Farmers commonly
leave sunflower in the field until the plant is completely dead and seed is
thoroughly dried. Heads are then cut off immediately and threshed in the field.
Often plants ripen at different times so the crop is left in the field for an
extended period until all heads have dried out. This means that much seed is
lost due to birds and also heads shattering with seed falling to the ground.
To reduce these
losses and to encourage rapid drying plants should be harvested as soon as the
backs of heads turn from green to yellow and the bracts around the edge of
heads turn brown. For a crop that ripens unevenly this means harvesting has to
be done in stages. Plants can be cut and stocked or each head can be pinned
upside down on its own stem. Alternatively, heads can be taken to a store and
put out in the sun each day to dry. If this is done heads should not be piled
on top of each other or they will rot.
After thorough
drying the heads are threshed by beating with sticks on mats or clean floor.
The seed should then be winnowed to remove debris and poorly filled seeds.
If sunflower
seeds are stored with a high moisture
content they may be attacked by moulds which may result in seed containing the
poison aflatoxin. For safe storage seed should be dried for two days in the sun
after threshing. The moisture content of stored seed should be less than 9.5
percent.
Aflatoxin.=is very toxic substance formed by fungus
Asperigillus flavus which grows on
seeds and nuts
0 comments:
Post a Comment