Seed screening, grading and packing
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The document discusses seed screening, grading, and packaging. It describes how seeds are screened using different sized meshes to remove debris and low quality seeds. Various machines are used to separate seeds based on physical properties like size, shape, density and surface texture. Seeds are graded using screens, indented cylinders, gravity tables, and color separators. Packaging involves filling bags to the correct weight, adding labels and storage information, and properly storing seeds based on material and environment. Vacuum packaging can extend shelf life by removing oxygen.
Seed screening, grading and packing
- 1. SEED SCREENING, GRADING AND PACKAGING Basavaraj Panjagal Ph.D Research Scholar Department of vegetable science K R C COLLEGE OF HORTICULTURE BANGLORE UNIVERSITY OF HORTICULTUREAL SCIENCES BAGALKOT Presentation on : 1 Basavaraj Panjagal
- 2. Seed screening • Removal of any debris or low quality seeds using different screeners to get good quality seeds 2 Basavaraj Panjagal
- 3. Seed screening meshes • Many seeds can be screened with several different mesh sizes of hardware cloth. Hardware cloth is readily available in the following mesh sizes: 1/2", 3/8", 1/4", and 1/8". • The 3/8" and 1/8" mesh sizes are the most useful sizes, but are the most difficult to find. • Aluminum window screen can be used for small seeds. 3 Basavaraj Panjagal
- 4. • screen material it should be mounted on a frame. • Professional seed screens are mounted on 12" square wooden frames. • Rough chaff is retained on the top screen, seeds in the middle screen, and small chaff and small seeds on the lower screen. 4 Basavaraj Panjagal
- 5. The air-screen cleaner • The air-screen cleaner is the basic machine in a seed-cleaning plant. • It makes seed separations mainly on the basis of three physical properties—size, shape, and density. • The typical air-screen cleaner now found in a farm seed-cleaning plant is a four-screen machine located beneath a seed hopper. • Seed flows by gravity from the hopper into a feeder that meters the seed mixture into an airstream, which removes light, chaffy material so that the remaining seed can be distributed uniformly over the top screen. 5 Basavaraj Panjagal
- 6. • The top screen scalps removes large material • The second screen grades or sizes the seed, • The third screen scalps the seed more closely, • Fourth screen performs a final grading. • The finely graded seed is then passed through an air- stream, which drops the plump, heavy seed, but lifts and blows light seed and chaff into the trash bin. 6 Basavaraj Panjagal
- 7. Scalper • It removes the larger inert matter from the seeds. If it contains a single sieve it is called as scalpers, two sieves – rough cleaners. The unit consists of a vibrating or rotating screen or sieve having perforation large enough to allow the rough seed pass through readily. 7 Basavaraj Panjagal
- 8. Selection of screens • The two basic screens for cleaning round- shaped seed are a round- hole top screen and a slotted bottom screen. • The round-hole top screen should be selected so as to drop the round seed through the smallest hole possible, and retain anything larger. • The seed drops through the top screen onto the slotted bottom screen, which takes advantage of seed shape and retains the round, good seed while dropping broken crop seed and many weed seed. • The basic screens for cleaning elongated seed (oats, fescues) are a slotted top screen and a slotted bottom screen. 8 Basavaraj Panjagal
- 11. Specific gravity separation This method makes use of a combination of weight and surface characteristics of the seed to be separated. • The principle of floatation is employed here. • A mixture of seeds is fed onto the lower end of a sloping perforated table. • Air is forced up through the porous deck surface and the bed of seeds by a fan, which stratifies the seeds in layers according to density with the lightest seeds and particles of inert matter at the top and the heaviest at the bottom. • An oscillating movement of the table causes the seeds to move at different rates across the deck. • The lightest seeds float down under gravity and are discharged at the lower end, while the heaviest ones are kicked up the slope by contact with the oscillating deck and are discharged at the upper end. • This machine separates seeds of the same density but of different size and seeds of the same size but of different densities. 11 Basavaraj Panjagal
- 12. Indented cylinder This helps to separate seeds according to the length. • The equipment consists of a slightly inclined horizontal rotating cylinder and a movable separating trough. • The inside surface has small closely spaced hemispherical indentations. • Small seeds are pressed into the indents by centrifugal force and can be removed. The larger seeds flows in the centre of the cylinder and is discharged by gravity. 12 Basavaraj Panjagal
- 13. Magnetic separator The magnetic separator separates seed according to its surface texture or related seed characteristics. • First, seed is treated with iron filings, which adhere to rough surface alone. • The treated seed lot is passed over a revolving magnetic drum and separated from smooth, uncoated seed. • It may help to add varied amounts of water while mixing seed and powder, depending on the seed type. • At any rate, the effectiveness of magnetic separation depends on the components of the seed lot and on the powder and water used in the treating operation. • The greater the difference between surface textures of the seed lot’s components, more effective will be the separation. 13 Basavaraj Panjagal
- 15. Colour separator • The colour separator is used to separate discoloured seed, greatly of lower quality. Separation based on colour is necessary because the density and dimensions of discoloured seed are the same as those of sound seed, so other machines are not effective for separation. • Electronic colour separation uses photocells to compare the seed colour with “background” which are selected to reflect the same light as the good seed • .Seed that differs in colour is detected by the photo cells, which generate an electric impulse. The impulse activates an air jet to blow away the discoloured seed. 15 Basavaraj Panjagal
- 17. • uses an electronic eye that can pick up different colors according to the way the machine is adjusted. • As seed falls down a shoot, it passes through the electric eye. • If the color of the seed is different than the desired color, the electric eye will activate a sudden burst of air that pushes that seed into a reject bin while the rest of the seed passes through to another bin. 17 Basavaraj Panjagal
- 18. Friction cleaning The air-screen combinations cannot remove debris that has a size and density similar to the seeds. However, if the debris has a different surface texture, it may be possible to remove by friction cleaning. • Any object rolling or sliding over a sloping surface encounters a certain friction depending on the texture of itself and that of the sloping surface. • Separation is made on a velvet cloth or rubber belt with variable inclination, which ensures that the slope necessary for the run off of the seed is different from the slope necessary for run -off of the debris. • The belt continuously moves upwards and removes the debris while the seeds roll down the slope. 18 Basavaraj Panjagal
- 19. Spiral separator • The separator, which classifies seed according to its shape and rolling ability, consists of sheet metal strips fitted around a central axis in the form of a spiral. • The unit resembles an open screw conveyor standing in a vertical position. The seed is introduced at the top of the inner spiral. • Round seeds roll faster down the incline than flat or irregularly shaped seeds, which tend to slide or tumble. • The orbit of round seed increases with speed on its flight around the axis, until it rolls over the edge of the inner flight into the outer flight where it is collected separately. • The slower moving seed does not build up enough speed to escape form the inner flight. Most spirals have multiple inner flights arranged one above the other to increase the capacity. 19 Basavaraj Panjagal
- 21. SEED PACKAGING • Seed packaging is the process of filling, weighing and sewing of bags with seed. 21 Basavaraj Panjagal
- 22. General steps involved 1. Filling of seed bags to an exact weight. 2. Placing leaflets in the seed bags regarding improved cultivation practices. 3. Attaching labels, certification tags on the seed bags, and sewing of the bags. 4. Storage / shipment of seed bags. 22 Basavaraj Panjagal
- 23. The factors to be considered • Kind of seeds to be packed. • Quantity of seed • Value of seed (OP or Hybrid) • Cost of packaging material • Storage environment in which the packed materials will be held • Period of storage • Transport of seed 23 Basavaraj Panjagal
- 24. An ideal storage facility should satisfy the following requirements: • Maximum possible protection from ground moisture, rain, insect pests, moulds, rodents, birds etc., • Necessary facility for inspection, disinfection, loading, unloading, cleaning and reconditioning. • It should protect grain from excessive moisture and temperature favourable to both insect and mould development, • It should be economical and suitable for a particular situation 24 Basavaraj Panjagal
- 25. Labelling on package Quantity: Number of seeds (estimated) Extraction: Date Technique of extraction Fumigation: Date (if undertaken) Method of fumigation, including chemicals Drying: Date Method Moisture content Quality: Purity percentage Number of seeds per unit weight (estimated) Germination test 25 Basavaraj Panjagal
- 26. Classification Materials for short-term storage: Most of these are non-rigid materials such as cotton, burlap, paper, and composite materials such as multi-wall paper and plastic film, or polyethylene bags. • Materials used for short-term storage are generally porous. • They adequately contain and protect the seeds from mixing, but do not provide protection from moisture or loss of seed viability. • Such materials are usually used for mechanically separating seed lots, and for transporting and shipping seed until the seed can be placed in environmentally controlled conditions for longer-term storage. 26 Basavaraj Panjagal
- 27. • Burlap bags: greatest strength, can be re-used many times, and can be stacked high without slipping of the stack. Cotton bags: The strength is dependent on the thickness of the weave and thread, and the quality of the seams. re- used, depending on the quality of the fabric. 27 Basavaraj Panjagal
- 28. • Plastic bags : Made of plastic material also are fairly strong but tend to slip when piled. Moisture impervious but vapour pervious plastic bags - < 300 guage Multi-wall bags: Are made of several layers of paper in a variety of types of construction. They have poor bursting strength when piled high or accidentally dropped, and if used repeatedly, they tend to become brittle along the folds and wear points. 28 Basavaraj Panjagal
- 29. • Cardboard boxes and cans: Though expensive, are re-usable, good for stacking, and provide some protection against mechanical injury to seed and to infestation by seed storage insects. 29 Basavaraj Panjagal
- 30. Materials for long-term storage • Metal and glass containers, properly sealed to prevent the exchange of moisture and gas, are the most commonly used containers. • They are the only reliable means of protecting seeds against humidity, insects, rodents, floods, and mechanical damage. 30 Basavaraj Panjagal
- 31. Vacuum packaging Vacuum packaging is removing air from the product pouch and hermetically sealing it. This increases storage or shelf life by inhibiting the growth of microorganisms and improves hygiene by reducing the danger of cross contamination. Vacuum packing also preserves protects against dehydration and weight loss. 31 Basavaraj Panjagal
- 32. Advantages of vacuum packaging: • A simple solution to packaging goods requiring protection from oxygen • Positive control of the moisture content of the produce • Inhibits the growth of aerobic spoilage bacteria • Lower costs than those of rigid containers • Longer shelf life for goods • Disadvantages of vacuum packaging • It is virtually impossible to remove all the oxygen, since small quantities will be trapped within cells. • Microorganisms which are not affected by oxygen are not advantageously affected by vacuum packing. 32 Basavaraj Panjagal
- 33. • Another material, often used for seed banks, is a heat-sealable barrier pouch. • Barrier pouches are a triple-laminate material made from paper, plastic, and foil. They are sealed with a heat sealer 33 Basavaraj Panjagal