Mustard is an annual herb cultivated as oil seed crop or as vegetable or as fodder, of which, 3 species are known for its condiment value. They are pale yellow or white mustard, brown mustard and black mustard. The leaves of the plant are alternate, long, bristly branched, etiolate, hairy on both sides. Flowers are small, yellow with petals, cruciform. Seeds are 1.5-3mm.
In India mustard’s no. of varieties are available in market. Brasicca juncea, Brassica hirta, Brassica nigra, mustard green, Indian mustard, kai choi are also available in the whole world.
Mustard is an annual herb with seedlings that emerge rapidly, but then usually grow slowly. Plants cover the ground in 4 to 5 weeks with favourable moisture and temperature conditions. The tap roots will grow 5 ft into the soil under dry conditions, which allows for efficient use of stored soil moisture. Plant height at maturity varies from 30 to 45 in. depending on type, variety, and environmental conditions. Flower buds are visible about five weeks after emergence. Yellow flowers begin to appear 7 to 10 days later and continue blooming for a longer period with an adequate water supply. A longer flowering period increases the yield potential. About half of the flowers produce dark, reddish-brown seeds that are retained in pods of 0.5 to 0.75 in. in length. Flowers pollinated during the first 15 days of the flowering period produce most of the seed.
The normal maturation of the crop, wind, and rain do not cause shattering before cutting. However, the actual harvesting operations can cause great shattering losses when the plants are overripe. Yellow mustard does not shatter readily and can be straight combined if the crop has matured uniformly (10% moisture) and is free of green weeds. If the crop is weedy or uneven in maturity it should be swathed. Swathing, if deemed necessary or preferred, should be done when 60 to 70% of the seed has turned yellow-green. Plants should be cut just beneath the height of the lowest seed pods. The swath will then settles into the stubble and reduce the chance of being blown by high winds. Yellow mustard does not cure quickly. Straight combining is therefore recommended at 12 to 13% moisture, followed by artificial drying, to obtain uniform quality and highest yield. Brown and oriental varieties will shatter more readily when ripe and should be swathed. The swathing should begin after the general leaf drop and when the overall field colour has changed from green to yellow or brown. Pods sampled from the middle of racemes from several plants, in arm representing the average maturity, should be examined for physiological maturity. About 75% of the seeds may have reached the mature colour of yellow or brown. The remaining green seeds will mature in the swath before combining. Swathing should be done under conditions of high humidity or when morning dew is on ripe pods to decrease shattering losses. Windrows tend to be bulky and subject to scattering by the wind. A roller or steel drum should be used to press the swath into the stubble. The combine should be adjusted so seeds are threshed completely by using the lowest cylinder speed, which is set at approximately 600 RPM, and the appropriate cylinder opening. The reel may cause shattering when straight combining, but it can be removed or lifted above the plants it the stand is good. If the reel is needed, remove half of the bats and reduce its speed. Cylinder speed may need to be adjusted during the day as crop moisture content may vary.
Packaging & Storage:
When the mustard seed reaches a moisture content of 10% or less it can be stored safely. The harvested seed should be handled carefully since it will crack easily when moved in and out of storage. The damaged seed becomes dockage and is a loss to the grower. Air temperatures for seed drying should not exceed 150°F and seed temperature should stay below 120°F. Use of drying equipment designed for corn or wheat may require some modification when drying mustard. A fine screen will be needed to prevent loss of the smaller seed. Storage bins must be free of cracks or holes.