The submitted sample is divided in the laboratory to obtain working samples are required for various seed tests for obtaining the working samples a slightly more quantity should be taken than required weight. One of the following methods should be used for seed sampling.
Methods
Mechanical divider method
In this method, the sample is mechanically divided by the seed dividers (the available types are Boerner and Gamet Seed dividers). This method is suitable for all kinds of seeds, except the extremely chaffy types. The apparatus dividers a sample passed through in into two approximately equal parts. The sample is reduced by passing the seed through repeatedly and removing one half on each occasion. This process of successive halving is continued, until a working sample of approximately, but not less than, the required size is obtained.
Random cups method
This method is particularly suitable for seeds requiring a working sample up to 10 gm provided that they are not of a extremely chaffy structure and provided that they do not bounce or roll (like Brassica spp.) In principle, six to eight small cups, or thimbles, are placed at random on a tray. After a preliminary mixing the seed is poured uniformly over the tray. The seed that falls into the cups is taken as the working sample.
Modified halving method
After preliminary mixing, the seed is poured evenly over the grid in the same way as it is poured in the random cups method. When the grid is lifted, approximately half the sample remains on the tray.
Spoon method
It is permissible to use this method only for samples of a single small-seeded species. A tray, a spatula and a spoon with a straight edge are required. After preliminary mixing, pour the seed evenly over the tray in the same way as it is poured in the random cupes method. With the spoon in one hand, the spatula in the other, and using both, remove small portions of seed from not less than five random places on the tray.
The hand halving method
This method is restricted to specified genera of chaffy seeds. The seed is poured on to a smooth clean surface and thoroughly mixed into a mound. The mound is then divided into half and each half is halved again. The process is repeated a couple of each half is halved again. The process is repeated a couple of times. The halved portions are arranged in the rows and alternate portions are combined and retained. The process is repeated until the sample of required weight is obtained.
Minimum weight of working sample
The working sample weight for purity analyses are calculated to contain at least 2500 seeds, but subject to a maximum of 1000g for the sample weights. For counts of other species these are 10 times the weight for purity, subject to a maximum of 1000g.
Ag.
Technologies
(Seeds)
