russell, T.E. 1975. Plantago wilt. Phytopathology 65:359-360.
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