Technical: Regulation of agricultural and horticultural seed.

 

Contact Details:
Division: The Official Seed Testing Station
Organisation: Department of Agriculture and Food
Address: Abbotstown Laboratory Complex, Snugborough Road, Dublin 15. .
Telephone: (01) 6072575.
E-mail: gary.duffy@daff.irlgov.ie.

Extract: Department of Agriculture and Food. (Text copied from DAF)

All the important agricultural and horticultural seeds are now subject to official certification and control requiring official testing for germination and purity.

This is the responsibility of the Official Seed Testing Station (O.S.T.S.) of the Department of Agriculture and Food.

Consequently the majority of tests are now carried out for official seed certification purposes while in the past they were mainly done for the seed merchants and farmers as an advisory service. This section outlines the range of tests available for the OSTS that may be relevant to you

Germination

The germination test determines the actual germination potential of normal seeds within a seed lot which can be used to compare the quality of different lots and also estimate the field planting value.

The accurate assessment of germination potential is carried out by competent seed analysts using specialised germinators and growth substrates. The aim is to determine the optimum germination capabilities of the seed under ideal conditions. The Station analysts are trained to recognise the major causes of poor seed germination, primarily abnormalities caused by disease or resulting from drying, mechanical, sprouting or dressing damage.

Germination tests take varying lengths of time to complete;
for example cereals take 12 to 14 days, while some grasses require 21 days and certain wildflower and tree species up to 6 weeks. 
The germinators used are designed so that the requisite amounts of heat, air, moisture and light specified by the ISTA Rules can be accurately controlled. If dormancy is involved the seed may be pre-chilled, pre-heated or treated with either giberellic acid or potassium nitrate before the actual germination test commences. The dormancy breaking treatment used depends on the species to be tested.

Analytical Purity

This determines the percentage weight of seeds in the sample under examination which is true to type and is genuine seed of the kind named. It does not confirm varietal purity, which can be only be obtained by growing the seed to maturity.

To determine purity the analyst examines the sample seed by seed, under magnification where necessary. All normal seeds of the desired species are segregated from the various impurities, and weighed to determine the percentage purity of the seed sample.

Impurities in a sample usually consist of

• Weed seeds
• Other crop seeds, 
• Inert matter, (e.g. broken grain, soil, scraps).

In the case of grasses, ‘seeds’ which are true to name but which contain no kernel (caryopsis), or contain only an undeveloped kernel, are regarded as inert matter and therefore classed as impurities. The components of the various impurities are identified in the final report produced by the Station. The significance of harmful impurities, such as noxious weeds, should not be overlooked.

Seed Weight

While information on the percentage germination is essential for good establishment of seeds, many growers also require information on the Thousand Seed Weight of the seed lot when planning seedling population.

The Thousand Seed Weight test based on ISTA Rules will be available, upon request, from January 2000.

Moisture Content

The official method for testing moisture content is by oven drying and temperatures and over periods of time specified according to the I.S.T.A. Rules. The moisture content is represented as a percentage of the sample weight.

The moisture content of seed can affect storage life and can also affect germination after chemical treatment.

Instantaneous moisture metres are generally accurate and are commonly used by seed merchants and growers. It is essential that they are checked regularly to ensure accuracy. The O.S.T.S. can, on request, conduct moisture tests on all kinds of seed. These results can be used to check the calibration of moisture metres.

Samples for moisture tests should be submitted in a strong plastic bag from which all the air has been removed and then tightly sealed.

Other Seed Testing Services

The O.S.T.S. also provides a range of tests in addition to the above, including tests on the seeds of grass and clover, peas and beans, linseed, vegetables, trees and wildflowers.

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