Seed storage may be defined, as the method of conservation of seed, obtained from the harvest until they are planted for successful crop production. The seeds are required to be conserved through proper Storage for a short or long period. During storage of seeds, moisture is controlled properly for the protection of deterioration.
Purpose of Seed Storage
1. The purpose of seed storage is to maintain the seed in good physical and physiological condition from the time they are harvested until the time they are planted.
2. To protect seed from insect, pest and disease.
3. To conserve seeds until they germinate for subsequent crop production.
Importance of seed storage
1 It increase crop yield.
2 To get adequate plant stands in addition to healthy and vigorous plants.
3 It decreases the seed borne disease due to change of local climate at storage.
Condition of storage
1. Seed storage aims at maintenance of its germination capacity more stringent condition are require than those to conserve the nutritional or industrial quality of seed.
2. During storage, some of the germination capacity is lost slowly or rapidly depending on storage conditions.
3. For dry seed storage, the store temperature and moisture will be low at 10°C and relative humidity 50%.
General Principles of Seed Storage
In view of the various factors affecting seed viability in storage, the following principles emerge as necessary for good storage
1. Seed storage condition should be dry and cool.
2. Effective storage pest control.
3. Proper sanitation in seed stores.
4. Before placing seeds into storage, they should be dried to safe moisture limits, appropriate for the storage system.
5. Storing of high quality seed only, i.e well cleaned, treated as well as of high germination with vigour and good prestorage history.
6. Determine seed storage needs in view of period or length of storage time, and prevailing climate of the area during storage period.
Stages of Seed Storage
The seeds are considered to be in storage from the moment they reach physiological maturity until they germinate, or until they are thrown away because they are dead or otherwise worthless. The entire storage period can be conveniently divided into following stages.
1. Storage on plants (Physiologically maturity until harvest).
2. Harvest, until processed and stored in a warehouse.
3. In storages (Warehouses).
4. In transit ( rail wagons, trucks, carts, railway sheds, etc).
5. In retail stores.
6. On the user’s farm.
Storage of Seed on Plants (Physiologically maturity until harvest)
Seeds are considered to be physiologically and morphologically mature when they reach maximum dry weight. At this stage dry down or dehydration of the seed is well underway. Dry down continues after physiological maturity until moisture content of the seed and fruit decreases to a level which permits effective and efficient harvest and threshing. This stage can be termed as harvest maturity. There usually is an interval time between physiological maturity and harvest maturity, and this interval represents the first segment of the storage period. Any delay in harvesting the seed after they reach harvest maturity maturity prolongs the first segment of the storage period.
The seed quality is greatly influence by prevailing environmental conditions; from the time seeds reach physiological maturity until harvest. Weathering damages are often a serious factor at this stage. As a result of weathering damages, seeds of many crops,
E. g. Soybean, lose their viability and vigour and are already low in germination even before they are harvested.
Several factors such as soil conditions, mineral nutrient deficiencies, during plant growth, water stress, high or low temperatures, disease and insect damage, etc. may also deteriorate seed quality by reducing viability and vigour at physiological maturity.
Other things being equal, the seeds that have begun to deteriorate due to one or more factors mentioned above subsequently will not store as well as the relatively, undeteriorated seed.
It is therefore, of the utmost importance, to maintain initial seed quality to the near maximum attainable, by keeping weathering and other types of damages to the minimum possible. This would mean raising a good health seed crop, early harvesting and adequate arrangements for seed drying.
Storage from Harvest until Processing
The period of harvesting and cleaning is frequently one of high temperatures. During this time seeds still have high moisture content. Seed deterioration can be rather rapid during this period. Transport from field to threshing floors, threshing floors to processing plants and at the processing plants, involves periods of storage during which deterioration can be rapid and serious, if the moisture content is above 13%. At moisture contents above this range, molds may grow on in the seed end heating may occur. It is therefore, necessary to take the utmost care in handling of material after harvest. If harvesting has been done above 13% moisture content, necessary arrangements for drying/aeration etc. of seeds are necessary to preserve seed quality. In addition, adequate care is necessary in handling the seed materials at this stage so as to prevent mechanical mixtures and maintain lot identity.
Storage of Seed in Warehouse
It is customary for seed men and others interested in storage of seeds, to give primary attention to rooms or buildings labelled as seed storages. Seed ageing and loss of germination during storage, cannot be stopped altogether, though it could be appreciably reduced by providing good storage conditions. Seed longevity in storage warehouses depends upon a number of factors.