बीज उधोग में बीज प्रसंस्करण
Seed lot obtained from the field, moisture content high and contains various impurities such as plant parts, sand, gravel particles, besides off-size seeds, weed seeds, damaged and deteriorated seeds. As a result, the quality and quantity of the seeds are reduced so a processing plant or unit required for healthy and improved seeds.
Seed processing refers to all the steps essential for preparation of harvested seed for marketing, i.e. drying, cleaning, grading, treating, bagging or packaging and storage of the seed, obtained after harvesting and threshing. So, seed processing is an important segment of the seed industry.
Principle of the seed processing
Complete cleaning and separation: The seeds free from the impurities, other crop seed, damaged and deteriorated seeds so, essential proper cleaning and grading of the seed.
Minimum loss of the seed: The seed processing operations are generally done by machines, during the operations some parts of the seed wasted. So, all care taken during the processing.
Mechanical efficiency: In the seed processing, Machines should remain in proper conditions, that causes operations can be done at high efficiency.
Minimum labour: The cost of seed processing remains minimum for more net profit so, required minimum labour for processing operations.
Improvement quality: Main aim of the processing obtaining, the pure, healthy and uniform seeds for better seed quality.
The various steps included in seed processing
1. Receiving the seed in the seed processing unit:
Before accepting a seed lot for seed processing plant, it fulfils the prescribed minimum standard i.e. purity, moisture content and their viability, for testing, a sample should be taken and tested in the seed laboratory.
2. Conditioning:
The seed after harvesting and threshing is not suitable for processing directly so removing the plant parts, pods, fuzz using machines that practice also called conditioning. Scalper, debearder, corn sheller, scarifier and huller etc. its require according the crops.
3. Seed drying:
It is essential to dry the seed for the safe moisture level to ensure the lonivity of the seed and preserve its value. It permits long-term storage, early harvest, efficient use of land and man power. The seed drying by two methods (a) sun drying (b) air drying.
4. Seed cleaning:
Removal or separation of undesirable foreign materials from the seed i.e. seed cleaning. The most common equipment used for pre-cleaning that are scalpers, debeaders, huller, buckhorn etc. and for basic seed cleaning done by air screen cleaner.
The air screen machine uses three cleaning elements. (a) aspiration (b) scalping (c) grading. The main parts of the air screen cleaner i.e. feed hopper, screens, brushes, screen knockers, shoes, eccentrics and fan. Screens are available in various size and shape, for example in wheat top screen 6.0 r, and bottom screen 2.10-2.30 s in millimetres.
5. Seed treatment:
Protecting the seed from seed-borne diseases and storage insects, for improving the germination by the seed treated with the physical, mechanical and chemical methods. The physical method is easy and cheap it includes:
- solar treatment: Seeds are soaked for 2 hrs and dried in sunlight for whole day on cemented floor e.g. Loose smut of wheat, pink boll worm of the cotton,
- hot water treatment: the seeds are soaked in hot water at 50◦C for 20 minutes this treatment used in the vegetables for controlling the Xanthomonas camestris,
- saline water treatment: 20 per cent saline solution used for controlling the ergot sclerotium in bajra and ear cockle in wheat (d) stream treatment: it is safe and effective in comparison to hot water treatment and dry heating, because requires lees time and lower temperature.
Kinds of seed treatment
1. Protection: Seed treatment involve surface treatment with fungicide/insecticide/pesticide it includes:
- Seed disinfection: Pathogen and insects are seated inside the seed, killing this type infection also called seed disinfection.
- Seed disinfestations: Some pathogen and insects are present on the surface of seeds; removal these type organisms are also called seed disinfestations.
- Seed protection: Some soil pathogens effects on seed germination and seedling growth so, protection from these type organisms.
2. Invigoration: Its used as a pre-sowing treatment for improving the germination and better seedling quality like growth regulatory nutrients, antioxidants and phtyo-hormones.
3. Pelleting: Coating on the seed with mechanical compression in the water soluble fungicides, insecticides and nutrients for protecting the seeds against the pathogen and insect-pest.
4. Fumigation: A volatile insecticides used in a confined area and treated seed lot must be kept tightly sealed, it used for protection of the storage seed insects.
Seed treating equipment:
- Drum mixer
- slurry treater
- panogen seed treater
- seed treatment by shovel
- seed treatment by auger
- mist-o-matic seed treater.
Packaging and Handling of seeds
After treating seeds are packaged into containers of appropriate size and weight (e.g. wheat 58 x 43 size in cms. and 12 kg net weight). In the modern packaging uses various materials and methods to sustain the original quality of seeds during the storage and transportation.
Packaging Material
The choice of packaging materials of the seeds to be depends on the type of seeds, the seed moisture content, storage duration, storage environment, cost of seed, the cost of packaging material and geographical area. They are classified into three classes;
- moisture vapour permeable container like jute bag, cloth bag, paper bag
- moisture vapour resistant container; jute bag laminated with thin polythene film and
- moisture vapour proof container; tin can, glass bottles, polythene bags and aluminium foil pouches.
Equipment used for packaging of seeds
- Bagger-weigher: Bagger-weighers and bagging scale used for fill and weigh a bag accurately in a single operation, it may be manual, automatic and semi-automatic.
- Bag sewing machine: Sewing machine are used for an open mouth bag filling and then after sewed with this machine. Bag sewing machine are precision, high speed machine it should be operated and maintained properly to prevent frequent break down and a short operating life. Bag should be moved on a slow moving conveyor to the feeding foot of the bag sewing machine. Seed packed in plastic bags are closed with a heat sealer, it more suitable when bags are hundreds to thousands.
- Platform scales: Lorry weigh-bridges are used primarily for weighing heavy loads of incoming seeds. Seed received in bags, containers and boxes can be handled by fork-lift trucks when a platform scale is available, it weighing up to 200 kilograms’ materials.
Handling
Many types of conveyors are available for moving unpacked and packed seed into, through or away from processing plant in different directions. Selection of the proper type of conveyors, for each operation receiving seed in the plant, moving seed from dryers, shellers and from one processing machine to another and finally moving packaged seed into storage.
Storage
After harvesting, maintain the quality of the seed until next sowing or its sale in the market. Storage of the seeds at low temperature, low humidity and low moisture.
On the basis of utilization and time seed stored three types, (i) short term, 6 months (ii) medium term, 18 to 36 months (iii) long term, 5 to 50 years. Basic requirements for better storage are:
Storage structures: According to the quantity of the seed, duration of storage and climatic conditions uses different type structures i.e. storage bin, warehouse.
Insulation: It protect the stored seed from the heat through the walls, roof and floor, insulating with a 1-3-inch-thick layer of material such as wood, plastic and fibre board.
Refrigeration: In the warm climatic conditions stored seeds required refrigeration, keep the storage temperature lower the usual ambient temperature.
Sealed container: Container should be sealed for maintaining the seed quality, with the safe moisture conditions.
Sanitation: Sanitation in the storage is very essential for seed protect from the insects, pests and pathogens.
Authors:
Madhu Choudhary*, Anita pareek and Rajwanti Saran
Division of Plant Breeding and Genetics
Rajasthan Agricultural Research Institute, Durgapura, Jaipur
e-mail: