The main objective of mixing and dividing of seeds is to obtain the representative homogenous seed sample for analysis by reducing the submitted sample to the desired size of working sample.
Method of mixing and dividing:
- Mechanical dividing
- Modified halving method
- Hand halving method
- Random cup method
- Spoon method
The reduction of sample size is carried out by the mechanical dividers suitable for all seeds except for chaffy and fuzzy seeds.
OBJECTIVE OF MECHANICAL DIVIDING
- To mix the seed sample and make homogenous as far as possible. To reduce the seed sample to the required size without any bias.
- The submitted sample can be thoroughly mixed by passing it through the divider to get 2 parts and passing the whole sample second time and 3rd time if necessary to make the seeds mixed and blended so as to get homogenous seed sample when the same seeds are passed through it into approximately equal parts. The sample is reduced to desired size by passing the seeds through the dividers repeatedly with one half remain at each occasion.
TYPES OF MECHANICAL DIVIDERS
(i) Boerner divider
(ii) Soil divider or Riffle divider
(iii) Centrifugal or Gamet divider
- Boerner divider:
It consists of a hopper, a cone and series of baffles/duckts directing the seeds into 2 spouts. The baffles/ducts are of equal size and equally spaced and every alternate one leading to one spout. They are arranged in circle and are directed inward. A valve at the base of the hopper retains the seeds in the hopper. When the valve is opened, the seeds fall by gravity over the cone where it is equally distributed and approximately equal quantity of seeds will be collected in each spout.
- Soil divider or Riffle divider:
It is a sample divider built on the same principles as the Boerner divider. Here the channels are arranged in a straight row. It consists of a hopper with attached channels, a frame work to hold the hopper, two receiving pans and a pouring pan. It is suitable for large seeds and chaffy seeds.
- Centrifugal or Gamet divider:
The principle involved is the centrifugal force which is used for mixing and dividing the seeds. The seeds fall on a shallow rubber spinner which on rotation by an electric motor, throw out the seeds by centrifugal force. The circle or the area where the seeds fall is equally divided into two parts by a stationary baffle so that approximately equal quantities of seed will fall in each spout.