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 Improver
Conventional upgrading With most conventional upgrading techniques, the seed quality is derived from external characteristics like size and color. Seed lots are cleaned to remove inert matter and weed or foreign seeds. Differences between seeds in shape, width, length, color, weight, etc, make it possible to separate a seed lot in two or more fractions. Techniques that are based on density have a more direct relation with the interior of the seed. The most advanced of these techniques is the fluid density separation. Fluid density upgrading A very precise separation in fractions can be obtained in solutions with different densities. This method may be effective even after other upgrading methods have failed. A trial upgrading always precedes a commercial production, as it is not possible to predict the upgrading effect.
The graph shows the effect on germination
capacity (%) of three different tomato seed lots, by removing consecutive
fractions through fluid density upgrading. Although quality of lot A was
improved from 73 to 84% good seedlings, the maximum germination capacity
was reached after removing 30% of the weight. Lot B initially had 8 % less
good seedlings than lot C. By removing 20% weight, germination capacity of
both lots increased to 92%. However, efficiency of upgrading for lot B was
much higher than for lot C. |
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