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Alternative Field Crops Manual


E.S. Oplinger1, D.H. Putnam2, A.R. Kaminski1, C.V. Hanson2, E.A. Oelke2, E.E. Schulte1, and J.D. Doll1

1Departments of Agronomy and Soil Science, College of Agricultural and Life Sciences and Cooperative Extension Service, University of Wisconsin- Madison, WI 53706.
2Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108. May 1990.

I. History:

Sesame (Sesamum indicum L.) is one of the oldest cultivated plants in the world. It was a highly prized oil crop of Babylon and Assyria at least 4,000 years ago. Today, India and China are the world's largest producers of sesame, followed by Burma, Sudan, Mexico, Nigeria, Venezuela, Turkey, Uganda and Ethiopia. World production in 1985 was 2.53 million tons on 16.3 million acres.

Sesame was introduced to the United States in the 1930s. Domestic production has been limited because of the lack of cultivars that can be harvested mechanically. In 1987, the sesame acreage in this country was less than 2,500 acres, about half of which were in Texas. The U.S. imports about 40,000 tons of seed and 2,200 tons of sesame oil annually, primarily from South America.

Upon ripening, sesame capsules split, releasing the seed (hence the phrase, "open sesame"). Because of this shattering characteristic, sesame has been grown primarily on small plots that are harvested by hand. The discovery of an indehiscent (nonshattering) mutant by Langham in 1943 began the work towards development of a high yielding, shatter-resistant variety. Although researchers have made sign)ficant progress in sesame breeding, harvest losses due to shattering continue to limit domestic production.

II. Uses:

Sesame seeds (approximately 50% oil and 25% protein) are used in baking, candy making, and other food industries. Oil from the seed is used in cooking and salad oils and margarine, and contains about 47% oleic and 39% linoleic acid. Sesame oil and foods fried in sesame oil have a long shelf life because the oil contains an antioxidant called sesamol. The oil can be used in the manufacture of soaps, paints, perfumes, pharmaceuticals and insecticides. Sesame meal, left after the oil is pressed from the seed, is an excellent high-protein (34 to 50%) feed for poultry and livestock.

III. Growth Habits:

Sesame is an erect annual (or occasionally a perennial) that grows to a height of 20 to 60 in., depending on the variety and the growing conditions. Some varieties are highly branched, while others are unbranched. Leaves are variable in shape and size and may be opposite or alternate. The bellshaped white to pale-rose flowers begin to develop in the leaf axils 6 to 8 weeks after planting and this continues for several weeks. Multiple flowering is favored by opposite leaves.

Sesame is normally self-pollinated, although cross pollination by insects is common. The fruit is a deeply grooved capsule (1 to 3 in. in length) that contains 50 to 100 or more seeds. The seeds mature 4 to 6 weeks after fertilization. The growth of sesame is indeterminant; that is, the plant continues to produce leaves, flowers and capsules as long as the weather permits. Sesame seeds are small and vary in color. One thousand seeds weigh about one ounce. The lighter colored seeds are considered higher quality.

IV. Environment Requirements:

A. Climate:

Commercial varieties of sesame require 90 to 120 frostfree days. Daytime temperatures of 77°F to 80°F are optimal; below 68°F, growth is reduced, and at 50°F germination and growth is inhibited.

Sesame is very drought-tolerant, due in part to an extensive root system. However, it requires adequate moisture for germination and early growth and a minimum rainfall of 20 to 26 in. per season is necessary for reasonable yields. Moisture levels before planting and flowering have the greatest impact on yield. Sesame is intolerant of water-logging. Rainfall late in the season prolongs growth and increases shattering losses. Wind can cause shattering at harvest and is cited as one reason for the failure of commercial sesame production in France.

Initiation of flowering is sensitive to photoperiod and varies among varieties. The oil content of the seed tends to increase with increased photoperiod. Because protein content and oil content are inversely proportional, seed with an increased oil content has a decreased protein content.

B. Soil:

Sesame is adaptable to many soil types, but it thrives best on well-drained, fertile soils of medium texture and neutral pH. Sesame, which has an extensively branched feeder root system, appears to improve soil structure. Sesame has a very low salt tolerance and cannot tolerate wet conditions.

C. Seed Preparation and Germination:

Seed should be cleaned thoroughly and treated with one ounce of 75% Captan per 100 lb of seed to prevent damping off. This treatment is especially important for nonshattering varieties because they are slower to emerge than the shattering varieties. Because the seeds of the nonshattering varieties spend more time in the soil before germination, they need more protection from fungal pathogens in the soil.

V. Cultural Practices:

A. Seedbed Preparation:

Sesame requires a warm, moist, weed-free seedbed. Good drainage is important, because the plant is extremely susceptible to waterlogging at any stage of growth. Since sesame is planted late, several generations of weeds can be killed by repeated tillage before planting.

B. Seeding Date:

Sesame should not be planted before the soil reaches a temperature of about 70°F—roughly one month after the last killing frost.

C. Method and Rate of Seeding:

Sesame can be seeded with a row crop planter equipped with vegetable planter boxes. Populations of 250,000 to 300,000 plants/acre in 18 to 30 in. rows have given the highest yields. This is about 1 lb/acre for 30 in. rows.

Depth of planting varies with soil type and soil moisture from 1 to 2 in. Uniform depth and seed rate are essential for stand establishment resulting in maximum yield.

D. Fertility and Lime Requirements:

Fertility requirements for sesame are similar to millet: 80 lb N, 20 lb P2O5 and 20 lb K2O per acre. The N recommendation is for soils with less than 2% organic matter. Reduce the N to 60 lb/acre for soils with 2% to 5% organic matter and to 40 lb/acre if the soil has more than 5% organic matter. The P2O5 and K2O recommendations are for soils testing in the "optimum" range. A pH of 5.6 or above is satisfactory. Lime and fertilizer recommendations are not presently available for sesame in Wisconsin or Minnesota. Specify "millet" on the Soil Information Sheet to obtain recommendations suitable for sesame. The P2O5 and K2O and up to half of the recommended N could be applied in a band alongside the row at planting if desired. There is not likely to be a "starter" effect, however, if the crop is planted after the soil temperature reaches 70°F, as recommended.

E. Variety Selection:

There is great diversity within the several hundred varieties of sesame. However, the sesame varieties are usually divided into two types: shattering and nonshattering.

Shattering varieties: Most of the shattering varieties grown in the United States have been produced from the variety Kansas 10, or K 10. The seeds of this unbranched variety have a high oil content—over 50%—but their bitter flavor limits their value on the whole-seed market. Some shattering varieties grown in the U.S. include: Margo, Oro, Blanco, Dulce, and Ambia.

Nonshattering varieties: Nonshattering varieties have been developed to allow mechanical harvesting. Though these varieties usually contain somewhat less than 50% oil, their seed is used for oil production only. Some nonshattering varieties include: Baco, Paloma, UCR3, SW-16 and SW-17.

Mechanical harvesting is more successful with varieties that have minimal branching and a height from the soil surface to the first capsule of about 12 in. See Table 1 for the results of test crops of sesame varieties

Table 1: Yield and varietal characteristics of sesame, Lubbock, Texas, 1977–79.

Yield (lb/acre)Seed colorHeight1Maturity2
Shattering varieties:
Nonshattering varieties:
1Short c 36 in.; Medium = 36 to 60 in.; Tall > 60 in.
2Early = 90 to 105; Medium = 106 to 120; Late = 120+ days.

F. Weed Control:

Because of their slow early growth, sesame plants are poor competitors against weeds. Select fields with low weed densities.

1. Mechanical: Cultivate sesame fields early and as close to the rows as possible. Shallow cultivation is recommended, because the fine, fibrous sesame roots grow close to the surface and are easily damaged. Early cultivation causes seedlings to grow faster, possibly as a result of improved soil aeration. After the plants reach a height of 3 or 4 in., they grow rapidly. Cultivate only as necessary to control weeds.

2. Chemical: No herbicides are currently registered in Wisconsin or Minnesota for use on sesame. In other areas the pre-emergence herbicides alachlor (Lasso) and trifluralin (Treflan) have been used successfully for weed control in sesame. Growers should check current labels for use of these or other products in their growing area.

G. Diseases and Their Control:

The most common sesame diseases are leaf spot, leaf and stem blights, Fusarium wilt, charcoal rot and root rot. Some of the disease organisms are carried on the seed. It is advisable to use disease-free seed and treat it with a fungicide before planting.

H. Insects and Other Predators and Their Control:

Sesame plants are often attacked and damaged by aphids. Thrips will stunt seedlings and injure developing flower buds so that capsules do not set. The gall midge (Asphondylia sesami Felt.) and various caterpillars have been important in some countries. Green stink bugs, red spiders, grasshoppers, cut.worms, armyworms and bollworms also attack sesame, but do not cause extensive damage. Check with your county extension office, crop consultant or chemical dealer about insecticides registered for sesame.

I. Harvesting:

Sesame is ready for harvesting 90 to 150 days after planting. In general, the unbranched varieties mature earlier. The crop must be harvested before the first killing frost to obtain high quality seeds. At maturity, leaves and stems tend to change from green to yellow to red in color. The leaves will begin to fall off the plants. The shattering and nonshattering types require different harvesting techniques. Caution is recommended to minimize seed damage and loss.

Shattering sesame varieties are usually swathed green and placed upright in small shocks, about 8 bundles per shock. Tighten the strings on the shocks in 2 or 3 days. In 2 weeks the crop will be ready to thresh. Light rains during this time will not seriously damage seed. Sesame should be threshed using a low cylinder speed (450 to 500 rpm). Screens may need to be adjusted (1/8 in. round perforations) for the small seed size. Nonshattering types can be combined directly at low cylinder speed.

J. Drying and Storage:

Sesame may be stored at room temperature for approximately 5 years without loss of viability. Freezing temperatures damage seed and make them less marketable.

VI. Yield Potential and Performance Results:

Domestically sesame is a relatively high risk crop. Sesame yields in test plots average 1,000 to 1,500 lb/acre, though as much as 2,300 lb/acre have been produced under irrigation in California. Commercial yields are usually lower.

The introduction of the nonshattering characteristic into high-yielding, normally shattering varieties carried with it a reduction in yield and/or seed quality. The development of higher-yielding nonshattering varieties is necessary for sesame to compete with other crops. Performance of shattering and nonshattering lines of sesame in trials conducted in Texas are summarized in Table 1.

VII. Economics of Production and Markets:

Currently sesame is being imported at a price of 43 cents/lb. This relatively high price reflects a world-wide shortage. Though the market for sesame seed is strong, domestic production awaits the development of high-yielding nonshattering varieties. It is advisable to establish a market before planting.

VIII. Information Sources:

The information given in this publication is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Minnesota or Wisconsin Extension Services is implied.

Last update December 2, 1997