Dear Readers, I have been thinking about this for a long time now and finally I decided to write a few posts about seeds, one of the most important plant reproductive materials.
Why exatly about seeds…?
Well, because they are important 🙂
They play an anormous role in agri- and horticulture, they are the alfa and omega of many things we produce. (Let’s just think about easy things as corn and peas… big fuss about the seeds we plant in order to harvest even more seeds…)
And, additionally, they are getting to be a burning issue (not only) in Europe.
You can see, read and hear many news, articles, brochures, romours about the seed market, companies, stakeholders, limited choices, GM products, “old-fashioned” breeding, chemicals, legislation and so on… It is hard to decide what to think sometimes, so I decided to write a few posts about the seeds, maybe it will be easier to have a clear view of the situation with a more solid technical knowledge.
Firstly I would like to give a general overview of the seed quality and seed testing before placing the reproductive material to the market.
First about seed quality… It is a really important question, as selling and using high quality seeds which are properly tested is not only a technical requirement, but also regulated by the law. Just to write an example, the marketing of cereal seeds is regulated in this Directive in Europe at the time being. It clearly says, that cereal seed placed on the market must be certified and for this certification certain seed quality requirements must be met. (So roughly… We have the seed, we get it checked by a laboratory, we get the certification and then we can go to the market with it).
So “what do we want from our seeds?” asks the presentation of the International Seed Testing Association (ISTA). The answer it not too difficult: we want them to be healthy, powerful, uniform, clean and of course we want them to be of the right variety.
Obviously, in order to ensure these characteristics, laboratory tests are inevitable. (It is very difficult to say of a corn kernel how strong it will germinate only by staring at it…)
Let’s see in these Directives what requirements we should meet exatly when our product is vegetable or cereal seed for example…
The most important things are to check the variety, varietal purity, analytical purity (also containt of other species) and germination.
Variety is always an important question… Before planting/sowing we obviously choose a variety, which satisfies our needs… for example it has good environmental adaptability, it is tolerant to certain pests, it has a more marketable crop etc. So it is really important for us to know that from our seed the right plant grows… And of coure it is also really important to know that all of our seeds will be like that and not only few of them.
So during the tests the esablishment of the variety and the varietal purity check are crucial. Besides the conventional methods (germination, field test etc.) now we have modern laboratory methods, such as molecular marker and microstellite techniques.
Just to write a few examples for the requirements in the EU: in case of certified seed the verietal purity of the lot must be 99,7% in case of rice (1. generation) and 90% in case of hybrid common oat and wheat.
We also have to test our seed for analytical purity (a measure of gross contamination). So when we have the right amount of seed of the right variety we have to ensure also the freedom from other species or any other inert matter. The means used for the filtering of the contaminating material are lenses, microscopes, sieves and blowers. For instance the minimum required analytical purity is 97% in case of onions, 95% in case of lettuce, 90% in case of corn (EU).
The next step in checking the quality of the seed lot is the germination test. The defenition of this is the following:
“The purpose of laboratory testing of seed germination is to assess seed quality or viability and to predict performance of the seed and seedling in the field.”
On this above link you can also read about the procedures, methods, equipment etc. in detail…
If we take a look at the European Marketing Directives we can write a few examples… The minimum germination of pepper must be 65%, of tomato and spinach must be 75%, of certified rye must be 85%.
One more important thing before marketing is to be assured that our seeds are not genetically modified (And they do not contain any.) GMO content always must be labelled, and the variety must be authorised for cultivation (e.g. in Europe the only GM variety authoried for cultivation is the MON810 corn.)
If we passed all these steps, our seeds are most probably healthy, vigorous and pure. From this point we still have a few things to pay attention to (lot sizes, labelling, etc.), but we are on a very good way to place the little reproductive material on the market 🙂
Check out this video at the end, it is really informative and introduces the system of sampling and testing of different seeds in the USA very well… Enjoy and see you next time! Grasp & share the horticulture 😉